NBSIR 73-121

Structural Tests of a Wood

Framed Housing Module

C. W. Yancey and N. F. Somes

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

113 I

March 26, 1973

Final Report

Prepared for Office of Research and Technoiog/

Department of Housing and Urban Development

Washington, D. C. 20410

NBSIR 73-121

STRUCTURAL TESTS OF A WOOD FRAMED

HOUSING MODULE

C. W. Yancey and N. F. Somes

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

March 26, 1973

Final Report

Prepared for Office of Research and Technology

Department of Housing and Urban Development

Washington, D. C. 20410

U. S. DEPARTMENT OF COMMERCE. Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director
i.
Contents

Page

1. Introduction 1

2. Test Structure 2

2.1 Housing System 2

2.2 The Selected Module 2

2.3 Fabrication Details 3

2.4 Condition of Module Before Testing 6

2.5 Support Assembly 7

3. Objectives and Scope 8

3.1 Service Life Racking - Test 1 9

3.1.1 Objective 9

3.1.2 Scope 9

3.2 Transient Floor Vibration - Test 2 9

3.2.1 Objective 9

3.2.2 Scope 9

3.3 Sustained Floor Load - Test 3 10

3.3.1 Objective 10

3.3.2 Scope 10

3.4 Repeated Racking - Test 4 10

3.4.1 Objective 10

3.4.2 Scope 11

3.5 Reversals of Racking - Test 5 11

3.5.1 Ob j ective 11

3.5.2 Scope 11

ii
Page

3.6 Racking to Capacity - Test 6 11

3.6.1 Objective 11

3.6.2 Scope 12

4. Test Setup and Instrumentation • 12

4.1 Service Life Racking - Test 1 12

4.2 Transient Floor Vibration - Test 2 14

4.3 Sustained Floor Load - Test 3 1^

4.4 Repeated Racking - Test 4 15

4.5 Reversals of Racking - Test 5 16

4.6 Racking to Capacity - Test 6 16

5. Load Program 17

5.1 Service Life Racking - Test 1 17

5.2 Transient Floor Vibration - Test 2 17

5.3 Sustained Floor Load - Test 3 16

5.4 Repeated Racking - Test 4 19

5.5 Reversals of Racking - Test 5 20

5.6 Racking to Capacity - Test 6 2^

6. Results 21

6.1 Service Life Racking - Test 1 21

6.2 Transient Floor Vibration - Test 2 22

6.3 Sustained Floor Load - Test 3 22

6.4 Repeated Racking - Test 4

6.5 Reversals of Racking - Test 5

6.6 Racking of Capacity - Test 6 24

7. Discussion of Results 25

7,1 Service Life Racking - 1 25

iii
Page

7.2 Transient Floor Vibration 30

7.3 Sustained Floor Loading

7.4 Repeated Racking ^2

7.5 Reversals of Racking ^2

7.6 Racking to Capacity

8. Conclusions

9. Acknowledgements

10. References ^ Tables 39

Figures ^2

Appendices

Appendix A 72

Record of Crack Formation on Interior Surfaces

Appendix B 91

A Typical Application of the Drift

Model to Test Data

Appendix C 92

Load-Deflection Curves for Test 1

iv
Notation

The following notation is applicable for the entirety of

this report:

Service Loads (psf)

D = dead load

E = earthquake load

L = live load

W = wind load

Deflections (inches)

dh = horizontal drift

dv = vertical net deflection

dvr = residual vertical net deflection

Dvr = residual vertical gross deflection

Lengths (inches)

h = height above either finished grade (ground outside

the building) or the interface between the building

system and separately-built basement, whichever is

higher.

1 = length of member

V
SI Conversion Units

In view of present accepted practice in this country

in this technological area, common US units of measurement

have been used throughout this paper. In recognition of

the position of the United States as a signatory to the

General Conference on Weights and Measurements which have

official status to the metric SI system of units in 1960,

we assist readers interested in making use of the coherent

system of SI units by giving conversion factors applicable

to US units used in this paper.

Length

1 in = 0.0254* meter

1 ft - 0.3048* meter

Area

1 in^ = 6.4516* x 10"^ meter^

1 ft^ = 9.2903 X 10"^ meter^

lb (Ibf) = 4.448 newton

kip = 4448 newton

Pressure, Stress

1 psi = 6895 newton/meter'^

2

1 psf = 47.88 newton/meter

Moment

1 kip-in = 113.0 newton-meter

Temperature C° = 5/9 (Temperature - 32)

*Exact value

Force

1

1

vi
List of Tables

Table Page

5.1 Test 1 (Ram forces and equivalent wind pressure) 39

5.2 Test 6 (Ram forces and eqivalent wind pressure) 40

6.1 Repeated Racking Test Results 41

A.l Initial Linear Measurements 86

A. 2 Second Record of Linear Measurements 87

A. 3 Difference Between Nteasurements in Tables A.l and A. 2 88

vii
List of Figures

Figure Page

2.1 Isometric View of Typical Townhouse Cluster 42

2.2 Module Floor Plan 43

2.3 Exterior Wall Section in Two-Story Structure 44

2.4 Plan and Details of Support Assembly 45

3.1 Test Floor for Transient Vibration - Test 2 46

3.2 Test Floor for Sustained Load - Test 3 47

4.1 Ram Locations for Test 1 ^8

4.2 Exterior Instrumentation on the Rear - Test 1 49

4.3 Exterior Instrumentation on the Front - Test 1 , 50

4.4 Cross Sections Showing Loading Rams and Instrumentation 51

4.5 Typical Instrumentation Arr<'mgement (Rear Wall) 52

4.6 Data Acquisition Equipment and Hydraulic Pumps 53

4.7 Typical Setup for Transient Vibration Testing 54

4.8 Partial View of Sustained Load Testing 55

4.9 Ram Locations for Tests 4, 5 and 6 56

4.10 Test Setup for Repeated Racking 57

4.11 Closeup View of Ram in Region Shown in Figure 4.10 57

5.1 Pressure Distribution Effected by Loading Rams - Test i 5 8

5.2 Loading Sequence for Test 4 59

5.3 Contributory Areas for Racking Loads in Test 1 60

viii
Figure Page

6.1 Profile of the Lateral Displacement for Varying Simulated

Wind Pressure - Test 1 61

6.2 Deflection versus Time Traces for Tests 2A and 2B 62

6.3 Deflection versus Time Traces for Tests 2AA and 2BB 63

6.4 Deflection versus Time Traces for Tests 2C and 2D 64

6.5 Deflection versus Time Traces for Tests 2CC and 2DD 65

6.6 Graphical History of Floor Deflection Due to Sustained

Loading - Test 3 66

6.7 Lateral Force at Ram 2 versus Net Horizontal Deflection

Along Plane 1 - Test 6 67

6.8 Lateral Force at Ram 2 versus Net Horizontal Deflection

Along Plane 3 - Test 6 68

6.9 Lateral Force at Ram 2 versus Net Horizontal Deflection

Along Plane 4 - Test 6 '69

7-1 Analytical Model for Drift Derivation - Test 1

7.2 Wind Pressure Versus Derived Drift Curves - Test 1 71

A. l Typical Set of Linear Measurements 85

B. l Lateral Force Distribution on Actual Structure Due

to Design Wind Pressure 89

C. l Force at Ram 3 versus Deflection Along Plane 1 for Profile

Shown in Figure 5.3a - Test 1 92

C.2 Force at Ram 3 versus Deflection Along Plane 1 for Profile

Shown in Figure 5.3b - Test 1 93

C.3 Force at Ram 3 versus Deflection Along Plane 2 for Profile

Shown in Figure 5 . 3a - Test 1 94

C.4 Force at Ram 3 versus Deflection Along Plane 2 for Profile

5.3b - Test 1 95

C.5 Force at Ram 3 versus Deflection Along Plane 3 for Profile

Shown in Figure 5.3a - Test 1 96

ix
I'orcc at Rajii 3 versus Deflection Along Plane 3 for Profile

Shown in rigurc5.3h - Test 1

I'orce at R^iiii 3 versus Deflection Alojig I'lane 4 for Profile

Showi in Figure 5.3a - Test 1

Force at Ram 3 versus Deflection Along Plane 4 for Profile

Shown in Figure 5.3b - Test 1

Force at Ram 3 versus Deflection Along Plaiie 5 for Profile

Shown in Figure 5 . 3a - Test 1

Force at Ram 3 versus Deflection Along Plane 5 for Profile

Shown in Figure 5 . 3b - Test 1

1. Introduction

This paper reports the results of tests to determine

the structural strength and stiffness characteristics of a wood framed volumetric housing module. The series of structural

tests was performed subsequent to a series of tests relating

to transportation by rail. The entire test program was

conducted in conjunction with the HUD- sponsored industrial

housing program, Operation BREAKTHROUGH. An integral part of

the transportation study was the shipment of the module, over

850 miles of rail track, from its point of manufacture to the

National Bureau of Standards (NBS) Structures Laboratory at

Gaithersburg , Maryland. This report refers to the transportation

only inasmuch as it concerns the module, and, in particular,

its condition at the start of the structural tests. The total

sequence of the tests closely simulated the experience of an

actual module as it undergoes manufacture , transportation,

erection, and in-service loading.

The concept of fabricating volumetric modules in a factory

and assembling them on the housing site to form complete dwelling

units is one that is growing in popularity within the building

industry. Such modules can have a width and length ranging

up to 12 ft and 60 ft, respectively, while their height is

approximately 10 ft. The feasibility of this concept hinges. • on the economics of transporting the units from a central point

of manufacture to distant construction sites.

Of the many factors to be considered in regard to transportation, its effect on the subsequent performance of the

module, as a component of the living unit, is of primary concern.

Cost considerations require damage incurred during regular

rail shipment to be held to a minimum. For the system in question,

transportation was particularly critical since the initial

production of modules would have to withstand rail shipment

1
for a distance exceeding 2000 miles. An experimental shipment

was therefore conceived, using a full-scale prototype module

of a configuration considered to be most critical for transportatior-'*

2. Test Structure l!^

2.1 Housing System ifit

The housing system represented in this study is characterized

by wood framed modules joined into clusters at the building

site to form units. The isometric view presented in figure

2.1, illustrates three such townhouses , arranged in a staggered

pattern. The exterior envelope and the interior partitions n are common throughout the system and are described in paragraph -ia 2.3. i% As structural integrals, modular units such as the test i

specimen are connected in various arrangements to resist l«i gravity live loads, environmental forces (i.e., earthquake, :!i snow and wind forces) and occupant loads (i.e. impact). The i\ arrangement utilized in this system is a four-module combination

which results in a two-story house. i,i

2.2 The Selected Module

The interface between adjacent modular units provides

a natural boundary in the selection of a test specimen. The

full-scale module selected for the transportation study and

the subsequent structural testing is designated as a secondstory front unit. The bold outline in figure 2.1 denotes

the boundary of the test module in relation to the remaining

three segments. Although its selection was predicated upon

choosing a module critical for transportation, the construction

of the module was thought to be representative of the system

in general.

As erected in the laboratory, the module was 59 ft-4

1/2 in long x 11 ft-9 1/2 in wide x 15 ft-7 1/2 in high.
As shown ill the Floor plan, figure 2.2, the module consisted

of two tlistinctly different portions. One portion enclosed

three bedrooms and was 40 ft-i 1/2 in long. The other, a

19 ft- 5 in- long living room space was a triangular prism

without any floor framing. Its function in the actual liousing

system is to provide a "cathedral ceiling" above the first

floor living room.

2.5 Fabrication Details

It should be noted that the module, being a prototype,

was hand-built by the manufacturer according to his tlien- current

plans and specifications. As the housing system v/as undergoing

a multi-stage structural evaluation of the plans, specifications

and calculations, these documents were necessarily mutable.

Therefore, it should not be construed that t)ie following details

of the module were indicative of the final construction details

of the housing system.

The roofing consisted of v;ind- resis tant shingles, of Underwrite

Laboratories, Inc. Class C, one layer of asplial t -s atur ated

felt underlayment (ASTM Specification D226, 15 lb type) and

a roof sheathing of plywood DFPA grade - trademarkcd "Standard

with exterior glue" 1/2-in thick. The 4 ft x 8 ft plywood

sheets were oriented so that the face grain ran parallel

to the snan of the roof rafters. The shingles were stapled

to the plywood with 16 ga staples, with 3/4-inch legs. The

rafters supporting the roofing surface xvere 2 x 6—^ members

of Douglas Fir, Construction Grade, spaced, 24 inches on

centers (o.c). The entire roof system of tiie test module

was hinged along the top plate of tlie front wall to reduce

the height of tlie shipping envelope; in its shipping position,

-As subsequently used throughout this report, size descriptions

such as 2 x 6 refer to nominal timber dimensions in inches,

in accordance with U. S. Product Standard PS 20-70, American

Softwood Lumber Standard, Department of Commerce, Wasliington,

D. C.

3
the plane of the roof was horizontal. In the laboratory, the

roof was rotated about the hinge until its plane made ^n angle

of 36° with the horizontal. The rafters were then braced

near the peak of the roof by 2 x 4 strut members which were

attached to the top plate of the rear wall by hinge connections.

The struts were positioned at an angle of 54° with the horizontal

and hence intersected the rafters at right angles.

"T^he ceiling surface consisted of one layer of 1/2-inch

gypsum wallboard (ASTM Specification C36-68). ^^^2/ ^-^^ supporting ceiling joists were 2 x 4's of Douglas Fir, 'Construction

Grade spaced 16" o.c. The wallboard was attached to the

joists with a bead of an elastomeric adhesive "nd 6d nails,

spaced at 16 in o.c. along the perimeter and 24 in o.c. at

intermediate members. The rim joists were double 2 x 6's

while the header beams were single 2x6 members.

All vertical framing members were 2x4 Douglas Fir

studs, spaced at 16 in o.c. The party wall between the middle

and south bedrooms (see figure 2.2) was of double stud construction,

with each line of framing separated by a 1/2-inch air space.

Single 2x4 members formed the top and sole plates for all

vertical framing.

The exterior surfaces of the walls were respectively finished

to be consistent with the position of the module in the

actual townhouse layout. The front wall was covered with

a single layer of 7/16-inch hardboard siding backed by a layer

of 1/2-inch f ire-retardant gypsum sheathing (ASTM C79-69). ^"-^ The hardboard sheets were applied vertically witli 4d S499D nails,

spaced at 16 in o.c. along the perimeter and at intermediate

studs. One x two battens were used at each vertical joint

as well as at intermediate studs.

— Numbers in brackets indicate references at the end of tlie

report

.

4
The rear wall, functioning as an interface between two adjacent

modules in the actual structure, was sheathed with 5/8-incli

plywood grade-marked "Standard". The plywood sheets were

attached to the studs with 6d tee nails, spaced at 6 inches

o.c. along the perimeter and at 12 inches o.c. along intermediate

members. Contiguous end walls of modules, such as the north

wall of the prototype module (see figure 2.2), were covered

with a double layer of 1/2-inch, Type "X" gypsum wallboard

(ASTM C36). The siding on the south wall of the module was

identical to that attached to the front wall. The wall section

in figure 2.3 shows the details of a typical exterior bearing

wall in the two-story building. The materials and construction

details specified for the roof, ceiling and front wall of the

module are illustrated in this figure.

All partition wall surfaces, except at the party wall

between the middle and south bedrooms, consisted of a single

layer of 1/2-inch gypsum wallboard (ASTM C36) . The party wall

serves as a fire barrier and, therefore, a double layer of

1/2-inch, Type "X" gypsum wallboard was used to cover each side

of the wall. The interior surface of all exterior walls consisted

of a single layer of 1/2-inch, Type "X" gypsum wallboard

(ASTM C36) . All interior and exterior gypsum wallboard was

attached with 4d S499D nails along with an application of an

elastomeric adhesive. A nail spacing of 16 inches o.c. was

used throughout.

The principal components of the floor were plywood subflooring-underlayment and 2x8 wood joists. The plywood

was 5/8 in grade- trademarked "Underlayment with exterior glue,"

Group I. The plywood sheets were oriented with the face grain

parallel to the span of the joists and they were secured by

nailing. Eight-penny common nails were spaced at 6 in o.c.

along the perimeter and at 10 in o.c. over intermediate supports.

The joists were designated as Construction Grade Douglas Fir

5
and their clear span measured 11 ft- 3 1/2 in. Conventional

16-inch joist spacing was used. Both the rim joists and header

beams were double members, consisting of a 2 x 10 nailed to a

2 X 12, tlie 2 X 10 being outermost.

Wall-to-wall nylon carpet, with foam padding, was installed

in the factory in all three bedrooms. Pre-assembled push-out

bay window assemblies were installed in the laboratory in the

north and middle bedrooms according to the plans (see figures

2.1 and 2.2). Bi-fold metal doors in closet openings were

installed at the factory.

2.4 Condition of the Module Before Testing

The module was visually inspected for damage or other

evidence of structural distress, upon its arrival at the laboratory.

All cracks in wallboard and other forms of local damage were

systematically documented. Prior to lifting and transporting

from the factory, reference points had been established on

the interior and exterior wall surfaces and linear measurements

were made between the reference points. These measurements

were repeated in the laboratory, so as to determine any dimensional

changes in the module caused by the handling and shipping

operations

.

It was observed that the interior surfaces incurred

two types of damage as a result of lifting and transportation:

The first type was hairline cracking on the surface of the

gypsum wallboard. These fine cracks were located mostly near

doorways, closet openings and window frames. There was no

apparent damage to the structural framing associated with

this cracking. In the second type, the wallboard tape, applied

to the joint between two adjacent panels of wallboard, was

torn at several locations, reflecting relative motion between

the panels. Most of the tearing occurred along the horizontal

6
joint formed by intersecting ceiling and wall panels. The

most significant tear was noted at the junction between the

ceiling and the south wall of the south bedroom. At this

location, the tape was split, revealing a 1/4-in wide separation,

between the wall. and the ceiling, that extended along the

joint for 12 inches.

All of the damage was readily repairable by conventional

surface treatment, prior to structural testing. The damaged

tape joints were repaired by re-taping and applying a joint

compound. The surface cracks in the gypsum were repaired

by application of joint compound. It should be noted '•hat

no nail popping was observed on any of the surfaces. Furthermore,

the exterior showed no significant damage.

The differences between "^he two sets of dimensional measurements,

previously noted, were determined and the results have been

tabulated in Appendix A. As indicated on table A. 3, the magnitude

of dimensional change ranges from -5/16 in to -s-y/S in. It

is important to note that there was no visible sign of distress

associated with these extreme values. Assuming a normal distribution

of the dimensional change, it is found that approximately

68 per cent of the changes fell between +1/8 in and -1/8 in.

2.5 Support Assembly

In its test position, the module was seated upon a wood

base, which was anchored to the laboratory test floor. To

simulate the ioint between the first and second story modules

in the actual structure, the perimeter beam for the support

assembly was chosen to match that specified for tlie firstfloor ceiling in the townhouse.

7
As shown in figure 2.4, the base consisted of 2 x 8 cross

beams, spaced at 4 ft-0 in o.c. and nailed to the perimeter

beam. Detail "A" shows the nerimeter beam as a 2 x 8 facejointed to the inside of a 2 x 10. The beam was notched at

10-ft intervals to accommodate the horizontal leg of a 5 in

X 4 in X 1/2 in steel angle. The vertical leg of the angle

was welded to two 5-inch channels, that were arranged backto-back and spaced far enough apart to accommodate a 1 1/2-

inch tie-down bolt. The bolt effected the necessary anchorage

to the laboratory test floor. A typical tie-down assembly

is described in detail "A" of figure 2.4. The orientation

of the module in relation to the support assembly can be determined

by referring to the notation "Front" and "Rear" on figures

2 . 2 and 2.4.

Due to length limitations on the laboratory tie-down

floor, approximately one-fifth of the module extended outside

the laboratory. Most of the living room space was enclosed

by a temporary shelter and was secured to a temporary concrete

slab with five angle tie-downs. A typical angle tie-down

is described in detail "B" of figure 2.4. Four 16d common

nails were used to attach the angle to tlie face of the perimeter

beam while a 3/4-inch diameter masonry anchor bolt secured

the horizontal leg to the concrete slab.

3. Objectives and Scope

The general objective of the series of six tests was to

quantify some of the structural characteristics of the wood

framed module which were not conducive to analysis and

to supplement these data with visual observations. Specific

objectives for the respective tests are cited in the paragraplis

that follow.

8
In the following chronological sequence of tests, the

racking tests were designed so that each test would be more

critical to the structural integrity of the module than the

one that preceded it.

3.1 Service Life Racking - Test 1

3.1.1 Objective

To determine the stiffness of the module with respect

to lateral load and to estimate the drift, at the secondfloor level in the actual building when it is subjected to

wind forces.

3.1.2 Scope

The module was subjected to static concentrated loads

simulating wind forces normal to the front face of the building

and the resulting horizontal and vertical deflections of selected

points were measured. No attempt was made to consider variations

of loading distribution or the module's response as a function

of time.

3.2 Transient Floor Vibrations - Test 2

3.2.1 Objective

To determine the damping behavior of the floor when subjected

to vibrations of relatively short duration, such as those

induced by human activities

.

3.2.2 Scope

This test recorded the decay of the amplitude of floor

displacement, with time, following a single impulse excitation.

9
The same procedure was performed for each of four combinations

of the point of delivery of impulse and the point of measurement

of displacement. This was done in order to observe the difference

in readings resulting from varying the combination. The

floor in the largest room, the north bedroom, was selected

for testing and its location is shown in figure 3.1.

3.3 Sustained Floor Load - Test 3

3.3.1 Objective

To determine the deflection of the floor, at critical

locations, both under a uniformly distributed load and subsequent

to its removal.

3.3.2 Scope

This was a two-day test performed on the south bedroom

floor, the location of which is shown in figure 3.2. Since

the floor construction was identical in all three rooms,

it was considered necessary to test only one floor.

Following this test, the triangular-shaped living room

space was completely severed from the bedroom portion and

all further testing was conducted on the remaining 40-ft -

1 1/2 in long module. It was concluded that this alteration

would result in a closer representation of lower-story construction

in the actual building.

3.4 Repeated Racking - Test 4

3.4.1 Objective

To document any detectable decrease in serviceability

and to determine if a reduction in lateral stiffness resulted

10
upon the module being subjected to repeated applications of

lateral loading.

3.4.2 Scope

One thousands cycles of simulated wind force were applied

at right angles to the front face of the module. Horizontal

and vertical deflections of selected points were measured.

Qualitative assessment of the structure's response was accomplished

by visually examining those areas identified as potential points

of distress.

3.5 Reversals of Racking - Test 5

3.5.1 Objective

To describe qualitatively the extent of distress and

damage to all visible connections and exposed components as the module was subjected to loading that, in magnitude, corresponded

to earthquake design provisions in the Uniform Building Code

[3].

3.5.2 Scope

Five cycles of reversed lateral load were applied at

right angles to the front face of the module. The structure

was visually examined for evidence of distress or failure

at the conclusion of testing.

3.6 Racking to Capacity - Test 6

3.6.1 Objective

To quantify the maximum lateral load which the module

could withstand.

11
3.6.2 Scope

Static lateral force was applied in increasing magnitude,

at right angles to the front face of the module until failure

occurred. Deflection data were periodically recorded and

the module was visually examined for signs of distress and

damage.

4. Test Setup and Instrumentation

4.1 Service Life Racking - Test 1

The five 10-ton hydraulic rams schematically located

in figure 4.1, were actuated through a dual manifold system.

Rams 1, 2 and 5 were branched from one manifold, while rams

3 and 4 were connected to a second line. In order to measure

the magnitude of force in the hydraulic systems, a load cell

was attached to one ram in each system. Hydraulic pressure,

corresponding to a particular jacking force, was monitored

visually from two single-channel strain indicator boxes.

A pressure transducer located in each manifold provided the

electrical input to the indicator boxes. The centerline of

each ram was measured to be 9 ft-9 in above the laboratory

test floor.

The rams were attached to reaction frames constructed

of rolled steel sections. The principal parts of a typical

frame consisted of a wide-flange column, 10 ft high, and a diagonal member consisting of two angles placed back-to-back.

The column was braced at mid-height by the diagonal member

and both elements were bolted to the laboratory floor. The

design capacity of each frame was 10 kip applied horizonally

at the top of column. Several reaction frames are shown in

figure 4.10.

12
A total of 40 linear variable differential transducers

(LVDTs) was used to measure displacement of the nodule. The

relative location of 28 of the transducers is shown in figures

4.2 and 4.3. The isometric view in figure 4.2 locates the

14 horizontal and 5 vertical transducers along the rear of

the module. An input signal was supplied to two X-Y recorders

by LVDTs no. 5 and 17. Thus, the combined signals of the

load cells and LVDTs enabled a load-deflection curve to be

plotted for all cycles of loading.

Nine LVDTs were attached to the front of the module (see

figure 4.3). Several dial gages with f range of + 1 inch

and graduated to 0.001 inch were employed along the front

to provide a check against the LVDT recordings.

One face of two shear wall panels was instrumented with

6 LVDTs. Schematic drawings of the rectangles formed by the

transducers are shown in figure 4.4 against the background

of the two wall panels, Plane 1 and Plane 3. Transducers

23 through 34 measured wall racking deformation. Figure 4.5

shows the detail of a typical support of LVDTs positioned

along the rear of the module.

Calibration of load cells, pressure transducers and deflection transducers was performed prior to all racking tests.

All data for this test, as well as most of the data for the

remaining racking tests, was acquired through the use of a computer-controlled automatic scanner and a digital voltmeter.

The capability of the system was 200 channels. The voltmeter

readings were recorded for the designated load levels, on

magnetic tape and also on a teletype console printout. The

entire array of data acquisition equipment is illustrated

in figure 4.6. The output data, as recorded on tape, was

later converted to engineering units and the results were

printed in tabular and graphical form by an electronic computer.

13
4.2 Transient Floor Vibration - Test 2

The test arrangement, as shown in figure 4.7, consisted

of a weighted leather bag, a bag-release mechanism, a tripod

for support and a linear variable differential transducer

(LVDT) for deflection measurement.

Lead shot was placed in the bag to increase its weight

to 25 lb. It was established that the potential energy of i the bag (weight of bag times height of drop) of 75 ft-lb was

sufficient to induce a measurable excitation of wood-joist

floors. Consequently, the bag was suspended 3 ft above the

finished floor.

The LVDT had a gage length of + 1.0 in and was calibrated

to measure increments of +_ 0.0001 in. A beam of adjustable

length, to which the LVDT was attached, is shown in the background

of figure 4.7. The beam spanned approximately 15 ft -6 in

between the north and south walls of the North Bedroom. To

insure that the response of the LVDT was in phase with that

of the floor at the point of observation, the plunger was

secured to the surface of the plywood underlayment -subfloor

.

An oscillograph, equipped with a galvanometer of 600 Hz response,

was used to record the LVDT output. A trace of the floor

response was printed on oscillograph recording paper.

4.3 Sustained Floor Load - Test 3

A total of five instruments were used to measure deflection.

Two were LVDTs and the remaining three were dial gages . Four

of these instruments are visible in figure 4.8.

The LVDTs were of +^ 1 inch gage length and were calibrated

to read increments of + 0.0001 in. The dial gages had a range

of + 1 inch and were graduated 0.001 inch. A strip-chart

recorder continuously recorded the output of the LVDTs, while

the dial gages were read periodically with the aid of a

14
telescope mounted on a tripod. The support beam, partiallyshown in figure 4.8, served as the base for the deflection

readings

.

4.4 Repeated Racking - Test 4

Two 10 -kip electro-servo hydraulic rams (2 and 3) , shovm

in figure 4.9, were located approximately equal distance

from the ends of the 40 ft - 1 1/2 in module. The reaction

frames employed in Test 1 were also used for this test. The

entire test setup is shown in figure 4.10. The load amplitude

and frequency, and the cyclic function were automatically

controlled by the servo- controlled console shown in the foreground.

The number of cycles of loading to be applied in a given test

interval was preset and a counter indicated when the total

number of designated cycles had been completed.

The centerline of the rams was 9 '-9" above the laboratory

floor. Each of the 10-kip rams was equipped with a load cell,

one of which can be seen in the closeup of figure 4.11.

The deflection gages employed for Test 1 were retained

for this cyclic loading test, with the exception of LVDTs 14,

15 and 16. These LVDTs were previously attached to the portion

of module that was severed. One LVDT was attached to each

spreader beam spanning between the reaction frames in order

to monitor the deflection of the beam at the point of application

of the load.

The input provided by the deflection gages and the ram

load cells were monitored and recorded through the use of tlie

same computer- controlled automatic scanner and digital voltmeter

discussed earlier. The voltmeter readings at 50-cycle intervals

were recorded on magnetic tape and teletype console printout.

15
4.5 Reversals of Racking - Test 5

The same basic testinj^ arrangement was used for Test

5 as was used for Test 4. The two 10 -kip electro -servo hydrauli

rams remained in the same location along the front of the

40 ft-1 1/2 in module. In order to transmit a tensile force

at the eave line, three 1/2-inch diameter threaded rods were

extended through the module to connector plates attached

to the front and rear faces. Two of the tension rods are

visible in the left foreground of figure 4.11. The load anplitu

and frequency, and cyclic function were automatically controlled

by the servo - control led console shown in figure 4.10.

The centerline of the rams was 9 ft - 9 in above tlie

laboratory floor. All of the LVDTs employed in Test 4 were

used for monitoring deflection.

4.6 Racking to Capacity - Test 6

As indicated schematically in figure 4.9, four loading

rams were employed in this test. Rams 1 and 4, both 10-

ton manually-operated hydraulic actuators, were positioned

at the ends of the test structure. The two 10-kip electroservo hydraulic rams, 2 and 3, were located approximately

equidistant from the ends. The centerline of each ram was

9 ft - 9 in above the laboratory floor.

A 5-kip load cell was attached to each of the 10 -ton

rams and a digital voltmeter was connected to one of the load

cells to monitor the load application. A servo -controlled

console controlled the load application of the two electroservo hydraulic rams.

The X-Y recorders provided a plot of load versus deflection

for all stages of loading. LVDTs 5 and 8 were wired to supply

the input for the deflection coordinate. The 10 kip load

cells attached to rams 2 and 3 were linked to the X-Y recorders

to provide the data for the load coordinate.

16
After each succeeding increment of loading, all 43 channels

of data input was recorded through the use of a digital voltmeter and a computer- controlled automatic scanner. A magnetic

tape recording was obtained in addition to a teletype printout.

5. Load Program

5.1 Service Life Racking - Test 1

Concentrated loads in five locations were applied to

the front face of the module at the eave line. The positions

of the loading rams were selected to simulate the racking

effect of a uniform wind pressure distribution along the length

of the front face. The normalized pressure distribution diagram

shown in figure 5.1 was included to show the deviation from

the ideal of unit pressure. The maximum deviation occurred

at the living room end and amounted to 6 percent.

The first loading of the test simulated the shear force

that, in the actual structure, is transmitted to the top of

the second story transverse walls. To allow for the resistance

provided by the adjacent module in the actual structure,

the simulated wind force, in this and in subsequent racking

tests, was taken to be one-half of the wind drag force calculated for the actual structure.

The second loading simulated the shear force that in

the actual structure is transmitted to the top of the lower

story transverse walls. The effect of the vertical load contributec

by a second-story module on the response of the module acting

as a first-story unit was not simulated during the the second

loading. Table 5.1 summarizes the magnitude of the ram loads

for successive increments of equivalent wind pressure.

5.2 Transient Floor Vibration - Test 2 v

An impact load was applied to the floor as a result of

releasing the 25-lb bag from the head of the tripod at a
hcifjht of 3 ft. The bag-release mechanism was onerated from

outside the test room in order to eliminate any damping effects

that may have been provided by test personnel.

Two impacts were delivered for each of the four combinations,

of the point of delivery of impulse and the point of measurement

of displacement, to observe the reproducibility of the results.

A displacement versus tine trace of the floor response was

recorded on photo-sensitive oscillograph paper.

5.3 Sustained Floor Load - Test 3

The uniform loading was effected by placing t\\ro layers

of sand bags over the 11 ft-0 in x 9 ft-7 in floor area. A

total of eighty bags was used, the individual weights of which

ranged from 78 lb to 82 lb. The average weight of the lot

was found to be 80 lb. The total weight superimposed on the

floor was 6,400 lb, resulting in a uniform pressure of 61

psf. The dead weight of the floor assembly was calculated

for the components as specified, to be 10 psf. Therefore,

the actual total gravity load was 71 psf.

The specified factored load combination for the test

was 1.5L + 1.2D. The values used for the dead weight and

the design live load (i.e. ID and IL respectively) were as

follows:

ID = 10 psf

*1L = 30 psf (bedroom in a s ingle - f ami ly dwelling)

Using these design load values, the total load required for

testing was 57 psf. This magnitude of loading amounts to

85 percent of the floor's required capacity. By comparing

Adoped from the FHA Minimum Property Standards , "Structural

Design Data," Appendix A, par, C-2 Floor Loads, Table 1 [4].

18
the actual test load with the specified load value, it is

seen that a 24,5 percent greater load was applied than was

required.

Vertical deflection of five points was recorded immediatelyafter the full load was applied and several times during

the subsequent 24 hours. The ability of the floor to return

to its initial position was quantified by recording the deflection

at the same points, upon unloading the floor. Measurements

were obtained immediately after the load was removed and at

several intervals during the subsequent 24 hours.

5.4 Repeated Racking - Test 4

Concentrated loads were applied at the eave line of the

front face of the module at two locations. These loads varied

with time in accordance with a half-sine wave. This test

involved 1000 cycles of loading from ID to (ID + 0 . 5W) . The

magnitude of the horizontal forces was determined by considering

the contributory area shown in figure 5.3b, minus the 19 ft3 in long living room space which had been severed from the

remaining bedroom portion. The loading used was considered

capable of closely representing the loading experience of the

actual structure during its service life. The design wind

pressure (i.e. IW) was taken to be 20 psf.

The 1000 cycles of loading were applied automatically

by the hydraulic rams and the load control was preset such

that 50 cycles of loading would be applied at a frequency

of 1 Hz. The maximum amplitude of loading during each cycle

was 2.5 kips per ram. Twenty blocks of these 50 cycles of

loading were required to complete the test loading. In addition,

there were two manually- controlled cycles of loading, one

preceding the first 50-cycle block and one following the

lOpOth cycle. The entire sequence of loading is shown schematically

in figure 5.2. The manually controlled cycles are denoted

as "static" cycles in the figure. Note that the abscissa is

19
intermittently labeled with a letter to establisli the terminals

of the 50-cycle blocks, as well as the points of zero and

peak load for tlie static cycles. The horizontal and vertical

displacements of selected points were measured at the terminals

of the 50-cycle blocks and residual deflection measurements

were obtained 24 hours after the 1,000th cycle.

5.5 Reversals of Racking - Test 5

The application of 5 cycles of lateral load, reversing

from +11: to -IE, was intended to provide a simulation of the

fatigue experience that the structure could undergo during

a major earthquake. Since there is no known requirement

for deflection limitation of a structure subjected to such

loading, the main consideration was the effect on t]ie visible

joints in the test structure and the change in stiffness of

the structure.

The magnitude of the test load was calculated in accordance

with the seismic provisions for two-story structures in the

1967 edition of the Uniform Building Code.^^-' Tlie weight calculatio

was based upon a two-story, wood- frame structure 40 ft-1 1/2

in long X 12 ft wide.

A sinusoidal forcing function was applied to the front

of the test module The frequency of the forcing function

was varied to observe any resulting differences in the characteristics of response. The three selected frequencies were 0,1

Hz, 0.5 Hz and 0.75 Hz.

5.6 Racking to Capacity - Test 6

It was discovered in Test 1 that no measurable increase

in residual deflection occurred after three cycles of loading

had been applied. In order to effect this "shake-down" condition prior to beginning the test, three cycles of loading

were performed by ram nos . 2 and 3. Figure 4.9 sliows the

20
location of the rams. The peak load in each cycle was approximately

100 lb per ram. Zero load readings were obtained before and

after the three cycles.

The racking test was begun with a load of 500 lb on each

of rams 2 and 3 and 250 lb on each of rams 1 and 4. This

2:1 ratio was maintained throughout the test in order to effect

uniform load distribution. The structure v/as then subjected

to monotonic loading and horizontal deflection at two points

was recorded using two X-Y recorders. Loads on rams 2 and

3 were generally increased in increments of 500 11) except

that in the early stages of the test the load level was increased

directly from 1000 lb per ram to 2000 lb per ram. At the

predetermined load levels, interior and exterior surfaces

were examined for signs of distress. Closet doors and the

three exterior windows were also checked for malfunction.

6. Results

Four tests involved racking response and two tests were

concerned with floor performance. Generally, the ^lata acquired

from the four racking tests had to be transformed •^o 'Engineering

units through the use of ^n electronic computer. In the case

of tests 1 and 6, curves relating applied load to resulting

deflection (i.e. P-A curves") were subsequently plotted automatically

for all deflection transducer channels. As a means '^f ronfirming

the reliability of the readout from the automatic -^^ata acquisition

equipment, X-Y recorders plotted ^-A curves for the response

at "^wo critical locations. A <?econdary check was accomplished

by using the readings of six mechanical dial gages at -"^arious

""ocations along the front of the test structure.

6.1 Service Life Racking - Test 1

A series of curves of applied load versus net horizontal

displacement are presented in figures A. 3 through A. 12.

21
The values on the abscissa were obtajnea by calculating

the tlifference between the horizontal deflection at tlie ton

of the rear wall and that at the ton of the sunnort assembly.

No attempt has been made to separate the f^ross horizontal

deflection at a point into its three components, i.e. deflection

due to 1.) rinid body rotation, 2.) curvature and rackin^^.

Five curves depictin.r the lateral displaccnent profile

are sliown in figure 6.1. These curves, corresponding, to

equivalent wind pressures of 13.19, 26.38, 35.50, 41.96

and 47.63 psf, illustrate the deformation behavior of the

test module relative to its oric^inal position.

6.2 Transient Floor Vibration - Test 2

The response of the test floor to the impact loading,

is presented in figures 6.2 through 6.5 in the form of deflection

amplitude versus time curves. There were t\.'0 trials for

eacli of the four setups (see ripht side of figure 6.2 and

6.3) and lience there are eight traces presented.

The response for the first trial within a given sctun

is denoted by the number 2 followed by a single letter (i.e.

2A) . The seconrl trial for the same setup is identified by

tlic number 2 followed by tA\'o letters (i.e. 2A.^) . In all

cases, the positive side of the trace corrosnonds to the

downward motion of the floor.

It sliould be noted that in three of the four test setups

tiie initial amplitude trace is truncated rather t!\an possessinr;

a vertex similar to the remaining amplitudes. This anor.ialy

was due to the limited outjnit of the amplifier in the os c i 1 1 o;'.rn'^h

recorder. The positive half of the first cvclc has been

extrapolated by dashed lines to indicate the probable initial

amplitude

6.3 Sustained Floor Load - Test 3

T]ie deflections recorded by a LYDT nlace l at the ccr;t';^r

of the south bedroom are presented in figure 6.6, v;hero tliev

22
are compared with results obtained by a dial gage. A second

LVDT was located 8 inches south of the one depicted schematically

in figure 6.6 and the two plots of deflection versus time

were identical. The lengths of time required by the loading

and unloading operations are presented for completeness. Since

the load was neither applied nor removed in a strictly regulated

manner, it is doubtful that the relationship between deflection

and time was linear. Consequently, dashed lines are used

to join points corresponding to the beginning and the end

of these two operations.

It should be noted that within each 24-hour observation

period, there were approximately 15 hours during which no

data was obtained from the dial gages. Consequently, dial

gage readings are concentrated near the ends of the creep

and recovery periods. In the case of the LVDT output, however,

the recording of data was continuous.

6.4 Repeated Racking - Test 4

The output from all LVDT's and from both load cells was

recorded at the terminal points of the 50 -cycle blocks. These

21 data points are indicated by the letters C through W on

figure 5.2. In the static cycles, data from all channels

was recorded at the points indicated by the letters A, B,

X and Y in figure 5.2. It should be noted that the data at

points X and and Y was acquired 24 hours after the 1000th

cycle was completed. By comparing the magnitude of the LVDT

readings for the 20 data points, beginning at point D, with

the reference reading obtained at point C, it was possible

to determine the ability of the module to recover its original

geometry. The comparison of the deformation response for

five channels is presented in table 6.1. The LVDTs selected

for presentation were located either at the top of the rear

wall or at the joint between the module and the support assembly.

23
Visual examination of the interior and exterior of the module

at each terminal point did not lead to the discovery of any

new damage or distress.

6.5 Reversals of Racking - Test 5

The five reversals of lateral load did not cause any

apparent structural damage to the test module or to the joint

at its base. No new cracks were observed nor did any old

cracks re -appear. The maximum amplitude of ram travel, as recorded by the strip chart recorder, was 0.15 inclies in

the direction of pull and 0.10 inches in the direction of

push. These values of maximum amplitude i^ere independent

of the frequency of the forcing function. The peak lateral

load was set on the control console at 4600 lb in each direction.

6.6 Racking to Capacity - Test 6

The deflection at each LVDT location was measured for

each increment of load. Curves were generated by electronic

computer to show the relationship between applied load and

net horizontal defleciton along planes 1, 3 and 4. It was

not possible to plot a curve for plane 2 because of a malfunction

in LVDT 17. The abscissa for each of the three curves (figures

6.7 through 6.9) \\ras obtained by subtracting the horizontal

deflection at the top of the support assembly froin that at

the top of the rear wall. The magnitude of the force at ram

2 is plotted along the ordinate of each curve.

The testing was terminated when the bond was broken

between the module base and the support assembly.

24
On the front side, the glue line failed in tlie vicinity of

the tie-down assemblies; consequently, the module was vertically

separated from, and laterally displaced relative to, the

support assembly. Between the tie-down assemblies the entire

module- support assembly was raised to the point that it lost

contact with the laboratory floor. Also, there was horizontal

splitting of the 2 x 10 perimeter beam adjacent to two of

the interior tie-down assemblies along the front of the support

assembly. These local failures were apparently caused by

a combination of tension perpendicular to the grain and horizontal

shear in the direction of the lateral force. The level at

which the splitting occurred coincided with the top of the

2x8 perimeter beam shown in detail "A" of figure 2.4. Tliese

cracks were tapered over their approximately two-foot length,

with the wider end being immediately adjacent to the tiedowns. Along the rear of the module, there was horizontal

splitting of the header beam in the vicinity of tlie interior

tie-down assemblies. The mode of failure was horizontal shear

deformation. Furthermore, the two most critical LVDTs , 8

and 11 were compressed to the fullest extent of their range

of 1 inch at the time the test was terminated.

7. Discussion of Results

The results of all the racking tests (Tests 1, 4, 5 G 6) are subject to the general qualification that an adhesive

with unknown durability properties was used in some critical

structural applications. It was not witliin the scope 'f

this test program to evaluate the durabilitv of tlie adhesive

"sed, so it is not possible to draw any conclusions about

its long-term performance from these tests.

7.1 Service Life Racking - Test 1

The total lateral force was interpreted as an equivalent

wind pressure in accordance with ANSI Standard A58.1 - 1972

25
[5]. Since the entire two-story structure falls within one

height zone, a uniform pressure was considered to act on the

projected wall area. According to section 6.5.3.2.3 and table

6, of A58.1, it is recommended that a pressure coefficient

of -0.7 be used normal to the leeward slope and -0.3 be used

normal to the windward slope. By performing two coordinate

transformations, the resultant horizontal force on the roof

can be represented by a pressure coefficient of +0.4 applied

normal to the vertical projection of the roof.

A comparison of columns (A) and (B) in table 5.1 will

show that the ratio between them changes after the total lateral

load value of 5150 lb. This change reflects the consideration

of two cases of contributory area. Although the test module

was designated as a second-story unit, it was concluded, after

comparing the plans and details of the upper and lower-story

units, that its lateral stiffness was reasonably representative

of that of a lower-story unit. Thus, the first four lateral

load tabulations in table 5.1, were designed to simulate the

wind pressure acting on the contributory area whose profile

is illustrated in figure 5.3a. The remaining five tabulations

were assumed to simulate the wind pressure acting on a wall

area extending from midheight of the lo\\fer story to the ridge

of the roof. The profile of the area contributing to the

second loading condition is shown in figure 5.3b.

In order to estimate the lateral stiffness of the tv/ostory structure in its site assembled position, it is first

necessary to determine the degree of correlation between the

test module and the actual structure. It has been previously

stated that the test module was a prototype of a second-story

front unit in the proposed structure. Tlie difference between

the test module and the proposed structure is the detail of

the support assembly. By comparing the details of the asser.il->ly as illustrated in figure 2.4 with those of the lower-story

ceiling (see figure 2.3), it is seen that tlie edge members

26
are identical. Otherwise, the ceiling diaphragm differs from

the support assembly since there is a difference in size and

spacing of the joists and an absence of gypsum wallboard from

the latter. This particular qualification notwithstanding,

it is still worthwhile to postulate a model that can be used

to relate drift at the second floor level to static wind

pressure acting normal to the longitudinal walls of the erected

structure. The analogy is presented pictorially in figure

7.1. The top illustration refers to the data points associated

with the vertical planes identified in figure 4.4. Total

lateral load applied to the test structure is denoted as P

while notations A^^, a^, and refer to the horizontal

planes in which lateral deflection was measured. In ascending

order the levels are: 1.) the laboratory floor, 2.) the top

of the support assembly, 3.) the floor of the module, and

4.) the ceiling of the module. In the bottom illustration,

the four horizontal diaphragms ^present in the actual structure

are labelled in ascending order. The total concentrated load

apportioned to the respective levels is symbolized by the

arrows on the left hand side of the sketch. The equations

yielding the gross horizontal deflection at levels 1 through

3 are shown on the right side of the sketch with deflection

at level 3 being referred to specifically as drift. A typical

application of the model to data acquired for plane 3 is included

in Appendix B. The resulting drift value was subsequently

used as one of the coordinates to locate a point on the drift

versus simulated wind pressure curve.

The result of plotting the derived drift as it varies

with the simulated wind pressure is presented in figure 7.2.

Three vertical planes, 2, 3^4., were selected for presentation

as the data showed them to be the most critically affected

by the test loading. The curves for planes 2 and 4 must be

qualified in that all four contributing data points alluded

to in the top sketch of figure 7.1 were not located along

the rear of the test module. In the case of plane 2, the

27
data for A^i^ and provided by LVDTs 39 and 38 respectively,

both of which were located on the front and offset approximately

3 ft from plane 2. In order to provide values for along

plane 4, the output from LVDT 22 was used. This transducer

was also located on the front and offset 8 1/2 in from plane

4. The primary assumption underlying this improvisation is

that the support assembly acted as a diaphragm subjected to

in-plane flexure. Therefore, it can be reasonably assumed

that the deflection measured at a point on the front of the

assembly is the same as that occurring directly in line with

that point on the rear.

It is also necessary to qualify the curve of drift versus

simulated pressure for the fact that the effect of the vertical

load provided by a second-story module was not simulated during

the loading.

The dashed vertical line in figure 7.2 coincides with

the conventionally accepted maximum allowable drift. This

value, h/500, where h is the height as defined in the Notation

section, is normally used in the design of medium and highrise buildings, and is associated with a w^ind having a 50-

year mean recurrence interval. Using the point of intersection

of this line with the curve derived for plane 4, it is concluded

tliat the maximum pressure at which the system would satisfy

this drift limitation is 21 psf.

The diagonal transducers that were installed on the walls

denoted as planes 1 and 3 (see figure 4.4) were expected to

afford a correlation between the deformation measured at

the wall surfaces and the lateral deflection measured at

the ceiling level of the test module. However, the test data

showed the change in length along the diagonals to be

an order of magnitude less than the corresponding horizontal

deflection. From this it is apparent that either the ceiling

diaphragm did not transfer a significant amount of the lateral

load to these two planes, or there was relative movement

28
between the wall framing and the gypsum wallboard surface.

Since compatibility must be satisfied between the ceiling

diaphragm and the transverse walls, it is reasonable to conclude

that resistance was provided by the transverse walls and that

relative movement occurred between the framing and the surface.

Figure 6.1 shows a set of profiles for lateral deflection

along the top of the rear wall. The five deflection transducers

from which the data were obtained, are numbered and shown

in their respective positions in the plan view at the top

of the figure. The curve between successive points is approximated

by straight lines. The shape of the profiles indicates that

the ceiling assembly underwent in-plane deformation while

transferring load to the <;hear walls. It is observed that

the maximum measured lateral displacement occurred in planes

3 and 4

.

It should be noted that the total wind drag applicable

to the actual structure was divided by a factor nf 2 to account

for the stiffness orovided by the second module. The construction

details indicated that the two modules were bolted together

near the top and bottom of their common wall with 3/8 inch

diameter through bolts. This mechanical connection '-'ould

presumably cause the two modules to deflect laterally in a compatible manner. Given two beams with identical properties,

when one is placed upon the other, the given load s shared

equally by the beams and the beams are compatible in deflection.

In a similar manner, two identical modules bolted in the manner

described above, could be expected to be compatible in deflection

and to participate equally in resisting lateral forces. However,

given that the transverse walls in the rear module may not

be distributed the same as those in the front module, the

distribution of the lateral deflection in the actual structure

may differ from that shown in figure 6.1. This qualification

to the profile curves is acknowledged.

29
There are ten curves presented in Appendix C, fij^ures

C.l through C.IO, which describe the measured net horizontal

deflection in the five previously identified pianos. Two

plots are presented for each plane, one for each of the contributor)

areas (see figure 5.3) on which the ram loads were based.

A study of figures C.l through C.IO reveals a coinmon behavior

with respect to deflection. There was a residual deflection

at the end of the first cycle of loading, but subsequent cycling

to the same maximum load did not result in a substantial increase

in this deflection. V/hen the maximum load level was increased,

there was likewise an increase in the residual deflection.

Furtlier cycling to the same peak load caused little increase

in residual deflection. This behavior may be attributed to

the removal of slackness in the connections. Once this slackness

was removed, the system behaved in a reasonably clastic manner

and the response was reproducible.

7.2 Transient Floor Vibration - Test 2

It is seen from figures 6.2 througli 6.5 tliat the impact

load v</as sufficient to create a measurable response in tJie

floor assembly. This study was concerned with damped free

vibration caused by a short - durat ion load and hence it is

necessary to account for the period of response (hiring which

tlie forcing function was on the floor system. This effect

is believed to be accounted for by neglectinp tlie first cvclc

of response because it is judged that the duration of the

load was no greater than the natural period of the subsystem.

The gain in amplitude observed between the time of 0.35 and

0.4 seconds suggests that at this point the bag made a second

contact with the floor. The range of the natural frequency

derived from the response curves extends from 23 IIz to 26

IIz. There was SO-6 success in reproducing the results of the

first trial in the two-trial sets. Tests 2B3 and 201) correlated

closely with the initial trials, 2B and 2D respectively. But

the results of tests 2A and 2C were not reproduced during

30
their sequels, 2AA and 2CC. In the latter two cases, there

was evidence of the superposition of a response of lower frequency

on the floor's response. One explanation for this occurrence

is that the beam supporting the deflection transducer mayhave been vibrating slowly, caused by some secondary motion

in the walls between which it spanned. This reasoning is

supported by the fact that there is a measurable shift in

the average deflection after 0.2 seconds in both of these

trials. It should be noted that the support beam was attached

to the surface of the walls by using rubber suction cups.

It is conceivable that the beam could have slipped down the

wall a short distance, due to vibration induced in the walls,

before the cups were secured again.

In analyzing the damping characteristics of the floor,

approximate decay envelopes can be drawn in six of the eight

traces. It is meaningless to attempt to extend the envelope

beyond the point where additional energy is introduced by

the bag's second impact on the floor. Therefore, the useable

portion of the deflection- time traces lies between the 2nd

and 8th cycles. It can then be generally concluded that in

all four test setups, the deflection amplitude in the 8th

cycle of oscillation has decayed to about 20% of the amplitude

of the 2nd cycle.

7.3 Sustained Floor Loading - Test 3

Examination of the test data shows that the maximum vertical

deflection occurred beneath the LVDT (location shown in figure

6.6). The magnitude of deflection at this point, under full

load, including the effect of creep, was 0.500 inches. The

full load deflection beneath the dial gage (located 8 inches

from the LVDT) was 0.431 inches or about 86 percent of maximum

floor deflection.

31
The increase in deflection due to creep was found to be

linear for both the instruments. Creep deflection amounted to

5.0 percent and 5.56 percent of the maximum deflection as

measured respectively by the LVDT and the dial gage. In the

removal of the superimposed load, was 81 and 91 percent

respectively. These recovery percentages compare favorably with

the American Concrete Institute's (ACI) criterion for evaluating

the performance of concrete construction under static load.

Section 20.4 of ACI Standard 318-71 [6] requires retesting of

construction failing to show 75 percent recovery, 24 hours

after load removal.

7.4 Repeated Racking - Test 4

The deflection data presented in Table 6.1 was chosen to

be representative of the total amount of data obtained. It

was found that the average final residual deflection was 10.4

percent (varied from 7.8 to 18.2 percent) of the maximum

deflection due to the superimposed loading. Thus, the structure,

after being subjected to 1000 cycles of simulated wind loading,

recovered approximately 90 percent of the maximum deflection.

These results must be qualified by the fact that the possiblydetrimental effects of aging and temperature changes on the

adhesive joining the module to the support assembly were not

allowed for.

7.5 Reversals of Racking - Test 5

Since there are no known criteria limiting the magnitude

of the maximum deflection and the amount of recovery, the

results of this racking test are qualitative. Although there

was almost one order of magnitude difference between the highest

and lowest frequencies used, the response of the structure

32
appeared to be independent of the frequency. The fact that

no cracking or other signs of distress were noted during the

course of testing is an indication that structural distress

probably did not occur.

7.6 Racking to Capacity - Test 6

As expected, the glue joint on the simulated windward

side was the critical zone of weakness in the test assembly.

This glue line was subjected to shear as well as direct forces.

A tensile force was transmitted to the joint when the magnitude

of uplift, caused by the overturning moment, was sufficient

to exceed the gravity force inherent in the module. The

dead load along the base of the windward wall was approximately

155 lb per foot. The geometry of the test configuration yields

the following relationship:

V = h X P = 0.019P

W L

where:

V = the uniform vertical force attributed to uplift (lb/ft)

P = the total lateral force (lb)

h = the height of the point of application of P above

the joint, 9.00 ft.

W = the width of the module, 11.67 ft.

L = the length of the longitudinal glue line, 40.125 ft

By assigning a value of 155 to V, it is seen that uplift

is imminent when P equals 8072 lb. The maximum total force

applied to the module was 16,920 lb. Once the ultimate stress

of the adhesive was exceeded, the glue line failed and the

module was separated from the support assembly. There were no

33
direct tests performed to determine the glue line strength.

The upward force was reacted by the tie-down assemblies and

so the separation occurred adjacent to the supports. The

lack of vertical restraint on the windward side made it possible

for relative horizontal displacement to occur between the

module and the support assembly.

It is observed on figures 6.7 through 6.9 that at the load

level of 3500 lb there was an offset in the horizontal deflection

with no apparent increase in loading. Since it is doubtful that

a "strain hardening "behavior was exhibited by the v\rood-frame

structure, it is concluded that the offset was attributed to the

means of loading. It is recalled that two hydraulic systems

were used in this test, ^he ordinate in the three figures

represents the force applied by rams 2 and 3, which were controlled

by an electronic console. Once the load level was -^et, the

servo-mechanism would automatically adjust the system until that

load is resisted. On the other hand, rams 1 and 4 were manually

activated. Accordingly, there was a time lag for applying the

end ram loads as well as for correcting any maladjustment that

might arise. Therefore, if the load began to drop off or if the

structure drifted away from the end rams, it would ^e necessary

for the operator to jack the ram until the desired load was

attained. Any additional movement of the LVDTs would appear on

the plots with no apparent increase in the load that is shown on

the ordinate

.

8. Conclusions

A summary of the conclusions drawn from the six tests are

listed below. All of the conclusions are subject to the pertinent

qualifications mentioned in Section 7.

34
1. Notwithstanding the fact that for some evaluative tests

the module represented a sample of one, its use was concluded

to be a practicable means of accomplishing evaluation byphysical testing.

2. Most of the test methods used were ad-hoc since no existing

standard methods were applicable to the tests. In view

of these shortcomings in test methodology, improved or

new test methods must be developed.

3. Based on the analytical model used to condition the results,

it is concluded that 21 psf is the maximum static wind

pressure at which the system satifies conventional drift

requirements as applied to medium and high-rise buildings.

4. When lateral wind load is simulated by concentrated forces

acting in line with a horizontal diaphragm, the strains

measured on the surface of the transverse walls are not

compatible with the lateral deflection undergone by the

diaphragm. The lack of correlation can probably be attributed

to the relative motion between the wall framing and the gypsum

wallboard.

5. For the range of lateral loads used to simulate service life

phenomena, the test structure behaved elastically after

the slack was removed. Accordingly, it is expected that

repeated applications of a given loading sequence will

yield highly reproducible results.

6. Using the results of six of the eight tests performed as

a basis, it was concluded that the natural frequency of the

test structure's floors lies between 23 and 26 Hz.

35
7. The percent of recovery, measured 24 hours after removal

of the sustained floor loading was a minimum of 81

percent. This compares favorably with the 75 percent

minimum recovery required by ACI Standard 318-71.

8. The structural integrity of the test module was preserved

through 1000 cycles of simulated wind loading. This conclusion is substantiated by the fact that there was

approximately 90 percent recovery of the maximum deflection.

9. The area of structural weakness for racking load resistance

was within the glue joint between the test structure and the

support assembly.

36
9. Acknowledgements

The authors acknowledge the contributions of the following

NBS staff and laboratory personnel:

Frank A. Rankin, Supervisory Technician, was in charge

of all laboratory handling, placement and dismantling of the

test structure. He also supervised the erection of the reaction

frames and the operation of mechanical equipment.

James Raines, Engineering Technician was responsible for

the placement of the electronic instrumentation and the

operation of the data acquisition equipment.

Randolph Williams, Physicist, was in charge of the advanced

stages of the electronic data processing.

Charles Bulik, Electronics Engineer, was responsible for the

coordination of the instrumentation and data acquisition

activities.

Felix Y. Yokel, Structural Research Engineer, contributed

many helpful suggestions and comments pertaining to the planning

and execution of the test program and to the preparation of the

report

.

Lymus Payton, Edward Tuma, James Warfield and James Seller,

Technicians, participated in the handling, placement and testing

of the test structure.

Cathy Glaze, Clerk Stenographer, performed the typing of

the several drafts of this report.

The technical review and helpful suggestions contributed

by Wayne C. Lewis, Research Specialist, Forest Products

Laboratory, are gratefully acknowledged.

37
10. References

[1] ASTfl C36-68 , Standard Specifications for Cynsum IVallboard, 1970 Annual Book of ASTM Standards, Cement, Lime,

Gypsum, Part 9, November 19 70, pp. 34-36.

[2] ASTM C79-67 , Standard Specifications for Gypsum Slieath-

:, ing Board, 1970 Annual Book of ASTM Standards, Cement,

Lime, Gypsum, Part 9, November 1970, pp. 60-61.

[3] Uniform Building Code, 1967 Fdition, Volume I,

International Conference of Building Officials.

[ 4 ] FHA Mini mum Property Standards For Multifam ily Housin.g , FHA No. 2600, US Department of Housing and Urban Development, Federal Housing Administration, Washington, D.C.

20410 , June 1969

.

[S] A58. 1-1972, American National Standards Institute,

Building Code Re quirements for Minimum Design Loads in

Buildi ng and Other Structure s, National Bureau of

Standards, 19 72.

[6] ACT Standard 318-71, American Concrete Institute, Building

Code Requirements for Reinforced Concrete, 1971.

38
(A) (B) (C) =3(A) H- 2(B) (D)

Ram Jacking Forces lb _ J Total Lateral Equivalent Wind

At Rams i,Z & 3 At Rams J & 4 JC UX, L-ti « i U Pressure, psf

192 r~ —~

b , jU

TOR /lO

R 7 7 iUoj 3861 1 Q 7ft

1 IK) /.D.Jo

1070 1860 6Q30 \JZJ .J\J J^s-J , Jsnu

1270 2190 81 80 Hi . y O

1440 2490 9300 47.64

1620 2810 10480 53„69

1800 3140 11680 59.82

Table 5„1 - Test 1 (Ram forces and equivalent wind pressure)

39
(A) (B)

Ram Jacking Force, lb

At Rams 1 & 4 At Rams 2 & 3

(C) = 2(A) + 2(B)

r

Total Lateral

Force, lb

(D)

Equivalent Wind

Pressure, psf

250

500

1000

1250

1500

1750

2000

2250

2500

2725

2820

500

1000

2000

2500

3000

3500

4000

4500

5000

5450

5640

1500

3000

6000

7500

9000

10500

12000

13500

15000

16350

16920

10.28

20.56

41.12

51.40

61.68

71.96

82.24

92.52

102,80

112.05

115.95

Table 5.2 - Test 6 (Ram forces and equivalent wind pressure)

40
LVDT READINGS (inches)

Run

Number

Load

(kips) 5 Ch

17

annel Numbers

8 19 35

n n 0.0 0.0 0.0 0.0 O.Q

u « uo J 0U Oft« . UoO 0U 11/1 . Xlf 0U , 077 U / / 0 Ot^l U . UOl

nu . nu u . uux 0 00"^ u . uuo 0u . 007 uuo 0u . 007 uu/ 0u . 007 uu/

X nu . mux nu . nn7 uu^ 0u Oii"^ . uuo 0 00'^ u . uuo 0U . 007 UU/i, 0u . 001 uux

L fl 07 U . UUH 0 00*^ u . uuo 0 00'^ u . uuo 0u . 007 uu/ 0u . 001 uux

o U . Uf u . uuo u . uuo 0u . OOA uuu 0U . OOA UUf 0u . 007 uu/

A U . U J u . uu / 0u . 007 uu / 0u . 007 uu / 0 OllA U . UUf 0u . 007 uu/

CD nu . nu 0 00"^ u . uuo 0 ooc; u . uuo 0 fioi; u . uuo 0U oo'j; . UUO 0u . 007 uu/

A

D u . u

0 00/1 U . UU4- 0u . 007 uu/. n 001 u , uu± 0 001 U . UU± 0.0

7 U . UM- 1u1 . OOQ uuy 0U . 007 UU / 0U . OOA UUD 0 00/1 U . UUf 0u . 007 uu/

QO 0 0"^ u . uo 0u . 01uxu0 0u . 007 uu / 0 00f\ U . UUD 0 00/1 U . UU4 0u . 007 uu/

Q 0u . OOQ uuy 0u . OOfi uuo 0U 00^^ . UUD 0U . OOA UUM- 0u . 007 uu/

1 n n HA 0u 01 0 . u±u 0u . OOQ uuy 0 00ft U . UUO 0 ooc; U . UUO 0 00"? u . uuo

1

1

U . UD 0U . 01UxU0 0u . OOQ uuy 0 01 0 U . U±U 0 oo^^ U . UUD 0 00*^ u . uuo

1 7 U . Uo 0u . 01uxu0 0U 01 0 . UxU 0 01 7 U . Ux/ 0U . 00^ UUD 0 00"^ u . uuo

J. J 0 DA 0u . OOR uuo U . UUD 0U 01 0 . UlU 0u . OOQ uuo 0u . oox uuo

D DA 0u . 01ux 0

u

0U . OOR UUO 0u . 01uxu0 0 OOc, u . uuo 0U 00/^ . UUS xo u . uo 0u . onuxx 0u . 01uxu0 0u 01 7 . ux/ U . UUD 0 00/1 U . UU'f ID u . uo 0 01 0 U . UJ.U 0 01 0 U . u±U (1 01

1

U . Ulx 0U 007 . UU / 0 00/1 U . UU4

1 7 J. / n 07 0 01

1

u . ux± 0 01 0 u . UxU 0 ni 1 U . Uil 0 007 u . uu / n nn/1 U . UU4

18 0.01 0.011 0.009 0.010 0.006 0.004

19 0.02 0.011 0.010 0.011 0.007 0.004

20 0.05 0.013 0.011 0.012 0.008 0.004

Static 2.50 0.051 0.098 U.121 0.076 0.054

Static 0.0 0.010 0.008 0.010 0.006 0.004

Table 6.1- Repeated Racking Test Results

Tlie word "static" in the column headed Run Number refers to the zero and peak load readings recorded during the initial and final

static cycles. See points A, B, C, X and Y in figure 5.2 on page 59.

Tlie numbers listed in the column headed Run Number refer to the

terminals of the 50-cycle blocks of loading. For example, Run

Number 1 on the table corresponds to terminal point D in figure 5.2

on page 59.

41
CN

o

a.

M-i >-i C (U 3 cn

<D 3

•l-i r-l > u

^- a

-U O

E C a O M H

•H

fx,
to

</) Te

ace' ing CL $

W> o E "o o <*- o

TJ

a> o» i_ c <i> > >

_J

liJ h-OZ

(Uoo ? z o ^ -o o c <*- ._ J O 0) O 0)

Qu e oo £oo

0) T3

<U X3 o c o 6

w. o Q.

ec CL

«/> 10 0)w c

•CJ a> *w c JZ Z3 o T3 CJ

UJ c

CO

(—1oo

1—» 3o

0)

•I-l

CO
1/2" PLYWOOD SHEATHING ASPHALT SHINGLES —

:

WEDGE BLOCKING2x8 ROS FACIA, FIELD APPLIED- —^ HINGE a 8^-0 O.C.-- 2x6 2x4 a I6 0.C 7/16" HARDBOARD SIDING

1/2" GYPSUM SHEATHING

1x2 WD BATTENS

1x8 ROS PLANT-ON24"o.c. RAFTERS

WD SILL1x8 ROS PLANT-ON—

1x12 ROS FACIA —

US ROS PLANT-ON

2x4 (3) 16" oc CONSTRUCTION BATTEN INSULATION

-BLOCKING

-2x6's

-1/2" PTD WD TRIM PTD WD JAMB

1/2" WD STOdL 2x4

WOOD TRIM

1/2 GYP WALLBOARD

•WOOD BASE

-2x4 BOTTOM Ft--CARPET -5/8" PLYWOOD

/2 GYPSUM WALLBOARD 2x4 TOP S. BATTEN INSULATION BLOCKING

2x6's 2x4 FLAT —PTD WD TRIM —PTD WD. JAMB

WD SILL1x8 ROS PLANT-ON

2x4 BOTTOM PLATE

2-2xl2's —

WINDOW

2x8's ® 16" oc

1/2 WD STOOL

: 2x4

1 WD TRIM

-« 1/2" GYPSUM WALLBOARD

, WOOD BASE

-CARPET A^-ssi^s^ss^t^^/^ PLYWOOD

3

-* 2x4 LEDGER

i . 2x4 PLATE

1/2" GROUT SPACE

-l/2"0 ANCHOR BOLTS @ 4'-0 oc POURED IN PLACE CONCRETE

SECTION THROUGH EXTERIOR BEARING WALL

Figure 2.3 Exterior Wall Section in TwoStory Structure

44
11^ 7-1" .

r

10'

10'

10'

10 REAR

J

.7X

M-2

TIE -DOWN BOLT

2X8 (TYP)

6 (TYP)

2 X 10 2x8 \

"*- 2-llt fc. ^

-|-^"(() TIE-DOWN

1, BOLT Iq/^5x4x-^'

J

- 2x8 at ^roc. /

LAB FLOOR

\

j \ STEEL

^

2-C5x6.7 BACKTO- BACK

DETAIL A- TYPICAL TIE- DOWN ASSEMBLY

^^ETAIL A —

FRONT

Z fcXfcX 3/8"/0'-&"

DETAIL B-TYPICAL ANGLE TIE- DOWN

DOORWAY TO STRUCTURAL LABORATORY

DETAIL B

/^NGLE TIE-DOWN (5)

PERIMETER OF TEMPORARY CONCRETE

SLAB AND ENCLOSING BUILDING

Figure 2.4 Plan and Details of Support

Assembly

45
c

CD •Hg

f-H CD O H

O

O

rH

05 M 5-1 to ^

H >

CD

5h

•H
q:oo

0)c

-U

•CO

(-1 o

[xj on

(1) o

0)

o

c

o

•H

+-> cS -M

H t/) »-> , 0)

O CT3 •H (U ^ IX

+-I CD W -P

eg

5-

•H

p..

PLANE I ^ PLANE 2

SECTION AT RAM I (PLANE 5)

Figure 4.4 Cross Sections Showing Loading

Rams and Instrumentation

51

S

4J «

ija

r-f o o CO a. m e C OC D o o d 'H

•xs

u

u ao

ud o Q> 6C •H M o O. o r-f CU c

pi

u C8

!h «8 >< x;

li) t« >^ H
Figure 4.7 Typical Setup for Transient

Vibration Testing
Figure 4.8 Partial View of Sustained

Load Testing

Figure 4.10 Test Setup for Repeated

Racking

Figure 4.11 Closeup View of Ram in

Region Shown in Figure 4.10
UJz

<

a.

ro

UJz

<

I

5 HYDRAULIC RAMS

1.02 1.02

NORMALIZED PRESSURE DISTRIBUTION

Figure 5.1 Pressure Distribution Effected

by Loading Rams - Test 1

58
FINAL

TIME

Figure 5.2 Loading Sequence for Test 4

59
Figure. 5.3a Second Story

0.4W

9

i

I J IW ]

I

?

Figure. 5.3b First Story

Figure 5.3 Contributory Areas for Racking

Loads in Test 1
14

LVDTS

17

CO

UJ UJ LiJ UJ z z z z

< < < <

_l 0. Q. Q. Q.

T

RAMS

PLAN OF RAMS AND HORIZONTAL TRANSDUCERS

LATERAL DISPLACEMENT PROFILE ALONG TOP REAR OF MODULE

Figure 6.1 Profile o£ the Lateral Displacement for Varying Simulated Wind

Pressures - Test 1

61
0.3125-

0.250-

TEST 2 A

LVDT- JOIST BAG-JOIST(SAME)

AMPLITUDE, INCHES

-0.0625

TEST 2B

LVDT-JOIST

BAG- BETWEEN JOIST

0.375-1

0.3125-

0.25-

0 1875-

0125-

AMPLITUDE.INCHES

0,0625-

0,0625-

0 125

LVDT U /M\ 25 LB BAG

i i i

.04 0.5 06

TIME, SEC

Figure 6.2 Deflection versus Time Traces

for Tests 2A and 2B

62
03125-1

025-

TEST 2AA

LVDT-JOIST

BAG-JOIST(Same)

0.1875-

0.0625-

AMPLITUDE, INCHES

-0.0625-

03125-1

TEST 2BB

LVDT-JOIST 0.1875 BAG-BETWEEN

JOIST

0.125-

AMPLITUDE.INCHES

-0.0625

0.0625-

Figure 6.3 Deflection versus Time Traces

for Tests 2AA and 2BB
04375-

0.375-

0.3125-

Q25-

TEST 2C

LVDT- BETWEEN JOIST BAG- BETWEEN JOIST

AMPLITUDE, INCHES

01875-

0.I25-'

00625-

-00625-

1 25 LB BAG

LVDT

777?

TEST 2D

LVDT-BETWEEN JOIST BAG-ON JOIST

0.25

OI875-

0125-

AMPLITUDE .INCHES

0.0625

-00625

Figure 6.4 Deflection versus Time Traces

for Tests 2C and 2D

64
TEST 2CC

LVDT- BETWEEN

JOIST

BAG- BETWEEN

JOIST

I Q3I25-, i

0.25-

0.1875

0.125-

AMPLITUDE, INCHES

0.0625-

-0.0625

TIME, SEC

TEST 2DD

LVDT- BETWEEN

JOIST

BAG-ON JOIST

0,25-

0.1875-

0.125-

AMPLITUDE, INCHES

Figure 6.5 Deflection versus Time Traces

for Tests 2CC and 2DD
JLd b

rod d

o

o

o

o

ro

CO

O

X

UJ

oCVJ

CO O CO

>, o

OwH

X

•U r-)

D 03 Q (D H

o

(!)

C

r-l O

.1} t-( O

x:

Cfl U-i (13 0) O O Q iJ

0)

00

(S3H0NI) NOI1331d3a
o

NET HORIZONTAL DEFLECTION (IN)

Figure 6.7 Lateral Force at Ram. 2 versus

Net Horizontal Deflection Along

Flane 1 - Test 6

67
o

^6

Q

Ram 2 vs (LVDT 8 - LVDT 35)

5 o

o

NOTE- Corresponds

to a [oral

lateral force c 169201b

0.14 0.28 0.42 0.5 6 0.70

NET HORIZONTAL DEFLECTION (IN)

Figure 6.8 Lateral Force At Rain 2 versus

Net Horizontal Deflection Alone

Plane 3 - Test 6

68
q

CVJ <

<

LLi O

ITo

<

UJ

o

in

Ram 2 vs (LVDT II - LVDT 13)

o

q

o

o

d

NOTE: Corresponds to a total lateral force of 16920 lb

0.0 0.08 0.16 0.24 0.32 0.48

NET HORIZONTAL DEFLECTION

Figure 6.9 Lateral Force at Ram 2 versus

Net Horizontal Deflection Along

Plane 4 - Test 6

69
A4

MODULE FLOOR

)))))m}n}}))W)}})})U}n)))))W)}))n

STRUG. LAa FLOOR

SECTION THROUGH TEST MODULE

a. LEVEL 3

lEvETF^

LEVEL I

p

SECTION THROUGH ACTUAL STRUCTURE

Figure 7.1 Analytical Model for Drift

Derivation - Test 1

70
0 0.2 h/500 0.4 0.6

DERIVED DRIFT AT SECOND FLOOR LEVEL (in)

Figure 7.2 Wind Pressure versus Derived

Drift Curves - Test 1

71
APPENDIX A

RECORD OV CRACK FORMATION ON INTERIOR SURFACES

Tlio followinr record described the cracking patterns

observed on the interior surfaces of the test module for the

entire history of lifting and shipping, prior to structural

testing. In order for the reader to relate the observed

cracking to one of the several events, a capsule history of

the handling operations is provided in tabular form.

Date ' January 13, 1971

January 14, 1971

January 14, 1971

January 14, 19 71

January 15, 1971

January 20, 1971

February 14, 1971

February 16, 1971

February 16, 1971

February 16, 19 71

Activity

Trial crane lift by the producer in

the assembly plant

Module lifted from assembly base onto

a flatbed trailer

Short trip by truck from assemi)ly plant

to rail siding

Module lifted from trailer to 89 '-6''

rail car

A series of five railroad humn tests

8 50 -mile rail trip from Michigan to NBS

Crane lift from rail car to a flatbed

trailer

1-mile truck ride to structures laboratory

Module lifted from flatbed trailer to

laboratory support assembly

It siiould be noted that the description of a given cracl;--

once identified- - is considered to be unchanged for subsequent

activities unless it is specifically noted. Tlie four room areas

of the module are assigned numbers from I to IV. Tlie Livin^:

72
Room Space is assigned the number I, the South Bedroom is

labeled Room II, the Middle Bedroom is labeled Room III and

Room IV is the North Bedroom. The four walls of any given room

area are labeled XF , XR, XS , XN , where X is a number from I to IV. The second symbol refers to the orientation of the wall

in relation to the floor plan in figure 2.2. The symbols F

and R refer to the front and rear walls, respectively; the south

wall is denoted by S and the north wall is denoted by N. Thus,

a designation such as IIF refers to the front v/all of the South

Bedroom.

Date: January 14, 1971

Module Status: a) Module resting on flatbed trailer at rail

siding, b) Module resting on rail car prior to

Bump Tests

Note: Observations were recorded for Status a) above and then

checked for Status b)

.

Room Number: II

Crack #1

Location: On v;all IIF, 11 1/4 in to the left of the lovjer

edge of the window frame.

Description of Crack:

Type: Vertical surface crack

Length: 15 1/4 in

Max. Width: 0.011 in

Crack #2

No data was recorded.

Crack #5

Location: On wall IIF, beginning just belov/ left edge of

window frame.

73
Description of Crack:

Type: Vertical, hairline Grack

Length : 15 in

Max. Width: Not measurable

Crack #4

Location: On wall IIF between bottom of v/indow sill and

electrical outlet.

Description of Crack:

Type: Vertical, hairline crack

Length: 10 in

Max. Width: Not measurable

Crack #5

Location: At intersection between the ceiling and wall

TIL. Crack begins at wall IIR.

Description of Crack:

Type: Horizontal crack in the tape at the joint.

Length: 12 7/8 in

Max. Width: 0. 216 in

Crack #6

Location: On wall IIF, 10 7/8 in to the left of the

windov/ frame

.

Description of Crack:

Type: Vertical, hairline crack

Length: 3 1/4 in

Max. Width: Not measurable

Crack #7

Location: At the corner formed by walls IIF and IIS,

beginning at the top of the base board and

extending upward to bottom of window sill.

74
Description of Crack:

Type: Vertical tear in the tape joint

Length: No data recorded

Max. Width: 0.060 in

Date: January 15, 1971

Module Status: Module resting on rail car ririor to Bumn Tests

Note: Module's interior was scrutinized prior to lifting from

trailer to rail car, but no data was recorded due to the

time element. However, it was generally observed that

all the cracks documented below were previously observed

when the module was resting on the trailer.

Room Number: III

Crack #1

Location: On wall IIIF, immediately to the right of the

header above the push -out bay v;indoH'.

Description of Crack:

Type: Horizontal, hairline crack

Length: 3 in

Max. Width: Not measurable

Crack #2

Location: On wall IIIF, extending the entire length between

the right hand corner of the push-out window

frame and the top of the baseboard.

Description of Crack:

Type: Vertical, hairline crack

Length: Approximately 20 in (not measured)

Max. Width: Not measurable

75
Crack #5

Location: On wall IIIF, at about the middle of the window

frame; extending from the head of the push-out

bay window to the ceiling.

Description of Crack:

Type: Vertical, hairline crack

Length: Approximately 16 in (not measured)

Max. Width: Not measurable

Crack #4

Location: On wall IIIF, extending from the left edge of

the header over the push-out bay window to the

ceiling

.

Description of Crack:

Type: Vertical, hairline crack

Length: Approximately 16 in (not measured)

Max. Width: Not measurable

Crack #5

Location: On wall IIIF, extending from the left hand corner

of the xvindow sill (push-out bay window) . Description of Crack:

Type: Diagonal, hairline crack

Length: 5 1/2 in

Max. Width: not measurable

Crack #6

Location: At the joint between wall IIIN and the ceiling.

Crack begins 5 1/2 in south of the closet (see

figure 2.2).

Description of Crack:

Type: Horizontal crack in the tape joint

Length: 21 in

Max. Width: Data not recorded

76
Date: January 15, 1971

Module Status: Module resting on the rail car prior to Bump

Tests

Note: Module's interior \^as scrutinized prior to the lift from

the trailer to the rail car, but no data was recorded.

However, it was generally observed that all the cracks

documented below were previously observed when the module

was resting on the trailer.

Room Number: IV

All cracks were located on wall IVF.

Crack #1

Location: At right edge of the header above the pusli-out

bay windov/.

Description of Crack:

Type: Vertical, hairline crack

Length: 3 in

Max. Width: Not measurable

Crack #2

Location: Located within the right 1/3 of the push-out

bay window, immediately above the header. Crack

extended full length between the header and the

ceiling.

Description of Crack:

Type: Vertical, hairline crack

Length: Approximately 16 in (not measured)

Max. Width: Not measurable

Crack #3

Location: Directly above the center of the push-out

v\?indow, extending from the header to t]\e ceiling.

77
Description of Crack:

Type: Vertical, hairline crack

Length: Approximately 16 in (not measured)

Max. Width: Not measurable

Crack #4

Location: Above the header o£ the push-out window; the

center of the crack was located 4 ft to the

south of the left side of the window frame.

Description of Crack:

Type: Vertical, hairline crack

Length: 4 in

Max. IVidth: Not measurable

Crack /f 5 Location: Projecting from directly above the left edge of

the window header.

Description of Crack:

Type: Vertical, hairline crack

Length: 2 in

Max. Width: Not measurable

Crack #6

Location: Situated between the bottom of the window sill

and the electrical outlet.

Description of Crack;

Type: Vertical, hairline crack

. Length: 7 in

Max. Width: Not measurable

Crack #7

Location: Situated between the electrical outlet and the

top of the baseboard.

78
Description of Crack:

Type: Vertical, liairline crack

Length: 4 3/4 in

Max. VJidth: Not measurable

Date: January 15, 1971

Module Status: Module resting on rail car subscqncnt to the

5th (i.e. the last) Bump Test

Room IJumber: II

Crack #5

Location: Previously given.

Description of Crack:

Same as before

Length: No change

Max. Width: Crack closed to the point t;iat vn'dt^: was no

longer measurable

Crack ff?> Location: On wall IIS, 1 in below the ceiling

Description of Crack:

Type: Horizontal, hairline crack

Length: Approximately 7 2 in

Max. Width: Not measurable

Date: Febraury 17, 1971

Module Status: Module resting on the laboratory su])port assembly

after final lifting

Room Number: I

79
Crack III Location: On wall IS at the joint betiveen the ceiling and

the v/all. Tiio crack projected rro):i a point

approximately midway dovm the sloping roof line.

Description of Crack:

Type: Diagonal crack in the tape, following the

slope of the roof.

' • Length: 7 in

Ilax. Widtli: Not measurable

Crack #2

Location: On wall IS, beginning at the ceiling line and

projecting downward. The topmost point of the

crack was located 1 ft- 10 in from wall I^

(actually no wall here, but ratlier an eave) . Description of Crack:

Type: Diagonal, hairline crack

Length: 12 in

Max. V/idth: Not measurable

Crack ffZ Location: On ivall IS, immediately adjacent to v/all IF,

near the bottom of th.e wall.

Description of Crack: Half -moon crack in the gypsum wall

board. Width of cracl: was not measur-

' able.

Room Number: II

Note: The following cracks were all observed on wall IIR.

Crack #9

Location: At the upper left corner the <loor jamb wbiich is

adjacent to the Living Room Space (see figure 2.2),

80

80
Description of Crack:

Type: Vertical surface crack

Lenjith: 12 1/2 in

Max. Width: 3/64 in

Crack no

Location: At the joint between v/all ITR and the ceiling,

near the corner formed by wall IIS.

Description of Crack:

Type: Horizontal tear in the tape joint.

Length: 28 in

Max. Width: No data recorded

Crack #11

Location: Projecting from the end of Crack .^10.

Description of Crack:

Type: Vertical, hairline crack

Length: 3 1/4 in

Max. Width: Not measurable

Crack #12

Location: To the north of the door jamb nearest the Living

Room Space.

Description of Crack:

Type: Vertical, hairline crack

Length: 11 1/2 in

Max. Width: 1/64 in

Crack #13

Location: At the joint between the wall and ceiling about

midway between walls UN and IIS.

Description of Crack:

Type: Horizontal, hairline crack in the joint.

81
LGngtli: 3 7 in

Max. Width: Not measurable

Note: The following cracks were all observed on v;all IIP and

their width was not measurable.

Crack #14

Location: Around vn.ndow frame.

Description of Crack:

Type: Vertical, hairline crack

Length : 4 1/4 in

C rack #15

Location: Above window frame at the ceiling line.

Description of Crack:

Type: Horizontal, hairline crack in the tape joint

Length: 9 1/2 in

C rack #16

Location: At the corner formed by walls ITF and IIS, beginning just above the end of Crack #7.

Description of Crack:

Type: Vertical tear in the tape joint

Length: 23 1/2 in

C rack #17

Data is too incomprehensible to report

Crack #18

Location: At the corner formed by walls IT^^ and IIS, near

the ceiling.

Description of Crack:

Type: Vertical, hairline crack in the tane joint.

Length: 2 1/2 in

82
Room Number: III

Crnck #7

Location: On \vall IIIR, at left edge of the door jamb.

Description of Crack:

Type: Vertical, hairline crack

Length: 9 1/2 in

Max. Width: Not measurable

Crack #8

Location: Along the joint between wall IIIR and the

ceiling, beginning 1 1/2 in from wall HIS.

Description of Crack:

Type: Horizontal tear in the tane joint, barely

visible in some places.

Length: 12 1/2 in

Hax. Width: Not measurable

Crack #9

Location: Inside the closet at the joint between the

ceiling and the walls.

Description of Crack: Hairline crack in the tape, extending completely around the perimeter

of the closet. The width was not

measurable

.

Room Number: IV

Crack #8

Location: Center of the crack was 2 in belov/ the ceiling

on wall IVN; crack began 4 '-6" from v;all corner

formed by wall IVR.

83
De.scriDt ion of Crack:

Type: Horizontal, hairline crack

Length : 48 in

Max. Width: Not measurable

C rack #9

Location: On viall IVN, beginning 1 in below the ceiling.

Description of Crack:

Type: Vertical, hairline crack

Length: 3 in

Max. Width: Not measurable

84
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88
19.25 AREA CONTRIBUTED BY THE VERTICAL

PROJECTION OF WINDWARD SURFACES

98.65 lb.

19731b.

j^EVB^^_____\. ^.65 1 b. LEVEL 3

LEVEL 2

LEVEL

86.181b.

04W

86.181b

?65.6 lb.:

411.2 lb

2^.6 lb.-- 178.2 Ib^

3564 lb

782 LOW

FORCE DISTRIBUTION FOR IW=I PSF

Figure B. 1 Lateral Force Distribution

on Actual Structure Due to Design Wind Pressure

89
SLM>1ATI0N OF FORCES FOR 1 psf PRESSURli .

llie following confutations represent the summation of horizontal forces

at the four levels shown in figure B.l , for a pressure of 1 psf.

Level 4 .

, 205.63 + 86.18 + 98.65 = 390.43 lb.

Level 3

98.65 + 205.6 + 304.25 lb.

Level 2

85.55 + 178.2 = 263.75 lb.

Level 1

85.55 + 178.2 = 263.75 lb.

Total Horizontal Force = 1222.18 lb.

90
A TYPICAL APPLICATION OF THE DRIFT MODEL TO TEST DATA

Total Applied Lateral Load,P ^ 5150 lb.

Equivalent Wind Pressure, IW = ^^^^ ^ x 20 = 26.378 psf

One-Half Wind Pressure = 26.378/2 = 1 3.189 psf

CONCENTRATED FORCES AT DESCENDING LEVELS OF THE ACTUAL STRUCTURE

Level 4, P = 13.189 x 390.43 = 5150 lb.

Level 3, P^ = 13.189 x 304.25 = 4013 lb.

Level 2, P^ = 13.189 x 263.75 = 3479 lb.

Level 1 P^ = 3479 lb.

CUMULATIVE FORCES AT DESCENDING LEVELS OF THE ACTUAL STRUCTURE

Level 3, P, + P^ = 5150 + 4013 = 9163 lb.

4 J Level 2,'432 P, + P^ + P^ = 9163 + 3479 = 12642 lb.

Level 1 P, + P, + P, + P = 12642 + 3479 = 16121 lb.

' 4 3 2 1

LOAD RATIOS

16121 12642 _ 9163 _ -, ^- ^150 ^^-^^'^ 2. -^= 2.4547 3. -^- 1.7793

PLANE 3

Load Factored Cumulative

LTOT Readings (in) Differences (in) P.atio A (in) A (in)

s s

6g = 0.110 = A^ - = 0.044 3.1304 0.1377 0.1377 - A^^^

£^Q= 0.062 = - = 0.048 2.4547 0.1178 0.2555 - A^^

6^^= 0.049 - A2 A^ - A^ = 0.057 1.7793 0.1014 0.3569 - A^^

6= 0.005 = A, 36 1

DRIFT = A^^ = 0.3569 in.

A/h = 0.3569/130 = 1/364
APPENDIX C

RAM 3 VS ( LVDT 5 - LVDT 7 )

Q. CN

CO

U

uu

0.02 0.04

NET HORIZONTAL DEFLECTION ( in)

Figure C.l Force at Ram 3 versus Deflection Along Plane 1 for Profile

Shown in Figure 5.3a - Test 1

92
NET HORIZONTAL DEFLECTION ( in)

Figure C.2 Force at Ram 3 versus Deflection Along Plane 1 for Profile

Shown in Figure 5.3b - Test 1

93
RAM 3 VS { LVDT 17 — LVDT 19 )

0.06

NET HORIZONTAL DEFLECTiON ( in)

Figure C.3 Force at Ram 3 versus Deflection

Along Plane 2 for Profile Shown

in Figure 5.3a - Test 1

94
NET HORIZONTAL DEFLECTSON ( in)

Figure C.4 Force at Ram 3 versus Deflection Along Plane 2 for Profile

Shown in Figure 5.3b - Test 1

95
RAM 3 VS ( LVDT 8 — LVDT 35 )

NET HORIZONTAL DEFLECTSON ( in)

Figure C.5 Force at Ram 3 versus Deflection

Along Plane 3 for Profile Shown

in Figure 5. 3a - Test 1

96
NET HORIZONTAL DEFLECTION (iN)

Figure C.6 Force at Ram 3 versus Deflection

Along Plane 3 for Profile Shown

in Figure 5.3b - Test 1

I

97
o

RAM 3 VS ( LVDT 11 — LVDT 13 )

0.0 0.01 0.02 0.03

NET HORIZONTAL DEFLECTION ( in)

Figure C.7 Force at Ram 3 versus Deflection

Along Plane 4 for Profile Shown

in Figure 5.3a - Test 1

98
0.02 0.04 0.06

NET HORIZONTAL DEFLECTION ( in)

0.08

Figure C. 8 Force at Ram 3 versus Deflection

Along Plane 4 for Profile Shown

in Figure 5.3b - Test 1

99
RAM 3 VS ( LVDT 14 — LVDT 16 )

0.0 0.02 0.04 0.06 0.08

NET HORIZONTAL DEFLECTION ( in)

Figure C.9 Force at Ram 3 versus Deflection

Along Plane 5 for Profile Shown

in Figure 5.3a - Test 1

100
Figure C. 10 Force at Ram 3 versus Deflection

Along Plane 5 for Profile Shown

in Figure 5.3b - Test 1

101