1983

BUILDING

TECHNOLOGY

PROJECT

SUMMARIES

U.S. Department of Commerce

National Bureau of Standards

Special Publication 44^-9

QC —

100

U57

1985

C. 2

1983

BUILDING

TECHNOLOGY

PROJECT

SUMMARIES

A/SS Special Publication 446-9

Editors

Noel Raufaste

Michael Olmert

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Gaithersburg, MD 20899

Issued June 1985

J'

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
National Bureau of Standards Special Publication 446-9

Natl. Bur. Stand. (U.S.), Spec. Publ. 446-9, 175 pages (June 1985)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1985
FOREWORD

The building research program of the National Bureau of Standards, the

Nation's central engineering measurements laboratory, is conducted by its

Center for Building Technology (CBT). CBT works cooperatively with other

organizations, private and public, to improve building practices. It conducts

laboratory, field, and analytical research. It develops technologies to predict, measure, and test the performance of building materials, components,

systems, and practices. This knowledge is required for responsible and costeffective decisions in the building process and cannot be obtained through

proprietary research and development. CBT provides technologies needed by the

building community to achieve the benefits of advanced computation and automation. CBT does not promulgate building standards or regulations, but its

technologies are widely used in the building industry and adopted by governmental and private organizations that have standards and codes responsibilities.

Construction is one of the Nation's largest industries. In 1984, new

construction put in place amounted to $310 billion, 8.4 percent of the Gross

National Product. Over two-thirds of the Nation's fixed reproducible wealth

is invested in constructed facilities that shelter and support most human

activities

CBT research provides knowledge for decisionmaking. This knowledge

includes characterization of the environments in which buildings must operate

(such as wind loadings), characterization and definition of the performance of

buildings, components, and systems (such as the mechanisms for heat loss through

a window or wall cladding element), and methods of testing for performance

iii
qualities that will apply equitably to a whole family of potentially competitive

proprietary materials and components.

The CBT staff of 160 includes 100 professionals, of whom 30 are registered

professional engineers and 50 hold doctorates. The principal disciplines are

structural, geotechnical, materials, electrical, and mechanical engineering,

physics, and chemistry.

Among the variety of special facilities and equipment at CBT are a largescale testing facility including a reaction buttress 45 feet high with a

latent force capacity of 1.2 million pounds in conjunction with the universal

testing machine of 12-mil lion-pound capacity is capable of testing structural

components 60 feet in height; a tri-directional structural testing facility

with its associated computer control data acquisition and processing equipment

capable of applying forces or displacements in three directions simultaneously

to full-scale structural components and systems; seven environmental chambers,

including a 30 x 40 x 50-ft chamber, for developing thermal performance modeling

techniques required for predicting human comfort and energy efficiency of

buildings; a guarded hot-plate that measures insulation performance of thicknesses up to 15 inches; a calibrated hot-box to provide precise measurements

of heat and moisture transfer in full-scale building wall and roof sections; a

five-story plumbing research laboratory with high-speed computer data acquisition

system to study the performance of water supply and drainage systems; reverberation and anechoic chambers, each 15,000 ft^, to define acoustical parameters

for building materials and methods to evaluate acoustical performance; daylighting laboratories; an illumination color laboratory capable of presenting eight

light sources independently; an outdoor solar-collector test-method development

area, including a passive solar test house and facilities for experimental

iv
solar heating and cooling systems; a network of outdoor material exposure

sites; materials reference laboratories include the Cement and Concrete Reference Laboratory sponsored by the American Society for Testing and Materials

and the AASHTO Materials Reference Laboratory sponsored by the American Association of State Highways and Transportation Officials; and a materials research

laboratory with a scanning electron microscope and other instruments for materials

characterization.

This report summarizes CBT's research for 1985, and is arranged according

to CBT's research programs. Each summary lists the project title, its activities,

point of contact in CBT, and sponsor. The reader is encouraged to review the

companion document, NBS Special Publication 457, Building Technology Publications ,

and its supplements. Final reports on the projects described here will be

listed in future issues of Building Technology Publications.

V

CONTENTS

Computer-Integrated Construction

Expert System for Durable Concrete 2

Expert System for Air-Infiltration Prediction

and Control in Buildings 3

Expert System for Selecting Concrete for Jet

Engine Test Facilities 4

Standards Interface for Computer-Aided Design 5

Construction Project Information Technologies 7 Building Data Protocols 9

Representation and Analysis of Construction Standards

and Specifications 10

CBT Information Management 12

Economic Methods for Building Standards 13

Structural Loads and Reliability

Dynamic Behavior of Three-Dimensional Steel Buildings 15

Analysis of General Combinations of Loads 16

Criteria for Structural Loads and Design 17

Dynamic Behavior of Compliant Offshore Structures 19

Punching Shear Study of Reinforced Shell 20

Mat Foundation for Offshore Gravity Structures

in Arctic Regions 21

Reliability of Wood Structures 22

Criteria for Design of Cladding Subjected to Wind Loads 23

Behavior of Glass Cladding Subjected to Wind Loads 24

Probabilistic Risk Assessments of Tornado Missle Damage 25

CBT Wind Tunnel 26

Structures/Mechanical Design Criteria for Low-Impact

Resistant Structures (LIRS) 27

Reliability-Based Design of Containments and Category I Structures 28

Structural Condition Assessment Standards 30

Pulse Echo for Flaw Detection in Concrete 31

NDT Methods for Concrete 32

Geotechnical Engineering

Standards for Foundations and Excavations 35

Soil Test Probe 36

Evaluation and Expansion of Liquefaction Data Base 37

vii
CONTENTS (Continued)

Earthquake Engineering

Inelastic Performance of Reinforced Concrete Columns 39

Inelastic Performance of Steel-Braced Frame Connections 40

Cyclic Strain Approach to Determining the Liquefaction

Potential of Level Sandy Sites 41

Cyclic Loading of Masonry Building Components 42

Seismic Safety in Construction 43

Technical Assessment of Earthquake Resistance 45

Thermal Analysis and Measurements

Evaluation of Thermal Anomalies 47

Heat Losses Through Thermal Bridges 48

Air Infiltration and Ventilation in Large Buildings 49

Thermal Modeling of Buildings 50

Evaluation of an Envelope Thermal Testing Unit 51

Measurement and Modeling of Fenestration Optics 52

Glazing Temperature Measurement 53

Thermal Performance of Fenestration Systems 54

Thermal Mass — Effect on Residential Cooling

and Heating Loads 56

Field Measurements of Wall Thermal Mass 58

Transient Heat Transfer Characteristics for Walls 59

Heat Transfer Coefficients for Insulated Walls 61

Experimental Heat Transfer Functions 62

Guarded Hot Plate Limit Assessment 63

Thermal Resistance Calibration Standard 65

Validation Guide for Energy Conservation Investment Program ... 66

Residential Interactive Testing Plan 67

Indoor Air-Pollution Concentration Model 68

Pressed Wood Model Evaluation 70

Specification for High-Technology Buildings 71

Underground Heat Distribution Systems 72

Acoustics

Building Acoustics Technology 75

Noise Isolation of Buildings Exposed to Aircraft Noise 77

Aircraft Noise Isolation: Residential Buildings 79

Lighting Research

Daylighting Studies 82

CEL-1 Lighting Program 83

Interaction — Lighting and HVAC Systems 84

Development of Illumination Model 85

Effect of Chromatic Adoption: Color Rendering and

Color Appearance 86

viii
CONTENTS (Continued)

Lighting Geometry and Contrast Measurement 88

Color Calibrator for FAA Weather Radar System 90

Safety Colors and Signs in Workplaces 91

Discriminability Features of Secure Documents 93

Design Criteria Impacts of Office Information Systems 94

Building Controls

Systems and Controls Laboratory 96

Electronic Bulletin Board 97

Energy Monitoring and Control System (EMCS) Algorithms 98

Controls Dynamic Modeling 99

Energy Analysis of Control Strategies 100

Non-Azeotropic Refrigerant Mixtures Research

Refrigerant Mixture Measurements in Two-Phase Flow 102

Performance of Non-Azeotropic Binary Refrigerants in

Residential Heat Pumps 104

Modeling the Performance of Non-Azeotropic Refrigerants

in Heat Pumps 105

Test Procedures for Energy Appliances

Furnace, Boiler, and Household Appliance Test Procedures . . . .107

Household Appliance Data Update 108

Water Heater Test Procedures 109

Solar Equipment

Control Strategies to Improve Solar Systems Performance Ill

Test Methods and Evaluation Procedures for Controllers

Used in Active Solar Systems 112

Second-Law Analysis of Solar Water Heating Systems 113

Thermal Performance of Passive Solar Aperatures and

Storage Components 114

Thermal Performance of Experimental Passive Solar Systems . . . .116

Experimental Passive Solar Systems 117

Radiative Heat-Transfer Modeling 118

Inorganic Compounds for Passive Solar Energy Storage —

Solid-state Dehydration 120

Inorganic Compounds for Passive Solar Energy Storage —

High Specific Heat Materials 121

Technical Problem Assessment 122

Technical Committee Assistance 123

Consulting and Advisory Services: Active Solar Heating

and Cooling 124

International Energy Agency Solar Program Support 125

ix
CONTENTS (Continued)

Plumbing Research

Hydraulic Load Limits in Drains 128

Load Modeling For Multistory Drainage Systems 129

Residence Times In Flow Separation - Water Mains 130

Quality of Building Materials

Application of Life-Test Analysis Concepts to Building

Materials 132

Environmental Degradation of Polymeric Cover Materials

for Solar Collectors 134

Dependence of Mechanical Properties on Mlcrostructural

Changes in Cover Plate Materials 135

Development of Tests for Predicting Adhesive-Bond

Durability 136

Nondestructive Early Detection of Corrosion and Delaminatlons

Under Protective Coatings Using the Thermal Wave Method . . . .138

Assessment of Nondestructive Evaluation Methods Applicable

to Construction 140

Organic Coatings 141

Improved Characterization of Coating System Performance 143

Coating Maintenance of Factory Coated Metal

Siding and Roofs 145

Degradation of Organic Protective Coatings 146

Revision of Tri-Service Coatings Manual 147

Tri-Servlces Technical and Scientific Support 148

AASHTO Materials Reference Laboratory 149

Performance of Roofing Systems

Probabilistic Study of Single-Ply Membranes 151

Performance Criteria For Bituminous Membrane Roofing 153

Quality Assurance of Roof Systems 154

Predicting the Performance and Service-Life of Concretes

Identifying the Degradation Mechanisms of Concrete 156

Measurement of the Strength of the Bond Between Old and

New Concrete 158

Performance Requirements, Tests, and Criteria for

Materials Used to Repair Portland Cement Concrete 160

Alkali-Silica Reaction in Concrete 162

Cement and Concrete Reference Laboratory (CCRL) 163

Cement Hydration Competence Project 164

X
COMPUTER-INTEGRATED

CONSTRUCTION
EXPERT SYSTEM FOR DURABLE CONCRETE

James R. Clifton

(301) 921-3458

Building Materials Division

Sponsor: National Bureau of Standards

Because of the potential importance of expert systems in selecting durable

building materials , knowledge of generic aspects of their development and use

is needed. Concrete was selected as the subject of a prototype expert system for

building materials selection for the following reasons. Concrete is the most

widely-used man-made construction material in the world. In the United States

alone over 700 million tons of concrete are placed each year. Although a

large knowledge base for selecting constituents for making durable concrete is

available, the knowledge is not easily available to all who need it. The

purpose of this project is to develop a prototype expert system that systematically provides recommendations in the selection of constituents for concrete

subjected to a broad range of service conditions.

In developing the expert system, the effects of the constituents of

concrete on its major deterioration processes will be identified. Deterioration processes which are being considered include freeze-thaw, sulfate attack,

corrosion of reinforcement, and expansive reactions between cement and aggregates. Then recommendations by experts on selecting constituents for concrete

subjected to such deterioration processes will be used as the basis for production

rules. This work will demonstrate the value of developing and using expert

systems, and provides an effective means for assessing durable concrete. The

expert system also will be useful to identify gaps in knowledge and guide

future research on concrete durability.

2
EXPERT SYSTEM FOR AIR-INFILTRATION PREDICTION AND CONTROL

IN BUILDINGS

Andrew Persily

(301) 921-2330

Building Physics Division

Sponsor: National Bureau of Standards

This research will couple expert system techniques with more

traditional computational techniques to develop an expert system capable of

predicting building air-infiltration rates and diagnosing potential air-leakage

problems. The knowledge base of the expert system will include existing

engineering knowledge concerning air infiltration as well as heuristic

knowledge based on field experience with air-leakage problems. CBT's Thermal

Analysis Research Program (TARP) will be used to predict air-infiltration

rates. CBT is developing a system to determine how a particular building

envelope and system design should be represented in TARP and to assign the

appropriate input parameters for a given building.

The resulting expert system is expected to predict infiltration rates

for a given building based on past field experience for the general building

design amended with as much case-specific information as is made available to

the expert system. The expert system will also predict air-flow rates between

rates between zones of a building, and may recommend supplemental ventilation

if the whole-building or local ventilation rates are anticipated to be excessively

low. Alternatives may be recommended for design details that are known to

lead to air-leakage problems.

3
EXPERT SYSTEM FOR SELECTING CONCRETE FOR JET ENGINE

TEST FACILITIES

James R. Clifton

(301) 921-3458

Building Materials Division

Sponsor: Naval Civil Engineering Laboratory (NCEL)

Port Hueneme, California

The Navy is planning the construction of numerous jet engine test facilities

in both the United States and foreign countries. These facilities will be

constructed largely from concrete. In the past, the concrete used in such test

facilities has frequently deteriorated prematurely. The necessary repairs have

been unanticipated and expensive. Many of the concrete failures have been

attributed to poor selection of the concrete mixture design, i.e., selection

of both the constituents of concrete and their relative proportions.

Expert systems are potentially very useful in making decisions on selection

of durable construction materials such as concrete. They can record in knowledge

bases the knowledge of experts on the durability of concrete. The knowledge

base can then be used to give recommendations at or near the level of human

experts, thus facilitating the selection process. The National Bureau of

Standards has been developing such an expert system, called DURCON, for selecting

the constituents of concrete and their proportions. DURCON can be further

developed and its knowledge base modified enabling it to give recommendations

on the selection of concrete for jet engine test facilities. The purpose of

the proposed project is to further develop and restructure DURCON so that it

specifically give recommendations on selecting durable concrete for jet engine

test facilities that may be exposed to different service conditions.

4
STANDARDS INTERFACE FOR COMPUTER-AIDED DESIGN

Kent A. Reed

(301) 921-3465

Building Equipment Division

Sponsor: National Bureau of Standards

Computer-aided design (CAD) is critical to the improvement of construction

productivity. Computers increasingly are used in producing engineering drawings

and related contract documents; however, more extensive use of computers is

being slowed by inefficient procedures for checking project-specific design

conditions against generic requirements couched within building codes, standards,

and project specifications. In particular, designers of commerically available

structural engineering software systems have "hard-coded" generic requirements

into their programs. As a result, multiple versions of the software systems

must be maintained with the codes and standards for different jurisdictions

built in. Periodically, these software systems are rendered obsolete as

standards-writing bodies alter their requirements. The need to maintain design

software current and also applicable across jurisdictional boundaries is critical.

With "hard-coded" standards data, this maintenance can be costly.

Current CBT research on the standards interface for CAD suggests that

this problem can be mitigated by physically separating generic standards data

from checking and other routines within CAD software systems. Previous work

at CBT has resulted in the initial elements of experimental standards interface

for CAD and a prototype system based on this concept is under development.

In FY84, the University of Illinois Department of Civil Engineering conducted

research under grant to define data-mapping techniques for linking generic

5
data described in standards with specific data contained in a design project

database. Completion of this research and demonstration of a functional

standards interface in a CAD environment is essential to the improvement of

productivity in building design.

Concepts developed here are expected to reduce significantly the time

required to produce more optimal building designs, to make CAD systems less

costly to develop and maintain, and to enable the comparative evaluation of

building designs under alternative versions of standards.

6
CONSTRUCTION PROJECT INFORMATION TECHNOLOGIES

Kent A. Reed

(301) 921-3465

Building Equipment Division

Sponsor: National Bureau of Standards

Building industry productivity may be enhanced significantly through

computer-integration of diverse design, construction, and operating procedures.

Impediments to such integration stem from inadequate project information models,

lack of formal interfaces between project participants, and lack of standard

protocols for representing and describing buildings in a computer-aided design

(CAD) environment.

The need for effective data exchange between different CAD systems first

was expressed in connection with the manufacture of components for aircraft

and other mechanical systems. To mitigate this problem, ANSI has incorporated

a version of the Initial Graphics Exchange Specification (IGES) into its standard

"Engineering Drawing and Related Documentation Practices — Digital Representation

for Communications of Product Definition Data" (Y14.26M).

In FY84, CBT convened a working group comprising CAD users, CAD vendors,

and researchers to explore the need for extensions to IGES for architecture,

engineering, and construction (AEC) applications. Based on the recommendations

of this working group, CBT coordinated the formation of the IGES/AEC subcommittee

responsible for recommending AEC graphic entities and monographic descriptive

attributes for IGES. Currently, CBT is the secretariat for this subcommittee.

The AEC subcommittee develops recommended practices for applying the current

IGES Standard to building problems, techniques and test cases for

7
measuring the performance of IGES translator software, and AEG application data

models for guiding the development of future versions of the IGES standard.

In the long term, the results of IGES/AEC and electronic building project

information management, in general, are expected to improve overall productivity

in building design and construction.

8
BUILDING DATA PROTOCOLS

Kent A. Reed

(301) 921-3465

Building Equipment Division

Sponsor: National Bureau of Standards

In the last two decades, the use of computers has penetrated every aspect

of the building process, including design, construction, and operation. Little

integration of these traditionally separate activities has occurred, however,

because there exist no effective standards for expressing and interchanging

information about buildings beyond the most basic elements. The many participants

in the building process continue to be plagued with the errors and inefficiencies

that occur because information is not available when needed, is incorrectly

transferred, and once transferred, is incorrectly interpreted. Rational

techniques for describing building practices and the elements of buildings and

their properties are needed to establish the technical bases for interface

standards that will support computer integration of the building process.

In this project, earlier work on developing common descriptions of buildings

and bulding elements will be reviewed, with particular attention given to the

activity of the Architecture, Engineering, and Construction Committee of the

Initial Graphics Exchange Specification Committee, and to the Computer Aided

Engineering and Architectural Design System under development by the U.S. Army

Corps of Engineers. Selected experts from universities and other laboratories

will participate in a workshop to define the scope and structure of future data

protocols. Preliminary protocols will be developed. A case study of the HVAC

equipment and loads in a small commercial building will be conducted to demonstrate

and test a portion of the preliminary protocols.

9
REPRESENTATION AND ANALYSIS OF CONSTRUCTION STANDARDS AND

SPECIFICATIONS

Kent A. Reed

(301) 921-3465

Building Equipment Division

Sponsor: National Bureau of Standards

CBT has sponsored with the Office of Product Standards Policy the

development of Standards Analysis, Synthesis and Expression Software (SASE).

SASE is built upon the work of CBT researchers and others, and is a systematic

method for the analysis of standards, codes, and specifications. SASE now

supports key standards analysis work in progress within CBT and is directly

associated with other CBT research on the standards interface for computeraided design, and on the development of expert systems for building design,

construction, and operation.

CBT researchers have proof-tested the SASE software in connection with

various application tasks, most notably an analysis of ACI 318-1977 (Chapter 4)

and a project sponsored by the Federal Trade Commission intended to develop a

common format for the model building codes. The proof-testing exercises

contributed substantially to an understanding of SASE's capabilities, and led

to the formulation of SASE modifications and enhancements.

Development of a portable SASE-sof tware system will be completed in FY85.

Known deficiencies in the computer program will be corrected. The code will be

brought into conformance with ANSI Fortran-77 specifications to ensure portability and reorganized for easy interfacing with external data-base management

systems. The SASE user's guide and associated tutorial materials will be

completed. Extension of SASE concepts into the areas of expert systems technology

10
and project criteria formulation will be explored cooperatively with researchers

at Carnegie-Mellon University.

The SASE technology will provide the building community with a rational

and systematic approach to achieving standards that are clear, complete, and

consistent. It will also provide a technical basis for CBT work on CAD standards

interface, project specifications and information systems, and expert systems.

11
CBT INFORMATION MANAGEMENT

Lawrence J. Kaetzel

(301) 921-2650

Center for Building Technology

Sponsor: National Bureau of Standards

Considerable work involving the centralization of data collection through

the use of multi-purpose mini- and micro-computing systems in the CBT Computing

Facility has been performed in recent years. Several major software systems

were developed to support the processing of management and scientific information

in an organized and efficient manner. However, the need to maintain and

enhance these systems continually arises due to the dynamically changing research

activities. It is essential that new information technologies be evaluated and

used to process CBT research data, technical publications, and fiscal information.

12
ECONOMIC METHODS FOR BUILDING STANDARDS

Harold E. Marshall

(301) 921-3701

Center for Applied Mathematics

Sponsor: National Bureau of Standards

The building community needs sophisticated, practical methods and guidelines for evaluating alternative building technologies in a consistent manner.

The need for standardized, improved methods and guidelines to help the building

community achieve affordable buildings that meet performance objectives stems

in large part from the rising costs of building materials, the high costs of

construction due to safety /environmental regulations, the alleged decline in

construction productivity, and the uncertain costs of energy.

Economic methods and supporting analyses will be specially developed for

application to building problems. A special publication on handling risk and

uncertainty in the economic evaluation of buildings will be produced for use by

ASTM in the development of a standard.

The building community will benefit from building economics methods

developed at NBS and adopted as recommended practices through the ASTM process

by achieving target levels of building performance with lower life-cycle

building costs.

13
STRUCTURAL LOADS

AND

RELIABILITY

14
DYNAMIC BEHAVIOR OF THREE-DIMENSIONAL STEEL BUILDINGS

John L. Gross

(301) 921-3146

Structures Division

Sponsor: National Bureau of Standards

The possible occurrence of a severe event such as strong earthquake

or wind must be considered when designing new buildings. Current design practice

in regions of high seismic risk focuses on the collapse of the structure as the

controlling limit state. Recent studies indicate that incremental collapse

must be considered in the design of steel structures located in high seismic

areas. The "P-delta effect" has been shown to lead to instability under working

loads as a result of severe ground motion. Accurate prediction of the inelastic

behavior of steel structures under cyclic loading depends on the realistic

modeling of strain-hardening effects. To complicate the situation, it has been

found that three-dimensional inelastic behavior must be considered to capture

the important effect of torsion.

Although nonlinear analysis techniques are generally available, they

have not found widespread acceptance in design practice largely due to their

complexity. Linear elastic analysis methods, which are widely used, often fail

to predict accurately the strength and deformation characteristics of complete

structures subjected to strong-motion earthquakes. Since such methods are both

simple to use and inexpensive, studies will be conducted to correlate computed

elastic response and realistic inelastic response of standard types of structures.

Guidelines can then be formulated for interpreting results of elastic analyses

to predict the strength and deformation characteristics of such structures.

15
ANALYSIS OF GENERAL COMBINATIONS OF LOADS

Bruce Ellingwood

(301) 921-3471

Structures Division

Sponsor: National Bureau of Standards

The prediction of extreme effects of structural loads has improved

significantly in recent years as a result of advances in probabilistic modeling

of load processes and in load combination analysis. Nevertheless, further

research is needed in this area because of the complexity and other limitations

of the methods available for load combination analysis. For example, these

methods become difficult to apply when three or more loads are acting

simultaneously, can treat only linear combinations of independent loads, with

a few exceptions, and are generally based on simplistic models developed to

capture only load extremes.

The research is conducted jointly by CBT and Cornell University. The

project continues efforts in the area of probabilistic analysis of structural

loads and is attempting to overcome some of the limitations of the current

methods for load combination analysis. A major objective of the project is

the development of simple and general approaches for approximating the largest

value distribution and other descriptors of individual load effects and their

combinations.

Eventually, the improved loading criteria would reduce building costs in

instances where current provisions are unnecessarily conservative, and would

lead to more uniform performance of buildings. Improved load requirements

would ensure safety, reduce maintenance, and increase occupant satisfaction.

16
CRITERIA FOR STRUCTURAL LOADS AND DESIGN

Bruce Ellingwood

(301) 921-3471

Structures Division

Sponsor: National Bureau of Standards

Current structural design standards rely on different approaches to

design, depending on the material or construction technology used. This tends

to complicate design when different technologies are employed in the same

structure. Differences in design philosophy (e.g., ultimate strength vs.

working-stress design) and a failure to consider uncertainties explicitly

cause a lack of consistency in the reliability and performance of different

buildings. Considerable effort has been devoted in the U.S., Canada, and

Europe to solving these problems using the unifying concepts of structural

reliability theory and probability-based limit states design. There is a need

to relate clearly new criteria to existing standards in the U.S. to gain their

professional acceptance. This research provides a basis for developing criteria

for the design of building structures that will ensure adequate reliability

against structural failure and unserviceability and would be appropriate for

all materials and construction technologies.

Under this project, engineering variables needed to describe serviceability

limit states are being identified from data in the literature and professional

experience. Structural load data are being analyzed using time series analysis

and other statistical analysis techniques to describe stochastically their

17
spatial and temporal variation. Full distribution and advanced first-order,

second-moment reliability analysis methods are being used to select appropriate

load combinations for serviceability checking. A comparative reliability

analysis of structural components and systems is envisioned to determine the

extent to which the reliability of individual components differs from the

reliability of structural systems considered as a whole. This project will

reduce building costs by simplifying the design process and stimulating market

competition between construction technologies. Improved serviceability

requirements will also result in less maintenance and increased occupant

satisfaction.

18
DYNAMIC BEHAVIOR OF COMPLIANT OFFSHORE STRUCTURES

Emil Slralu

(301) 921-3169

Structures Division

Sponsor: Minerals Management Service

This project will assess the potential of modern structural reliability

techniques to estimate nominal failure probabilities of such structures.

For selected types of compliant offshore structures, this project will provide

detailed mathematical models of loadings, responses, and limit states that may

occur as a result of their dynamic behavior under wind and wave action.

Researchers will review fundamentals, practical methodologies, and compute

programs pertaining to structural reliability, and will maintain close contact

with the American Bureau of Shipping, Det Norske Veritas, the Navy Department,

and other agencies with an interest in structural reliability of compliant

offshore structures under dynamic loads. This research will assist the Mineral

Management Service in ensuring acceptable risks to the public as far as the

safe operation of compliant offshore structures is concerned.

19
PUNCHING SHEAR STUDY OF REINFORCED SHELL

H.S. Lew

(301) 921-2647

Structures Division

Sponsor: Minerals Management Service, Dept. of Interior

Concrete offshore structures offer great potential for the safe and

economical development of mineral reserves in the Artie region. Such structures

may experience high concentrated loads from ice with intensities in the range

of 100 tons/sq ft. (lOMPa). Under such a high intensity load, the outer

shell, which serves as the ice wall, may experience punching shear failure.

Experience has shown that if designed in accordance with existing guidelines,

the exterior shells would become very thick so that it would not be possible

to tow the structures through relatively shallow waters. At the present time

there are no rational criteria available for the design of thick and heavily

reinforced concrete shells, particularly of lightweight concrete subjected to

high intensity concentrated loads.

The performance of concrete shell elements subjected to high local forces

will be studied. The behavior of shell and plate elements will be studied

using small scale physical models. Tests will be made on 1/6-scale and

1/3-scale models to study the size effects. The experimental program will be

supplemented with analytical studies to predict the expected performance of

the test specimens. The analytical models will simulate the multi-axil stress

states within thick members and will incorporate non-linear material behavior.

Full-scale tests will be conducted to verify the analytical model.

20
MAT FOUNDATION FOR OFFSHORE GRAVITY STRUCTURES IN

ARCTIC REGIONS

Felix Y. Yokel

(301) 921-2648

Structures Division

Sponsor: Mineral Management Service

Offshore gravity structures planned for the Beauford Sea must survive a

hostile environment. The structures will be built in moderate ocean depth

(60m range) and will rest on mat foundations. There is no past service record

for designing these structures. The structures will have to resist large dynamic

environmental loads including ice thrust and ice floe impact, waves, wind, and

earthquake. Difficult soil conditions will be encountered, including unstable

deposits which are frozen but close to the melting point and thus sensitive to

minor changes in thermal regime. Little is known about the problems associated

with these deposits, such as characteristics of permafrost in a saline environment

and possible effects of gas hydrates under melting conditions. Other problems

include bottom irregularities resulting from ice guaging and soil liquefaction

caused by wave action and other dynamic loads.

CBT will conduct a state-of-the-art study and a review of planned design

procedures. Gaps in knowledge and data base will be identified. Design limit

states will be identified and defined. An assessment will be made of

uncertainties with the determination of load and resistance parameters.

21
RELIABILITY OF WOOD STRUCTURES

Erik Hendrickson

(301) 921-2186

Structures Division

Sponsor: National Bureau of Standards

This project is aimed at developing practical resistance criteria for

limit states design of engineered wood structures, taking into account random

variations in strength and creep-rupture behavior. The research will focus

on developing probabilistic design criteria for glue-laminated and engineered

heavy-timber structural elements. This type of construction competes with,

and can be considered, in some cases, a viable alternative to reinforced

concrete and steel construction.

Statistical descriptions of the strength of wood will be based on existing

and newly acquired strength data obtained from the Forest Products Laboratory's

In-Grade Test Program. This response of structural wood elements to random

live, snow, wind, and dead load will be considered. Probability laws for the

extremes of these loads and their variation in time will be investigated for

potential use in reliability and cumulative damage analyses. The strength

analyses to determine the effect of loads must account for the creep-rupture

phenomena in wood. Various load duration models and damage accumulation theories

will be examined to discover which model may be best and to examine the effects

of using different models. The development of a probability-based limit-state

design for wood will help make wood design more compatible with other types of

construction and encourage its use as an engineered construction material.

22
CRITERIA FOR DESIGN OF CLADDING SUBJECTED TO WIND LOADS

Emil Siraiu

(301) 921-3169

Structures Division

Sponsor: National Bureau of Standards

Modern analytical and experimental tools from the fields of wind

engineering (aerodynamics of bluff bodies in turbulent boundary layer flows),

nonlinear mechanics of plates, structural reliability, and materials testing

will be used in this project with a view to developing rational criteria for

cladding design. Data from full-scale and wind-tunnel investigations of wind

loads on cladding will be reviewed and studies will be conducted to determine

the effect of pressure time history (including frequency content) on glasscladding load capacity. Results obtained at CBT concerning the feasibility of

inferring glass cladding load capacity from testing of small glass samples

will be used to demonstrate the practical applicability of this approach.

This research will be of use to the cladding industry and to codes and

standards organizations and Federal agencies charged with developing criteria

for reliability and serviceability of structures. It is anticipated that the

results will be presented to the glass industry with a view to securing its

involvement in CBT research. Consistent design procedures will reduce economic

losses and the number of accidents due to cladding damage in windstorms, and

will lead to improved economy by reducing overdesign in instances where current

provisions are unnecessarily conservative. This work also could lead to

revisions of ASTM Standard E330 dealing with standard test methods for exterior

glazing and curtain walls.

\

23
BEHAVIOR OF GLASS CLADDING SUBJECTED TO WIND LOADS

Emil Simiu

(301) 921-3169

Structures Division

Sponsor: National Science Foundation

This project will obtain data on the magnitude of the constants in the

relationship between rate of subcritical crack growth and stress intensity,

and on the probability distribution of initial glass strengths. A reliabilitybased format for designing glass cladding for wind loads will be developed

that accounts realistically for both load and strength variability.

Consistent design procedures will reduce economic losses and the number

of accidents due to cladding damage in windstorms, and will lead to improved

economy by reducing overdesign in instances where current provisions are

unnecessarily conservative. This work also could lead to revisions of ASTM

Standard E330 dealing with standard test methods for exterior glazing and

curtain walls.

24
PROBABILISTIC RISK ASSESSMENTS OF TORNADO MISSILE DAMAGE

Emil Simiu

(301) 921-3169

Structures Division

Sponsor: Nuclear Regulatory Commission

Among the possible causes of damage to nuclear power plants is the impact

of objects, usually referred to as missiles, that are propelled by tornado

winds. The Nuclear Regulatory Commission (NRC) requires that the probability

of tornado-borne missiles attaining critical speeds and hitting nuclear-power

plants should not exceed 10"^ in any one year. This project is concerned

with assessing reports submitted by utilities to NRC concerning the effect of

tornadoes on the safety of various components of nuclear power plants.

The assessments will be carried out using probabilistic, statistical, and

numerical simulation tools, as well as information concerning frequency of

occurrence and physical characteristics of tornadoes, and aerodynamic characteristics and potential number and location of objects susceptible of becoming

tornado-borne. This work will assist NRC in ensuring acceptably small risks

of accident in the operation of nuclear-power plants.

26
CBT WIND TUNNEL

Richard D. Marshall

(301) 921-2170

Structures Division

Sponsor: National Bureau of Standards

This project will support the aerodynamic and structural design of a

NBS/NSF regional boundary-layer wind tunnel and liaison with the NBS Plant

Division concerning space modification, coordination of equipment procurement,

and construction contracts. The effort also will consider mechanical engineering

applications for the completed facility. Facility design will be based in

part on test data obtained from previous studies carried out on 1/4-scale

components of the proposed tunnel, and on the recommendations of an NSF-supported

advisory committee. This new facility, based on performance criteria, will

enable CBT to address important problems in several areas of building technology.

In addition to providing new opportunities for competence development, it

will also enable CBT to more effectively respond to the research needs of

other Federal agencies.

26
STRUCTURES/MECHANICAL DESIGN CRITERIA FOR LOW-IMPACT

RESISTANT STRUCTURES (LIRS)

spencer Wu

(301) 921-2186

Structures Division

Sponsor: Federal Aviation Administration

The potential hazard of an aircraft colliding with approach lighting

structures during landing or take-off operations has led FAA to investigate the

possibility of developing a structural system with low impact resistance. The

goal of designing LIRS is to impart minimum damage to aircraft in the event of

an accidental collision. "Breakaway" mechanisms in structural systems have

been considered by FAA to meet this need. But to ensure the effectiveness of

such a system, the characteristics of the structural systems (including components

such as the electrical conductors) need to be investigated. Analytical models

for the numerical simulation of LIRS subjected to aircraft impact are also needed.

This research program will consist of three separate activities.

Activity I is to investigate the behavior of electrical conductors by performing

static and dynamic pull tests of these conductors used for approach lighting

LIRS. Activity II involves the analysis, erection, and testing of an antenna

support structure. Activity III will be devoted in the development of analytical

models for the prediction of response of LIRS subjected to aircraft impact.

This research will improve the understanding of the impact phenomenon and

support the development of design criteria for LIRS.

27
RELIABILITY-BASED DESIGN OF CONTAINMENTS AND CATEGORY I STRUCTURES

Bruce Ellingwood

(301) 921-3471

Structures Division

Sponsor: Brookhaven National Laboratory (BNL)

The unpredictable nature of the possible loads on nuclear power

structures and uncertainties in structural properties and behavior mandates a

probabilistic approach to an assessment of structural safety and performance.

Structural reliability theory has been applied to earthquake engineering, wind

engineering, ocean engineering, aerospace structures, and to the development

of load factors, load combinations, and resistance factors for ordinary building

construction.

In the nuclear industry, there also has been a trend toward the use of

statistical analysis and probability theory for safety evaluations. Rational

methods for reliability evaluation of strength and loads are urgently needed.

Structural designers and regulatory authorities will take advantage of these

methods if they do not lead to significant additional complexities at the

design level.

Under this joint project with Brookhaven National Laboratory (BNL), CBT

has responsibility for the analysis of service and extreme environmental loads

and for developing the basic design load-combination methodology. BNL has

responsibility for analyzing accidental loads, postulating accident scenarios,

dynamic structural analysis of the nuclear structures, and testing the design

procedure. Probability-based load and resistance criteria are being developed

for concrete contaminants and shear wall structures. These new probability28

I'
based procedures should enable designs to be obtained in which the associated

risk of unsatisfactory performance is realistic and consistent with the objectives

of the regulatory authority.

29
STRUCTURAL CONDITION ASSESSMENT STANDARDS

James H. Pielert

(301) 921-3481

Building Materials Division

Sponsor: National Bureau of Standards

Throughout the U.S., there is increasing concern about the need to

more fully use the existing building stock. The commercial and residential

renovation and rehabilitation markets are each currently in the $50 billion

per year category. The building rehabilitation process requires many technical

decisions by designers, builders, and building officials relative to the condition of existing buildings. But the data needed to make these conditionassessment decisions are broadly dispersed and not readily accessible. It is

necessary to subject such information to a consensus review and provide the

design community with resource standards on building condition assessment for

selected materials (concrete, metals, masonry, wood, etc.).

Technical support to the ASCE Standards Committee on Structural Condition

Assessment will include preparation of standards outlines and draft information

based on CBT and other relevant research, providing CBT staff support to technical issues as appropriate including review of draft standards, and coordination with other related standards activities (ASTM, ACI , etc.). Administrative

support will include providing a chairman to the committee, organization of

committee membership, holding two meetings of the full committee, apd ensuring

that ASCE standards process be followed. This project will result in a more

uniform approach to building rehabilitation and more efficient use of the

existing building stock.

30
PULSE ECHO FOR FLAW DETECTION IN CONCRETE

Nicholas J. Carino

(301) 921-3146

Structures Division

Sponsor: Office of Nondestructive Evaluation

Presently there is no satisfactory method to locate internal defects

in concrete structures. The pulse-echo method, which is based on the

interaction of stress waves with internal discontinuities, has the

potential to fill this need. However, before this method can be implemented,

a fundamental understanding is required of how stress waves propagate

through and interact with flaws in a heterogenous material as concrete.

The objective of this research is to gain a fundamental understanding

of the interaction of stress waves with internal discontinuities in

concrete structures. Such knowledge is required to develop test methods

and proposed standards for using the pulse-echo technique for nondestructive

evaluation of the internal condition of existing concrete structures.

A research program was initiated in FY 1983 to develop the needed

knowledge to implement the pulse-echo technique. In FY 1984, experiments

demonstrated the feasibility of using a pulse technique based on a pointsource and a point receiver to locate planar defects in concrete. In

FY 1985, the research will investigate the feasibility of the pulse

technique to locate realistic defects in concrete specimens.

31
NDT METHODS FOR CONCRETE

Nicholas J. Carlno

(301) 921-3146

Structures Division

Sponsor: National Bureau of Standards

Despite advances in concrete technology, there is no satisfactory method

for locating internal defects in hardened concrete structures. The need for

this capability is increasing with the current national emphasis on rehabilitation of existing structures and on quality-acceptance systems. The pulse-echo

method has the potential to fill this need if a fundamental understanding of

wave propagation in concrete can be achieved, and if standards are developed

for using the technique.

In pulse-echo testing the most common techniques for introducing the stress

pulse are with an electrical transducer or by mechanical impact. A transducer

produces essentially plane waves that propagate through the material and are

reflected by interfaces. However, a satisfactory transducer for sending pulses

into concrete does not exist. The impact technique that produces spherical

waves is attractive because of its simplicity, but signal interpretation is

more difficult than with the transducer source.

In FY84, the main objectives of this work were to investigate the feasibility

and reliability of the impact technique and to develop an appropriate transducer

source. From tests on a large concrete slab containing known defects, it was

shown that under the correct conditions the impact technique was capable of

locating the defects. It was found that the two essential items are a highfidelity receiving transducer and impact with a short contact time. Numerical

32
solutions for an infinite plate were carried out and the results aided in

interpreting the experimental signal traces.

Based on the encouraging results obtained with the point-source-point

receiver impact method, one of the objectives of the FY85 effort will be to

develop a source and receiver that can be used under realistic field conditions.

In addition, signal-processing techniques will be investigated to enable easier

interpretation of the signal records. A new concrete specimen containing

realistic concrete defects, such as cracking, honeycombing, and reinforcing

steel, will be fabricated for evaluating the test method. Work on this project

will be a cooperative effort involving CBT and the Korean Standards Research

Institute.

33
GEOTECHNICAL

ENGINEERING

34
STANDARDS FOR FOUNDATIONS AND EXCAVATIONS

Felix Y. Yokel

(301) 921-2648

Structures Division

Sponsor: National Bureau of Standards

Even though most structural failures and distress are associated with

inadequate foundations and very large sums of money are invested in excavation

work, there is currently no national standard for foundations and excavations

in the U.S. As a consequence, effective code regulations are either absent or

differ from location to location, causing difficulties and confusion in the

introduction of new technologies and in the application of standards systems.

CBT assists the American Society of Civil Engineers in the development of

standards for foundations and excavations by serving as a secretariat for the

Committee on Foundation and Excavation Standards and supporting the activities

of the working committees by providing leadership and technical input. Pending

availability of adequate financial resources, CBT will also take the initial

steps in the development of a probabilistic code format for foundation and

excavations. Additionally, CBT provides the technical basis for standards

developed by other agencies outside the ASCE, At the present time these

include: Mobile Home Foundations (ANSI A225) and Excavation Safety (OSHA, an

eventually ANSI A10.12), and will probably extend into areas of geotechnical

in-situ measurements and laboratory testing.

35
SOIL TEST PROBE

Felix Y. Yokel

(301) 921-2648

Structures Division

Sponsor: Tri-Services Conunittee

The problem of soil exploration at shallow depths (less than 3m) has been

generally neglected by the geotechnical profession. Existing methods for use

at these depths are either inaccurate or too expensive. Since most residential

structure foundations and utility lines are located at shallow depths, there is

a need for an accurate, practical, and inexpensive method of exploring and

classifying soils at shallow depths.

During a study of soil anchors, CBT Identified an ideal tool for this

purpose consisting of a small diameter helical screw that can be Inserted by

one man. The torque necessary to turn the screw can be correlated with the

shear strength of the soil. In the first stage of the project, three sizes of

test probes for different soil strengths will be built, and test probe readings

will be correlated with cone penetrometer, plate loading, and laboratory tests.

This will enable CBT to model and calibrate the device. In the second stage,

operational prototypes will be built and design charts for practical applications will be prepared. Use of the soil test probe will substantially reduce

the cost and improve the quality of site exploration and foundation design.

For inaccessible sites, it also will result in improved reliability, of

foundation performance, since other exploration methods may not be feasible.

36
EVALUATION AND EXPANSION OF LIQUEFACTION DATA BASE

Riley M. Chung

(301) 921-2648

Structures Division

Sponsor: National Science Foundation

The purpose of this research is to better define and expand the data base

linking Insitu measurements by the Standard Penetration Test (SPT) and the

Cone Penetration Test (CPT) with the determination of the liquefaction potential

or cyclic mobility of sites with saturated granular soils.

The project was coordinated to coincide with the exploration of Japanese

sites where liquefaction occurred on May 26, 1983. Results of the study enabled

CBT to compare U.S. and Japanese SPT liquefaction data base. It will enable CBT

to establish energy ratio that can be used to normalize all the liquefaction SPT

data throughout the world. These data bases can then be applied to re-assess

and, if necessary, revise the existing liquefaction resistance design curves.

37
EARTHQUAKE

ENGINEERING

38
INELASTIC PERFORMANCE OF REINFORCED CONCRETE COLUMNS

William Stone

(301) 921-2198

Structures Division

Sponsor: California Department of Transportation

National Science Foundation

National Bureau of Standards

Federal Highway Administration

A national workshop on Earthquake Resistance of Highway Bridges held in

January 1979 identified research needs and established priorities in the area of

seismic aspects of highway bridge design. One of the highest priority research

needs identified was to determine the effects of scale factor on bridge column

design to determine whether the behavior of small sections can be extrapolated to

large cross sections and to examine the performance of selected full-scale details

This project will determine the influence of size (scale factor) on the

seismic performance of columns. Experimental programs on large-scale specimens

are expensive and difficult to conduct; hence, the limited availability of data

in the literature. Careful planning of a test program will produce much needed

full-scale performance data over a range of axial loads and column designs.

Such a range is necessary to examine the effect of scale factor since such an

effect will likely be dependent on the column mode of failure. CBT will examine

the behavior of approximately 1/6 scale test specimens. The scale tests are

expected to identify problems of scale effect. If necessary, a complete

examination of scale effects will be possible in the future using the data

obtained in this research.

The research will provide a technical base that is currently unavailable to

determine if there is scale effect for very large cross section columns.

39
INELASTIC PERFORMANCE OF STEEL-BRACED FRAME CONNECTIONS

John Gross

(301) 921-3146

Structures Division

Sponsor: National Bureau of Standards

This project will study the gusset plate behavior and the connection of

braced elements with columns and beams in steel frames. The investigation

will involve experimental testing of planar-braced steel frames. The selection

of specific variable and specimen design will be coordinated with analytical

studies in progress at the University of Arizona. The experimental tests will

provide vitally needed information that is not presently available and will

serve as the basis for validation of mathematical models being developed.

40
CYCLIC STRAIN APPROACH TO DETERMINING THE LIQUEFACTION POTENTIAL

OF LEVEL SANDY SITES

Riley M. Chung

(301) 921-2648

Structures Division

Sponsor: National Bureau of Standards

The object of this study is to determine the correlation between cyclic

strain, excess pore-water pressure buildup, degradation of shear modulus,

increase of damping ratio, and associated volume change for silt and silty sandy

soils, and to develop a new design approach (or modify present design methods)

based on these correlations. Current laboratory work on silty soils will be

expanded to include variables such as confining pressure, density, overconsolidation ratio, and number of strain cycles to: (a) determine the threshold strain

value, and (b) develop proper material models for the silty soils required for

seismic response analysis. The work should also include a thorough literature

review of the seismic analysis methods to pave the way for the planned analytical

work in FY86 and beyond.

Results of this research will be passed on through design provisions and

standards, publication in technical journals, presentation at technical meetings,

and by adoption of new methods of engineering analysis by agencies such as the

Nuclear Regulatory Commission, the Bureau of Reclamation, and the Federal

Highway Administration. It will also serve as the basis for further research

in geotechnical earthquake engineering. This research will also lead to a

new, more reliable method of determining liquefaction potential, cyclic mobility,

and seismically induced settlements of level sandy and silty sites.

41
CYCLIC LOADING OF MASONRY BUILDING COMPONENTS

Kyle Woodward

(301) 921-2160

Structures Division

Sponsor: National Bureau of Standards

The process of developing tentative seismic design provisions for both

unreinforced and reinforced masonry building components reveals a scarcity of

information on ultimate strength characteristics. Since seismic resistance is

now based primarily on ultimate strength considerations, the lack of such

information for masonry is detrimental to rational design of buildings subjected

to seismic loadings. Here, experimental tests will provide vitally needed

information not now available that will serve as the basis for development of

mathematical models. The characteristics of a number of failure modes will be

examined to identify the significant parameters affecting each.

Analytical expressions for predicting failure as a function of key parameters

will be developed. Later experimental testing will determine the generality of

the proposed analytical expressions. This research will provide engineers

with a sound base not currently available by presenting experimentally verified

rational approaches for ultimate strength design.

42
SEISMIC SAFETY IN CONSTRUCTION

E.V. Leyendecker

(301) 921-3471

Structures Division

Sponsor: Federal Emergency Management Agency

The Federal Government must set an example for others to emulate by its own

actions, including the institution of more effective hazards mitigation measures

in its own facilities. In recognition of these needs, the Congress passed the

Earthquake Hazards Reduction Act of 1977 (P.L. 95-124), and the President

established the National Earthquake Hazards Reduction Program (NEHRP) the

following year. The NEHRP established the Interagency Committee on Seismic

Safety in Construction.

The purpose of the Interagency Committee on Seismic Safety in Construction

(ICSSC) is to assist the Federal departments and agencies involved in construction

to develop and incorporate earthquake hazards reduction measures in their ongoing

programs. These will be based on existing standards when feasible and will be

consistent with 0MB guidelines.

NBS will provide technical and administrative support to the activities of

the ICSSC that are aimed at meeting the Committee's specific objectives. Specific

objectives cited in the NEHRP include:

• develop seismic design and construction standards for

Federal projects

• develop guidelines to ensure serviceability, following an earthquake, of vital facilities constructed or financed by

the Federal Government,

• develop guidelines that provide for independent State and

local review of seismic considerations in the construction

of critical facilities constructed and financed by the

Federal Government where appropriate.

43
• develop guidelines for including earthquake hazards

reduction activities in ongoing Federal programs,

• develop a strategy to identify existing Federal buildings and

other structures that pose unacceptable earthquake-related

risks,

• coordinate the development of guidelines for the consideration

of seismic risk in the development of Federal lands.

ICSSC will cooperate with State and local government and private

organizations in developing nationally applicable earthquake hazard

reduction measures. Using consensus procedures, the ICSSC will recommend earthquake hazard reduction practices suitable for use by Federal agencies. ICSSC

recommended practices will not be mandated for use by Federal agencies except by

Executive Order, but they may be adopted as required practices by the various

Federal agencies following their established practices for implementing

regulations

.

44
TECHNICAL ASSESSMENT OF EARTHQUAKE-RESISTANT DESIGN PROVISIONS

E.V. Leyendecker

(301) 921-3471

Structures Division

Sponsor: Federal Emergency Management Agency

This project is a continuation of work with the Building Seismic Safety

Council (BSSC) in its effort to support Improved seismic design criteria. CBT

will provide support as the technical secretariat of the BSSC Trial Design Overview

Committee which is working on resolution of technical issues resulting from the

BSSC ballot on the Tentative Seismic Design Provisions. These tentative seismic

design provisions prepared by the Applied Technology Council, a group affiliated

with the Structural Engineers Association of California, were published in 1978.

The work was based substantially on CBT's effort. In 1980 and 1981 CBT developed

and headed a project to review and refine these provisions. The results of this

review and proposed revisions were presented to the Building Seismic Safety

Council, a national body whose goal is to improve the public safety through

improved seismic design, for their consideration and subsequent use in conducting

trial designs for evaluation purposes. The amended design provisions have been

evaluated through a national trial design program and submitted to BSSC

membership for approval.

CBT will work with a panel of experts to identify new research and practical

experiences ready for incorporation into revised design provisions. High priority

technical areas (one or more) will be selected and remaining technical problems

resolved.

Results of this effort will include preparation of possible "code" provisions

for seismic design. These will be available for consideration by BSSC and others.

46
THERMAL ANALYSIS

AND

MEASUREMENTS

46
EVALUATION OF THERMAL ANOMALIES

Richard A. Grot

(301) 921-3501

Building Physics Division

Sponsor: Department of Energy

Thermographic inspection of insulated buildings often shows that there

are thermal anomalies in the insulation system from improperly installed

insulation, convective air movement in the insulation, and moisture damage to

the insulation. At present there is no method for quantifying the heat loss

due to these anomalies so that the impact of correcting the anomalies can be

judged.

This project will investigate the adequacy of several in-situ methods for

quantifying the heat losses due to thermal anomalies. The use of thermography

will be assessed for quantifying temperature and heat flux. Laboratory tests

will be performed on representative thermographic systems to determine their

characteristics for making quantitative measurements. The in-situ use of heat

flow meters and calorimeter boxes for measuring the heat losses due to thermal

anomalies will be investigated. Guidelines will be established for each of

these methods and an assessment of their accuracy will be made. This project

will enable building researchers and diagnosticians to determine the severity

of heat loss due to thermal anomalies in the building envelope and thus give a

sound basis to recommend remedies.

47
HEAT LOSSES THROUGH THERMAL BRIDGES

Richard A. Grot

(301) 921-3501

Building Physics Division

Sponsor: Department of Energy

As buildings become more insulated, the heat loss due to structural

members becomes significant and can degrade the performance of the insulation

system by about 10 to 20 percent. These parts of the structure may also

experience condensation and thus become potential sources of building

deterioration. Current analyses and models of the building envelope ignore

the presence of thermal bridges.

Methods for detecting the presence of thermal bridges will be developed.

Generic types of thermal bridges will be analyzed using the Oak Ridge National

Laboratory "Heating 6" finite difference heat transfer program. In-situ

measurement methods for quantifying the heat loss from thermal bridges will be

developed. This method will include the use of heat flow meters and calorimeter

boxes for measuring the heat loss due to the thermal bridge and the heat loss

of the insulated wall section. The data will be analyzed to determine the

degradation in performance of the insulation system due to thermal bridging.

The results will be compared with the theoretical predictions of "Heating 6."

48
AIR INFILTRATION AND VENTILATION IN LARGE BUILDINGS

Richard A. Grot

(301) 921-3501

Building Physics Division

Sponsor: Department of Energy

Availability of a consensus measurement method for evaluating ventilation

efficiency will give building designers, owners, and users a tool for measuring

the energy efficiency with which ventilation systems achieve an effective level

of contaminant removal. A useful relationship between pressurization and

infiltration in commercial buldings will enable the use of pressurization

testing to evaluate different building designs and the effectiveness of shelltightening retrofits.

In this project, test methods already developed for measuring the efficiency

of veiitilation will be applied to modern commercial buildings. These methods

will determine the amount of air exchange that is effective in removing

contaminants from the work space. The methods are based on the injection of

tracer gas into various zones of the building and determination of the buildup

and decay of the tracer gas in the work space and in the exhaust air. Initially

the CBT automatic air infiltration system developed for application to large

buildings will be used. The procedure will be evaluated by testing at least

three different commercial buldings and using the results to determine the

effectiveness of the ventilation systems. In addition, CBT will continue the

collection of air infiltration and ventilation data in three large commercial

buildings that have passive solar design features and large atria. Fan

pressurization tests will also be conducted on these buldings to study the

relationship between air tightness measurements using fan pressurization and

infiltration measurement using tracer gas.

49
THERMAL MODELING OF BUILDINGS

George Walton

(301) 921-3633

Building Physics Division

Sponsor: National Bureau of Standards

CBT has developed the Thermal Analysis Research Program (TARP) , which can

predict the interzone heat transfer and interzone movement of air, moisture,

and contaminants. Under this project, the accuracy of this model for predicting

air infiltration and interzone air movement in large buildings will be investigated

using data collected by CBT's automated air infiltration system. Development

of a multi-tracer interzone air infiltration system will be completed and used

to collect interzone air movement data in two large buildings. A simple model

will be developed for the inclusion of thermal bridges into the computer model.

50
EVALUATION OF AN ENVELOPE THERMAL TESTING UNIT

Richard A. Grot

(301) 921-3501

Building Physics Division

Sponsor: Oak Ridge National Laboratory

Presently there are no rigorous assessments of in-situ measurement methods

for determining thermal resistance. The Department of Energy has designed and

fabricated a prototype thermal envelope testing unit which in principle is capable

of measuring the dynamic response of walls.

CBT will determine the usefulness and accuracy of the envelope thermal

testing unit (ETTU) developed by the Lawrence Berkeley Laboratory for the Department of Energy. The device will be used on CBT field projects to determine the

practical problems and field sources of errors resulting in its use. Guidelines

will be developed for using the ETTU. Measurements will be made in the six CBT

thermal mass buildings and the results compared with the known thermal resistance

of these walls. A series of test walls of typical construction will be built

and installed in a small test cell in the environmental chamber. Measurements

will be made on these walls under various simulated thermal conditions. These

walls can be later tested in the CBT guarded hot box. From these tests the

accuracy of ETTU will be determined under various environmental conditions. The

sources of error will be determined and the results compared with those of other

test methods.

The data and guidelines resulting from this project will be offered to

ASTM and ASHRAE as a basis for possible development of a standard test method or

for the inclusion in the ASHRAE Handbook series.

51
MEASUREMENT AND MODELING OF FENESTRATION OPTICS

George Walton

(301) 921-3633

Building Physics Division

Sponsor: Department of Energy

This research will develop a general procedure for modeling the optical

performance of windows in building energy and day lighting analysis programs.

It also will propose and demonstrate a test procedure which would determine

the coefficients used by the window optical model.

Windows have a major impact on the energy requirements of most buildings.

Solar gains may greatly decrease heating loads or increase cooling loads and

daylight can be used to decrease lighting and cooling loads. Solar gain and

daylight calculations should be closely related since they deal with different

wavelength distributions of the same solar spectrum, but there is no unified

approach to the modeling of windows.

The research will begin with a thorough review of theoretical optics for

detailed fenestration calculations, simplified analysis procedures, and test

methods. Theoretical models of several window systems will be developed

using detailed optics. These will be compared to the existing simplified

algorithms in terms of the impact on predicted building energy requirements.

In ensuing years, additional simplified algorithms will be developed for

innovative window systems. The accuracy of a method for simulating a complex

multilayered window based on the properties of the individual layers will be

tested.

This research will produce algorithms for modeling the optical performance

of windows, a general optical model of windows, a test procedure for determining

coefficients for the model, and the demonstration and validation of the test

procedure.

52
GLAZING TEMPERATURE MEASUREMENT

Stanley Liu

(301) 921-2607

Building Physics Division

Sponsor: National Bureau of Standards

This project will assess the accuracy of thermal-contact thermometry and

radiation pyrometry to measure glazing temperature under irradiated conditions

and evaluate unique temperature measurement techniques for glazing materials.

A literature search on recent temperature measurement techniques for solid

transparent bodies will be conducted. The accuracy of thermal contact thermometry

and radiation pyrometry to measure glazing temperature wil be determined.

Unconventional techniques to measure glazing temperature will be evaluated.

Among these are multiple sensors of various sizes, the use of strain gages,

the use of changes in properties of a single glazing as a function of temperature,

and the use of thermocouple shields.

The results will give solar equipment designers an accurate test methodology

for solar collectors and passive solar glazing components and systems. The

method will also aid in the measurement of glazing surface temperatures for use

in convective heat-transfer coefficients in building-energy calculations.

53
THERMAL PERFORMANCE OF FENESTRATION SYSTEMS

Michael E. McCabe

(301) 921-2308

Building Equipment Division

Sponsors: DoE Building Systems Division

DoE Passive Solar Division

This project will identify and quantify the surface heat transfer

mechanisms which occur in building fenestration systems under laboratory and

field conditions. Also, this research will develop a technical basis for a

standard laboratory test method for measuring heat transfer rate data for use

in calculating building energy requirements.

This research involves two phases. In Phase 1, research is aimed at

developing a proposed technique to measure surface heat transfer coefficients

and experimentally measure the variation in U-value with wind speed and

ambient temperature. This will be undertaken in a cooperative effort with

the University of Massachusetts at Amherst. The results of this project will

be submitted to a joint task group within ASTM to draft a standard test method

describing the specific equipment and measurements to be taken for determining

the U-value (overall transmittance) and C-value (surface conductance) of

various types of building assemblies, including fenestration systems and to

draft a standard practice that describes the specific test conditions, mounting

provisions, preconditioning requirements, and calculation procedures for

analyzing fenestration system test data obtained using the Standard Test Method.

In Phase 2, activities will focus on assessing the need for measurements

on fenestration of representative geometries, reveals, etc. Field testing

will be performed of the HFM/SGU test articles using the Lawrence Berkeley

54
Laboratory facility at selected field sites suitable for both wintertime and

summertime climatic conditions and the passive solar calorimeter. Field

test results will be compared with laboratory test results to determine the

laboratory testing procedure that best correlates with the field test results.

55
THERMAL MASS - EFFECT ON RESIDENTIAL COOLING AND

HEATING LOADS

Douglas M. Burch

(301) 921-3754

Building Physics Division

Sponsor: Electric Power Research Institute

The objectives of this project are three: (1) to analyze previously

measured test results of the NBS thermal mass test buildings to investigate

the effect of building envelope and building operation parameters on reducing

and delaying peak space heating/cooling loads; (2) to investigate the effect of

the thermal mass of the interior partition walls and interior furnishings on

reducing and delaying peak summer cooling loads; and (3) to compare space

heating/cooling loads predicted with two computer programs called EMPS and TARP

to corresponding measured heating/cooling loads.

High peak electrical utility loads make it necessary for the public

utility companies to install larger and more expensive electrical generating

equipment in power plants. In addition, high peak loads often cause more

expensive fuels to be consumed during peak load periods. Public utilities

are interested in investigating innovative ways to construct and operate

buildings to reduce the peak electrical load on the utility.

Using previously measured test results from CBT's six, one room thermal

mass test buildings, the effect of wall mass, wall insulation, thermostat set

temperature, and special operation modes (including night ventilation cooling

and winter night termperature setback on reducing and delaying peak space

heating/cooling loads will be analyzed.

A conventional wood-frame partition wall will be installed in an uninsulated

wood-frame building and an uninsulated masonry building. The partition walls

will divide the interior spaces of these buildings into equal size rooms of

66
equivalent floor space connected by a door. These two buildings will

subsequently be exposed to an 8-week summer cooling season. Interior

furnishings consisting of office furniture will be installed in the woodframe building during a 3-week period of the summer cooling season. The

effect of partition walls and interior furnishings will be assessed by

comparing these peak cooling load correlations to corresponding correlations

without interior mass features present.

Fourteen-day data files containing measured outdoor weather parameters

will be created for the previously measured winter heating season, intermediate

heating season, and summer cooling season. The last three days of these

files will contain measured heating/cooling loads and indoor temperatures for

the six test buildings. During these measurements, the buildings did not

contain partition walls and interior furnishings. For each of these 14-day

data files, heating/cooling loads will be predicted using TARP and EMPS

computer programs and will be compared to corresponding measured heating/cooling

loads. Similar comparisons will be carried out using the summer partition

wall and interior furnishing test results. After EMPS is validated it will

be used to investigate the effect of wall mass and interior mass features on

the peak heating/cooling loads and annual heating/cooling energy consumption

for a typical residence.

67
FIELD MEASUREMENTS OF WALL THERMAL MASS

Douglas Burch

(301) 921-3754

Building Physics Division

Sponsor: Department of Energy

There is a real need to measure and experimentally evaluate the energy

savings attributable to thermal mass in buildings, so that present energy

conservation standards can be modified where appropriate to reflect benefits

realized from thermal mass. The FY84 report on partition wall tests was

deferred into FY85. This was necessary because the field partition wall

measurements using the test cells were unrepresentative of the thermal performance of typical residential buildings because the solar gains for the test

cells were very small. To extend the field measurements into typical house

situations, CBT's computer model TARP will be used to analyze partition wall

effects in a well insulated residential prototype and a poorly insulated

residential prototype. The validation of TARP will compare measured space

heating/cooling loads for the test cells with corresponding predicted loads

using the TARP program.

The experimental field data reported will provide a preliminary validation

of calculation procedures for predicting the impact of wall thermal mass on

residential residences in selected climates. The results will enable HUD, DoD,

FmHA, ASHRAE, building designers, and materials trade associations to perform

credible evaluations of the cost-effectiveness of various design and material

strategies. Recommended delta-R values will provide guidelines in the interim.

58
TRANSIENT HEAT TRANSFER CHARACTERISTICS FOR WALLS

Douglas M. Burch

(301) 921-3754

Building Physics Division

Sponsor: Department of Energy/Oak Ridge National Laboratory

Calibrated hot boxes have previously shown poor agreement between

measured specimen heat transfer and corresponding predicted values using

dynamic heat transfer models when the wall specimen is subjected to time-varying

boundary conditions. The lack of agreement is largely due to measurement errors

in the specimen heat transfer caused by failure to account for time-varying

flanking heat transfer through the frame around the wall specimen. Another

problem is each laboratory uses a different time-varying outdoor boundary

condition and reports the heat-flow response at the inside specimen surface. As

a result, the heat-flow responses measured by the various laboratories cannot be

usefully compared.

Under this project, monolithic and homogeneous wall specimens having known

thermal resistance will be installed in the CHB. The metering and climatic

chambers will be operated at steady temperature conditions. The feasibility

will be investigated to empirically determine the conduction transfer

functions (CTFs) for the flanking loss.

The feasibility of developing conduction transfer functions (CTFs) for

flanking losses and wall heat transmission will be determined. The

availability of CTFs will provide techniques for predicting time-varying

performance of wall systems when exposed to dynamic thermal conditions.

The CTFs and the concept of their use will be made available to the

design profession. Designers and engineers will be more able to predict

59
accurately the dynamic thermal performance of wall systems. The ability

to better predict performance will allow designers to assess and recommend

energy-conserving system designs.

60
HEAT TRANSFER COEFFICIENTS FOR INSULATED WALLS

Thomas K. Faison

(301) 921-3501

Building Physics Division

Sponsor: Department of Energy

With the advent of sharply higher energy and housing costs, the highly

insulated prefabricated wall and the double-stud superinsulated wall have begun

to appear on the housing market. Measurement of overall steady-state heat

transmission coefficients have not been conducted for such highly insulated

walls. The steady-state theory in ASHRAE's handbook cannot be used to predict

the overall heat transmission coefficient for these walls because the theory

does not adequately account for the significant effect of structural members.

In this project, a series of steady-state tests will be carried out using the

NBS Calibrated Hot Box (CHB) to experimentally measure heat transmission

coefficients for the following two wall systems: A prefabricated insulated wall

(nominal R-16) and a double-stud superinsulated wall. Measured heat transmission

coefficients will be compared with corresponding predicted values using both

steady-state heat transfer theory and a finite-difference heat transfer model.

Project technical staff will meet with technical representatives of the

National Association of Home Builders Research Foundation, the Manufactured

Housing Institute, and DoE to arrive at wall prototypes that are

representative of highly insulated walls for the housing market. A contractor

familiar with these types of walls will be used to fabricate each of the wall

systems

61
EXPERIMENTAL HEAT TRANSFER FUNCTIONS

Thomas K. Falson

(301) 921-3501

Building Physics Division

Sponsor: National Bureau of Standards

Until recently the transmission of heat through composite construction such

as walls and roofs has been calculated on the basis of a steady-state model. As

dynamic models have been developed, much of the data base has remained steadystate with adjustments made to compensate for dynamic response to climatic/

environmental changes. The Calibrated Hot Box provides CBT with unique capability

to perform needed research to determine experimentally the relationships

necessary for deriving the conduction transfer functions for composite wall

assemblies. The Guarded-Hot Plate provides precision necessary to measure the

effects of convective heat transfer in low-density fiber insulation. This work

supports the CBT research on thermal performance of composite wall systems.

These measurements will be made and the effect of convective transfer will be

quantified with respect to density and aspect ratio (thickness to width) of

insulation specimens. The data developed from these activities will benefit

standards-generating organizations such as ASHRAE, ASTM and ANSI, and architects,

engineers, specification writers, and building code officials. These findings

will be of special use as a design aid and to estimate annual energy performance

of buildings.

62
I

j GUARDED HOT PLATE LIMIT ASSESSMENT

Brian Rennex

(301) 921-3195

Building Physics Division

Sponsor: Department of Energy/Oak Ridge National Laboratory

Accuracy of measurement and quality control of the manufacturing process

of thermal insulation are very important to the industry and consumer. The

increased accuracy of thermal conductivity measurements makes it unnecessary

for industry to compensate for uncertainty by overinsulating. The impact of

having the NBS 1-meter Guarded Hot Plate (GHP) in service for thick insulation

measurement, according to the industry and the U.S. Chamber of Commerce, is an

annual savings to the consumer of $90 million. The National Bureau of Standards

has recently conducted an assessment of need for thermal reference materials

that can be used as calibration specimens. Several materials show promise for

expanding the ranges of temperature and thermal conductivity. The GHP was

designed to be an accurate tool for conducting reseach and measuring the heat

flux through thermal insulation and other building materials. The limitations

of the apparatus and the effect of varying temperature and other control parameters

over a finite range are important for future research on standard reference

materials.

A detailed investigation of the thermal properties of Min-K, or another

material will be undertaken. The thrust of this study will be to demonstrate

the variability of heat flux relative to the control variables (temperature,

ambient pressure, thickness).

The insulation industry needs standard reference materials that cover

extended ranges of thermal conductivity and temperature. This research effort

63
will document the operational limits of the NBS GHP. The results will allow

accurate calibration of heat flow measurement apparatuses used in the industry's

quality control, research and development efforts. Conservative allowances to

account for large measurement uncertainties can be eliminated, allowing reductions

in cost to Industry and the consumer.

64
THERMAL RESISTANCE CALIBRATION STANDARD

Brian G. Rennex

(301) 921-3195

Building Physics Division

Sponsor: Department of Energy

This project will explore the feasibility of developing a new calibration

standard for thermal resistance measurement equipment such as guarded hot

plates (ASTM C-177) and heat flow meters (ASTM C-518). At present only two

materials are available from CBT for calibrating guarded hot plates and heat

flow meters. One is a dense fiberglas board and the second is a low-desity

fiberglas blanket. A need exists to supply the measurement community with

calibration samples whose apparent thermal conductivity and thermal resistance

is both higher and lower than those now available, either using materials

that more nearly resemble those that will be measured in current production

or using an entirely new calibration material approach; for example, plastics,

insulating concretes, loose fill materials, or something like a variable

wall spacing and wall thickness honeycomb type of material, whose thermal

conductivity could be changed at will. Given success in this venture, a

measurements laboratory desiring calibration would have the flexibility for

calibrating their devices at or near the several ranges of values expected

to be measured, thus improving the precision and acccuracy of their measurement

system. Much money will be saved by the manufacturing industry if their

production machines can be set more precisely to produce the R-values required

without excessive factors of safety. This, in turn, could lower prices to

the consumer.

65
VALIDATION GUIDE FOR ENERGY CONSERVATION INVESTMENT PROGRAM ,

j

Yai-May Chang ! (301) 921-2330 ' Building Physics Division

Sponsor: U.S. Air Force ^

The objective of this project is to develop a guide for existing techniques I

I that can be used to validate energy and cost savings achieved in the Air Force

j Energy Conservation Investment Program (ECIP) for projects in the Military Family

Housing (MFH) and Military Construction Program (MCP)

Techniques considered for use in this guide will include spot metering,

before and after metering, flip/flop equipment use, and regression analysis.

Some additional applicable techniques include thermography, historical fuel use

data, normalizing data by variable degree days, and measuring thermal conductance.

The guide will identify all types of ECIP facility retrofits to be examined

using these techniques (i.e., add insulation, replace lighting, reduce

infiltration, add storm windows, add shading devices, furnace replacment, HVAC

replacement, furnace derating, install heat pumps, install turbulators, waste

heat recovery, night setback, etc.) and the proposed techniques to validate

these retrofits. The guide will also specify which particular techniques are

best suited to validate each type of retrofit. Data and calculations for each

validation technique will also be provided to illustrate its use.

66
RESIDENTIAL INTERACTIVE TESTING PLAN

Andrew K. Perslly

(301) 921-2330

Building Physics Division

Sponsor: Department of Energy

This project will investigate the merit of fullscale interactive testing

of residential buildings. The study is to specifically address the interaction

of various parts of the building envelope and subsystems as they relate to the

function of the building to achieve energy conservation. A multi-year DoE

testing plan also will be developed.

67
INDOOR AIR-POLLUTION CONCENTRATION MODEL

Preston E. McNall

(301) 921-3447

Building Physics Division

Sponsor: Environmental Protection Agency

A comprehensive analysis of pollution migration in buildings requires

accurate simulation of all processes affecting pollutant concentration. These

processes are infiltration, generation, dilution, reaction, removal, and

exf iltration. CBT recently developed its comprehensive dynamic building

simulation model, TARP. In addition to detailed thermal conduction and

radiation calculations, TARP computes infiltration and interroom airflows by

considering the flows through all openings (doors, cracks, etc.) and requires a

mass balance in each room. The flows are a function of wind, stack effect, and

forced ventilation. The TARP model automatically handles the infiltration,

exf iltration, and interroom dilution aspects of the contaminant equation which

are the most computationally complex part of the problem. It can serve as a

framework for adding other components of the contaminant equation.

TARP would have to be expanded: first, detailed models would have to be

developed for generation, reaction, and removal of various contaminants.

Processes which are temperature-, humidity-, or pressure-dependent are using

parameters already computed by TARP. Second, an air handling/ducting system

model is needed to complete the simulation of forced interroom airflows and

filtration devices. Third, the effects of interroom convection must be understood

so that the simplified model can be developed. This area is primarily concerned

with local air velocities, ventilation effectiveness, and removal of contaminants

68
that have localized sources. Detailed models would be too time-consuming to

include in long-term simulation. The resulting model will be widely used by

building professionals, the Environmental Protection Agency, and the private

sector.

69
PRESSED WOOD MODEL EVALUATIONS

Samuel Silberstein

(301)921-2758

Building Physics Division

Sponsor: Consumer Product Safety Commission

This project will evaluate indoor air quality models including one

developed by the National Academy of Sciences (NAS). The NAS model is being

used by the Consumer Product Safety Commission (CPSC) to predict indoor

formaldehyde concentrations resulting from pressed wood products in residences.

CBT constructed special measurement chambers to measure formaldehyde

emission rates of full scale particleboard underlayment , plywood paneling, and

medium-density fiberboard. CBT also constructed a prototype two-room house

where several characterized specimens can be placed simultaneously to simulate

real-life conditions. This equipment is located in one of CBT's environmental

chambers, which has controlled constant temperature and humidity. The

measurement chambers and prototype house are instrumented with an automated

tracer-gas decay air exchange rate measurement system and an automated system

for measuring formaldehyde concentrations.

From the measured emission rates of the pressed wood products and the air

exchange rate of the house, formaldehyde concentration is predicted, using a

mass-balance model, and compared with measured concentrations. These data,

collected at "standard conditions" of 23°C and 50% RH, are then used with the

NAS model to predict emission rates and concentrations at different combinations

of temperature and RH. The temperature and RH of the environmental chamber

are changed to predetermined conditions and the series of studies is repeated

to compare the results to the predictions of the NAS model. The results of

this study will enable CPSC to assess the validity of their models.

70
SPECIFICATION FOR HIGH-TECHNOLOGY BUILDINGS

Richard Grot

(301) 921-3501

Building Physics Division

Sponsor: General Services Administration

The design and construction of modern high-technology buildings will place

more stringent requirements on thermal performance, environmental components,

air-conditioning contol, and ventilation systems. In an effort to achieve higher

levels of efficiency and more precise operation, conflicts between design

assumptions, construction integrity, and building operations can arise. A

better understanding of the thermal, environmental, and operational characteristics

of high-tech buildings is essential to avoid design errors that may result in

a building unsuited to its tenants. At present, many buildings are now reported

as environmentally "sick," unable to meet thermal comfort criteria and air

quality standards.

Under this project, CBT is developing guideline specifications for the

diagnostic evaluation of thermal and environmental performance of high-technology

office buildings to be constructed by the General Services Administration (GSA).

Specifications are in the Master Format, developed by the Construction

Specifications Institute, as modified by GSA guidelines. The building

specifications are being developed around existing diagnostic techniques developed

by CBT for GSA on previous projects. However, these techniques will be modified

to take advantage of the types of communication and control systems to be

installed in high-technology office buildings.

71
UNDERGROUND HEAT DISTRIBUTION SYSTEMS

Jin Fang

(301) 921-2278

Building Physics Division

Sponsor: Department of Defense Tri-Services Committee

Many underground heat distribution systems in military . installations are

failing because ground water is corroding the conduit that covers the thermal

insulation around the carrier pipe. Since it is extremely expensive to replace

the entire underground system, it is desirable to have an accurate and easy-touse instrument that will detect only the segments of the system that have

failed.

Last year, a simulated small-scale underground piping system consisting of

two electrically heated pipes buried in dry sand showed that heat loss measurement

by the thermal probe technique was in satisfactory agreement with the measured

electrical power input to the simulated underground system. However, there is

some discrepancy between the calculated and measured heat-loss values for tests

involving wet sand. This may be caused by inhomogeneous settling of sand and

moisture during the course of the test. A field test based on the thermal

probe technique was performed for the system installed on the James Madison

University campus in Harrisonburg, Virginia. The calculated depths and locations

of the underground pipes agree reasonably well with the values found in architectural drawings. However, this field test showed that further refinement of

drilling procedures as a part of the motorized auger is required for various

hard soils encountered in field measurements and that the instrumentation used

should be further developed for more automated calculation of the test results.

72
The CBT measurement method is based on a simple heat transfer theory to

calculate the heat-loss values from the earth temperature profile over the

underground heat sources, provided that the thermal conductivity of the earth

and the separation distance of the sources are known. Further validation of

this instrumentation system and comparison of its performance with other

measurement techniques are needed in actual installations. Eventually, the

results of this project will assist in developing innovative underground heat

distribution systems and encourage wider use of existing underground systems.

73
ACOUSTICS

74
BUILDING ACOUSTICS TECHNOLOGY

Siraone L. Yaniv

(301) 921-3783

Building Physics Division

The state-of-the-art in building acoustics has not changed significantly

in several decades and most acoustical parameters are still determined from

sound pressure measurements using the diffuse sound field theory of sound

propagation. Inherent in this model is the assumption that the sound pressure

level—the parameter to which people respond—differs from sound power level

the rate at which acoustic energy is put into a room—by a constant amount in

any room as long as the observation position is sufficiently removed from the

source, and the room exhibits a very limit range of acoustical characteristics

believed to be representative of residential and office spaces.

Unfortunately, diffuse sound field conditions are extremely difficult to

achieve even in a specially constructed laboratory, and are seldom encountered

in real buildings. Accordingly, determinations based upon far-field sound

pressure measurements and the diffuse sound field theory yield results with

large errors, and predictions of field performance from laboratory data that

are chronically unreliable. Because building designers are generally cognizant

of the inaccuracies associated with both acoustical data and predictions, they

often react by costly overdesign. However, experience has shown that, despite

the building industry's reliance on overdesign many buildings fail to meet

acoustical specifications and require costly corrective measures after the

fact.

75
The purpose of this multi-year project is to reexamine the relationship

between sound power, sound pressure, sound absorption and decay in rooms, using

data bases acquired by means of newly developed computer-based measurement

tools that do not rely upon diffuse sound field theory. This work will allow

for the development of significantly more reliable test methods and analytical

tools for characterizing and predicting the acoustical performance of building

spaces, systems, and materials. These analytical tools in turn will be used to

develop computational algorithms for use in computer-aided design.

76
NOISE ISOLATION OF BUILDINGS EXPOSED TO AIRCRAFT NOISE

S.L. Yaniv

(301) 921-3783

Building Physics Division

Sponsor: U.S. Department of Transportation

Federal Aviation Administration

The need to reduce the noise exposure experienced by individuals in the

vicinity of airports led to the passage by Congress of the Aviation Safety

and Noise Abatement Act (P.L. 96-193) of 1979. With the issuance of the

Federal Aviation Regulations Part 150 "Airport Noise Compatibility Planning"

a method was established for dealing with the noise impacts around airports

nationwide. While any program involving airport noise compatibility planning

involves many facets, one major aspect of such a program concerns the reduction

of the noise exposure of individuals located in buildings impacted by airport

noise. The technical data bases on the noise isolation of buildings from

aircraft noise and on approaches for soundproofing buildings are scattered

throughout the literature. These data are not readily available to noise

compatibility projects sponsors, FAA airport field employees or other

concerned people. A uniform method for quantitatively evaluating building

noise isolation and obtaining cost estimates to achieve a degree of noise

isolation improvement is required to insure that limited resources are used

usefully, fairly, and consistently among all FAA regions.

The purpose of this research is to provide FAA airport field employees,

local and state government staff, and other interested parties with a uniform

methodology in a workbook format, using look-up tables, charts, graphs, and

simplified calculation procedures to assess noise isolation. As required by

FAA PART 150, the time-averaged A-weighted sound level will be used as the

77
noise metric for the guidelines. These two requirements — workbook format

and A-weighted sound level measure — establish the technical approach which

will involve four tasks:

- data search and analysis to identify and select acceptable

techniques and materials for mitigating aircraft noise intruding

into buildings, to characterize aircraft noise sources to allow

for estimating the A-weighted noise isolation with changes in

the noise spectrum.

- identify major parameters such as source-building distance,

angle .of incidence, percentage of envelope area for each building

component and indoor room conditions required to quantify the

building noise isolation and the sensitivity of the noise

isolation to each parameter.

- develop cost estimates to implement the noise mitigation

techniques previously identified.

- prepare an acoustic field booklet to obtain field data necessary

to evaluate noise mitigation measures; and, guidelines describing

how to synthesize the field data, evaluate and/or develop noise

mitigation techniques including a series of technical appendices

that describe the derivation and data used to develop the field

booklet and the guidelines

78
AIRCRAFT NOISE ISOLATION: RESIDENTIAL BUILDINGS

S.L. Yaniv

(301) 921-3783

Building Physics Division

Sponsor: U.S. Department of Defense

Navy

Aircraft noise Is a concern to the Federal Government, airport operators,

state and local governments, the aircraft and building Industries, and the

public. There Is a need for airports to meet transportation requirements and

the continuing demand for urban expansion that protects airport neighbors

from excessive noise. These conflicting needs are a continual source of

annoyance and also a threat of conflict between airports and their neighbors

that sometimes end in law suits.

The overall outdoor-to-indoor aircraft noise isolation characteristics

of three types of residential building envelopes shall be estimated from

noise insulation data on building envelope components and constructions, FAA

and/or Navy take-off flight profiles, noise contour maps and spectral data of

aircraft flyovers and their changes with distance. These estimates will be

based on a model for predicting the aircraft noise reduction provided by

residential and public building envelopes being developed by NBS for the

Federal Aviation Administration. All estimates of building envelope noise

isolation will be based upon existing information on the noise insulation of

windows, doors, roofs, and walls using, to the fullest extent possible,

accepted engineering practices, whenever available, and will not include

testing of materials and/or building components, noise sources or sampling of

environmental noise.

Noise isolation estimates will be confined to the envelope of three

residential building types: conventional single detached housing.

79
manufactured detached housing and multlfamily dwellings such as townhouses,

and/or garden apartments. Only construction practices common in Florida will

be explored. For each construction type, the noise isolation will be estimated

for at least two but no more than three types of architectural exterior finishes

(e.g. wood, siding, brick veneer). Based on these analyses, modifications to

current building practices in the State of Florida will be recommended to the

Navy.

80
LIGHTING

RESEARCH

81
DAYLIGHTING STUDIES

Stephen J. Treado

(301) 921-2680

Building Physics Division

Sponsors: National Bureau of Standards

Tri-Services Committee

Naval Civil Engineering Laboratory

The type, size, and configuration of window openings have a strong impact

on building lighting, heating, and cooling loads. Daylight has been shown to

have good potential for reducing lighting energy requirements; however, the

effect of daylighting schemes on building heating and cooling energy requirements must also be considered. Since the luminous efficacy of solar radiation

is typically two to three times that of electric light sources, the substitution of the proper levels of daylight for electric lighting can reduce heating

and cooling loads substantially, while providing psychological and aesthetic

benefits.

This year, the existing CBT luminance and illuminance distribution

measurement capabilities wil be expanded to enable measurements on and about

any task surface, for daylit and electric-lit spaces. Improved modeling and

simulation procedures will be developed for incorporation into daylit calculation

routines. The relationship between task visibility and daylighting design will

be investigated. Daylight calculations also will be integrated with radiant

exchange calculation procedures so that radiance (thermal) calculations include

luminance distribution and interior illuminance calculations.

82
CEL-1 LIGHTING PROGRAM

Steven J. Treado

(301) 921-2680

Building Physics Division

Sponsor: Naval Civil Engineering Laboratory

This project will support and maintain the CEL-1 lighting computer program

and use it in conjunction with the BLAST program to evaluate various fenestration

options for visual performance, building thermal and lighting loads, and building

energy consumption.

Daylight utilization has long been recognized as an effective means of

reducing the amount of energy required for interior building illumination. To

determine the impact of daylighting on building energy, the effect of daylighting

options on HVAC system loads, lighting loads, and visual performance must be

evaluated in a comprehensive manner. As a result, a hybrid version of BLAST/

CEL-1 has been developed to allow the simulation of building energy performance,

including lighting system performance and the effects of daylighting. To enable

the development of design guidelines for effective fenestration use in buildings,

the sensitivity of building energy usage to fenestration design must be evaluated

as a function of other building parameters.

Results of this work are expected to decrease building energy requirements.

83
INTERACTION - LIGHTING AND HVAC SYSTEMS

Stephen J. Treado

(301) 921-2680

Building Physics

Sponsor: Department of Energy

The objective of this research is to obtain the heat transfer

characteristics of various lighting systems in typical room, to develop a

database for detailed lighting heat balance calculations, to analyze the

components of lighting heat transfer, and to evaluate the Influence of wall

and floor construction and HVAC design on lighting and cooling/heating loads.

ASHRAE studies indicate that electric energy consumption in commercial

buildings constitutes as much as 50% of total building energy use. Since the

early 1970' s efforts have been made to reduce the lighting energy consumption

without reducing its illumination performance, such as the development of

high efficiency ballasts, high efficacy light tubes, and the use of day lighting.

This work will result in construction of a lighting test facility. A

calorlmetrlc chamber will be constructed within the existing large NBS

environmental facility. This chamber will be constructed to emulate an office

space with at least one wall capable of being exposed to the equivalent of

exterior conditions.

This project is a combined, cooperative effort between the U.S. Department

of Energy (DoE), the Electric Power Research Institute (ERPI), DublnBloom Associates and Ross & Baruzzlnl, Inc. (DB-RB) , and the National Bureau

of Standards (NBS).

The thermal performance of lighting systems in actual room environments

will be examined using a calorlmetrlc chamber and the large CBT environmental

chamber. The environmental chamber will be used to provide the "outdoor"

condition for the calorlmetrlc chamber, in which various lighting system and room configurations will be tested.

84
DEVELOPMENT OF ILLUMINATION MODEL

Stephen J. Treado

(301) 921-2680

Building Physics Division

Sponsor: National Bureau of Standards

This project focuses on two aspects, luminance distribution and color

rendering, as a function of electric lighting and daylighting systems and

configurations. Prediction of the luminance distribution from luminaires and

fenestration and consequent visibility of office tasks is needed for input to

any design for interior space. In addition, prediction of the spectral reflectance as a function of light-source spectral-power distribution is needed to

account for color within the space. Procedures are needed to allow the calculation of interior illumination conditions, and provide for displaying the

resulting information in a graphic (two- or three-dimensional) format.

The FY85 effort will define the parameters for inclusion in a comprehensive

illumination model and determining existing programs and subroutines. A simplified model will be developed, possibly using a variant of CEL.l or a similar

program. In future years, this model will be further developed and evaluated,

and has the potential for wide use within the illumination and engineering

community.

85
EFFECT OF CHROMATIC ADOPTION: COLOR RENDERING AND COLOR

APPEARANCE

Gerald L. Howett

(301) 921-2670

Building Physics Division

Sponsor: National Bureau of Standards

Only when the light source closely resembles daylight can the appearance

of an object's reflection be predicted accurately from physically measured

chromaticity . Because of the phenomenon of chromatic adaption (the eye's

"discounting the color of the illuminant") , this coordination between appearance

and chromaticity breaks down if the color of the light source departs significantly from that of daylight. A striking example of the shifts that can occur

is the case of blue objects seen under high-pressure sodium light. At present,

no formula is widely agreed-upon as being an accurate prediction of either

the effect of chromatic adaption, or the appearance of colors seen under

chromatic light sources.

The ultimate goal of a new color-appearance formula will require several

lines of experimentation and computer modeling work, over a period of at least

three to five years.

In FY85, three activities will be addressed: first, recent CBT studies of

color appearance have depended on verbal reports that are only semi-quantitative.

A more advanced approach is to match the appearance of samples under various

light sources with the appearance of one sample from a large set of colors

Illuminated by a fixed reference source. Equipment to carry out such matching

will be constructed by modifying an existing apparatus, and an experiment will

be completed and reported.

86
Second, the partially disassembled Maxmellian-view optical system will be

restored to operational status and modified to provide for continuous scanning

around. the spectrum locus and onto the purple line (where perceptually pure red

lies). In FY86 , an experiment using this equipment will determine constant-hue

loci under adaptations to various light sources. The result will be a quantitative

specification of what chromaticities a sample must have to appear, for

example, to be a pure red hue, under adaptation to each of the light sources

used.

Third, the most successful color-appearance formula to date was developed

by Judd at NBS in 1939. It has predicted several sets of experimental data

with moderate success. A start will be made on computer optimization to improve

the agreement of the formula with these same data. In FY86 , an improved version

of the formula will be published. In FY87 and beyond, experiments will be done

to confirm the predictions of the new formula with further fine-tunings carried

out as needed.

87
LIGHTING GEOMETRY AND CONTRAST MEASUREMENT

James A. Worthey

(301) 921-2177

Building Physics Division

Sponsor: National Bureau of Standards

The purpose of this research is to develop a technique for measuring blackwhite contrasts in complex situations. Also CBT will develop a new technique

for color-rendering calculations. There is an opportunity for rapid

technical progress with respect to measurement of black-white contrasts

and improvement of lighting geometry. It is generally understood that

contrast is the stimulus for vision. No method exists, however, for

measuring contrast in realistically complicated scenes. Since the eye

probably makes some use of every edge, highlight and texture available to it,

a realistic contrast meter should in some way "see" these features.

In the human eye, there are some 10^ receptors for daytime vision. From

data gathered by the receptors, the visual system extracts object features such

as edges and highlights, and them assembles a model of external reality, relying

on a number of parallel methods of extracting three-dimensional information from

the two-dimensional images on the two retinas. These methods of extracting

information are a topic of current research, but in general terms they include

"shape from shading," perspective, detection of observer motion through

"streaming" of points in the retinal image, and stereopsis, which is the recovery

of depth information from the disparities between the two retinal images.

Extensive programming will be developed for manipulating images and for computing

two-dimensional Fourier transform and a summary measure of contrast.

88
In the area of color contrasts and lighting, as in the black-white area

there is a need for research that better defines the systematic effects of a

lighting change on color appearance. This effort involves developing computer

programs for calculating color appearance as a function of light source

spectral power distribution. In FY 85, computer programs will be developed to

predict and quantify color contrasts as a function of illuminant. These will

allow manipulation and graphing of light source spectral power distributions

and object spectral reflectances.

The ultimate goal of the color-rendering work is a comprehensive new

method to compute the main effects on object color of a change in lamps. This

will provide explicit guidance to people designing building illumination

systems. Proper control of lighting geometry and color rendering has

great potential for providing good vision and reduced energy output.

89
COLOR CALIBRATOR FOR FAA WEATHER RADAR SYSTEM

L. G. Porter

(301) 921-2660

Building Physics Division

Sponsor: Federal Aviation Administration

This project will evaluate the effectiveness of a CBT-designed color

calibrator for measuring the relative luminance of colors used on a CRT display

for a Radar Remote Weather Display System (RRWDS). It also will determine the

effect of existing building lighting environments (in terms of illuminance,

spectral power distribution [SPD], and location [geometry]) on the luminance

and chromaticity characteristics of the RRWDS CRT display. CBT will recommend

color tolerance limits for the color and luminance of each Weather Intensity

Level (WIL) , standard procedures for use of the color calibrator, guidelines

for the RRWDS building lighting environment. Data on the performance of the

color calibrator for calibrating video display units are urgently needed,

particularly for different ambient illumination conditions. Changes in the

illuminance and spectral composition of lighting systems may greatly alter the

perceived luminance and chromaticity of the colors used to indicate weather

intensity.

90
SAFETY COLORS AND SIGNS IN WORKPLACES

Belinda L. Collins

(301) 921-3141

Building Physics Division

Sponsor: Occupational Safety and Health Administration (OSHA)

The purpose of this research is to develop criteria for using safety

colors and signs in workplaces. The emphasis is on developing criteria for

using colors to code safety information, under energy-efficient (high intensity

discharge) and mixed-light sources, and criteria for specifying the size of

words and symbols as a function of viewing distance.

The Occupational Safety and Health Administration has begun revising its

rules for the use of safety colors and signs in workplaces ( Federal Register ,

Feb. 15, 1983). Although colors and signs are required for warning of workplace hazards and providing safety information, the research base for setting

these requirements is inadequate. In particular, the use of High Intensity

Discharge (HID) lights with poor color rendering may nullify color coding.

As a result, CBT developed a set of experimental, retroref lective and fluorescent safety colors for use under these lights. The effectiveness of these

colors is being experimentally validated under a variety of individual light

sources, including some newer HID sources, as well as under mixtures of high

and low CRI sources.

A two-phase effort is planned. In the first, an 18-month phase, the use

of colors to code information will be documented, along with existing sign/color/

symbol specifications. Two laboratory research projects will be conducted. In

the second phase, methods for predicting the overall effectiveness of safety

signs using words, symbols, and innovative colors will be developed, along

91
with methods for predicting color appearance. Research findings will

increase knowledge of the fundamental characteristics of color appearance

and symbol visibility, while providing information upon which to base

recommendations for safety color and sign use.

92
DISCRIMINABILITY FEATURES OF SECURE DOCUMENTS

Belinda L. Collins

(301) 921-3141

Building Physics Division

Sponsor: Bureau of Engraving and Printing

The ultimate objective is to determine those features of existing and

proposed secure documents (paper currency, postage stamps, drivers' licenses,

social security cards, savings bonds, money orders, credit cards) that are

most effective in deterring counterfeiting. The objective of this phase is to

identify experimentally those features of counterfeit and genuine paper currency

that may be useful in supporting identification of their counterfeit nature,

under a variety of lighting conditions. The focus will be on the interactive

effects of light-source parameters and currency features such as color and

security devices.

This program is expected to result in redesign of the current system of

paper currency, and ultimately to similar measures for other types of secure

documents. Such measures are needed to reduce the threat posed by increasingly

sophisticated counterfeiting operations.

93
DESIGN CRITERIA IMPACTS OF OFFICE INFORMATION SYSTEMS

Arthur I , Rubin

(301) 921-3470

Building Physics Division

Sponsor: Office of Information Resource Management,

General Services Administration

The objective of this research is to develop design criteria for automated

offices which satisfy the information management requirements of the General

Services Administration and other federal agencies. This research involves

an examination of current information systems and future trends as they are likely

to be influenced by new technologies. Among the issues to be examined are the

use of microcomputers computer securty and privacy, and the requirement for

information resource guidelines.

During FY 85 work will consist of literature searches of information

management, data and word processing technologies, security and privacy issues

as they relate to organizational requirements, and existing guidelines for the

development of information management systems. Surveys will be conducted by NBS,

GSA, and other federal agencies to determine the use of office automation

hardware and software. An analysis of these data will provide information about

the effectiveness of these systems in meeting organizational needs, and to

identify potential problem areas that merit office design consideration.

This work will enhance the process of upgrading the current Information

Systems activities of GSA, based on paper-based records, to the more effective

use of electronic media. The office design and electronic data findings will

be disseminated as guidelines for use throughout the Federal Government.

94
BUILDING

CONTROLS

95
SYSTEMS AND CONTROLS LABORATORY

I

I

I

! George E. Kelly j (301) 921-2144

j Building Equipment Division

Sponsor: National Bureau of Standards

The focus of this program will be developing mathematical models and

measurement techniques for evaluating the performance of building systems and

controls, encouraging energy conservation in buildings through improved control

strategies and software, and developing guidelines for automated building

management systems. This research effort will complement CBT's current DoEsponsored research program aimed at documenting the energy savings potential

of the most commonly employed HVAC control strategies, developing algorithms

for building control systems, evaluating the reliability of automated building

management systems, and studying the application of sensors in energy monitoring

and control systems.

This year's effort calls for the verification and refinement of HVACSIM

using the NBS Administrative Building, development of the necessary supporting

documentation for HVACSIM, and the production of a Users' Guide. A workshop on

the integration of building services will be held in early 1985. Research

aimed at evaluating the benefits of whole bulding control and various control

algorithms using the Administration Building will begin in the summer of 1985.

96
ELECTRONIC BULLETIN BOARD

George Kelly

(301) 921-2144

Building Equipment Division

Sponsor: Department of Energy

This project will create and operate an Electronic Bulletin Board that

will support technology transfer by distributing information relating to CBT's

recently developed building/HVAC/control systems simulation program, HVACSIM.

While copies of this program will probably be distibuted through NTIS,

user support of such a program (i.e., answering questions, providing updates,

assisting those with unique problems, etc.) is extremely important to its

successful use by the private sector. The establishment of an electronic

bulletin board will allow users with questions or problems to leave electronic

messages. Answers to these questions or problems would then be formulated by

Building Equipment Division personnel at their convenience and left on the

bulletin board for all to read. This will ease technology transfer from the

public sector to the private sector and also, hopefully, reduce the amount of

time spent by CBT personnel answering the same questions repeatedly.

The software to operate an Electronic Bulletin Board will be purchased or

leased and the bulletin board will be installed on CBT's minicomputer. It

will be operated for a trial period to evaluate the usefulness to the private

sector and the number of persons using it . It also will encourage the use of

the new HVACSIM program by the private sector. In addition, it will provide

valuable information on the role of such bulletin boards in technology transfer

and information exchange in the future.

97
ENERGY MONITORING AND CONTROL SYSTEM (EMCS) ALGORITHMS

William B. May

(301) 921-3839

Building Equipment Division

Sponsor: U.S. Navy and Department of Energy

There are no standardized, nonproprietary EMCS algorithms available for

use by companies entering the building controls field. Many of these companies

lack training and experience in HVAC systems, building controls, and algorithm

development. As a result, the building owner or manager who purchases their

system is often stuck with an EMC system that either doesn't work or only

partially works.

To assure a minimum level of performance of EMC systems, CBT plans to

develop public-domain algorithms for HVAC/building applications. Past work

concentrated on the completion of algorithms for the control of building air

handlers, including optimal start/stop, scheduled time of day stop/start, duty

cycling, demand limiting, temperature reset, and economizer cycle. This year,

the effort will involve the validation and refinement of these air handling

algorithms, development of a model and computer program to emulate a building/

HVAC system controlled by an EMCS, and development of evaluation procedures

for quantifying the energy savings expected from an EMCS prior to its purchase.

The development of public domain algorithms for EMC systems should greatly

improve their performance, especially for systems made by small manufacturers,

and lead to increased energy conservation in commercial buildings. Specifications of such algorithms will help to assure that future energy measurement

and control systems provide at least this minimum of capability.

98
CONTROLS DYNAMIC MODELING

Choel Park

(301) 921-3774

Building Equipment Division

Sponsor: U.S. Navy and Department of Energy

Current the building simulation programs; e.g., BLAST 2, DoE 2

do not account for HVAC control dynamics. As a result, there exists

little reliable data on the amount of energy waste in buildings due to control

dynamics and no information on how to design and operate building

control systems to optimize dynamic performance.

This research concentrates on developing simulation models to predict the

dynamic, "minute-by-minute" performance of building systems. This work will

address the most common types of HVAC systems and will include research to

develop simulation models for building equipment, HVAC components, controls

and zones, and the simulation of the entire building/HVAC/control system.

Work in FY84 concentrated on verifying and refining models of the various

components found in building air handlers and developing a simple building

shell model and an interactive "front end" for a building/HVAC/control system

simulation program called HVACSIM. Work in FY85 involves documenting these

HVAC component and building shell models, and developing information that will

encourage the use of this new program.

99
ENERGY ANALYSIS OF CONTROL STRATEGIES

James Kao

(301) 921-3844

Building Equipment Division

Sponsor: Department of Energy

This study is needed to independently document the potential energy savings

of different commonly used strategies. Last year, CBT used the computer program

BLAST 2 to evaluate control strategies for a variety of HVAC systems in a

large office building, a large retail store, a small office building, and a

school in different regions of the country. Typical strategies studied were

dry bulb economizer cycle, enthalpy economizer cycle, hot and cold deck temperature reset, zone control, floating space temperature, and scheduled setback.

The results of these individual research studies will be combined and summarized

in a report. This study will encourage energy conservation by providing design

engineers and building owners with factual information on the benefits of the

most commonly employed control strategies. It will also lay the groundwork

for the future development of an advanced analysis tool for evaluating control

dynamics and advanced control strategies.

100
NON-AZEOTROPIC

REFRIGERANT

MIXTURES

RESEARCH

101
REFRIGERANT MIXTURE MEASUREMENTS IN TWO-PHASE FLOW

David A. Didlon

(301) 921-2994

Building Equipment Division

Sponsor: National Bureau of Standards

The convective heat transfer coefficent is the single most important

property for the design of heat exchangers. For those heat exchangers which

have internal boiling or condensation coupled with forced convection (e.g.,

refrigerant systems, steam power systems), the complexity of flow conditions

are such that coefficient values are normally completely empirically based.

Since this study focuses on binary mixtures that are non-azeotropic (different

boiling/ condensation points), the problem is complicated even further. In

single-component fluids it is typical to establish an empirically-based functional relationship between the convective heat transfer coefficient and the

other transport properties (e.g., conductivity, visocity) for a given range of

flow patterns and thermodynamic conditions. Once these relationships are

established for categories of fluids, it is possible to predict the heat transfer coefficient based on the measurements of other transport properties that

are significantly easier to make. In the area of non-azeotropic mixtures,

virtually no such relationships among the transport properties exist.

The specific group of fluids that will be studied are f luorocarbons that

are used or intended to be used as refrigerants. The apparent advantages of

using non-azeotropic mixtures in refrigerant systems are improvement in efficiency, less environmental (ozone) impact, multi-level evaporators, and selflubricating working fluids. The evaluation of any of these possible advantages

102
entails an overall performance evaluation of the refrigerant system, which in

turn requires knowledge of the transport properties of the refrigerant.

The heat transfer data and relationships that evolve from this study will

be used by researchers in the refrigeration industry to quantify the advantages

of binary mixtures in their future refrigeration systems design. Also, they

will provide CBT with a measurement facility that is equally applicable to the

wide variety of binary mixtures found in chemical plants.

103
PERFORMANCE OF NON-AZEOTROPIC BINARY REFRIGERANTS IN

RESIDENTIAL HEAT PUMPS

David A. Didlon

(301) 921-2994

Building Equipment Division

Sponsor: Oak Ridge National Laboratory

The objective of this research is to quantify the performance of the

typical residential heat pump operating with a non-azeotropic binary refrigerant

mixture as a working fluid. The purpose is twofold. First, CBT is currently

modifying its heat pump performance simulation model to include non-azeotropic

mixtures as the working fluid. This empirical study will be the hardware test

verification needed to confirm the new cycle simulation. The second purpose

is to measure the potential of these mixtures operating in a heat pump as

typically designed today; that is, one designed to operate on a single-component

refrigerant.

It is anticipated that the adoption of this concept in products being

offered to the consumer could come about within three years. In certain

climatic zones, this is estimated to offer an annual seasonal performance

increase of four to five percent. The impact on cooling performance is

currently being evaluated.

104
MODLEING THE PERFORMANCE OF NON-AZEOTROPIC REFRIGERANTS

IN HEAT PUMPS

David A. Didion

(301) 921-2994

Building Equipment Division

Sponsor: Electric Power Research Institute

The objective of this study is to develop a simulation model of a vaporcompression cycle operating with binary non-azeotropic refrigerant mixtures and

to perform a parametric evaluation of the energy performance advantages of

these mixtures for heat pumps. Conventional vapor-compression heat pumps use

single component refrigerants or azeotropic mixtures (those which have a single

boiling-condensing temperature-composition phase diagram) as their working

fluid. The use of non-azeotropic mixtures as the working fluid appears to

offer several advantages in the area of energy conservation. The major impact

of this study will be the creation of the facility (the simulation model) to

quantify the thermodynamic performance of these non-azeotropic mixtures in

today's heat pumps and in future designs. The second impact will be the

establishment of data on mixtures that may be used in other machinery systems.

105
TEST PROCEDURES

FOR

ENERGY APPLIANCES

106
FURNACE, BOILER, AND HOUSEHOLD APPLIANCE TEST PROCEDURES

Esher R. Kweller

(301) 921-2627

Building Equipment Division

Sponsor: Department of Energy

This project will provide the industry, via DoE, an equitable testing and

rating procedure for determining the seasonal energy performance of central

residential furnaces, boilers, and household heating equipment. It also will

assist DoE in this effort by conducting laboratory studies of furnaces, boilers,

and household heaters and their associated equipment. The Energy Policy and

Conservation Act (PL 94-163) and the National Energy Conservation Act (PL 95-619)

require the Department of Energy to prescribe test procedures for various

residential appliances, including furnaces, boilers, and household heating

equipment. Test procedures for furnaces were published in the Federal Register

in May 1978 (including test procedures for household heaters). Since then,

DoE has updated and will continue to update the procedures to include new

product designs coming on the market. On March 28, 1984, DoE published a

comprehensive revision of the test procedures for furnaces, boilers, and household heaters, including new procedures for modulation-controlled equipment and

unvented gas and kerosene heaters. During the course of this development, CBT

has supported DoE in expanding or modifying the test procedures. This work

will encourage energy conservation through the production of more efficient

equipment for residential space heating.

107
HOUSEHOLD APPLIANCE DATA UPDATE

Joseph Greenberg

(301) 921-3285

Building Equipment Division

Sponsor: Department of Energy

The Energy Policy and Conservation Act as amended by the National Energy

Conservation Policy Act requires the development of test procedures, labeling

rules, and energy efficiency standards for consumer appliances. Representative

data, such as energy efficiency and energy use, are needed for these programs.

These data have changed over time due to increases in energy prices, changes in

consumer behavior, the availability of more efficient appliances, etc. In

response to comments received during public reviews, this project will assure

that tests, labeling rules, and standards are based on a consistent framework

that uses the latest available data. These new values, if adopted and used,

will give a truer picture of overall household appliance energy consumption

and savings. This year, CBT will complete this work for room air-conditioners,

central air-conditioners, furnaces, and water heaters.

108
WATER HEATER TEST PROCEDURES

James E. Harris

(301) 921-2935

Building Equipment Division

Sponsor: Department of Energy

The Energy Policy and Conservation Act (PL 94-193) has mandated that

household appliances, including water heaters, be labeled for energy use using

standardized testing methods. Thus, it is necessary to establish standard

test procedures that allow the accurate determination of energy efficiency,

are repeatable, and not burdensome to perform. The objectives of this project

are to expand and/or modify the DoE water heater test procedures where required

and to provide laboratory data, analyses, and recommendations related to the

test procedures. In addition, CBT will participate in ASHRAE Standard Committee

(SPC 115P) activity and will evaluate forthcoming proposed ASHRAE standard for

testing the performance of heat pump water heaters. CBT also will participate

in ASHRAE Standard Committee (SPC 124P, newly formed), "Method of Testing for

Rating Indirect Water Heaters." CBT will evaluate the forthcoming proposed

ASHRAE standard for indirect water heaters for applicability to labeling

the annual cost of operation.

109
SOLAR

EQUIPMENT

110
CONTROL STRATEGIES TO IMPROVE SOLAR SYSTEMS PERFORMANCE

A. Hunter Fanney

(301) 921-3620

Building Equipment Division

Sponsor: Department of Energy

In this project, CBT will explore ways in which the performance of solar

systems that employ heat exchangers may be improved by using various control

schemes. The schemes to be investigated control the flow rate through the

storage tank side of the heat exchanger to minimize mixing within

the storage tank and maximize the delivered thermal energy.

This reduction in flow rate will be studied in detail because it offers

the advantage of increased performance without increasing the complexity and/or

cost of the system. In the past, selection of the flow rates through both

sides of the heat exchanger has been based on the desire to maximize collector

efficiency. This approach has neglected the effect that higher flow rates

tend to reduce thermal stratification within the storage tank, which increases

the inlet temperature to the heat exchanger resulting in a decrease in the

heat exchanger effectiveness.

The proposed work in FY85 consists of three major activities: first,

measurement of typical heat-exchanger effectiveness for various flow rates and

inlet-fluid temperature conditions; second, using the results of the activity

above, detailed computer simulations of the complete system will evaluate the

effect of flow rate on the performance of systems that use a heat exchanger;

and third, heat exchanges will be added to two identical systems at the test

facility. Extensive experimental comparisons will be made between the performance

of the system using typical flow rates on the storage tank side of the heat

exchanger and one which uses selected flow rates.

111
TEST METHODS AND EVALUATION PROCEDURES FOR CONTROLLERS USED

IN ACTIVE SOLAR SYSTEMS

Joseph Greenberg

(301) 921-3285

Building Equipment Division

Sponsor: Department of Energy

The field performance of many active solar systems has not been as good as

expected. Data from instrumented sites indicate that approximately 40 percent

of the monitored systems have performed at one-half, or less, of design

expectations. Problem areas have included corrosion, leaks, poor design and

installation, and poor reliability of control systems (including sensors).

Controllers have been identified as the least reliable solar components in

various studies of field problems.

CBT held a meeting with controller manufacturers in August 1983 to obtain

recommendations for future research. One of the high-priority research areas

identified was the development of test and evaluation procedures for controller

hardware. In the future, the availability of the draft test methods will help

establish a uniform basis for measuring and reporting the performance of these

components. They also will provide a basis for users to establish needed

performance levels and aid in improving the reliability of solar controllers.

112
SECOND-LAW ANALYSIS OF SOLAR WATER HEATING SYSTEMS

A. Hunter Fanney

(301) 921-2538

Building Equipment Division

Sponsor: Department of Energy

The second law of thermodynamics establishes the maximum possible

efficiency for a system by revealing the amount of energy that is theoretically

usable, called the available energy (exergy), in any process that works between

the same temperature limits. A second-law analysis, therefore, provides the

means to evaluate the effectiveness of a given system and can guide the optimization of system performance by identifying which inefficiencies are avoidable

and which are exacted by nature.

Second-law analyses are becoming more common in solar engineering, but to

date they have focused either on fundamentals such as the appropriate definition

of a thermodynamic source temperature for solar radiation or on advanced technologies such as solar cooling. Little work has been done to analyze the

performance of simple solar energy systems.

In this project, CBT will conduct second-law analyses of the performance

of two solar domestic systems and their associated components. Based on these

analyses, recommendations for system modifications to improve second-law

efficiencies will be made. Estimates will be made of the improvement in

overall system effectiveness that will result from recommended modifications.

This research will guide the development of new optimization methodologies for

solar energy systems.

113
THERMAL PERFORMANCE OF PASSIVE SOLAR APERTURES AND STORAGE

COMPONENTS

Michael E. McCabe

(301) 921-2308

Building Equipment Division

Sponsor: Department of Energy

The objective of this project are to identify and quantify the heat transfer

mechanism that occur in building fenestration systems and storage components to

develop standard methods for measuring thermal performance. At the present

time, computer models of these components are often based on simplifying

assumptions of one-dimensional heat flow and uniform and constant thermophysical

properties. However, actual components used as apertures or storage elements

often violate these assumptions, resulting in erroneous prediction of building

energy performance. As an alternative to computer modeling, testing of actual

components can provide realistic data upon which to improve the models and

thereby obtain a good understanding of the dynamic heat transfer mechanisms.

Indoor test apparatus are convenient to use but are not yet able to

accurately simulate the environmental conditions required to characterize the

thermal and optical performance of advance components. This problem can be

overcome by testing in the natural outdoor environment. Outdoor test apparatus

are less convenient to use but provide the most realistic thermal environment

for testing components. The combination of outdoor and indoor testing of

components, the development of computer models based on first priciples, and

validation of these models using the experimental data will provide the basis

for quantifying dynamic heat transfer mechanisms in components. Outdoor test

data obtained in the CBT calorimeter for a number of fenestration systems and

114
collector-storage walls provide a data base for continued study of dynamic heat

transfer mechanisms. These data can also be used to improve the realism of the

indoor test methods and lead to the development of standards-testing procedures.

Since improvements in the performance of components and systems is one of the

long-terra goals of the DoE program, it is essential that appropriate techniques

be developed to measure the thermal performance of advanced compdnents.

115
THERMAL PERFORMANCE OF EXPERIMENTAL PASSIVE SOLAR SYSTEMS

Bal M. Mahajan

(301) 921-3294

Building Equipment Division

Sponsor: Department of Energy

This project will measure zone-to-zone air flow In various passive solar

systems under different experimental conditions to support the development and

validation of Interzonal heat-transfer algorithms.

Experiments will be conducted at the GET test facility with an open

passageway between the Trombe wall cell and control cell, and between the

control cell and direct gain cell. The velocities of air flowing from zone to

zone will be measured under different test conditions: cell air temperature

free floating and fans on, and cell air temperature free floating and fans off.

The data will be examined for the effects of temperature, stratification, and

forced air movement within each cell. The effects of the remaining variables

on Interzonal air flow will be studied in FY86.

116
EXPERIMENTAL PASSIVE SOLAR SYSTEMS

Joseph Greenberg

(301) 921-3285

Building Equipment Divison

Sponsor: Department of Energy

The DOE Passive Solar Experimental Systems Program was established to

collect, analyze, and archive detailed laboratory, test-cell, and building

performance data of high quality. These data are to be used for the validation

of whole-building energy-calculation methods and component models and for the

development of new algorithms that characterize the behavior of innovative

components, systems, and subsystems in buildings. At present, the NBS Passive

Test Building is one of nine test facilities or buildings in the experimental

systems network of five passive heating facilities and four passive cooling

facilities. In addition, other data are being taken at several other facilities,

both within and outside of DoE sponsorship. The data needs of the users and

the tests conducted by the test facilities are periodically reviewed by a

Coordinating Committee and others.

In FY84, CBT in collaboration with the Coordinating Committee prepared a

draft multi-year plan for the Experimental Systems Research Program. In FY85,

this multi-year plan will be completed and published. Based on FY85 activities,

CBT will provide DoE with recommendations for revising the multi-year plan.

117
RADIATIVE HEAT-TRANSFER MODELING

Michael E. McCabe

(301) 921-2308

Building Physics Division

Sponsor: National Bureau of Standards

The objectives of this project are to develop a computer code that models

the admission and subsequent absorption of the radiant flux from sun and sky in

partially transparent building spaces.

A matrix formulation of solar radiative heat transfer in partially

transparent enclosures has been developed. The enclosure model predicts the

instantaneous rate of solar energy absorption at each surface of an enclosure

into which beam and diffuse solar radiant energy are transmitted. The computer

code SUNFLX has been developed to model ideal transmitting surfaces and surfaces

that reflect energy in a diffuse manner. Algorithms to compute diffuse radiative

view factors and beam radiative blockage factors based on configuration geometry

have been obtained and will be incorporated into the code. Tabular values of

the optical properties of typical glazing systems will be provided with the

option of user-provided optical characteristics.

The significance of the code with respect to building energy balances in a

simple geometric enclosure will be determined by comparing predicted results

with buiding energy analysis codes such as TARP/BLAST, DOE-2 , etc., and with

solar building codes such as TRNSYS, DEROB, and PASOLE. Detailed parametric

studies will be performed to determine the accuracy of the existing codes and

therefore the domain of applicability of SUNFLX.

118
Generalization of the code to include both nonideal radiant transmisison

through glazing systems and mixed specular and diffuse reflecting characteristi

of surfaces will be investigated. The computer code will also be applied in

the prediction of daylighting distribution in complex geometric enclosures.

119
INORGANIC COMPOUNDS FOR PASSIVE SOLAR ENERGY STORAGE - SOLID-STATE DEHYDRATION

Leslie Struble

(301) 921-2635

Building Materials Division

Sponsor: U.S. Department of Energy

The objective of this research is to assess the potential of a hydrated

calcium aluminate sulfate salt (Candlot's salt or ettringite) and related

salts as phase change materials for passive solar energy storage. Solar

energy storage may utilize latent heat stored and released by a material

during a phase change. This phase change often, though not necessarily,

involves melting and freezing. To be used for energy storage, a phase change

must involve a high change in enthalpy (e.g. 100 cal/g) and must be fully

reversible. For passive energy storage, the phase change must occur at

temperatures below approximately 40°C. Other considerations are that the

material be safe, nonflammable and nontoxic. Dehydration and rehydration of

Candlot's salt, appears to offer potential for this application.

The experimental approach is to develop procedures to synthesize Candlot

salt and a number of phases of the same type, involving substitution of

various constituents. These phases will be characterized and their thermal

properties measured, particularly dehydration temperatures and enthalpy chang

during dehydration. Reversibility of the dehydration will be determined for

each material.

120
INORGANIC COMPOUNDS FOR PASSIVE SOLAR ENERGY STORAGE - HIGH SPECIFIC HEAT MATERIALS

Leslie Struble

(301) 921-2635

Building Materials Division

Sponsor: U.S. Department of Energy

The objective of this research is to assess the potential of a hydrated

calcium aluminate sulfate salt (Friedel salt) and related salts for passive

solar energy storage. Solar energy storage utilizes either latent heat

(change in enthalpy associated with a phase change) or sensible heat, the

heat stored or released when the temperature is raised or lowered (specific

heat). The objective in developing a system for sensible heat storage is to

find a high specific-heat material, which is stable under the operating

conditions of the system. Other considerations are that the material be

safe, nonflammable and nontoxic. Hydrated calcium aluminate sulfate salts

appear to offer potential for this application.

The experimental approach is to develop procedures to synthesize Friedel

salt and a number of phases of the same type, involving substitution of

various constituents. These phases will be characterized and their thermal

properties measured, particularly specific heat.

121
TECHNICAL PROBLEM ASSESSMENT

Robert D. Dikkers

(301) 921-3285

Building Equipment Division

Sponsor: Department of Energy

This project will provide technical support and assistance to the Solar in

Federal Buildings Program established under the Energy Policy and Conservation

Act and the National Energy Conservation Policy Act. The Solar in Federal

Buildings Program (SFBP) was established to show Federal confidence in and

focus public attention on proven applications of solar heating and solar heating

and cooling technology that can be used in the private sector. SFBP rules

published in the October 19, 1979, Federal Register referenced performance

criteria for solar heating and cooling systems in commercial buildings (NBSIR

76-1187) prepared by CBT. As of June 1984, 731 SFBP projects were still active.

During prior years (FY80-83), CBT staff have provided recommendations

concerning data collection and evaluation activities that should be carried

out under the SFBP. In FY84, a CBT staff member was selected to serve as a

member of the SFBP Editorial Review Board. The objective of this board is to

provide recommendations concerning the scope and type of technical reports and

information to be prepared and disseminated under the SFBP. During FY85, NBS

staff will continue to participate in the SFBP Editorial Review Board and to

provide other technical assistance to the SFBP as may be requested.

The impact of this program will be widespread since data collected on the

design, construction, and performance of solar heating and cooling systems in

the SFBP will provide the solar community with valuable information for improving

solar equipment.

122
TECHNICAL COMMITTEE ASSISTANCE

Robert D. Dikkers

(301) 921-3285

Building Equipment Division

Sponsor: Department of Energy

It is expected that solar standards, being developed by ASHRAE , ASTM, and

other organizations, will provide industry, government officials, designers,

and consumers with a uniform basis for the evaluation, development and selection of solar energy materials, components, and systems. CBT will actively

participate in various committees of organizations (e.g., ASHRAE, ASTM, ISO,

ANSI) now engaged in standards development and planning activities. Where

appropriate, CBT staff will provide research data and draft standards to assist

these committees in the preparation of voluntary consensus standards. The

nationally accepted voluntary consensus standards for solar materials, components, and systems will contribute to developing a viable solar industry.

123
CONSULTING AND ADVISORY SERVICES: ACTIVE SOLAR HEATING

AND COOLING

Robert D. Dikkers

(301) 921-3285

Building Equipment Division

Sponsor: Department of Energy

Under this task, CBT will provide consulting and advisory services to

technically support DoE (Active Heating and Cooling Division) . These services

include the following activities: active participation in conferences sponsored

by DoE, SERI, ASHRAE , and other organizations to discuss performance criteria,

standards, and various research activities; meetings with representatives of

other government agencies (Federal and/or State) and foreign governments at

the request of DoE to discuss CBT solar energy program activities; active

participation in DoE planning and program review meetings; and review and

evaluation of requests for proposals, contractor reports, program planning

documents, and other program activities.

124
INTERNATIONAL ENERGY AGENCY SOLAR PROGRAM SUPPORT

A. Hunter Fanney

(301) 921-2538

Building Equipment Division

Sponsor: Department of Energy

This project will enhance the U.S. solar research program by participation

in Task III of the International Energy Agency Solar Heating and Cooling Research

Program. The intent of the first subtask under this project is to establish

a reliable, adequate methodology for relating the instantaneous performance of

a solar collector as determined in collector testing to the day-long performance

of that collector in a system. The current testing procedure eliminates or

minimizes the very real effects of wind, sky temperature, distributions of

direct and diffuse solar radiation, and nonsteady-state operation. These

effects must be taken into account in determining collector performance in a

system.

The purpose of the second subtask is to establish the quantitative basis for

evaluating candidate materials for solar collectors. The current test methods

are based on qualitative indicators that cannot be related easily to real

performance. Most can give a relative ranking of performance but none indicates

at what rank the performance becomes unacceptable for the intended application.

This situation generally results in over-specification of materials by designers,

with an attendent increase in cost.

The purpose of the third subtask is to establish a method where the longterm performance of a solar domestic hot water system can be adequately predicted

using he results of short-term tests. The long-term performance of a system

125
is the only reliable indicator of its effectiveness to the user. The methodology

must include transformation of test results from arbitrary conditions of test

to the real conditions at the installation site. In addition, the methodology

should allow for component substitutions to be made without requiring a complete

retest of the modified system. The test procedures will result in a consistent

terminology and universally accepted data reporting on an international basis.

126
PLUMBING

RESEARCH

127
HYDRAULIC LOAD LIMITS IN DRAINS

Lawrence S. Galowin

(301) 921-3293

Building Equipment Division

Sponsor: Trl-Servlces

This project will determine hydraulic drain load-carrying capacities for

building plumbing drainage systems by applying the Plumbing Load Drainage Design

multi-network computer program. The program will be applied to representative

military buildings to provide new guidelines for facility and base engineers.

This new procedure takes Into account vertical stack annular flow and

attenuation In horizontal drains dependent upon pipe parameters, base flows,

and surge waves. Initial loading conditions for any sequential, simultaneous,

random, and discrete fixture discharges into the system can be prescribed.

Prior procedures and design calculations, based upon drainage fixture units,

cannot account for the time-varying hydraulic discharge profiles from fixtures

and yield results that underestimate system hydraulic capcaclties.

The results of this work will provide revisions for hydraulic load limits

during the site planning phase in new Installations or for existing drainage

pipe systems where changed functions and occupancy usages occur. Dissemination

of the results will advance the applications for computer-aided design methods

in the plumbing field and contribute to the ASPE Data Book for Plumbing Design.

128
LOAD MODELING FOR MULTISTORY DRAINAGE SYSTEMS

Lawrence S . Galowin

(301) 921-3293

Building Physics Division

Sponsor: National Bureau of Standards

This project will expand the existing flow network analysis program for

building drainage systems by the introduction of top-entry branch-junction

boundary conditions and iterative recalculation procedures so the program is

more useful as a design tool. The results will contribute to introduction of

the new computer-based design methods for building plumbing drainage systems.

Traditional plumbing c^de requirements and design practices for drains are

based upon conservative tabulations of permissible pipe size derived from

empirical factors for the hydraulic capacity. Dissemination of CBT reports and

articles for inclusion in the American Society of Plumbing Engineers Data Book

"Fundamentals of Plumbing Design," can expand the opportunity for computer-aided

design in the plumbing field.

129
RESIDENCE TIMES IN FLOW SEPARATION - WATER MAINS

Lawrence S. Galowin

(301) 921-3293

Building Equipment Division

Sponsor: U.S. Environmental Protection Agency

This research has two objectives. The first is to evaluate flow separation

conditions and eddy formations at cavities and obstacles at pipe walls in water

distribution mains. The second is to develop a residence time flow model for

recirculation in cavities; experimentally determined surface ramp contours of

growth from deposits at wall obstacles.

Potential degradation of potable water quality in water mains was related

to pipe wall encrustations by the Environmental Protection Agency. The hydraulic

phenomena governs the local conditions at and adjacent to the wall where

corrosion, chemical and biofilm adhesion occur. The transport and deposition

of particulates, chemicals, and nutrient retention for bioorganisms were identified as dependent on residence times.

CBT will develop flow separation and eddy formation modeling to simulate

flow conditions at wall obstacles. Representative separated regions at wall

obstacles and stagnation conditions at imperfectly aligned pipe sections,

gasketed joints, fittings and valves, roughness sites and corrosion/encrustation

sites will be considered in the modeling. Computer programs that account

for viscosity diffusion will also be assessed. Comparisons with

limited published experimental data profiles will be made. The findings will

provide a preliminary model for EPA use as a technique for predicting local

pipe conditions for distributed potable water quality.

130
QUALITY

OF

BUILDING

MATERIALS

131
APPLICATION OF LIFE-TEST ANALYSIS CONCEPTS TO BUILDING MATERIALS

Jonathan W. Martin

(301) 921-3208

Building Materials Division

Sponsor: National Bureau of Standards

Reliable prediction of service life is needed to aid the selection and use

of polymeric building materials. But major technical barriers to the development of predictive models arise from the complexity of the degradation processes,

particularly the synergistic effects of ultraviolet radiation, temperature,

moisture, and other factors. Currently, predictive models and accelerated

tests do not account for this synergism. The thrust of this research is to

develop stochastic models incorporating synergistic degradation effects.

These models will be validated against laboratory and outdoor test data.

Prior research has led to the development of a stochastic model as a

function of two of the above degradation factors (ultraviolet irradiance and

temperature) and two degradation processes (thermal degradation and photo

degradation) using polymethylmethacrylate (PMMA) as a model material. The

model is fundamentally based in that the parameters of the model are in terms

of material degradation processes. Parts of the model have already been verified

against 25 published data sets. The agreement between the model's prediction,

empirical data, and the fundamental mechanisms of chemical degradation, are

very good. The full model is currently being validated against laboratory data

and validation will be completed in FY85.

This research will extend the model to include moisture and to mathematically

clarify the causes of thermal degradation. The work will be done in collaboration

132
with the staff of the NBS Polymers Division. PMMA specimens will be exposed

to several relative-humidity levels, keeping irradiance and temperatures

constant. The level of moisture in each specimen will be measured using a

Fourier transform infrared measurement technique. Degradation of the materials

will be measured using gel-permeation chromatography. In the mathematical

modeling phase of the research, extensions will be made to the current stochastic

model. Degradation will be modeled in terms of the chemical/physical changes

occurring within the material.

133
ENVIRONMENTAL DEGRADATION OF POLYMERIC COVER MATERIALS

FOR SOLAR COLLECTORS

David Waksman

(301) 921-3114

Building Materials Division

Sponsor: Department of Energy

Virtually all of the durability testing that has been perfornied to date on

polymeric materials for solar energy applications has concentrated on their

degradation when exposed to elevated temperature and ultraviolet radiation. Little

emphasis has been placed on degradation caused by moisture or by the combined

effects of moisture, temperature, and solar radiation.

Under this project, moisture-related degradation that has occurred in cover

materials exposed in previous CBT programs will be characterized. Carefully

controlled exposure tests will be conducted for representative materials to determine

their degradation mechanisms and degradation rates and to establish a basis for

predicting the useful service lives of these materials. Research will be performed

to develop the data to a stochastic mathematical model for predicting the synergistic

degradation effects of moisture, ultraviolet . radiation, and temperature. The

model will also be validated for one or more additional materials to demonstrate

its broad applicability.

Knowledge gained in this research will assist industry in formulating polymeric

materials for solar applications and the evaluation procedures developed, in

cooperation with organizations such as ASTM, will aid the selection and use of

polymeric materials. The development of validated mathematical models also will

significantly advance the current state-of-the-art in predicting the rates of

degradation of materials which will, in turn, aid in providing evaluation tools

for selecting and using such polymers.

134
DEPENDENCE OF MECHANICAL PROPERTIES ON MICROSTRUCTURAL

CHANGES IN COVER PLATE MATERIALS

David Waksman

(301) 921-3114

Building Materials Division

Sponsor: Department of Energy

Primary emphasis in developing ASTM procedures for evaluating solar

materials degradation has been placed on their engineering properties, i.e.,

integrated transmittance and absorptance, emittance and tensile strength.

Little emphasis has been placed on the use of changes in the primary

microstructural properties of these materials for early detection of changes

in the engineering properties which are, in general, less sensitive indicators

of materials degradation. An understanding of primary degradation mechanisms

and their influence on engineering properties is essential for the formulation

of improved products by industry and early detection of materials degradation.

CBT will determine the relationships that exist between micro and

macro-level changes in the mechanical properties of polymeric materials.

Measurements will be made of changes in the chemical, i.e., molecular weight,

and physical, i.e., microstructural (microcracking) , properties of materials

exposed in the NBS cover plate and collector reliability/durability programs.

The relationships between changes in these properties and the macroscopic

(mechanical) properties of these materials will be determined.

135
DEVELOPMENT OF TESTS FOR PREDICTING ADHESIVE BOND

DURABILITY

Jonathan W. Martin

(301) 921-3208

Building Materials Division

Sponsor: U.S. Army, NARADCOM

All branches of the military use lightweight, air transportable,

rigid structures which serve as combination shipping containers and

shelters for many types of tactical and life-support services. The use

of these shelters has Increased rapidly In recent years and life-cycle

costs have become a major consideration. The shelters are fabricated

from either paper honeycomb core or foam plastic sandwich panels.

While honeycomb panels have several potential advantages, field experience

has shown many problems. De-bonding of panel components, stemming from

poor adhesive performance, is a frequently observed problem. To address

poor adhesive performance, a need exists for developing improved

accelerated tests and probabilistic based mathematical models to aid in

predicting service life.

CBT will expose honeycomb sandwich panels to a cyclic temperature

environment at 95 percent relative humidity. The panels will be monitored for

delaminations as a function of exposure time. The time at which delamlnations

are detected is the service life for the panel. The service life for

panels exposed to the same exposure conditions will be used in determining

a suitable theoretical life distribution. The parameters of the life

distribution will be used in determining the time-tranformatlon function

relating time to failure and thermal stress. This transformation

function will be useful in predicting service life under varying environmental

stresses. The development of Improved accelerated tests and probabilistic

based models will provide the technical bases for standards for adheslves

136
used in honeycomb sandwich panels. These standards will contribute to

the technical basis for the expansion of the military shelter program

which is to take place in the 1980' s under the newly-formed inter-servi

committee designated the Joint Committee on Tactical Shelters. The

benefits will be improved performance of military shelters and spinoff

benefits for civilian shelters.

137
NONDESTRUCTIVE EARLY DETECTION OF CORROSION AND

DELAMINATION UNDER PROTECTIVE COATINGS USING THE THERMAL

WAVE METHOD

Tinh Nguyen

(301) 921-3208

Building Materials Division

Sponsor: National Bureau of Standards

United States corrosion related problems are estimated to cost more than

100 billion dollars annually. The use of coatings is one of the most effective,

economic and widely-used means to prolong the service life of corrosion-prone

substrate materials used in buildings and infrastructures. Current methods

to detect and assess corrosion of steel under protective coatings, and

delamination at the metal/coating interface involve visibly observing or

destructively peeling off the film. Another method, thermography, was recehtly

developed at CBT for the non-destructive detection of corrosion and blisters

under protective coatings. All of these methods suffer a major disadvantage:

the detection is only possible after the materials have been severely damaged.

Thus, one of the objectives in research on service life prediction of coatings

on steel is to develop a nondestructive method to detect very early corrosion

and delamination under pigmented coatings. A recently developed method,

thermal-wave imaging, has been applied in the semiconductor industry to detect

and image small subsurface defects, microcracks and dopant regions. It

appears from these results and from our preliminary work that the method has

the potential for use in the early detection of corrosion and delamination

under coating films. Thermal wave detection and imaging are dependent on

material properties such as specific heat, thermal conductivity and density,

and the modulation frequency of the electron beam used.

The objective of this research is to investigate the depth of penetration

of thermal waves in coatings for detection of corrosion of steel protected by

138
these coatings. To address this question, corroded steel specimens will be

coated at incremental thicknesses. Modulation frequencies and phase shifts

will be varied until the corrosion is imaged.

Development of a nondestructive method for early detection of corrosion

and changes at the organic coating/metal interface will permit quick assessment

of coating performance in many different environments and rapid screening of

experimental coatings and corrosion inhibitors. This could lead to better

understanding of the degradation mechanisms, improved coatings and coating

systems, and improved accelerated testing methods; also, it could ultimately

reduce testing time and cost.

I,

139
ASSESSMENT OF NONDESTRUCTIVE EVALUATION METHODS

APPLICABLE TO CONSTRUCTION

James R. Clifton

(301) 921-3458

Building Materials Division

Sponsor: Naval Civil Engineering Laboratory (NCEL)

Nondestructive evaluation (NDE) methods offer significant advantages

over traditional methods for determining the properties of construction

materials, especially in the making of in-situ measurements of materials.

CBT completed a study on NDE methods, "In-Place Nondestructive Evaluation

Methods for Quality Assurance of Building Materials," in 1982. Since then,

advances in the state-of-the-art of some NDE methods have taken place. The

purpose of the project is to update the assessment and to identify

emerging and advanced NDE methods.

The research will consist of four tasks. The first is to identify

and evaluate current Navy practices relative to the use of NDE methods in

the construction and service cycle of buildings and other structures. The

second is to determine the state-of-the-art of the use of NDE methods

in the construction industry. In the third, emerging NDE methods that have

application to naval diagnostic needs will be identified. Also, promising

advanced NDE methods which require further research and development before

they are ready for routine use will be identified. Needed research in the

area of NDE methods for naval construction applications will be addressed in

the fourth task.

140
ORGANIC COATINGS

Dr. Mary McKnight

(301) 921-2635

Building Materials Division

Sponsor: Tri-Services Materials Committee

The annual cost associated with protective coatings in the U.S. for

buildings and structures is estimated to exceed 8 billion dollars. If the

most effective criteria for the selection, specification, and use of protective

coatings were available, it is estimated that as much as 25 percent of

these expenditures could be saved. An essential element of selection and

use criteria for protective coatings is service life. But currently

available methods for predicting service life based upon short-term tests

do not adequately meet the need for data to aid selection, specification,

and use.

The objective of this research is to develop improved test and evaluation

methods for predicting service life of protective coatings under in-service

use conditions to aid in selecting and using protective coatings. CBT

will develop improved test and evaluation methods to aid service life

prediction. The thrust will focus on 1) identifying and modeling the

mechanisms of degradation and 2) identifying properties and characteristics

which are effective indicators of degradation and performance. The scope

of the research is limited to protective coatings for steel.

In FY 84, the project focused on refining mathematical models for

service life prediction for coatings on steel, evaluating current test

methods used to characterize performance of waterborne emulsions and

developing improved test methods, and transferring state-of-the-art

141
inforaatlon on selection and use of coatings by initiating revision of the

Paint and Protective Coating Manual. The waterborne emulsion work will

support development of an ASTM standard specification for interior flat

latex wall paints. In FY 85, research to better characterize initial

properties of the coating system will be initiated and support for developing

an ASTM standard specification for interior waterborne paints.

142
IMPROVED CHARACTERIZATION OF COATING SYSTEMS PERFORMANCE

Mary McKnlght

(301) 921-2635

Building Materials Division

Sponsor: Naval Civil Engineering Laboratory (NCEL)

The need for Improved short-term tests to aid quantitative service-life

prediction of coating systems is well documented. A primary weakness of

current short-term or accelerated tests Is the procedure used to characterize

the state of deterioration (level of performance) of the coating system.

Currently, most evaluations of performance of coating systems are made using

visual standards. These standards are quite qualitative and are not suitable

for evaluating systems in the early stages of deterioration. If the need for

improved service life prediction methods is to be met, quantitative and

sensitive methods for characterizing the performance of coating systems must

be developed and implemented. This research is directed to Improvement of

characterization procedures for performance of coating systems.

The research is divided into two parts. The first builds upon

preliminary research and will use Infrared thermography for quantitative

characterization of degraded coating systems. The second is a literature

review of other non-electrical characterization procedures. For the first

part, the evaluation of coated laboratory steel panels for corrosion and

blistering using infrared thermography will be computerized. Computer software

has been developed to digitize the image. The number of the deteriorated

areas and the total area of deterioration will be quantitatively determined,

accumulated over time and stored in a computer. The data will be retrieved

and analyzed as desired. The second part consists of a literature review

143
and contacts with research laboratories to identify additional nonelectrical

state-of-the-art methods used to characterize and measure deterioration of

coating systems. These methods will be evaluated for practicality for

quantitative determination of the degraded state of a coating system and

detection of early stages of deterioration. Research needs for the development

of potentially attractive methods will be identified.

144
COATING MAINTENANCE OF FACTORY COATED METAL SIDING

AND ROOFS

Mary E. McKnight

(301) 921-2635

Building Materials Division

Sponsor: Air Force Engineering and Services Center

The Air Force has constructed many facilities with sheet metal siding or

roofing. Many of these buildings are more than 20 years old. Periodic

coating maintenance is required to maintain these facilities. Current

directives and guidance do not adequately address problems associated with

maintenance of these buildings. As a result, Air Force bases are using a

mixture of coating systems that 1) often fail prematurely, 2) inadequately

protect the facility, or 3) are excessively difficult to recoat.

CBT will develop technology to improve preliminary guidelines for

maintaining metal siding and roofing. This will be accomplished by producing

laboratory and field test methods. Laboratory and field test methods will

be selected and candidate maintenance coating systems and application methods

will be tested and evaluated. Surface preparation techniques will be evaluated

taking into consideration the type and condition of the substrate. Using

the initial results of the laboratory and field tests and information from

condition assessment procedures, interim criteria will be prepared for

recoat ing metal siding and roofing. This work will be published as a pamphlet

or short document and distributed to Air Force bases.

145
DEGRADATION OF ORGANIC PROTECTIVE COATINGS

Mary E. McKnight

(301) 921-2635

Building Materials Division

Sponsor: National Bureau of Standards

This project focuses on the identification of mechanisms leading to blister

formation and corrosion. It aims at developing improved methods for characterizing

coating reactions and properties that control degradation at the steel/coating

interface. Previous research has led to preliminary mathematical models for

predicting the growth of blisters and a method, based upon infrared thermography,

for detecting degradation beneath coatings.

This year, research on interfacial degradation mechanisms will use Fourier

Transform Infrared Spectroscopy (FTIR) to study the molecular changes at the

steel/organic coating interface. The information obtained will be used for

elucidating the mechanisms of coating degradation and for identifying the

factors controlling degradation. The proposed research will study the coatingsteel interactions before and after exposure to corrosive environments and

relate these to the protective characteristics of coatings.

Several types of organic coatings will be put onto steel surfaces. FTIR

will be used to study steel/coating interactions at the interface. The coated

specimen will then be exposed to environmental conditions simulating in-service

exposure. The specimens will be reexamined using both FTIR and optical

microscopies. Molecular behavior will be correlated with rate of degradation.

146
REVISION OF TRI-SERVICE COATINGS MANUAL

Mary E. McKnight

(301) 921-2635

Building Equipment Division

Sponsor: Naval Facilities Engineering Command

Northern Division

The Tri-Service Paints and Protective Coatings Manual (MOllO, AF85-3 or

TM5-618) is the prime document used by engineering commands to specify coatings

systems for facilities maintenance. The document provides base engineers with

general information on coating chemistry, surface preparation and application

procedures, inspection, failure analysis and safety. The last revision was

completed about five years ago. Since new coatings are available, the manual's

revision is necessary.

Information from technical literature and government and industry coating

experts will be used to update the manual. Techniques to increase the ease of

information transfer will be investigated and used as appropriate. Chapters on

field inspection instruments and procedures and safety will be written. When

revisions are completed, the Navy will publish it and distribute to military

bases. The improved coating systems specification will result in improved service

life and lower maintenance costs for military facilities.

147
TRI-SERVICES TECHNICAL AND SCIENTIFIC SUPPORT

Robert G. Mathey

(301) 921-2629

Building Materials Division

Sponsor: Tri-Services Committee

The military servies are facing a wide range of building-related problems.

In response, this project provides technical and scientific support and

consultative services on building materials and systems as required by the

Tri-Services Building Materials Investigational Program Committee. The work

includes laboratory tests and field investigations for solving building problems.

Recommendations are made on the selection of materials and systems and their

application and performance. In the past, problem areas have covered plumbing,

masonry, roofing, corrosion, mechanical systems, insulation materials, and

underground piping. The benefits of this research, however, extend far beyond

its military application, to other government agencies and into the private sector.

148
AASHTO MATERIALS REFERENCE LABORATORY (AMRL)

James H. Pielert

(301) 912-3481

Building Materials Division

Sponsor: American Association of State Highways and Transportation Officials

Under this project, with the support of AASHTO Research Associates working

under CBT supervision, measurement services are provided to both public and

private laboratories working on transportation studies. At present, attention

is focused on the testing of soils and bituminous materials and the measurement

of frictional properties of highway. Procedures used in performing conventional

quality assurance tests are observed for conformance with applicable national

standards. Related test apparatus is checked with inspection equipment traceable

to CBT-calibrated devices. Deficiencies noted during Inspections are brought

to the attention of laboratory managers. In addition, proficiency-test samples

are distributed at regular intervals to obtain information on laboratory

performance. The primary goal of the AMRL is improvement in the quality of

testing in bituminous and soils laboratories. Specific products include a

detailed report on each inspection performed; a comprehensive report on each

round of proficiency-sample testing; and input to the work of standards

committees, such as data for use in standards for testing soils and bituminous

materials.

149
OF

ROOFING

SYSTEMS

150
PROBABILISTIC STUDY OF SINGLE-PLV MEMBRANES

James R. Clifton

(301) 921-3458

Building Materials Division

Sponsor: National Bureau of Standards

In developing and demonstrating a probabilistic method for predicting

service life of single-ply roofing membranes, membranes will be subjected over

time to both mechanical and thermal stresses. Time-to-failure distributions

will be obtained for each experimental condition (minimum of three temperature

levels and three mechanical stress levels). The degree of functional dependence

of the time-to-failure distribution parameters on temperature and mechanical

stresses will be determined through time-temperature superposition and timemechanical stress equations. Other experimental variables that will be used

include membrane characteristics (seam, no seam), and characteristics of the

thermal insulation (gap and no gap between insulation boards, no insulation).

Both creep and stress relaxation experiments will be performed. EPDM (ethylene

propylene diene monomer) will be used as the first-test membrane material,

representing the rubber-like single-ply membrane family. Other membrane

materials which may be used in future studies are modified bitumens and thermoplastics, and other rubber-like materials.

Information on the service life of membranes will help minimize premature

failures of the $3 billion or more of single-ply membranes that are estimated

to be put in place every year. Also, this project will serve to demonstrate

to the roofing community the benefits of the probabilistic method in predicting

the service lives of roofing materials.

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In the second part of FY85, research will be carried out to develop a

method to measure the pore size and pore-size distribution of coatings. These

are particularly important characteristics in understanding the rate-controlling

processes of degradation. The method will collect data essential for advancing

the predictive modeling phase of coatings research.

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PERFORMANCE CRITERIA FOR BITUMINOUS MEMBRANE ROOFING

Walter Rossiter

(301) 921-3109

Building Materials Division

Sponsor: E.I. duPont de Nemours & Company

CBT developed preliminary performance criteria in the late 1970 's for

the selection of conventional 4-ply built-up bituminous membranes composed

of organic or glass felts and hot bitumen (asphalt and coal tar pitch).

The performance criteria were empirically determined based on field performance

and laboratory data. In recent years membranes containing reinforcing

fabrics (e.g. polyester) with properties considerably different from those

of conventional reinforcing felts have been introduced. Currently about

2 billion square feet of bituminous membrane roofing are applied annually

in the United States at a cost of over 6 billion dollars.

The objectives of this study are to reassess performance criteria for

bituminous membrane roofing and to revise preliminary performance criteria

in those cases where a technical basis exists for revision. The first

phase of the study will be to augment the technical basis to be used in

reviewing earlier preliminary performance criteria. In the second phase

of the study, criteria will be revised for those attributes selected in

the first phase. The revisions will take into account the results of

tests on laboratory-prepared and field specimens.

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QUALITY ASSURANCE OF ROOF SYSTEMS

Walter Rossiter

(301) 921-3109

Building Materials Division

Sponsor: U.S. Postal Service

The objective of this project is to provide the technical basis for the

Postal Service to improve quality assurance in the design, construction, and

maintenance of low-sloped roofing, and select cost-effective and durable

materials and systems for use in new, replacement, and repair roofing applications.

The total roof area of the buildings used by USPS is estimated to be more than

200 million square feet. The majority of these buildings have low-sloped

roofing systems. A conservative estimate of USPS annual roofing costs is over

$50 million for repair, replacement, and new construction. This project consists

of a planning effort to include discussions with key USPS personnel to obtain

an understanding of USPS roofing practices and types of roofs. This is followed

by roofing problem identification, design of roofing systems, materials selection,

roofing systems installation and application practices, and maintenance practices.

The project's product will be a report describing the results of the study

and recommendations for improving the quality assurance of USPS roofing and

recommendations for further research. The findings will assist USPS reduce

premature roofing failures through improved material selection and maintenance

practice. It also will provide information on the types of roofing material

failures experienced in service which will be valuable in planning the future

course of roofing research at CBT.

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PREDICTING

THE PERFORMANCE

AND SERVICE-LIFE

OF CONCRETES

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IDENTIFYING THE DEGRADATION MECHANISMS OF CONCRETE

Larry Knab

(301) 921-3120

Building Materials Division

Sponsor: National Bureau of Standards

Improved recognition and understanding of degradation mechanisms in concrete

and the effects of the environment on these mechanisms is needed to assess

degradaton in concrete, and to develop improved models to predict the service

life of new concrete or the remaining service life of existing concrete. The

purpose of this project is to develop a technical basis for improved prediction

of concrete performance including improvements in methods of characterizing

degradation, understanding of degradation mechanisms, and tools (e.g., mathematical

models, expert systems) for predicting concrete service life.

In FY84, the microstructural details of the fracture zone in mortar

subjected to cyclic loading were compared with those for mortar subjected to

monotonically increasing load using the fluorescent thin-section method developed

in FY83. Data indicated little, if any, microcracking at the one micrometer

level and above with either cyclic or monotonic loading. It appears that crack

tortuosity and/or aggregate bridging (interlock of aggregate with matrix)

provide traction across the crack walls behind the crack tip for the loading

types studied. In addition to providing information on the microstructural

details of the fracture zone, fluorescent thin sections should be useful in

elucidating other cracking processes, whether resulting from chemical reactions,

corrosion of reinforcement, freeze-thaw action, or high-temperature curing.

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In FY85, improved methods of characterizing the microstructure of concrete

and mortar are being investigated. Emphasis is on the recognition and enhancement of the microstructure as related to degradation mechanisms. Advanced

methods for characterizing both fine microstructure (less than one micrometer)

and coarse microstructure (greater than one micrometer) of sound and deteriorated

concretes will be demonstrated.

The quality of the concrete used to rebuild America's infrastructure will

be improved as a result of this study. Improved methods for characterizing

degradation will be used to provide the basis for: (1) condition assessment of

existing concrete structures, including those needing repair or rehabilitation,

and (2) developing models and expert systems to predict the service life of new

concrete or the remaining life of existing concrete.

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MEASUREMENT OF THE STRENGTH OF THE BOND BETWEEN OLD

AND NEW CONCRETE

Leslie Struble

(301) 921-2635

Building Materials Division

Sponsor: Tri-Services Committee

Good bond between old and new concrete is essential to the repair of

concrete structures. Available methods to achieve a strong bond generally

involve both preparation of the old concrete surface and use of materials with

epoxy resin or other polymers incorporated in the fresh concrete. To evaluate

the repair materials, the tensile strength of the bond between the new material

and the old concrete should be measured directly, but at present there is no

commonly accepted test. The development of such a test is the objective of

this project.

The principal features of the test method will include: preparation of

samples with a single planar interface between the constituents, tensile loading

normal to this interface using grips that minimize shear or torque, and testing

the bond between new and old cement paste, rather than concrete, because paste

is considered the critical constituent for bond strength. Samples will be

prepared by casting fresh cement paste or related repair material against

a smoothed surface of old hardened paste.

Test development will be based on a method used in an earlier study of the

bond between cement paste and aggregate, though modification of the grips will

probably be required. The grips used earlier exert considerable compressive

force on each end of the specimen, and the paste may not be sufficiently strong

to withstand this force.

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Once the test has been modified and shown to be effective, it can be used

in future years to determine what parameters in the fresh paste or repair

material affect the tensile strength of the bond between fresh paste and old

paste, and to provide selection criteria for repair materials.

This research will benefit concrete technology, especially the repair of

concrete structures. It also will provide the Department of Defense with

improved criteria for selecting of materials for repair. In addition, it will

add to our fundamental understanding of bonding in concrete, a phenomenon

important in many aspects of concrete science.

159
PERFORMANCE REQUIREMENTS, TESTS, AND CRITERIA FOR MATERIALS

USED TO REPAIR PORTLAND CEMENT CONCRETE

Larry Knab

(301) 921-3120

Building Materials Division

Sponsor: U.S. Army Corps of Engineers through Waterways Experiment Station

An important part of the U.S. Army, Corps of Engineers' REMR program is

the repair of concrete. A large number of materials are currently available

for repairing concrete. Often, however, their performance has been

unsatisfactory. The lack of success with these materials has been attributed,

at least in part, to an inadequate technical basis for their selection. The

purpose of this research is to determine preliminary performance criteria for

selecting materials to repair concrete structures which have cracks, spalls,

or scaling. The determination of performance criteria for materials selection

should improve the field performance of materials used in concrete repair.

Existing knowledge on performance requirements, tests, and criteria for

materials used to repair portland cement concrete will be analyzed. Published

information on the relationship between performance requirements and performance

in service will be studied. Based on this information, the performnce

requirements (e.g. , resist shear forces) and associated material properties

(e.g., shear strength) for the important in-service degradation factors, such

as mechanical stress, temperature and temperature fluctuations, moisture,

aggressive chemicals, ultraviolet light, and time of exposure will be

identified. A rationale for determining performance tests and criteria based

on existing knowledge will be developed. Performance tests and criteria will

then be determined for appropriate performance requirement - degradation

factor combinations, based on existing knowledge. Needs for new performance

160
tests and criteria will be identified and developed. The project will be

performed in three phases. Performance requirements, tests, and criteria

will be determined for materials used to repair cracks (Phase I), spalls

(Phase II), and scaling (Phase III) in concrete. Based on assessment of

existing performance criteria, a research plan for developing needed

performance tests and criteria will be developed.

161
ALKALI-SILICA REACTION IN CONCRETE

Leslie Struble

(301) 921-2635

Building Materials Division

Sponsor: National Science Foundation

The objective of this research is to explore whether the alkali mineralogy

of cement affects the mortar expansion due to alkali-silica reaction. Alkalisilica reaction is a major concern in the production of durable concrete.

Reaction between alkalies from the cement and reactive silica in the aggregate

may cause expansion, cracking, and occasionally significant weakening of the

structure. The mechanisms involved in this reaction are not well understood,

and this research was undertaken to improve our understanding.

The experimental approach consists of determining the distribution of

alkalies within a group of commercial portland cements with a variety of

alkali mineralogies, and measuring expansion of mortar bars prepared using

these cements and various reactive and unreactive aggregates.

162
CEMENT AND CONCRETE REFERENCE LABORATORY

(CCRL)

James H. Pielert

(301) 921-3481

Building Equipment Division

Sponsor: American Society for Testing and Materials, U.S. Army Corps of

Engineers

Over $4 billion of hydraulic cements are produced in the United States each

year. The value of the concrete construction in which these cements are used is

estimated to be on the order of $20 billion. Because of the large amounts of

money and critical construction materials involved, standardization of testing to

enhance the reliability of quality-assurance measurements is most important. The

CCRL contributes to this standardization through on-site inspections of apparatus

and procedures used in the testing of cements and concretes, the distribution of

proficiency test samples, laboratory investigations of testing problems, and

participation in the activities of standards development groups. This work is

performed by ASTM Research Associates working under CBT supervision.

Services under the project include the on-site inspection of the laboratory

and the distribution of proficiency test samples. Procedures used in performing

conventional quality assurance tests are observed for conformance with applicable

national standards. Related test apparatus is checked with inspection equipment

calibrated by NBS personnel. Proficiency test samples of portland cement,

concrete, blended cement, and masonry cement are distributed at regular intervals

to obtain information on laboratory performance. Participation in the work of

ASTM technical committees by CCRL staff is a mechanism used to provide the

standards community with information developed by the inspection and proficiency

sample programs.

163
CEMENT HYDRATION COMPETENCE PROJECT

Paul W. Brown

(301) 921-3458

Building Materials Division

Sponsor: National Bureau of Standards

The objective of this project is to improve understanding of the physics

and chemistry of cement hydration and the development of microstructure in

pastes of Portland and related cements; also, to demonstrate the understanding

through development and validation of mathematical models based on probable

physical and chemical mechanisms. This research will develop a fundamental

understanding of reactions of portland and related silicate cements with water

and develop mathematical models for predicting the courses of the reactions

under various conditions. The work began with studies of the hydration of

various preparations of the most important solid phase in portland cements,

tricalcium silicate, and have since been extended to other cement phases and

mixtures of phases. The work consists of simultaneous development of fundamental

mathematical models based on alternative conceptual models. The mathematical

models are tested experimentally and revised as needed. Tricalcium silcates

and other cement phases used as starting materials are obtained from the few

available sources or when necessary manufactured in the laboratory. They are

characterized in such terms as chemical composition, particle size and shape

distribution, specific surface area, crystallite size, crystal defects, and

grain boundary compositions. The materials are reacted with water and solutions

of ionic and non-ionic compounds to determine the effects of temperature, and

water-solid and water-surface area ratios on the mechanisms and kinetics of

164
the reactions. Techniques used are electrokinetic phenomena, heat evolution,

volume change, electrical conductivity, x-ray diffraction, differential scanning

calorimetry, surface area measurements by gas adsorption, image analysis, and

chemical analysis of the aqueous phase. The image analyses are based on results

obtained with the scanning electron microscope and the new STEM. This work

is carried out in consultation with scientists at the Center for Materials

Sciences and the Center for Applied Mathematics. Studies of tricalcium silicate

hydration were concentrated in the first two years of the project, and studies

of tricalcium aluminate and mixtures of cement phases began in the third year.

In the fourth year, investigations on tetracalcium aluminoferrite were carried

out. A complementary activity carried out in the project is participation in

the committee on mathematical modeling of cement hydration in RILEM (The International Union of Testing and Research Laboratories for Materials and Structures.

165

JJ. U . S . GOVERNMENT PRINTING OFFICEi 1 9 8 5 -4 6 t " 1 0 5 / 2 0 I 7 3


U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology