NBS BUILDING SCIENCE SERIES 146

Evaluation of Construction

Loads in Multistory Concrete

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NATIONAL BUREAU OF STANDARDS

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HATICI.'AL eiTRZP.VI OP ETAIJDAHDS NBS BUILDING SCIENCE SERIES 146 ^J^"^

^ "

Evaluation of Construction

Loads in Multistory Concrete

Buildings

S. G. Fattal

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

Sponsored by:

The Occupational Safety and Health Administration

U.S. Department of Labor

Washington, DC 20001

o

Q

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued February 1983
Library of Congress Catalog Card Number: 82-600579

National Bureau of Standards Building Science Series 146

Natl. Bur. Stand. (U.S.), Bldg. Sci. Ser. 146, 139 pages (Feb. 1983)

CODEN: BSSNBV

U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1983

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Price $6.00

(Add 25 percent for other than U.S. mailing)
ABSTRACT

Construction loads in a multistory flat plate concrete building were measured

using strain-gaged metal shores and an analog recorder. The instrumented shores were placed within an interior bay of the third story under the formwork for the

fourth story floor slab, and loads on the shores were measured continuously

over a 24-hour period during the casting and partial curing cycle of that slab.

The loads on some of these shores, when subsequently used as reshores in the same bay, were measured during an 8-hoar period which included the casting of

the fifth story floor slab. A time-lapse camera, operating synchronously with

the load data acquisition system, gathered simultaneous photographic evidence

of the construction activities during load monitoring periods. This report

presents a complete documentation of the field data in compact form for subsequent use in related studies. The load data is interpreted and compared with

construction load and design provisions of current standards.

Yiey Words: concrete buildings; concrete casting; construction loads;

construction standards; falsework; field measurements; flat

plate; floor slab; fonrMork; instrumented shores; load

measurement; multistory construction; shored constructi.on

.

iii
ACKNOWLEDGEMENTS

The author expresses his appreciation to the following individuals for their

contribution: Tom Ruschell and Frank Rankin made significant contributions

towards the execution of the project including the design, assembly, calibration and field testing of the instrumentation package and monitoring construction loads at the site. H.S. Lew provided valuable guidance and critically

reviewed the manuscript.

Nick Paleologus, Construction Manager and Larry Munday, Job Supervisor, of

Miller and Long Construction Company, provided valuable assistance and cooperation by making all the pertinent information about the structure available to

NBS and by facilitating access to, and data acquisition from, the construction

site

.

iv
TABLE OF CONTENTS

Page

ABSTRACT Hi

ACKNOWLEDGMENTS Iv

1. INTRODUCTION 1

2. FIELD INVESTIGATIONS 5

2.1 Description of the Building 5 2.2 Construction Systems 6

2.3 Instrumentation 9

2.4 Time Lapse Photography 10

2.5 Field Installation 10

2.6 Field Measurements 11

3. REDUCTION OF DATA 15

3.1 Construction Load History 15

3.2 Time Lapse Data 17

A. ANALYSIS OF DATA 19

4.1 Static Loads on Shores 19

4.2 Live Loads 23

4.3 Dynamic Effects 24

4.4 Design Basis 25

4.5 Loads on Reshores 26

4.6 Function of Time Lapse Data 30

5. SUMMARY AND CONCLUSIONS 31

6. RECOMMENDATIONS 35

TABLES

FIGURES. .

.

REFERENCES

APPENDIX A - Slab Reinforcement Details and Selected Specifications .... A-1

APPENDIX B - Construction Schedule and Concrete Cylinder Test Data B-1

APPENDIX C - Selected Data on Shoring Systems C-1

V
Facing page: Plaoement of concrete

in the fifth floor slab.
1. INTRODUCTION

In multistory flat plate building construction, it is common practice to

support the freshly cast slab at a particular floor level by a system of shores

extending one or more stories below. The number of stories requiring shores

and reshores (shores reinstalled after stripping the formwork) normally depends

upon the imposed construction loads, the rate of construction and the strength

and stiffness properties of the partially cured concrete. The rate at which

concrete matures is, in turn, a function of many parameters such as, curing

1
temperature, the properties of its constituents, effect of any admixtures,

surface-to-volume ratio and prevailing ambient conditions.

There is no well-defined or generally accepted procedure for determining

optimum shoring requirements where the partially erected concrete building is

called upon to resist the applied construction loads. The diversity of past

practices is illustrated by the 17 different shore-reshore combinations indicated in figure 1.1. The design of a safe and economical shoring scheme is an analytically complex problem which is compounded by the limited amount of

available information on construction loads and on the mechanical properties

of concrete at early ages [1]*.

The need to develop a reliable data base on construction loads and their effect

on partially completed buildings is underscored by the fact that a high percentage of structural failures occur during construction [1]. According to one survey of structural failures over a ten-year period [2], there have been fewer

collapses of structures during their service lives as compared to collapses that

have occurred during construction. The same source notes that many collapses

occur during concrete placing where construction loads have reached a maximum

on a structure whose strength is only partially developed.

The problem of shoring in multistory construction has been the topic of

analytical investigations by various authors [3-8]. The main thrust of these

investigations has been focused on the interaction between falsework and floor

slabs under construction loads based on certain assumptions regarding the

structural characteristics of the partially cured concrete and the shoring

assembly, and the effect of these assumptions on analytical results. More

recently, construction loads have been monitored at selected high-rise building

sites by means of instrumented shores during the casting cycles of several

stories [2, 9, 10, 11]. On the basis of this data, methods have been proposed

for predicting construction loads on shored slabs and formulating formwork

requirements as a function of type of cement, placing temperature and rate of

construction.

This report describes the evaluation of construction loads at the site of a 6-story flat plate office building. The equipment used in this investigation

consisted of metal shores instrumented with strain gages and hard wired through

signal-conditioning amplifiers to a multi-channel tape recorder housed in a mobile van adjacent to the structure. The building is nine bays long and six

bays wide and all bays are 20 ft (6.1 m) square except in the interior core region where their spans vary. Each floor slab was cast in four consecutive

transverse sections in as many days, so that allowing for the placement of

columns, reinforcement and falsework, the construction progressed at the rate

of about one floor per calendar week.

* Number in brackets refer to the bibliography listed at the end of this report.
The instrumented shores were placed within an interior bay of the first section

at the third floor level. The loads on the shores were monitored during a 24-

hour period, the first six hours of which was approximately the time it took

to cast the first section of the fourth story floor slab. Some of the instrumented shores were subsequently used as reshores in the same bay following the

removal of formwork. The loads on these reshores were monitored over an 8-hour

period which included the casting of the first section of the fifth story

floor slab.

During these casting operations, the construction activities were monitored by

an automatic time-lapse camera beamed on the work area. The camera was placed

on the roof of an adjacent building and operated at four second intervals. The

purpose of the camera was to identify the source, nature and time of occurrence

of construction loads for later comparison with the measured loads. The camera

also provided the type of visual information which can be examined to deteirmine

the feasibility of estimating construction loads by means of time-lapse

photography alone.

The load data gathered in the field are presented in this report in the form of

continuous plots of the individual shore loads as a function of time. The plots

were developed using a strip chart recorder. Some of these plots show markings

along the time scale that represent points in time when concrete was discharged

from the bucket onto the deck. These markings were established by examining

the films taken by the time-lapse camera.

The loading on the shores and reshores obtained in the field is analyzed and

compared with the corresponding design provisions in current codes and standards. Based on these comparisons, conclusions are drawn on the adequacy of

existing load provisions in the design of falsework systems used in concrete

building construction.

The material documented in this report provides a data source for static and

dynamic load effects in shored concrete construction. In addition, it provides

information useful in the development of a generally applicable methodology for

the evaluation of construction loads and their effects on the partially completed

structure under diverse types of field conditions. Therefore, the methodology

use in this particular study is described in all its aspects, including concrete

cylinder test results, the construction sequence and pertinent information on

the structural characteristics of the building and the shoring system.

3
Facing page: Calibration

instrimented frame shores

in the lahoratory
2. FIELD INVESTIGA.TIONS

2.1 DESCRIPTION OF THE BUILDING

The building selected for this study is a six-story concrete flat plate

structure intended for commercial use. A typical floor plan for the second

through sixth stories is shown in figure 2.1. All bays are 20 feet (6.1 m)

square except in the service core area which has the framing plan shown in

figure 2.2.

5
The story heights are specified on a longitudinal section through the core area shown in figure 2.3. Figures 2.4 and 2.5 are respective views of the east and

south sides of the building during construction of the fifth story floor slab.

The above-grade portion of the building consists of nine longitudinal bays, in

the north-south orientation, and six transverse bays. The parking garage is the

story below grade level which extends three additional bays beyond the tower at

the south and east sides, and is accessed by a ramp along the north side.

Information above the fifth story floor slab is not included in this report

because that portion of the building was not yet in place at the time the

field investigations were concluded.

The design specifications call for 3000 psi (20.70 MPa) regular weight (150 pcf

or 2A00 kg/m3) concrete, 8-in (203-mm) thick floor slabs, and design live loads

of 80 psf (3.8 kPa) plus 20 psf (960 Pa) for partitions in the office area

(figure 2.3), and 100 psf (A. 79 kPa) for the stairs. Supplementary details for

the reinforcement in a typical floor slab and selected structural specifications

excerpted from the contract drawings are found in appendix A.

2.2 CONSTRUCTION SYSTEM

The falsework for the construction of the floors in the tower section consists

of 5/8-in (15.875-mm) plywood forms laid across aluminum joists spaced at 19.2

in (488 mm) on center. The joists are supported by aluminum stringers spaced

at approximately 10 ft (3.05 m) on center in the orthogonal direction. The

stringers are supported by steel shores spaced at approximately 4 ft (1.2 m) on center along the stringers. The shores bear against the concrete floor

directly below the floor to be cast. Figure 2.6 is a partial view of the

shoring system below the second floor slab, which also appears in figure 2.7

in the background. The portion of the floor shown in the foreground of figure

2.7 has already been stripped of formwork and reshored.

The detailed sequence of construction is documented in table B.l of appendix B.

This information was assembled from the job superintendent's daily construction

log files. By scanning through table B.l, the shoring sequence for casting the

consecutive floor slabs can be established.

The slab-on-ground (SOG) is cast first. This is at the basement level, a full

story below finished grade (figure 2.3). It should be noted that the foundation slab is cast in seven sections proceeding from south toward north. This

scheme allows operations for framing of falsework, casting of columns, placement of steel bars for the slab above, and other construction activities to

proceed while the placement of the foundation slab is still in progress.

The first story floor slab, which is at grade level, is cast in ten sections.

Thereafter, each consecutive floor is cast in four sections in as many working

days, which are usually consecutive. The sections are cast in the numerical

sequence indicated in figure 2.1 which also defines their respective areas.

This scheme allows construction to proceed at a maximum rate of approximately

6
one complete floor per calendar week. Therefore, the slab directly below the

floor section being cast is seven (or more) days old.

It is noted from table B.l, that section 1 of floor 2 was cast on May 5. At

that time, the formwork for sections 1 through 5 of floor 1, which include the area under section 1 of floor 2, had been already stripped and reshored. This

practice of stripping and reshoring before casting the same section at the next

level was followed throughout the construction of the building.

Figure 2.8 shows the concrete casting schedule for the slabs up to the point

when casting of section 2 of floor 5 was completed. The numbers without parentheses indicate casting dates of the various floor slab sections. The number

within parentheses designate the dates when the formwork below the various sec- tions was stripped and reshores installed. Note that stripping of formwork for

the second and third floors occurred typically seven calendar days, and for the

fourth floor six calendars days, after casting, indicating an accelerating

trend of construction. A similar trend is observed in the time interval between

the casting of the same section in consecutive floors. The interval for the

second to fourth floors varied between eight to 13 days while that for the

fourth to fifth floor was reduced to seven days.

The criterion used in this job for stripping the formwork was that the concrete

in the slab should attain a minimum strength of 2250 psi (15.52 MPa) , which is

75 percent of the specified 28-day compressive strength: fc' = 3000 psi

(20.70 MPa). This required testing of control specimens at early ages corre- sponding to the time interval between casting and stripping of the various

sections. Table B.2 shows concrete cylinder test results at 5, 7 and 28 days

along with other control data which were part of the job superintendent's

record.

For this building, the minimum number of shored and reshored stories at any

given time is specified as one and three, respectively. This means the first

time any reshores could be removed was after casting the fourth floor and

before casting the fifth floor. Figure 2.8 specifies the date, shown in brackets, where the basement reshores in section 1 were removed; it should be noted

that this operation was carried out before casting section 1 of the fifth floor

but after section 1 of the fourth floor and the reshores below it were in place.

This procedure was followed during the construction of the rest of the building.

The shoring sequence and forming requirements for typical floor areas specified

in the contract documents are reproduced in figures 2.9 and 2.10. From the

standpoint of evaluating the distribution of construction loads to the floors

below, two additional aspects of the shoring operations need to be highlighted;

the method used for simultaneous stripping of formwork and installing reshores,

and the number of reshores used. Both of these are spelled out in the specifications shown in figure 2.9. In the first case, the first step is to install

the reshores directly against the plywood forms. This is followed by the

removal of the existing shores, stringers and joists, thereby transferring the

loads from the slab above to the reshores. The last step is to remove one

7
reshore at a time, strip the form above it and reinstall the reshore

(figure 2.9).

In the second case, the specified reshoring scheme after stripping the

formwork is illustrated in figure 2.10. This is referred to as the 100 percent

reshoring plan, according to which, eight reshores are installed for every ten

shores removed. Thus, when a story is reshored , there will be three additional

shored stories below it, assuming enough stories have been completed. However,

in accordance with the shoring requirements (figure 2.9), only the top two

stories will conform to the 100 percent shoring plan. The lower two shored

stories will conform to the 75 percent reshoring plan as illustrated in figure

2.10. As noted above, the reshores from the lowest story (75 percent reshores)

are removed before casting the next floor.

The shoring specifications in the contract documents (figure 2.9) make reference

to an independent set of documents for the design and installation of the shoring system. The shoring scheme for a typical floor (third through sixth floors)

is shown in figure 2.11, which was excerpted from the referenced documents. A

typical shoring profile outside the core region (section A-A, figure 2.11) is

shown in figure 2.12.

From figures 2.11 and 2.12 the following will be noted. The same aluminum beam

section is used for both the stringers and the joists. They are typically 21

ft (6.4 m) long except some of the joists, used between columns or in the core region, are shorter (16 ft or 12 ft; 4.9 m or 3.7 m) . Since the spacing

between shore legs is about 4 ft (1.2 m) , the stringers are continuous over

six supports as shown in figure 2.12. They are overlapped about 5 ft (1.5 m) over two adjacent shore legs (figure 2.12). In the case of the joist supports,

because the stringers are approximately 10 ft (3.1 m) on center, the 21 ft

(6.4 m) joists are continuous over three stringer supports with a typical overlap of 1 ft (0.3 m) . The aluminum beam is actually a composite section having

a U-shaped top flange which integrates a square wood section for the purpose of

nailing the plywood forms to the joists. Hereafter, this beam will be referred

to as the "Aluma beam" which in the term used by the supplier.* The sectional

and structural properties of the beam are found in appendix C.

Several types of shores were utilized in the construction of this building.

Appendix G identifies, and provides details for, each of the types. The heavy

duty steel single post shore was mainly used for the purpose of reshoring the

second story floor slab. Two of these shores (with round perforations) may be seen in figure 2.7. The steel single post shore was used as a shore as well

as reshore in above-ground stories. The nominal 4 x 4 in (100 x 100 inm) wood

post , which was assembled from two 4x4 sections jointed by two Ellis* type

* The United States Government does not endorse products or manufacturers.

Trade or manufacturers' names appear herein only because they are considered

essential to the object of this document.

8
clamps, were used mostly as reshores . The frame-type steel sho re, consisting

of two legs and three horizontal cross-bars, were used as shores in the aboveground stories. It was also used for the purpose of shoring and reshoring the

first story in the stacked mode combination with a frame shore having four

horizontal crossbars. Several of these stacks of frames can be seen in

figure 2.7. The hardware attachments for the metal shores are identified in

appendix C, along with material and structural properties of the miscellaneous

shores, and test data for the frame shores.

2.3 INSTRUMENTATION

Three frame shores, of the type with three cross-bars, and five single post

shores were instrumented with electrical resistance strain gages and calibrated

in the laboratory for use as construction load transducers in the field. Thus,

a total of eleven shore legs were instrumented.

The Instrumentation for each shore leg consisted of four 1/4-in (6.35-mm)

strain gages of identical stock mounted at the same longitudinal location and

at 90 degrees to one another around the circumference. Two of the gages

were installed in the direction of the shore axis, and on diametrically opposite faces, to compensate for flexural effects. The other two gages were also

installed on two diametrically opposite faces but were oriented at 90 degrees

with respect to the axis of the post. The gages were protected with neoprene

rubber padding to protect them from accidental damage in the field.

The single post shores were calibrated individually in a universal testing

machine. They were loaded to 10 kips (44.5 kN) and then unloaded four consec- utive times. The strain gage output signals under a 6V bridge excitation were recorded at 2-kip (8.9 kN) load intervals during the four loading-unloading

cycles.

The frame shores were calibrated in two different ways. First, each shore

column was calibrated as above (figure 2.13). Next, the frame was loaded

centrally via a cross-beam (figure 2.14) and calibrated as above except a 20-kip (89 kN) peak load was used in this case.

The calibration factors for the individual shores are listed in table 2.1.

They were calculated by averaging the replicate results. In all cases they

turned out to be constant, indicating a linear response within the range of the

applied loads. However, the factors for the frame columns, when loaded individually, were, in most cases, slightly different from those obtained by simultaneous loading, the biggest difference being about 2.4 percent. The differences

may be attributed to the flexural effect of the top cross-beam ledger of the

frame when the columns are loaded individually (the gages were mounted below

the top cross-beams, figures 2.13 and 2.14).

It was estimated that the peak load that a shore column will experience in the

field would be in the neighborhood of 5 kips (22 kN) , or 7.5 kips (33.4 kN) if an allowance is made for a 50 percent dynamic load factor. This corresponds to a

9
maximum (unconditioned) transducer output signal of approximately 2mV , based on

the calibration factors specified in table 2.1. Assuming further that a 1 percent resolution is desired, the recorder should be able to sense any load fluctuation greater than 1 percent (corresponding to a transducer signal of 20yV)

of the estimated peak shore load.

Such low signals are unrealistic to expect under field conditions where the

potential noise may be several times greater. The proximity of a transmission

tower to the site was an additional concern. Consequently, it was decided that

the signals from the transducers should be amplified close to the source before

they are transported via cables to the recording device, which, in this case, was located about 120 ft (36 m) away from the source.

The signals from 11 load channels were conditioned independently by as many

amplifiers. A full range output setting of lOV was used for a 2mV input

signal resulting in an amplification ratio of about 5000 to 1. The exact gain

of each amplifier obtained by individual calibration before use in the field

is given in table 2.1. The last column of this table gives the calibration

factors for the amplified signals from the eleven transducers.

The last basic component of the data acquisition system was a multi-channel

analog tape recorder which received the 11 amplified signals via 120-ft (36-m)

cables. A twelfth channel was utilized in conjunction with a digital time

code generator to relate the continuously recorded signals from the individual

channels to a real time frame.

2.4 TIME LAPSE PHOTOGRAPHY

An automatic time lapse camera was used for the purpose of gathering

photographic evidence of construction activities during load monitoring periods.

The camera provided a visual means by which live loads of equipment and personnel could be identified and uncoupled from the dead load of freshly cast concrete. In addition, it simplified the interpretation of dynamic load effects

by identifying their source and nature.

The camera was battery powered and was equipped to operate at settings of one

frame per 0.5 to 99.5 seconds in 0.5-second intervals as well as at 16 frames

per second, which is the standard setting of a movie camera. Other features

included weather resistant housing, automatic exposure control, an f/1.2 zoom

lens, super 8 mm format cartridge loading, and a film footage counter. The

installation and use of the camera in the field is described in the next

section.

2.5 FIELD INSTALLATION

The actual shoring layout in the first section of a typical story is shown in

figure 2.15. Note that this layout is slightly different from the original

shoring plan shown in figure 2.11.

10
After calibration, the instrumented shores were delivered to the job supervisor

for use as part of the shoring in the first section of the third story. When

this shoring was being installed, no special instructions were given to the

workers regarding the placement of the instrumented shores other than specifying

their location within the overall shoring scheme used. The intent behind this

omission was to develop a feel about possible fluctuations in shore preloads,

due to differences in snugness after they are in place, that might be reflected

in the results of subsequent measurements of shore loads.

Figure 2.15 indicates the location and numerical order of the instrumented

shores. They were all placed within a single bay, identified in the figure by

the solid square columns. This area represents a typical interior bay away

from the core region.

The procedure for installing the falsework was as follows. The frames were erected first in braced pairs to form free-standing towers (figure 2.15). Next,

the stringers were placed in the U-shaped shore heads parallel to the frames

and levelled by adjusting the telescoping staff heigths. The single post shores were then erected snug against the stringers and the Aluma joists were placed on top of and across the stringers. The 4 x 8 ft (1.2 x 2.4 m) forms were then tightly fitted and nailed to the joists with the face grain of the forms

running across the joists. Finally, the formwork was levelled by making the

necessary fine adjustments in the shore heights.

The data acquisition equipment was installed after the falsework was in place

and the area cleared of workers and materials. To keep the length of transducer lead wires to a minimum (within 15 ft or 4.6 m) , the amplifiers were placed

as close as possible to the instrumented shores. They were mounted on racks

and housed in an enclosed metal container equipped with an intake fan (figure

2.16). The lead cables from the amplifiers were bundled and lowered over the

edge of the slab (figure 2.17) into a mobile van near the south side of the

building (figure 2.18) where they were attached to an analog recorder housed

in the van.

The time lapse camera was mounted on an adjustable tripod placed on the roof of a six-story structure on the south side of the building (figure 2.19 and 2.20).

This was not the best location for the camera because the inclination of the

lens axis from horizontal was in the 6 to 9 degree range when beamed on the

work area. A 45-degree inclination would have been preferable because it would

have offered a 'better perspective of both horizontal distances and heights.

However, there were no other surrounding buildings and mounting the camera on the crane tower or on a work platform would have possibly subjected it to excessive movement or interfered with the construction work. In this respect the

remoteness of the camera (250 ft or 76 m) from the work area was an advantage.

2.6 FIELD MEASUREMENTS

Figure 2.22 shows the framing plan of the shoring system in the third story for

a 3-bay square area in which the center bay contains the instrumented shores.

11
The location of each shore in this region was established by means of

independent tape measurements. The coordinates of the second and first story

reshores for the same region were obtained in a similar manner. These are shown in figure 2.23 and 2.24, respectively. Note that the number of reshores

in the second and first stories correspond, respectively, to the 100 and 75

percent shoring schemes shown in figure 2.10.

Table 2.2 presents a summary of the time sequence of field investigations

carried out over a 24-hour period starting with the placement of concrete in

the first section of the fouth story floor slab. At this site, a crane was used to deliver concrete to the deck in a 2 cubic-yard (1.53 ra-^) capacity

bucket. Figure 2.25 shows the loaded bucket being lifted off the ground on

the west side. The crane tower, located within an exterior bay (fifth bay

from the south side), is seen in figure 2.26.

The placement of concrete in the first section proceeded from east to west at

the rate of about 2/3 cubic yard (1/2 m-^) per minute (or at 3 minute intervals

between deliveries). Since this section requires about 150 cubic yard (115

m-^) of concrete, it would take approximately 4 hours and 75 deliveries to

complete the job. The actual figures were about the same: 3 3/4 hours (table

2.2) and 82 deliveries (chapter 3).

The first bucket was delivered at 8:00 a.m. (table 2.2). The data acquisition

system was set up 2 hours before that but because of a power interruption, the

first calibration was completed at 8:56 a.m., or about one hour after casting

began. Thereafter, the amplified signals from the eleven shore transducers

and the time code generator were recorded on tape at a speed of 15/16 ips

(23.8 mm/s) continuously (except for short interruptions for calibration or

to change the tape) until 8:30 a.m. the following morning. The system was calibrated at the beginning and end of each of the two tapes used, and at

intervals varying between two to five hours. The need for and frequency of

these calibrations were based on earlier checks of tape recorder drift during

miscellaneous field tests of the data acquisition system. All calibrations

were made at zero and 5V amplifier output levels.

During recording, the amplifier output signals were visually monitored on an oscilloscope equipped with a cathode ray tube. The time code generated signal

was also monitored visually on a digital clock which was synchronized with an electric clock mounted on an exterior shore (figure 2.21).

The time lapse camera took frames at 4-second intervals during the period

7:20 a.m. to 3:25 p.m., with one 5-minute interruption to replace the cartridge.

In order to capture sufficient detail, the camera was kept zoomed upon the work

area where concrete was being cast by rotating it manually on three different

occasions as casting progressed from east to west. The clock came in view only

during the two intermediate orientations of the camera. However, this was not

a major drawback because the clock was used primarily for convenience and as an approximate check of the clock mechanism of the camera.

12
When the third story was reshored six days later, the five instrumented shores

and two of the instrumented frames were reinstalled in the same bay as reshores.

Figure 2.27 shows their layout within the same 9-bay region shown in figure 2.22.

As before, the coordinates of all the reshores in this region were obtained by

independent measurements.

The loads on the instrumented reshores were recorded during the casting of the

first section of the fifth floor slab. This occurred the day after the third

story was reshored. The set-up and field investigations were the same as before. The duration, however, was shorter as indicated in table 2.3. The data

acquisition system was disconnected before casting was completed. Actually,

most of the slab was cast before 12:00 noon; there were only four more bucket

deliveries in the afternoon. The time lapse camera, however, kept operating

until after the casting had been completed. This marked the end of the field

Investigations

.

13
Facing page: Framing and shoving

layout below formoork of fifth

floor slab.

14
3. REDUCTION OF DATA

3.1 CONSTRUCTION LOAD HISTORY

It will be recalled that a total of three tapes were required to gather

construction load data. For convenience, these tapes will be identified by

numbers in the chronological sequence they were used. Tapes 1 and 2 contain

shore load data over a 24-hour period starting with the casting of the fourth

story floor slab. Tape 3 contains load data for the reshores used in the

third story during the casting period of the fifth floor slab a week later.

15
The channel numbers on the tapes are consistent with the numbering sequence

for shores and reshores appearing in figures 2.22 and 2.27, respectively.

For clarity, a frame-type shore column will be referred to simply as a shore

or reshore, depending on its function.

The field data is reproduced in the form of plots of the individual load

channel outputs against time using a strip chart recorder. The plots in

figure 3.1 through 3.6 represent the data for shores 1 through 11 contained

on tape 1. The full range of the strip chart paper represents a lOV tape

signal (20V in the case of channel 10). The three intermediate calibrations

at 0 and 5V levels appear in each of these plots. Although the initial and

final calibrations are not reproduced, they were used, along with the intermediate calibrations, to make the appropriate corrections for drift. This

explains the slightly oblique abscissae appearing in some of the plots. The

ordinates were converted to load units on the basis of the calibration factors

shown in the last column of table 2.1.

It was mentioned earlier that casting started about one hour before the first

calibration was completed. However, during that interval, the instrumented

shores experienced only minimal loads because the bays being loaded were remote

from that area and no other unusual loads were witnessed by the camera. The

development of shore loads occurred mostly during the time interval 9:00 to

10:30. The time scale in figures 3.1 through 3.6 is too compressed to allow

an adequate study of this transition stage.

Figures 3.7 through 3.12 were developed for that purpose. They represent

partial shore load histories in the interval 9:00 to 10:30 a.m. on an expanded

time scale. The points in time when concrete was discharged from the bucket

onto the deck are indicated by numbered points along the time axis. This

information was obtained by examining the films of casting activities taken by

the time lapse camera. The points were rounded to the nearest minute and are plotted as such. This explains why, in some cases, sudden jumps in shore

loads do not coincide exactly with the plotted points.

The time scale of the latter set of curves is still too compressed to exhibit

fully the dynamic nature of transient loads when concrete is discharged. The

inserts, however, serve that purpose. They are displayed at a selected number

of locations where the curves are too steep to be distinguishable from vertical.

The inserts were developed using the same scale for the ordinates as the parent

curves and expanding the time scale by a factor of 20.

Shore load histories for the second half of the 24-hour period are exhibited in

figures 3.13 through 3.18. They were developed from information contained on tape 2. Since the time lapse camera was not used during this period, the source of sharp fluctuations observed in most of the plots starting just before

7:00 a.m. is not known. This was about the time when the construction crew resumed work on the deck to proceed with the placement of concrete in the next

section (section 2, figure 2.11) of the fourth floor slab. The inserts in

16
figures 3.15, 3.17 and 3.18, where the time scale is expanded by a factor of

320, indicate the dynamic nature of load fluctuations in some of the shores.

The data on reshore loads were reproduced in the same manner as above. First,

the entire contents of tape 3 were plotted on a compressed time scale as shown

in figures 3.19 through 3.23. The reshore loads were then replotted using an expanded time scale for the period 9:00 to 10:30 a.m. to show the development

of loads more clearly. The resulting plots are shown in figures 3.24 through

3.28, together with a selected number of inserts at locations where sudden

changes in ordinates are indicated. Note that these changes coincide with the

various discharges of concrete represented by consecutively numbered points

along the time axis.

3.2 TIME LAPSE DATA

Time lapse photography provided a means by which the source, nature and time of

ocurrence of construction loads could be identified and related to measured

loads. The results obtained by analysis of the time lapse films are presented

in the form of diagrams and tables.

Table 3.1 compiles time lapse data obtained on the day shore load measurements

were made. The frame numbers and corresponding real time listed in the first

two columns provide the time reference for the construction events identified

in the last column. The events listed are those associated with a principal source of loading. They include the 82 pours comprising the fourth floor

slab, instances of maximum number of people found in one bay, and instances of

superimposed materials on the newly completed slab. The third column specifies

the time it took to discharge concrete from the bucket for the various pours

assuming it to be equal to the number of frames times the 4-second time lapse

interval used. Column 4 specifies the height of pour estimated by using, as visual human scale, the worker operating the lever arm controlling the flow of

concrete from the bucket. For that purpose, the worker's anthropomorphics were assumed that of the 95th percentile U.S. adult male subject [14]. The multiple

entries in this column match the corresponding numbers of exposures in the

first column. Casting events numbers 26 through 50 appear in the partial shore

load history plots shown in figures 3.7 through 3.12.

Table 3.2 compiles time lapse data obtained on the day reshore loads were measured. This table is similar to table 3.2 in format and type of content

and needs no further comments. Casting events 31 through 55 appear in the

partial reshore load history plots shown in figures 3.24 through 3.28.

In addition to the foregoing information, examination of the time lapse films

identified approximately the areas occupied by the various pours. Figures 3.29

and 3.30 superimpose the areas occupied by the pours in the fourth and fifth

story floor slabs, respectively, on the third story shoring plan, which typifies

the fourth story shoring plan as well. The arrows in these figures represent

the general direction of travel of the bucket during the discharge of concrete.

17
Facing page: Layout of reinforoement

in floov slab prior to casting.
4. ANALYSIS OF DATA

4.1 STATIC LOADS ON SHORES

The general trend of shore loads over the 24-hour measurement period may be

examined by reference to the two sets of plots shown in figures 3.1-3.6 and

3.13-3.18. It should be kept in mind that the measured loads represent, in

addition to the weight of the concrete, loads which are transient in nature,

such as effects produced by impact or the weight of construction equipment,

materials and personnel. On the other hand, the weight of the falsework,

19
reinforcing bars and any initial precompresslon in the shores, will not appear

as part of the load data.

Because the load-history plots include effects from more than one source, it is

important to distinguish loads attributed to the weight of the concrete, herein

referred to as "static loads" for convenience, from those which are transient

in nature. According to the load-history plots, the static loads were almost

fully developed by 10:30 a.m., or shortly after the 50th pour was completed

(see figures 3.7-3.12). This is understandable because, according to

figure 3.29, casting had progressed well beyond the bay where the instrumented

shores were located. Thereafter, the loads on most shores kept increasing somewhat, reached their respective peaks during the time interval 6:00 - 8:00 p.m.,

then decreased gradually until 6:48 a.m. the following day (see lower insert,

figure 3.18). The period between 6:48 and 8:00 a.m., when load measurements

were terminated, is marked with sharp load fluctuations which were particularly

significant in the case of shore 11. The cause of these disturbances is not

known with certainty because there is no photographic evidence of construction

activities which were known to have resumed at the beginning of that period.

Table 4.1 has been prepared to simplify comparison of static shore loads

occurring at specific points or periods in time. The first set of load data

(appearing in the second column) represents the static components of shore

loads at 11:43 a.m., which is the time when casting had just been completed

(see table 3.1). This was the earliest time where the area in the vicinity of

the instrumented shores became and remained free of objects and workers.

The next two columns in table 4.1 represent, respectively, the maximum static

loads, occurring between 6:00 and 8:00 p.m., and those occurring at 6:48 a.m. the following day, or just before construction work was resumed. The column

labelled "tributary loads" are static loads on the shores calculated according

to the tributary areas shown in figure 4.1(a). The entries in the column

labelled "distributed loads" were obtained by analysis, taking into consideration the structural response of the Aluma joists and stringers based on the

gridwork layout shown in figure 4.1(b). The sectional and material properties

of the Aluma beams are specified in appendix C.

The last column of table 4.1 represents the incremental static loads due to the

combined weight of the formwork, reinforcing bars, Aluma beams and the shores,

expressed in units of distributed loads per unit floor area, as follows:

psf (Pa)

3/ 4-in (19-mm) plywood formwork:

Reinforcing bars (fig. A.4)

:

Aluma beams (appendix C)

:

Steel shores (appendix C)

:

2.6 (124)

2.8 (134)

3.1 (148)

1.2 ( 57)

20
The total incremental static load of 9.7 psf (465 Pa) represents 9.7 percent

of the 100-psf (4.79 kPa) static load due to the weight of the concrete.

Thus, the incremental loads on the shores were estimated by multiplying the

distributed static loads by a factor of 0.097.

Referring to figure 4.1(b), it is noted that the Aluma joists are laid out in

the east-west direction and span over three stringer or shore lines in the

north-south direction. The joists coming into the bay overlap at the middle

shore line (shores 3, 8, 9 & 5) and are continuous over the outer shore lines

(shores 2, 6, 7 and 4, 10, 11). As a result of this layout, the middle line of

stringers (within the middle strip) receive only 60 percent of the loads transmitted to the outer lines of stringers (within the column strips), with one exception. The two joists spanning along column lines 8 and 9, respectively,

transmit more loads to the middle line than to the outer line of stringers.

The distributed loads in table 4.1 reveal the effect of this particular gridwork

layout. For example, the loads on shores 3, 8, 9 are about 60 percent of those

on shores 2, 6, 7 (or 4, 10, 11), respectively, as expected. Differences

between shore loads in a coimnon line (shores 2, 6, 7 or 3, 8, 9) are also to be

expected because of unequal spacing of shores and differences between interior

and end support reactions (shores 2 or 3 vs. shores 6, 7 or 8, 9).

Assuming a unit weight of 150 pcf (2400 kg/ra^) for concrete in accordance with

the mix design specifications, the static load in an interior bay will be

39.7 kips (177 kN) . This load will be carried by 10 shores on the "average".

The 11 instrumented shores should then support a load of about 43.7 kips

(194 kN) , or about 7 percent less than the sum of the distributed loads

(46.78 kips or 208.2 kN, table 4.1). This difference is not significant in

view of the approximation involved in estimating an "average load" on a group

of shores in a bay. For a similar reason, loads based on tributary areas (figure 4.1a and table 4.1) do not provide a good estimate of load distribution

to the shores. The approximation in this case is mainly due to the omission

of the effect of the aluma beam gridwork in the redistribution of applied loads

to the shores.

A key question from the designer's standpoint is whether distributed loads

provide a good enough approximation of dead loads. Collectively, the measured

loads (col. 2, table 4.1) are 12 percent less than the sum of distributed loads.

This difference is on the "safe" side and still not very significant. However,

within the group, a considerable amount of disparity exists between individual

shore loads. Note, in particular the 8-k (36-kN) difference between the loads

on shores 4 and 10 (see col. 2, table 4.1), a condition not likely to be

anticipated in design.

There may be a feasible explanation for the difference noted above if, for some reason, shore 4 does not develop fully its share of the superimposed

load. In that case, the adjacent shores, one of which is shore 10 (figure

4.1b), will pick up additional loads. By the same token, but to a lesser

extent, shore 3 will also pick up some of the load while the load on shore 11

21
will be relieved. The trend of the load data seems to corroborate these

observations. Note, for instance, that the measured loads on shores 3 and 11 were respectively more and less than the corresponding distributed loads determined by analysis. In the case of the remaining 7 shores, the ratio of

distributed-to-measured loads varied between the limits of 0.78 (shore 7)

and 1.42 (shore 1).

The statistical significance of load fluctuations such as the above cannot be

fully assessed without additional field data. It is not known, for instance,

if, within the limits of practical tolerances, more uniformity between shore

loads can be achieved by improved workmanship in the field. In this case,

probably more care was exercised in installing the instrumented shores than

the other shores in general. The possibility exists that such fluctuations

are inherent to the system and tighter control conditions may be impractical

and/or ineffective in achieving a more uniform load distribution. If this

turns out to be the case, it will become necessary that the design of the

shoring system provide for overloads which are not presently considered. The

magnitudes of these overloads may be determined by reliability studies once a statistically significant data base through additional field investigations

becomes available.

In view of the large scatter between shore loads observed in this study,

however, it appears likely that both improved controls in the field and consideration of overloads in design may be required. Improvements in the field would

involve tightening tolerances in the alignment, spacing and level of precompression in the shores as well as tightening maintenance, repair and replacement

requirements or procedures for the shoring system components.

Shores are subjected to various amounts of compression when the falsework is

installed. It should be noted that non-uniform precompression in the shores

will increase the static loads on some of the shores and decrease them on others, but will not alter the total static load on all the shores. In this

case, the possibility exists that shore 4 was subjected to less initial precompression than the other shores, or it may not even have been initially in contact with the stringer. However, according to figures 3.8 and 3.11, both

shores 4 and 10 started developing loads at the same time. In fact, until

9:07 a.m., shore 4 developed loads at a faster rate than shore 10. This suggests that shore 4 was structurally engaged initially, and the fact that it

failed to continue developing additional loads indicates a loss of axial stiffness, perhaps due to premature yielding of a damaged component, misalignment,

etc

.

If shore 10 were designed on the basis of distributed static loads alone, its

allowable load of 5.19 + 0.50 = 5.69 kips (25.3 kN) would have been exceeded by

more than 50 percent and the margin and safety would have dropped accordingly,

from 2.5 (table 2, apppendix C) to 1.6. The manufacturer's recommended allowable load on the shore, for a staff extension of 1.7 ft (0.52 m) in this case,

is 8.7 kips or 39 kN (table 2, appendix C) . This is close to, but less than

the total static load of 8.91 kips (39.6 kN) on that shore. The maximum static

22
load on the rest of the shores (sums of cols. 3 and 7, table 4.1) are well

below the specified allowable load.

4.2 LIVE LOADS

The design of the shores appears to be generally conservative because it uses

a 50-psf (2.40-kPa) live load in addition to the dead load (or total static

load). Actually, according to the time lapse films, live loads attributed to

workers and miscellaneous hand-operated tools (rakes, trowels, etc.) were only

a small fraction of the assumed live load at this site. For instance, during

the 48th pour, 10 workers were observed in the bay area over the instrumented

shores (table 3.1). This represents an average live load of about 5 psf

(240 Pa) in that bay. According to figure 3.29, the concrete in that bay was already in place. Therefore, it would be reasonable to assume that maximum

live loads attributed to workers can occur with full dead load and the two can

be superimposed for design purposes.

Whether a 50-psf (2.40-kPa) live load is reasonable to assume in the analysis

of construction load effects for design purposes cannot be answered with cer- tainty without additional field data. In this instance, other, and more critical, sources of loading in the "live load" category occurred during and after

the placement of concrete. Live loads resulting from the storage of materials

and equipment occurred at 1:31 p.m., or about two hours after casting had been

completed (see table 3.1). The materials were mostly stacks of forms, some of

which were placed in the bay above the instrumented shores. The transient

dynamic peak loads occurring during the placement of concrete are examined in

the next section.

Figures 3.1-3.5 indicate a noticeable increase in shore loads occurring around

2:50 p.m. and lasting for about 30 minutes. The starting time coincides with

the time a stack of forms was placed in bay 4-2* containing the instrumented

shores (table 3.1). However, the event of major significance was the placement of an air compressor unit in bay 3-3 at 3:03 p.m. The compressor weighs

about 3500 lb (1585 kg), which is about one-half the weight of a bucketful of

concrete, but is concentrated at the two wheels and a bracket post.

According to figures 3.1-3.5, the presence of the compressor did not have a major effect on the instrumented shores which were within the bay sharing a common corner with the bay supporting the compressor. It is estimated that a static load of approximately 1 kip (4.5 kN) can be transmitted to a shore from

a wheel directly above. This excludes additional dynamic effects that would occur during its placement, movement or operation.

* Bays are identified by counting from west to east then from south to north

starting with the bay at the southeast corner of the building.

23
The compressor was used to blow construction debris from the deck surface.

Since its location can vary, it could cause an additional live load of say, 1.5

kips (6.7 kN) , inclusive of dynamic effects, on any shore. This is within the

"average" 2-kip (8.9-kN) load per shore corresponding to the assumption of 50

psf (2.40 kPa) live load used in the design of the system.

On the basis of the foregoing assessment of shore loads, it would appear that

the design live load is generally adequate for superimposed loads after the

slab is cast. It should be pointed out, however, that in the case of shore 10,

the allowable load is exceeded even without live load or impact during placement

of concrete. Furthermore, the possibility of the compressor being placed on

top of that shore, thereby causing a combined load well in excess of its

allowable design load cannot be ruled out.

4 .3 DYNAMIC EFFECTS

Table 4.2 presents a summary of maximum shore loads in which peak dynamic loads

resulting from the placement of concrete are included. The two sets of plots

in figures 3.7-3.12 and 3.13-3.18 were the source of the tabulated loads.

Load increments due to dynamic effects alone may be uncoupled from static and

other transient loads as explained below.

The first set of data represents the maximum ordinates of the curves shown in

figures 3.7-3.12 during the casting period 9:00-10:30 a.m. and the corresponding pour numbers. The second set of data represents maximum ordinates of the curves shown in figures 3.13-3.18 during the period 6:48-8:30 a.m. the following day. As noted earlier, there is no photographic evidence to identify the

types of construction activities in this latter period. Since the casting of

the adjacent section of slab had not resumed, however, it is likely that the

construction activities involved preparatory tasks prior to the placement of

concrete, such as the use of the compressor to clear debris from the deck to be

cast, delivery and placement of miscellaneous construction materials and equipment on the finished slab, etc. In the process, the possibility of the compressor having been moved to the bay above the instrumented shores cannot be ruled

out. This would provide a plausible explanation for the large dynamic

disturbances occuring on some of the instrumented shores.

The f if th column in table 4.2 gives the ratios between the maximum tabulated

loads (shown underlined) and the corresponding static loads occurring at 11:43

a.m. (table 4.1). Noting that the static loads exclude all transient effects,

these ratios represent factors by which the static loads are augmented due to

the combined effect of all transient loads. Therefore, the factors representing dynamic effects due to casting operations will be somewhat less (up to five

percent less) than the listed ratios for all the shores except shores 5 and 11

in which the maximum loads did not occur during the casting period. In particular, the ratio for shore 6 will be closer to 1.24 without the contribution of

the 10 workers observed in bay 4-2 while the 46th bucket was being discharged

(table 3.1)

.

24
After maklmg these allowances, it is noted that dynamic effects cause increases

of the static (or dead) loads on the individual shores ranging from a low of

about three percent to a high of about 90 percent, or 60 precent (shore 11) if

shore 4 is exluded. If, instead of ratios, the differences between the underlined

loads in table 4.2 and the corresponding static loads in column 2 of table 4.1 are considered (as shown in the last column of table 4.2), the incremental loads

due to dynamic effects will range from a low of 0.16 kips (0.71 UN) to a high

of 1.39 kips (6.19 kN)

.

4.4 DESIGN BASIS

Current practices in the design of shoring systems may be compared with measured

shore loads by reference to provisions in existing codes and standards and the

design basis that was actually used for this particular project.

According to ACI Standard 347 [15], vertical loads to be considered in design

consist of dead loads, defined as the weight of formwork together with the

weight of freshly placed concrete, and live loads, defined as the weight of

workmen, equipment, runways and impact, which "shall" be taken as not less than

50 psf (2.40 kPa) of horizontal projection. The definition for dead and live

loads in ANSI A10.9 [16] is similar . However, the minimum allowance for live

loads and formwork is specified as 20 psf (960 Pa)

.

The design loads used for this project are consistent with the ACI provisions

cited above; the design of the shoring system was based on a dead load of 105

psf (5.03 kPa) , of which 5 psf (240 Pa) represented the weight of formwork,

and a live load of 50 psf (2.40 kPa) . The corresponding distributed loads on the shores would then be the distributed static loads due to the 100-psf

(4.80-kPa) dead load of the concrete (table 4.1), multiplied by a factor of

1.55 to account for live loads and formwork. The resulting design loads for

the shores will then be the entries in column 2 of table 4.3.

On the other hand, if this system were designed in accordance with ANSI A10.9,

the design loads would have been those listed in column 3 of table 4.3, which

were obtained from distributed static loads (col. 6, table 4.1) multiplied by a factor of 1.2 to account for live load and formwork.

The fourth column of table 4.3 presents the maximum measured loads, shown

underlined in table 4.2, augmented by the incremental static loads in the last

column of table 4.1, to account for the weight of falsework and reinforcement

not included in the measurements.

On the basis of the data presented in table 4.3 the following observations can

be made. With the exception of shores 2 and 4, design loads, calculated in

accordance with the ACI 347 code provisions, and taking into consideration the

load response of the Aluma beam system, fall within the recommended design load

of 8.7 kips (38.7 kN) for the shores. The calculated design loads of shores 2 and 4 exceed the recommended design load by about two percent, which is

insignificant

.

25
The actual design loads compare favorably with measured loads although the

latter show significant fluctuations in static (dead) loads from shore to shore

as well as loads attributable to dynamic effects (live loads). Thus, in the

worst situation (shore 10) , the measured load exceeded the recommended design

load by about 18 percent, which is a tolerable limit in a design based on a safety margin of about 2.5 for the shores. It is therefore concluded, in so far as this particular study is concerned, that the assumption of a 50-psf

(2.40-kPa) live load is likely to compensate for actual differences in shore

loads due to all effects. However, the possibility of overloads occurring on shores other than those instrumented should not be ruled out.

The same conclusions cannot be drawn with regard to design loads based on ANSI

A10.9, which, in the worst situation (in the case of shore 10), will have underestimated an actual load by about 53 percent. Even if the load on shore 10 is

regarded as an unusual occurrence, ANSI-based design loads will still have

been exceeded by about 30 percent (in the case of shore 7).

On the basis of the foregoing observations, and in conjunction with this case

study, actual dynamic (impact) effects, coupled with dead load fluctuations

seemingly inherent to the system, can produce substantially higher loads on certain shores than those based on the 20-psf (958-Pa) minimum allowance for

live load plus formwork stipulated by ANSI A10.9. This underscores the need

for recognition of a potentially critical overload problem that could result if

current ANSI load provisions were followed in the design of shoring systems.

4.5 LOADS ON RESHORES

Figures 3.19-3.23 show the development of loads on the nine reshores in the

third story during the placement of concrete in section 1 of the fifth story

floor slab. The ordinates in these plots represent loads due to the weight of

the concrete and any transient loads which may have occurred during the casting

operations. Since the load data were gathered after the reshores were in place,

they do not include the initial precompression on the individual reshores.

To simplify the interpretation of reshore data it is important to isolate the

static component of loads due to the weight of the concrete from transient

loads. However, the load history plots for the reshores are conspicuously void

of the characteristic dynamic spikes and "wiggles" appearing in the shore load

data. The absence of dynamic spikes may be attributable to the fact that the

reshores were one story removed from the source of loading and therefore, pulse

type effects were attenuated through the falsework system and the slab above

before propagating to the reshores.

A note of clarification is needed about the vertical dips appearing randomly

in all the plots (figures 3.1-3.28). Most of the dips retained their vertical

shape when the data were played out using a time scale expanded by a factor of

320. Therefore, it was concluded that the dips were not related to loads but

26
could have been caused by other factors such as electronic dropouts or system

noise. Where this was not the case, the plots were retained and reproduced as inserts to the load history plots (figures 3.17 and 3.27).

The effect of transient loads due to the weight of construction personnel and

equipment is not sharply defined in the load data plots. The maximum number of

workers observed in one bay was 12. This occurred during the 10th pour in bay

6-2 (figure 3.30 and table 4.2). When concrete was being placed in and around

bay 4-2, the number of workers observed in that bay was six or less. This

corresponds to an average live load of about 3 psf (144 Pa) in that bay.

Therefore, for all practical purposes, the reshore data may be assumed to

represent static loads.

Figures 3.19-3.23 show that most of the loads on the reshores developed during

the period 9:00-10:30 a.m. Thereafter, the loads kept increasing slowly at

different rates. At the time measurements were discontinued, the loads on reshores 2, 4, 5, 7, 8 appeared to have levelled off while those on reshores

1, 3, 6, 9 were still rising, although at a slow and diminishing rate.

Table 4.4 compiles the maximum static loads on the reshores occurring at the

end of the measurement period. The tabulated loads for reshores 1, 3, 6, 9 may

be slightly shy of their respective peaks. The portion of the static loads

carried by the fourth story floor slab may be estimated using the data in tables

4.1 and 4.4. Noting that the specified shoring layout in the second through

sixth stories is the same, it would be reasonable to assume that the sum of

shore loads in column 3 of table 4.1 can be used to approximate the sum of

loads on the corresponding shores in the fourth story. Since the load in a bay

is shared by ten shores on the "average" , the sum of shore loads in table 4.1

(43.6 kips or 194 kN) is reduced by the factor 10/11 to 39.6 kips (176 kN)

.

Similarly, the sum of reshore loads (table 4.4, col. 2) is reduced to 9.5 kips

(42.3 kN) by multiplying it with the ratio 8/9 in which the numerator designates

the "average" number of reshores in a bay and the denominator is the total

number of instrumented reshores. The difference, 39.6-9.5 = 30.1 kips (134 kN)

,

will then represent approximately the portion of the total superimposed load

resisted by the fourth story floor slab.

According to the above estimate, only about 25 percent of the total superimposed

load of 40 kips (178 kN) is transmitted to the reshores. In round numbers, the

loads carried by the fourth story floor slab and the third story reshores are

30 kips (134 kN) and 10 kips (44 kN) , respectively. If three stories were

reshored, as specified in the plans, the 10-kip (44-kN) load from the third

story reshores would be shared by the third, second and first floor slabs which

are interconnected by reshores within the second and first stories.

The portion of the total load transmitted to the third story reshores appears

to be low. It would seem that these reshores should have received more than

one-half of the superimposed load of the freshly placed concrete. A detailed

investigation of load redistribution to the lower floors is beyond the scope

27
of this report. However, it is possible to obtain an estimate on the range of

distributed loads by examining limiting situations.

A lower bound estimate can be obtained by assuming the axial stiffness of the

reshores to be infinite and the stiffness properties of the slabs in the first

through fourth floors to be identical. The superimposed loads will then be

shared equally by the participating slabs so that each floor will carry a load

of 10 kips (45 kN) ; vs. the 30-kip (134-kN) load on the fourth floor estimated

from the field data. Obviously, the upper bound situation in which the reshores

are assumed to have no axial stiffness corresponds to the total load of AO kips

(178 kN) being supported completely by the fourth floor. According to a simplified analysis, in which stiffness estimates for the floor slabs and reshores

were made based on the data in appendices B and C, respectively , the load carried

by the fourth floor would be 13 kips (58 kN) , which is slightly over the lower

bound estimate.

The large discrepancy between the results of analysis and measurement cannot

be explained satisfactorily on the basis of the existing data. The likelihood

of a measurement error is ruled out because the gain of the amplifiers were

set in the laboratory and was checked before and after the field study, and no error could have been made in the development of the data plots because the zero- and 5-Volt calibrations reproduced on all the plots are correct. On the

other hand, according to the time-lapse films, an outrigger was in place on the

second floor (figure 2.1) when the fourth floor was being cast. This raises the

possibility that reshores removed from bay 4-2 in the second story to permit

the evacuation of formwork components via the outrigger, had not been reinstalled at the time the fifth floor was being cast. If this were the case, the

calculated loads in the third story reshores would be in agreement with the

measured loads.

An important factor in the design of reshores is the amount of precompression

they will be subjected to in the field. According to the procedure described in

section 2.2, reshores become initially compressed when they are first erected

against the forms while the shores are still in place. In the process, part of

the loads on the shores is relieved. When the shores and Aluma beams are re- moved next, the rest of the shore loads is transmitted to the reshores, which

will now carry about the same total load that was previously acting on the

shores

.

The total amount of precompression on the reshores at this stage (before forms

are dropped) may be estimated conservatively as the dead load of the fourth

floor slab (40 kips or 178 kN per bay) , plus an incremental load due to the

weight of the falsework and reinforcing bars above (3.9 kips or 17.4 kN; see section 4.1). After adjusting these values by the ratio of the number of

instrumented reshores to the "average" number of reshores in a bay, the total

28
precompression on the reshores may then be estimated at (40 +3.9) (9/8) = 49.4 kips (220 kN) .

The above estimate puts the "average" precompression in an instrumented reshore

at 5.49 kips (24.4 kN) . If, instead of an average value, the total precompression is prorated to the individual reshores in accordance with the proportions

in which they shared the superimposed static loads (as shown in table 4.4,

col. 2), the preloads on the reshores will be those shown in column 3 of table

4.4. The total load in the last column of the table is the sum of the preloads

and static loads on the individual reshores.

According to the above estimate, the allowable load of 8.7 kips (39 kN) would

be exceeded in the case of reshores 2 and 9 by 23 and 55 percent, respectively.

On the other hand, if it is assumed that the preload is shared equally by the

reshores, the total loads on the individual reshores will be within the specified allowable load.

The two alternative assumptions in the above analysis provide an indication of

the possible range of values on reshore loads. However, in the absence of

specific data on preloads, coupled with uncertainties about the number of

reshored floors, there is no assurance on how closely either set of data in

table 4.4 represents actual conditions.

In the final stage of the formwork stripping operations (see section 2.2), the

reshores are removed and reinstalled one at a time, permitting recovery of

forms. This process can alter significantly the distribution of reshore loads

that existed prior to form removal. The assumption that reshores are installed

in a manner to free them of compression would be the lower bound situation

which will not control their design (conditions at the end of the first stage

will) but will create the most critical loading condition in the fourth story

floor slab. It is very likely that in practical situations the reshores are reinstalled with a certain minimum degree of snugness to keep them from falling

off during the progress of formwork removal and to control the deflection of

the slab above.

At the other extreme, the reshores may be reinstalled in a manner to inhibit

completely the deflection of the fourth floor. This will restore precompression

levels comparable to those at the end of the first stage. It is noted that

increasing the snugness of the reshores will increase the redistribution of

loads from the upper to lower floors.

4.6 FUNCTION OF THE TIME LAPSE DATA

Time lapse photography associates a measured effect with the event that produces

it by "visual" means. The time lapse data obtained from this study were used to

identify the source, type, location, and generally, the magnitudes of applied

loads in relation to measured effects. For example, the location and sequence of

the individual pours (figures 3.29 and 3.30) and their time of occurrence

(tables 3.1 and 3.2), together with the specified unit weight and amount of

concrete in each pour, were used to determine the dead weight of the concrete

and its distribution at any given time. These were then related to the corresponding measured loads on the instrumented shores and reshores (figures 3.7-3.12

and 3.24-3.28)

.

29
As noted earlier, measured loads combine the effect of static and dynamic loads.

The time lapse data identified periods during which impact and other peak transient loads occurred (tables 3.1 and 3.2), as well as periods when the slab in

the vicinity of the instrumented shores was free of personnel and objects. The

latter information was used to uncouple the static component of shore loads

from transient effects.

The capability to distinguish between static and transient loads identified a basic function of time lapse photography in the study of construction loads.

The information contained in the time lapse films suggests other possible uses

as well. For example, its potential for predicting impact loads can be examined

if additional information becomes available from field investigations making

simultaneous use of time lapse equipment and direct data acquisition systems.

In that case a statistical correlation may be sought between measured impact

loads and the height, rate and duration of concrete pours (such as documented

in tables 3.1 and 3.2). Alternatively, an analysis of the dynamic response of

the system can be performed using a forcing function for impact modelled with

the aid of the time lapse data. The analytical model can then be refined to

produce results consistent with measured impact loads.

If it can be demonstrated that time lapse photography can provide meaningful

information on transient as well as static loads, it would offer an attractive

alternative for extensive and economical surveys of construction loads in which

direct measurements are made only selectively for the purpose of verification

of loads based on time lapse data.

30

Facing page: Casting of ftoov stab

using orane tower and huoket for

delivery of oonorete.
5. SUMMARY AND CONCLUSIONS

construction loads in a multistory concrete flat plate ^^^^^^ J^^^^^^'

by means of strain gages mounted on shores and -^^^-^

^^^f ^^^^^3^^"

loads were those occurring during the casting of upper story ^1°°^

^^J^^!

Simultaneously, a time-lapse camera was used for the purpose of .dentifyxng

the construction activities associated with the measured loads.

The results of the field study are presented in this report as load versus

time plots for the Individua/instrumented shores and reshores. In addxt.on,

31
the time lapse information was used to develop tabular and graphical data on the height, rate and sequence of pours, which were in turn used to

separate the component of measured loads due to the weight of the concrete

from those due to impact and other transient effects.

The following statements summarize the major findings and conclusions of

this study.

1. The distribution of dead loads due to the weight of a freshly cast

slab to the shores below is influenced by the structural configuration of the gridwork of joists and stringers supporting the forms.

This effect was verified by an analysis in which the structural

response of the gridwork was taken into consideration. On the

other hand, when the superimposed load was prorated to the shores

according to tributary areas, the results of the analysis did not

correlate well with measured loads.

2. The maximum measured impact load on a shore occurring during the

placement of concrete was 1.29 kips (5.74 kN) . This corresponds

to an equivalent uniform live load of about 33 psf (1.6 kPa)

.

The live load of construction personnel and various tools and

materials was about 5 psf (240 Pa)

.

3. The combined dead load of forms, reinforcing bars, and the shoring

system was about 10 psf (480 Pa), or about 10 percent of the dead

load of the concrete in the slab.

4. Considering loads from all sources, the assumption of a 50-psf

(2.40-kPa) live load is likely to compensate for non-uniformity

of residual forces on the shores when they are first installed,

and for fluctuations in loads due to various other causes.

5. The results of this study show that construction loads stipulated

by the ACI 347 Standard are reasonably close to the peak construction loads measured. However, in several instances, the live loads on the individual shores exceeded those that were obtained on the

basis of the live load stipulated by the ANSI A10.9 Standard.

6. The following differences were observed between shore loads and

reshore loads attributed to a freshly cast floor. On the average,

the loads on the reshores were 25 percent of those on the shores.

This meant that 75 percent of the applied load was resisted by the

7-day old fourth floor. None of the reshores exhibited the charactersitic dynamic spikes in shore loads occuring during the placement of concrete. This suggests that impact type loads are likely

to attenuate within the top story. Consequently, impact loads may

need to be considered in design only for the part of the shoring

system within the top story.

32
The amount of precompression in the reshores can be a significant

factor in their design. No direct measurements of precompression

were taken in the field. However, at one stage of the stripping

operations, it is possible to install the reshores in such a manner as to relieve the loads that were previously carried by

the shores. As a result, when a new floor is cast, the total

loading on the reshores may exceed that on the shores. If, in

addition, the effect of non-uniform distribution of loads on the

reshores is considered, it is possible that the total load on some

of the reshores may exceed their allowable design load capacity

by considerable margins.

33
Facing page: Placement of conarete

in the hay above the instvwnented

shoves.

34
6. RECOMMENDATIONS

The experience gained from this field study underscores the importance of

additional field data on shore and reshore loads. In particular, it is recom- mended that field investigations concentrate on measurements of the level of

compression in reshores when they are first installed and thereafter, when

successive floors are cast. At present there is virtually no field-based

information on this subject.

35
Additional field studies are needed to develop a good data base for a reliable assessment of load fluctuations on shoring systems and for the

formalation of construction load criteria in design.

The construction loads obtained in this study, are, in many instances, far

in excess of those specified by the ANSI A10.9 Standard. It is recommended

that that the ANSI construction load provisions be reexamined in the light

of these findings.

To assemble needed field information on construction loads, it is recommended

that improved data acquisition systems be developed with capabilities of

assembling and processing a large amount of field data in a time- and costeffective manner. In particular, the utilization of tmie lapse equipment as the principal mechanism for gathering this information should be further

explored

.

36
TABLES AND FIGURES

37
Table 2.1: Calibration factors for shore loads

Channel

Number*

Test

Height

(ft)

Load /mV

Strain Gage

Output**

(kip)

Amplifier

Gain

V/mV Strain

Gage Output

Load/lOV of

Amplified

Output**

(kip)

Single

Post

Shores

1 9.417 4 . 016 5025 7 . 992

2 9.417 3.788 5010 7.561

3 9.417 3.846 5005 7 .684

4 9.417 3.984 5010 7.952

5 9.417 4.167 5000 8.333

Frame

Shore

No. 1

6 9.833 3.984

(4.016)

5000

7.968

(8.032)

7 9.833 3 . 636

(3.623)

5020

7 .243

(7.218)

Frame

Shore

No. 2

8 9.833 3.788

(3.759)

5035

7.523

(7.467)

9 9.833 3.788

(3.802)

4985

7.598

(7.627)

Frame

Shore

No. 3

10 9.833 3.571

(3.571)

5030 7.100

(7.100)

11 9.833 3.496

(3.413)

5035

6.943

(6.778)

1 kip -= 4.45 kN

1 ft = 0.305 m

* Channels 1 through 5 correspond to strain gages mounted on single

post shores 1 through 5 respectively. Channels 6-7, 8-9, and 10-11

correspond to strain gages mounted on double-post frame shores 1, 2 and 3, respectively.

A*

The calibration factors in parentheses were obtained by simultaneous

loading of the frame shore legs with the loading head positioned con- centrically with respect to the frame.

38
Table 2.2: Field data ] og for 24-hr period

on 5/27-28 starting with placement

of concrete in section 1 of fourth

story floor slab

EVENT DATE TIME

TR initial zero check 5/27 06-15

Start recording 07 : 21

:

00

Power loss 07 • 27

Start TL roll 1 07 :33

Power restored 07 : 52

Casting begun 08 : 00

TC synch, w/ wall clock 08 : 3 6

:

30

Calibr. 1, tape 1 (0 & 5 V) 08 • 50- 00 - 08 • 56 • 00

Calibr. 2, tape 1 11:00: 40 - 11

:

07 : 00

End TL roll 1 11 :34

Start TL roll 2 11 : 39

Casting completed 11 :43

Ambient temp. 72F (22C) 12:00

Ambient temp. 74F (23C) 13 : 00

Calibr. 3, tape 1 13 :00: 00 - 13 : 06: 20

Ambient temp. 77F (25C) 15:20

TL camera off 15:25

Calibr. 4, tape 1 15:52: 00 - 15: 58: 05

Ambient temp. 78F (26C) 16:00

Power interruption 16:11: 00 - 16: 14: 30

Ambient temp. 85F (29C) 19:10

Calibr. 5, tape 1 19:43: 00 - 19: 46: 00

Rewind & replace tape 19:47 - 20 00

Calibr. 6, tape 2 20:01: 30 - 20: 06: 30

Calibr. 7, tape 2 5/28 00:01: 00 - 00: 09: 15

Ambient temp. 7 OF (21C) 00:10

Ambient temp. 64

F

(18C) 05:00

Calibr. 8, tape 2 05 : 08

:

00 - 05: 15: 25

Calibr. 9, tape 2 08:28: 00 - 08: 34: 00

Ambient temp. 68

F

(20C) 08:30

39
Table 2.3:

EVENT

Ambient temp. 75F (24 C)

Calibration 1

Start TL roll 1

Casting begun

Ambient temp. 7 6F (24C)

Calibration 2 Ambient temp. 82F (28C)

Calibration 3

End TL roll 1

Start TL roll 2 Ambient temp. 86F (30C)

Calibration 4

Tape off

Casting completed

TL camera off

Field data log during

casting of first section

of fifth story floor slab

6/3

TIME

07 :00

07:01:00 - 07:17:00

07:42

07:45

09:00

09:01:00 - 09:05:38

10:59

10:59:30 - 11:04:40

11:41

11:42

13:00

13:00:00 - 13:04:00

13:05:00

13:53

14:28

40
Table 3.1: Data from time lapse films

related to measurements of

shore loads

Real Time Fll J-'LlLcll IVai—lOT> LLJli r\\J T1. Height of Event Number (h r :min) PoUT" L W Li- J_ TsGP^ \ ^ — * / Pour ( in)

1

-J7 : 33 - Start roll 1 370-3 /

:

Q JO 16 47 ,49,49,64 Pour 1 404-7 o

:

Ul 16 24,24,49,64 2

437-9 0 : niUJ 12 38 X 3 3

474-6 o

:

U J 12 47 X 3 4

510-1 Q . Ub 8 24,38 5 543-4 8 . 0 : 1lUr\ 8 64 X 2 6

588-9 o0 , 1 T 8 47 X 2 7

623-4 Q . o

:

15 8 64,24 8

654-5 o

:

± / 8 56 X 2 9

687-8 1 Q ly 8 56 X 2 10

720-1 o

:

ZZ 8 47 X 2 11

752-3 Q . o

;

8 47 X 2 12

802-5 o : O "7 Z / 16 24 X 4 13

841-6 Q , o

:

J (J 24 38 X 6 14

879-80 o0 jZ 8 24 X 2 15

914-5 Qo 8 44 X 2 16

955-6 0

"3 7 8 64,47 17

994-5 Qo ^ U 8 56 X 2 18

1026-8 QO 12 64,56,47 19

1062-7 OO All 24 47 X 6 20

1100-1 QO

A 7 8 24,56 21

1141-3 QO

R n jU 12 38 X 3 22

1175-6 QO dZ 8 47 X 2 23

1208-9 QO 54 8 56 X 2 24

1244-6 O0 12 64,24,38 25

1283 QO

Q , jy 4 44 26

1283 QO

. Q : _>y - 8 men in bay 5-1

1326-8 9 : Uz 12 56 X 3 Pour 27

1326-8 o

y : Uz - 10 men in bay 5-2,

6 men in bay 5-1

1366 & 1371 : u J 8 47 ,38 Pour 28

1408 9 :07 4 67 29

1442 9 .in 4 78 30

1489 9 :13 4 47 31

1489 9 :13 9 men in bay 5-2

1538-40 9 :16 12 47 X 3 Pour 32

1592-3 9 :20 8 38 X 2 33

1632-4 9 :23 12 24 X 3 34

1671 9 :25 4 64 35

1731-2 9 :29 8 47 X 2 36

188 6-8 9 :39 12 44 X 3 37

1886-8 9 :39 8 men in bay 4-2

41
Table 3.1 (con't.)

r J. dtii ti xvcdx i jjne uurat xon oi Hexght of Ev ent

V iir . niiu J r our ^, sec ) Pour (in)

1921-3 9:42 12 47 X 3 Pour 38

1981-2 9:46 8 56,47 39

2016-7 9:48 8 38 X 2 40

2049-50 9:50 8 24,44 41

2085-7 9:53 12 24 X 2, 38 42

2122-3 9:55 8 64,47 43

2165-6 9:58 8 76,47 44

2195-6 10:00 8 38,47 45

2225-6 10:02 8 44 X 2 46

2225-6 10:02 - - 10 men in bay 4-2

2255 10:04 4 38 Pour 47

2297-8 10:07 8 86,47 48

2297-8 10:07 — — 10 men in bay 4-2

2310- 10:08-

2550 10:24 - - Hoisting misc. mat 'Is

2561-2 10:24 8 47 X 2 Pour 49

2595-7 10:27 12 38 X 3 50

2626-9 10:29 16 24 X 4 51

2657-9 10:31 12 47,64 X 2 52

2696-8 10:33 12 47 X 3 Pour 53

2725-6 10:35 8 47,56 54

2756-7 10:37 8 47 X 2 55

2787-8 10:39 8 38,56 56

2815-7 10:41 12 38 X 3 57

2863-4 10:44 8 76,47 58

2895-7 10:47 12 47 X 3 59

2930-1 10:49 8 47 X 3 60

2959-61 10:51 12 56,64 X 2 61

2987-8 10:53 8 38 X 2 62

3049-50 10:57 8 56, 76 63

3081-3 10:59 12 56 X 3 64

3113-7 11:01 20 47 X 2,38 X 3 65

3147-51 11:04 20 47 X 3,64 X 2 66

3185-8 11:06 16 47 X 2,56 X 2 67

3218-20 11:08 12 56 X 3 68

3249-51 11:10 12 31,47 X 2 69

3281-2 11:12 8 56 X 2 70

3312-5 11:14 16 56 X 2,76 X 2 71

3359-62 11:18 16 64 X 2,76 X 2 72

3388-94 11:20 28 64 X 7 73

3420-2 11:22 12 47 X 2,64 74

3450-1 11:24 8 47,56 75

347 6-7 11:25 8 47 X 2 76

3558-9 11:31 8 76 X 2 77

3588-91 11:33 16 47 X 2 78

3603 11:34 End roll 1

Roll Change -

? Pour 7 9

Roll Change - ?

9 Pour 80

42
Table 3.1 (con't.)

Frame Real Time Duration of Height of Event

No. (hr :min) Pour (sec) Pour (in)

1 11:39 Start of roll 2 11-19 11:40 36 47 X 9 Pour 81

56-9 11:43 16 47 X 2,56 X 2 Pour 82

Frame

No.

Real

Time Event

1680 13:31 3-ft high stacked forms placed on bay 6-1

1750 13 :36 1 1/2-ft high stacked forms placed on bay 6-1

2020 13 : 54 1 1/2 ft high stacked forms moved to bay 5-2

2034 13:55 4-ft high stacked forms placed in bay 6-2

2100 13:59 3-ft high stacked forms placed in bay 6-2

2140 14:02 Ditto

2/00 14 : 06 Ditto

2640 14:35 4-ft high stacked forms placed in bay 3-2

2690 14:38 Ditto

2750 14:42 Ditto

2850 14:49 4-ft high stacked forms placed in bay 4-2

2890 14:52 3-ft high stacked forms placed in bay 6-3

3060 15:03 3500-lb compressor placed in bay 3-3

3240 15:15 Stack in bay 4-2 split into 3 stacks, same bay

3270 15:17 Middle stack of precedent removed

3395 15:25 End of roll 2

1 in = 25.4 mm

43
Table 3.2: Data from time lapse films

related to measurements of

reshore loads

Frame Real Time Duration of Height of Event

No. (hr :min) Pour (sec) Pour (in)

1 7 :42 Start roll 1

36-7 7 :45 8 38,47 Pour 1

74-6 7 :47 12 47,56,67 2 110-1 7:49 8 47 X 2 3

147-9 7 :52 12 47 X 2, 53 4

185-7 7:54 12 47 X 3 5 223-4 7 : 57 8 38,64 6

258-9 7 : 59 8 38,47 7

294 8 : 02 4 56 8

325-6 8 :04 8 47,64 9

360-2 8:06 12 47, 64 X 2 10

360-2 8 : 06 12 men in bay 6—1

397 8 :08 4 76 Pour 11

437-8 8:11 8 56 X 2 12

470-1 8 :13 8 64 X 2 13

504-5 8 :16 8 47, 38 14

558-9 8:19 8 56, 76 15

616-8 8 : 23 12 47 ,56,76 16

652-3 8:25 8 56, 47 17

686-7 8:28 8 31 X 2 18

732-4 8 : 31 12 76 X 3 19

765-7 8 • 33 67vJ / XA. 2^ 47 J ^ / 7 97-8nn X1 6VJ ^6 44 X 2 47 21£m X O J J —_) O • JO 1 9 868-7 n 76/ U XA. J3 93

91 3-5 8 '43 X ^ 47 X 2 , 64 24

QS9-3 8 '45 8 47 67 25

Q87-Q 8O •

• A8HO X1 9z 47*-r / xA. J3 ^96O

1 1 on ft • O • _J J A 47 97

1135-7 8 : 58 12 44,61,76 28

1173-4 9: 00 8 38,76 29

1209 9 • 03 4 56 30

1259 9:06 4 56 31

1259 9 : 06 9 men in bay 4—2

1 ? QA - S 8 56, 64 Pour 32

J. J J VJ -L 9'n 8 38 , 56 33

1364-5 9:13 8 56^47 34

1401-2 9:15.5 8 47 , 64 35

1436-7 9:18 8 64 X 2 36

1469-71 9:20 12 56,47,56 37

1503-4 9:22 8 56,76 38

1532-8 9:24 28 39

1577-9 9:27 12 56,47,56 40

1619-20 9:30 8 47,67 41

1652 9:32 4 47 42

44
Table 3.2 (con't.)

Franie Real Time Duration of Height of Cvent

No

.

(hr :inln) Pour (sec) Pour (in)

168 6-7 9: 34.5 8 38,47 Pour 43

1720-1 9: 37 8 47,64 44

17 54 9 39 4 67 45

1800 - 2000 9: 39 - - Hoist misc. mat 'Is 2069-70 10 00 8 47,56 Pour 46

2106-7 10 02.5 8 47,56 47

2137-9 10 04.5 12 47 X 2,76 48

2176 10 07 4 9 49

2274-5 10 14 8 56,64 50

2323-4 10 17 8 31,47 51

2357-9 10 19 12 56 X 3 52

2389-90 10 21 8 76 X 2 53

2457-8 10 26 8 47,56 54

2498 10 28.5 4 56 55

2527 10 30.5 4 67 56

2566 10 33 4 67 57

2633 10 37.5 4 56 58

2765-6 10 46 8 47,56 59

2800-1 10 49 8 76 X 2 60

2836 10 51 4 76 61

2867-8 10 53 8 56 X 2 62

2900 - 10 55 - Stairs, misc. mat'ls

3050 11 05 hoisted

3116-7 11 10 8 56,64 Pour 63

3149-50 11 12 8 64 X 2 64

3181 11 14 4 76 65

3222-4 11 17 12 24,47,38 66

3251-4 11 19 16 47 X 2,56 X 2 67

3292-3 11 21.5 8 76 X 2 68

3322-3 11 23.5 8 56 X 2 69

3347-9 11 25 12 76 X 3 70

33 93-4 11 28 8 56,64 71

3421 11 30 4 64 72

3447-8 11 32 8 38,56 73

347 6-8 11 34 12 47 X 2,76 74

3510-13 11 36 16 38 X 4 75

3542-3 11 38 o0 21 ,47 1 6 35/4-5 11 40 o8 7 6x2 / / 3592 11 :41 End roll 1 1 11 :42 Start roll 2 96-9 11 :48.5 16 56 X 2,76 X 2 Pour 78

156 - 462 11 :53 15 38 - 56 Pour 79, 16 fr/s

574-9 11 :61 24 56 X 6 Pour 80

1798 - 1803 13 :23 24 56 X 6 81

1860-3 13 :27 16 47 X 4 82

1913-9 13 :31 28 64 X 3,76 X 4 83

2434-40 13 :53 28 9 84

1 in = 25.4 mm

45
4J

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46
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CO B o

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4-1

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to . >> t3 S to

to • P

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a, CTv c^ 00 c^ CM in m CN o

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to a- O vO 00 00 in ON o O rH O •H CO <f o CO in vD CO CM

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47
Table 4.3: Comparison between design and

measured shore loads

onore Actual AMC T A T n O AJNbi A ±U.y Measured

No. Design Design Loads Loads

Loads (kips) (kips)

(.kips;

1 6.29 4.87 3.40

2 8.90 6.89 5.32

3 5.29 4.09 5.00

4 8.90 6.89 1.45

5 4.46 3.46 4.13

6 8.04 6.23 6.30

7 6.90 5.34 6.93

8 4.88 3.78 4.26

9 3.91 3.02 2.26

10 8.04 6.23 9.52

11 6.90 5.34 3.71

Total 72.51 56.14 52.28

1 Kip = 4.45 kN

48
Table 4.4: Summary of static loads on reshores

Reshore

No.

Maximum

btatic Load

(kips)

Precompression

(kips)

Total Load

(kips)

• 1 1.00 4.65 5.65

2 1.89 8.78 10.67

3 0.96 4.46 5.42

4 1.15 5 ,34 6.49

5 0,75 3.49 4.24

6 1.18 5.48 6.66

7 0.68 3.16 3.84

8 0.64 2.97 3,61

9 2.38 11.07 13.45

Total 10.63 49.40 60,03

1 Kip = 4.45 kN

49
co- m-

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51
52
53

Figure 2.6: Shoring system in

first story

Figure 2.7 Stripping and reshoring

in the first story

55
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56
FRAMING POURMG

MM. TME

POURING

ODAY

FRAMING POURING

FRAMMG POURMG

FRAMING POURING

5 DAYS 8 DAYS

0

13 DAYS 16 DAYS

n

M

21 DAYS 24 DAYS SHORES & RESHORES SEQUENCES (Typical Areas)

Hill WACO' STEa SHORES

I I I 4^4 BACK PROPS

* 4x4 BACK PROPS SHALL BE IN PLACE BEFORE FORMWORK IS REMOVED BEARMG ENDS OF RESHORES CAN BE REDUCED 15%

AND SHALL BE CONSIDERED ADEQUATE

29 DAYS 32 DAYS

MATERIALS

:

Plywood: 5/8" B-B Plyform Class I. Reshores: 4x4 wood posts - Southern Pine K.D., No. 2 Grade.

3x4 wood posts - Douglas Fir, No. 1 Grade.

Formwork & Shores: Standard "WACO" shores and standard "ALUMA" Building

Systems Inc. Beams & Stringers

FORMWORK NOTES

Design Standards Used

The formwork design conforms to the following standards:

A. ACI 347-68.

B. ACI Publication SP-4 , Fourth Edition.

C. National Design Specification for Wood Construction - 1977 Ed.

D. Table I - Supplement to 1977 edition of National Design Specification

for Wood Construction.

E. Plywood Design Specification published by American Plywood Association

in December, 1976.

F. Plywood for Concrete Forming published by American Plywood Association.

G. Various other technical publications and test data.

Shoring and Reshorlng

As a minimum requirement during a pouring operation, the section of concrete in the process of being placed shall be supported by the formwork receiving the concrete, plus three (3) lifts of reshores below that section (See Shores & Reshores Sequence - typical areas)

.

Removing Formwork & Reshoring Slab (Typical Areas)

When a pour is at least five (5) days old and field cured cylinders indicate

a concrete strength in excess of 75% of the design strength of (f^, = 3000 psi

@ 28 days) the slab shall first be back-propped and then the horizontal and vertical formwork can be removed. Where the pl3rwood cannot be removed because

of the 4x4 reshores the contractor shall remove the 4x4 reshores one at a time, lower the plywood, and immediately replace the reshore before removing

another reshore. The slab will then be supported by four (4) lifts of 75% reshores. (See Typical Floor Reshoring Plan). Shores shall remain in place

until concrete has achieved 100% of design strength (f^ = 3000 psi 9 28 days) and always one (1) lift of formwork and three (3) lifts of reshores beneath

any slab to be poured.

Removing Formwork & Reshoring Slab (High Framing Area Greater than 10 '-0")

In areas where the unbraced length of reshores exceeds ten (10) feet contractor

shall use WACO heavy duty steel reshores.

Formwork, shores, reshores, bracing, etc. shall comply in every respect with

the contract specifications except 100% reshores may be substituted for shoring

as noted in specifications and placed in accordance with these drawings.

Figure 2.9: Shoring specifications

57
CL CL

T

I./4

1

EXTERIOR EDGE OF SLAB

A

EDGE RESHORE CONDITION

NO SCALE

CL CL

L

NOTE: 'WACO' heavy duty

shores must be used between

1st & 2nd floor as reshores

4x4 WOOD RESHORES, OR HEAVY DUTY 'WACO' POST SHORES

75% RESHORING PLAN (see shores & reshores sequence for lifts where can be removed)

Figure 2.10: Reshorlng plan

58
Q

LU

CO

00

u o UJ z t/> CO

o

OQ Of

U. O

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©©©©©©©

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59
Notes

1. Indicates 0701-89 Post Shore

2. Indicates ALUMA Joist

3. Indicates ALUMA Stringer

General Notes

Safe allowable loads have been determined through field and laboratory

tests carried out by independent engineering firms. The capacities shown

are based on safety factors as noted.

Equipment

1. Heavy duty scaffolding used in this project to have a nominal capacity

of 10,000 lbs. per leg and to be used in accordance with this drawing

and manufacturer's specification. (for garage) (if applicable).

2. Vertical shores to be ACROW type size 12 or equivalent.

3. Aluminum beams to be as per ALUMA-SYSTEMS section 35020.

Lumber

4. All lumber stresses are in accordance with CSA Standard 086-1970 with

allowance of 25% for short term loading for 4x6 and 2x10 and 25% for

short term loading plus 10% for load sharing members for 4x4. Grade

is structural no. 2.

Working Stresses Used: 4x4 4x6 and 2 x 10

Bending 1800 p.s.i.

Horizontal Shear 150 p.s.i. Modulas of Elasticity 1.76 x 106 p.s.i.

Plywood to be 11/16" concrete grade B.C. fir S2S.

Loads

5. Live load assumed 50 psf . Dead load 150 pcf.

6. Capacity of ALUMA-Systems ' beam is 300 lbs. per linear foot (nominal).

7. Design limit for reflection is SPAN/360.

Miscellaneous Notes :

8. All scaffolding and shoring to be effected plumb and level.

9. All splices in lumber joists and stringers to be over their supports.

10. Face grain of plywood to run at right angle to support.

11. Lumber shall be as specified and free of large knots and visible defects

12. Joists and stringers consisting of two or more members shall be nailed, bolted or clamped together.

13. All base plates to be nailed to sills.

14. All stringers in U-Heads to be centrally placed, wedged, equally packed

from both sides and securely nailed. Butt joints in stringers shall be directly over frame legs.

15. This shoring is not designed for motorized equipment.

16. Reshoring, if required, is the responsibility of the contractor.

17. Sills or sleepers to be 2x8 min . on concrete slab and 2 - 2x8 on grade.

18. Scaffold and shoring shall be erected in accordance with the approved

drawing

.

19. ALUMA Building Systems, Inc. must be notified of any changes to or deviations from this drawing.

Figure 2.12: Shoring profile and specifications

60
Figure 2.13 Calibration of frame shore columns

Figure 2.1A: Calibration of frame shore

61
62
Figure 2.16: Instrumentation in third story deck.

Figure 2.17: Installation of lead cables to on-site

recorder

.

63
Figure 2.18: Location of mobile van housing data

acquisition system

Figure 2.19: Location of time lapse camera.

64
65
SCALE

Coordinates of Shores (ft)*

X Coords.

3.33

11.92

21.92

31.67

41.67

52.08

Y Coords,

k*

-0.67

3.33

7.76

12.50

16.50

20.00

24.25

28.67

32.67

35.83

40.00

44.83

48.83

52.67

57.33

* 1.0 ft = 0.305 m

** Except as noted in sketch

Figure 2.22: Third story shores

66
I ELLIS TYPE WOOD POST

' STQL SMGLE POST

SCALE

Ckaordlnates of second story reshores

Row (x,y) in ft., rows in order of increasing y

Line C (0.00, 10.00) (0.00. 29.92) (0.00, 49.92)

W. Line (5.50, 0.00) (5.50, 5.08) (4.75, 9.83) (7.17, 15.58)/(5.00, 21.83)

(4.25, 29.83) (4.25. 34.83)7(5. 08, 44.58) (5.25, 50.00) (5.75, 55.00)

Midspan (10.67, 20.00) (10.00, 40.00) (10.33, 60.00)

E. Line (15.00, 0.00) (15.00, 5.75) (15.00, 10.25) (15.00, 15.58)/

(15.33, 25.42) (14.50, 30.25)/(14.25, 44.17) (14.25, 49.83)

(14.25, 54.75)

Line D (20.00, 10.41) (20.00, 30.17) (20.00, 49.75)

W. Line (22.83, 0.00) (22.83, 5.67) (22.83, 9.50) (22.83, 9.50) (22.83, 15.25)/

(25.17, 25.08) (25.17, 29.92) (25.17, 34 . 58) / (25. 67 , 45.67)

(23.42, 49.75) (25.33, 54.67)

Midspan (31.33, 20.00) (30.08, 40.00) (30.08, 40.00)

E. Line (35.00, 0.00) (35.25, 3.75) (35.50, 8.50) (35.50, 13 .25)/ (34 . 50, 24.67)

(34.50, 29.92) (34.50, 34 .75) / (36. 25 , 45.00) (36.25, 50.00)

(36.25, 54.42)

Line E (38.50, 0.00) (40.00, 10.25) (40.00, 29.82) (40.00, 29.83)

W. Line (44.58, 0.00) (44.92, 4.92) (44.92, 9.92) (44.92, 14 . 92) / (44 .75 , 24.75)

(44.75, 30.00) (44.75, 34 .83)/ (44 .42 , 40.92) (44.67, 50.33)

(44.67, 54.33)

Midspan (50.42, 5.75) (50.00, 20.00) (50.00, 39.08) (49.92, 60.00)

E. Line (55.08, 0.00) (55.25, 10.17) (55.25, 15.25)/(55.83, 23.67)

(57.50, 29.00) (55.83, 31.17) (53.58, 34 .83) /(58 .00, 45.00)

(55.25, 50.58) (55.25, 55.17)

Line F (60.00, 10.33) (60.00, 49.83)

NOTE: 1.0 ft. - 0.305 m. Figure 2.23: Second story reshores

67
<z>

<8>

<9>

(10

SKGLE POST STEL SHORE Y • STEL FRAME SHORE POST

SCALE

0 2 4 6 m

0 5 10 ft

i-

-20'-0"

t

20'-0"-

(!)

20'-0"

20-0"

20'-0"

20-0"

Coordinates of first story reshores

Row (x,y) in ft., rows in order of increasing x

Line 10 (6.00, 0.00) (14.50, 0.00) (26.75, 0.00) (33.58, 0.00)

(46.33, 0.00) (54.00, 0.00)

S. Frame (8.25, 4.42) (12.25, 4.42) (28.17, 5.83) (32.17, 5.83)

(47.75, 5.67) (47.75, 5.67) (51.75, 5.67)

Mid span (0.00, 10.67) (20.00, 11.08) (40.00, 10.17) (60.00, 10.17)

N. Frame (8.25, 14.50) (12.25, 14.50) (28.17, 15.92) (32.17, 15.92)

(47.75, 15.75) (51.75, 15.75)

Line 9 (10.17, 20.00) (29.42, 20.00) (50.83, 18.75)

S. Frame (8.83, 23.67) (12.83, 23.67) (27.92, 23.75) (31.92, 23.75)

(47.67, 24.17) (51.67, 24.17)

Midspan (0.00, 30.17) (20.00, 11.08) (40.00, 10.42) (60.00, 9.92)

N. Frame (8.83, 33.75) (12.83, 33.75) (27.92, 33.83) (31.92, 33.83)

(47.67, 34.25) (51.67, 34.25)

Line 8 (9.83, 40.00) (31.00, 40.00) (50.83, 40.00)

S. Frame (7.58, 43.75) (11.58, 43.75) (26.92, 44.33) (47.67, 45.17)

(51.67, 45.17)

Midspan (0.00, 9.75) (0.00, 10.58) (0.00, 8.42) (0.00, 9.58)

N. Frame (7.58, 53.83) (11.58, 53.83) (26.92, 54.83) (30.92, 54.83)

(47.67, 55.25) (51.67, 55.25)

Line 7 (9.75, 60.00) (30.00, 60.00) (49.08, 60.00)

NOTE: 1.0 ft. = 0.305 m. Figure 2.24: First story reshores

68
Figure 2.25: Loading of the concrete

bucket

Figure 2.26: Casting of floor slab

69
—STEEL FRAME SHORE

EaiS TYPE WOOD POST

• SINGLE STEEL POST SHORE

NO. : INSTRUMENTED RESHORES

SCALE

0 2 4 6 m

10 ft

<z>

<i>

<I>-

20-0"

9

•4 .5

20'-0"

20-0" -20-0" 20-0"-

2O'-0"

Coordinates of third story reshores

Row (x,y) in ft., rows in order of increasing y

Line C (0.00, 9.75) (0.00, 30.00) (2.67, 40.00) (0.00, 51.00)

W , Line (4.83, 0.00) (4.83, 5.00) (4.83, 10.08) (4.83, 15.33)/

(4.58, 24.92) (4.58, 29.92) (5.50, 35.50)7(5.33, 45.25)

(5.33, 50.25) (5.33, 55.33)

Midspan (9.92, 20.00) (10.58, 40.00) (10.00, 60.00)

E. Line (15.17, 0.00) (14.75, 5.33) (14.75, 9.58) (14.75, 14.75)/

(15.00, 24.92) (15.16, 29.33) (15.16, 34 .58) /(14 .42 , 43.25)

(14.58, 50.08) (14.58, 55.83)

Line D (20.00, 10.50) (20.00, 29.50) (20.00, 50.00)

W . Line (24.75, 0.00) (24.83, 5.25) (24.83, 10.17) (24.83, 14.08)/

(25.25, 25.08) (24.75, 30.58) (24.75, 34 . 58) /(25 .00, 45.00)

(25.00, 50.00) (25.00, 55.42)

Midspan (30.08, 20.00) (29.08, 40.00)

E. Line (34.67, 0.00) (35.08, 4.83) (35.25, 11.25) (33.58, 16.75)/

(34.25, 4.58) (34.67, 30.33) (34.67, 34 . 33) / (35 . 50, 44.50)

(35.50, 50.50) (35.17, 55.67)

Line E (40.00, 9.83) (40.00, 29.75) (40.00, 50.08)

W. Line (44.92, 0.00) (45.00, 5.08) (45.00, 9.83) (45.00, 14.83)/

(45.42, 30.00) (44.58, 34.83) (45.42, 39 . 67) / (45 .83 , 45.92)

(45.33, 50.67) (45.33, 55.58)

Midspan (50.00, 20.00) (50.67, 29.92) (49.67, 40.00) (50.25, 60.00)

E. Line (54.58, 0.00) (54.75, 4.67) (54.75, 9.92) (54.75, 14.83)/

(54.25, 24.83) (55.17, 29.83) (54.58, 34 .75)/ (55 .42 , 44.75)

(55.42, 49.58) (55.42, 54.33)

Line F (60.00, 9.92) (60.00, 29.92) (60.00, 49.67)

NOTE: 1.0 ft = 0.305 m

Figure 2.27: Third story reshores

70
71
GV01 QVOl

72

74
75
CO m ^ CO CM ^ o

(sd!>|) QVOI

76




81

CHANNEL 1 —

i

: 1 ; :

1

i — —

-i-r

•-1 •

1

.... — U

1

"1 — — 1 — -

r - ....

....

I —

1 —

1 — —

1 --

•

[— 1 L \

'

—

i ----

-J-—

1

-

1

1 1 1 III 1 1

1 1

1 1

1 1 1

1 1 1

1 1 1

21 22 23 24 1 2 3 4 5 6 7 8

1

i ;

: 1 ! -

1I1 — -J 1 -\ [ —

1

! —J —

1

:

; .: 1. i 1 :

a

CHANNEL 2 REAL TIME [hrsj

Figure 3,13; Shore load history, tape 2, chs. 1 and 2

83
CHANNEL 3

-

-

ft:-

i i

'

Ii:: ;:

\\\':

- T"

1 1

1 1 1

1 1 1 1 1 1 1

1 1 1 1

21 22 23 24 1 2 3 4 5 6 7 8

i—

Hrf

1 .1 L CHANNEL 4 REAL TIME (hrs)

Figure 3.14: Shore load history, tape 2, chs. 3 and 4

84
CHANNEL 5 m

-7:15:20

4 sec

1 r

J I i_ I J L J L J L

21 22 23 24 1 7 8

5h

4

3-

1 -

1

r CHANNEL 6

T V

REAL TIME |hrs

Figure 3.15: Shore load history, tape 2, chs. 5 and 6

85
CHANNEL 7

21 22 23 24

it

T r CHANNEL 8 r

REAL TIME (hrs]

Figure 3.16: Shore load history, tape 2, chs, 7 and 8

86
CHANNEL 9

.... -•

1 1

1

i — — — ....

i—i

hi j

- ——

i

1 I—

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1 1 1

1 1 1

1 1 1 1 1 1 1

1 1 1 1 1 1 1

1

1

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7

6

5

4

3

2

1

0

14

12

10

8

6

4

2

0

o

T \ 1 1 r CHANNEL 10 REAL TIME (hrs)

Figure 3.17: Shore load history, tape 2, chs. 9 and 10

87
Trr w

I- m U n JL_

6:!}2:08 — \ •*-A «pr

V

-^4 sec - T

-1-.

21 22 23 24 1 2 3 4 5 6 7 8

CHANNEL 11 REAL TIME (hrs)

Figure 3.18: Shore load history, tape 2, ch. 11

88
CHANNEL 1

.._

, - —

CASTING PERIOD

(TVP 1 — —

— —

- \ " tUUIPMtNl UALIUKAIlUN 1 YK

- — — —

- -rrr

1 -.^ : -I r

I 1 1 1 1 1

1 1 1

8 9 10 11 12

1

!

—f JI .11

=?= ri" I

=1 f

1 1 4r -T I 1 CHANNEL 2 REAL TIME (hrs)

Figure 3.19: Reshore load history, chs. 1 and 2

89
CHANNEL 3

_

-

r'A<> 1 r tn inlU -

i !

1

i f -1 1 r T

1 1

I 1

1

1 1

1

\ ] T

1 8 9 1C 11 12

V

-(./A ST N 5 ( {IG D1 j—

1

1 t

CHANNEL 4 REAL TIME [hrsj

Figure 3.20: Reshore load history, chs. 3 and 4

90
CHANNEL 5 —

• _

i

i : ;ii

i

!

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C ASTl Pi oc —J

.-

1

1 —i—

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1

1

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I 1

1 1

1 8 9 10 11 1 2

1

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I

-t1

1 1 —1 1 \ 1 1 CHANNEL 6 REAL TIME [hrs]

Figure 3.21: Reshore load history, chs. 5 and 6

91
CHANNEL 7

"I

IS' G PERll)D

-

li

1 1 I 1

'

1 1

1 1 1 1 1 1 1

1 1 1 8 9 10 11 12

: --

CI IS"^l^ G PE:ri OD —

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f

1::t

1

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i r

- —1 r I 1 1 1 1 1 1 1 1 CHANNEL 8 REAL TIME |hrs|

Figure 3.22: Reshore load history, chs. 7 and 8

92
—

I

... — —

:!: i::: jii: i i ;

:

: : !

:

P

TTTT

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i'i: 4

rfi-

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1

8 9 10 11 12 CHANNEL 9 REAL TIME (hrs)

Figure 3.23: Reshore load history, ch. 9

93
egOuo

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(1)

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CD

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95

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97
o

ro <N >- o

(sd!>|) avoi

98
99
100
<i>

(9>

ay

<8> i

<i>

ft

SCALE

0 2

0 10

4

' 6 m AX

I 20 (t * *

^4 r-^

^8 I ^10 :

• 3

9.88' -9.88' 10.20"

CD) (t CD

(a) Tributary areas

-9.75' 10.0'

.4

CD)

SPACING OF STRINGERS. r4 I\|

^

^4l —

4-

3.68

'

3.58'

4.21'

4.34'

3.87'

r

SPACING OF

JOISTS 1.6' O.C.

(b) Distribution through beam

support system

Figure 4.1: Bases for calculated static loads

101
REFERENCES

1. Research Needs in Civil Engineering, Civil Engineering Journal, ASCE, New

York, N.Y., December 1979.

2. Lasisi, Mohammed Y. I., Formwork and Shoring to Floors of Multi-Storey

Flat-Slab Buildings, Master's Thesis, University of Ottawa, Ottawa, Canada,

1976.

3. Nielsen, Knud E. C, Loads on Reinforced Concrete Floor Slabs and Their

Deformations During Construction, Proceedings Swedish Cement and Concrete

Research Institute, No. 15, Stockholm, Sweden, 1952.

4. Grundy, Paul, and Kabaila, A., Construction Loads on Slabs with Shored

Formwork in Multistory Buildings, Journal of the American Concrete Institute, December, 1963.

5. Beresford, F. D., An Analytical Examination of Propped Floors in MultiStorey Flat Plate Construction, Constructional Review, Vol. 37, Australia,

November 1964.

6. Blakeley, F. A., and Beresford, F. D., Stripping of Formwork for

Concrete in Buildings in Relation to Structural Design, Civil Engineering

Transactions, Institute of Engineers, Australia, October 1965.

7. Taylor, P. J., Effect of Formwork Stripping Time on Deflections of Flat

Slabs and Plates, Australian Civil Engineering and Construction, Vol. 8,

No. 2, February 1967.

8. Marosszeky, M., Construction Loads Imposed on Multi-Storey Structures,

Civil Engineering Transactions, Institution of Engineers, Australia,

April 1972.

9. Agarwal, R. K., An Experimental Investigation of Shoring Systems for HighRise Flat-Slab Structures, Master's Thesis, University of Ottawa, Ottawa,

Canada, May 1972.

10. Agarwal, R. K. and Gardner, Noel, J., Form and Shore Requirements for

Multistory Flat Slab Type Buildings, Journal of the American Concrete

Institute, November 1974.

11. Lasisi, Mohammed Y. and Ng, Simon F., Construction Loads Imposed on HighRise Floor Slabs, Concrete International, The American Concrete Institute,

February 1979.

12. ASTM C31-69, Standard Method of Making and Curing Concrete Test Specimens

in the Field, ASTM Standards, Part 14, 1979.

102
13. ASTM C39-72, Standard Test Method for Compressive Strength of Cyindrical

Concrete Specimens, ASTM Standards, Part 14, 1979.

14. Fattal, S. G., Cattaneo, L. E. , Turner, G. E., and Robinson, S. N.

,

Personnel Guardrails for the Prevention of Occupational Accidents, NBSIR

76-1132, National Bureau of Standards, Washington, D.C., July 1976.

15. ACI Standard 347-68, Recommended Practice for Concrete Formwork, American

Concrete Institute, Detroit, Michigan, 1968.

16. ANSI AlO. 9-1970, Safety Requirements for Concrete Construction and Masonry

Work, American National Standards Institute, New York, New York, 1970.

103

APPENDIX A

Slab Reinforcement Details

and Selected Specifications

A-1
NOTES FOR REINFORCED CONCRETE

All reinforced concrete details shall be in accordance with A.C.I. 315.

All reinforced concrete for framed slabs, beams, girders and walls shall

have a 28 day compressive strength of 3000 p.s.i. except as noted. See

notes on column schedule for strengths of concrete for columns o Walls

engaging columns shall have the same strength concrete as the column.

All reinforcing steel shall be high strength billet steel conforming to

ASTM specification A615-60, and all reinforcing bars not noted to be #4.

Deformations shall be in accordance with ASTM A-305.

All reinforcing bars shall be continuous or lapped not less than 36 bar

diameters where spliced, or unless otherwise noted or shown.

Where main reinforcement of beams and slabs is not continuous with adjacent

beams and slabs, top bars shall be extended 36 bar diameters beyond the

centerline of support where possible, otherwise the end bars shall be hooked

beyond the centerline of support

»

Where bar lengths are given on drawings, the length of hook, if any, is

not included

o

Slabs under concrete walls shall be adequately shored until walls have set.

Place the first slab bar a distance of one-half the normal bar spacing from

face of wall or beam.

Concrete protection for reinforcement:

beams and columns = 1?"

slabs = 3/A"

walls: exterior face = 2" and interior face = 3/4"

Provide spacers, chairs, ties, etc. as required and necessary for assembling,

placing and supporting all reinforcing in place.

All concrete shall be vibrated, using deep spade type for walls and columns

of such length to extend to within two feet of bottom of wall or column.

Vertical wall or column bars when spliced at a framed door shall be lapped

at least 30 bar 'diameters of the upper size baro

Welded wire mesh to conform to ASTM A-185 and to be placed as indicated on drawings. Lap edges of wire mesh at least 6" in each direction. Fs = 25,000

p.s.i.

A2
1' /20"x20" CORNER COLUMN

r

Typical Slab Reinforcement Layout

A3
I
APPENDIX B

Construction Schedule

and

Concrete Cylinder Test Data

B-1
Table B.l Sequence of construction

Ambient Condition

Day

Low

Temp.

(F)

High

Temp.

(F)

Weather

Code

Construction

Activity

2/26 28 38 C, W Cast ftgs. A8-A12, C8-C12, E10-E12

nil 27 38 C Cast ftgs. Bll, B12, D8-D12, E8, E9

F8-F12

2l2?> 29 35 S

2/29 5 -

3/3 10 33

3/4 25 50 C Cast ftgs. B8-B10, G8-G12, 18-112;

cast part S wall ftg.

3/5 R

3/6 42 63 S Cast ftgs. A1-A7, B7, C7, E7, H8-H12

-ill 36 65 S Cast ftgs. B1-B6, D7, E6, F6, F7, 06,

G7, H7, 17

3/10 34 Cast ftgs. C5A, C6A, C6B, D5, D6 , D6A,

F5, G5, H5, H6, 16; cast part W wall

3/11 42 46 S, W Cast ftgs. C1-C3, E5, F4, G4, H4, 14,

15; strip wall cast 3/10

3/12 27 38 S Cast ftgs. Dl, D2, C5, C6, C7A, El,

E4, Fl, F3, G3, H3, 13; cast part E wall ftg.

3/13 34 SN

3/14 SN

3/17 52 58 R

3/18 52 57 R, S Cast ftgs. C4, D3, D4, D4A, E3, E4,

E5A, E6A; cast 112' S wall

3/19 39 60 S Cast ftgs. C4A, F2, Gl, G2, HI, H2,

11, T2; cast part S wall ftg.

3/20 47 57 S Cast part W & SE walls, part E wall

ft.

B-2
Table B.l - Cont

.

Ambient Condition

Day

Low

Temp

.

(F)

High

Temp

.

(F)

Weather

Code

Cons true t ion

Activity

3/21 60 63 R -

48 54 C Strip wall

3125 51 60 S Cast part E wall, crane pad; strip walls

3/26 48 60 S Strip E wall, cast part E wall & 5800 sf

ground slab

3/27 37 54 S 4800 sf ground slab cast #2; cast 60' NE

wall; strip E wall

3/28 48 50 C Cast 6000 sf ground slab & part W wall;

strip walls

3/31 48 54 R

4/1 46 61 S Framing sects. 1 & 2 of Fl.l; strip

walls; cast part of W & N walls

kll 45 69 s Cast cols. D12, E12, F12 , 012, Cll, Dll,

Ell, Fll, Gil, CIO, DIO, ElO; framing

sects. 1 & 2, fl.l; strip W & S walls

4/3 52 69 s Cast cols. Hll, H12, 111, 112 & bott.

elev. pit; framing sects. 1-3 to fl.l;

strip walls; cast 7200 sf SOG

4/4 57 62 R, S Erect framing for sect. 2 fl.l

4/5 42 70 S Erect framing for sect. 2 fl.l

4/7 59 70 S Framing sects. 1-3 & elev. shaft (3 SOG;

cast cols. C9, E9, F9, G9, H9, 19, FIO,

GIO, HIO, 18 C12 & 4000 sf SOG

4/8 57 62 S Framing sects. 1-4 & core area @ SOG;

cast 4800 sf SOG & cols, in sects. 3, 4

4/9 61 70 R, S Framing sects. 1, 3

4/10 61 68 S Cast cols. G6-G8, H6, H7 , F6 , F7 , E7

,

D7, C7, B7, B6; framing sects. 3, 4; cast 5200 sf SOG

B-3
Table B.l - Cont

.

Ambient Condition

Day

Low

Temp.

(F)

High

Temp.

(F)

Weather

Code

Construction

Activity

4/11 61 77 s Framing sects. 3 6i 4; cast sect. 2 fl.l

& Cols. @ sects. 5 & 6

4/14 61 R Framing sects. 3 & 4 & cols, sects. 5 &

6 fl.l

4/15 58 61 S Framing sects. 3 & 4 & cols, to fl.l

cast 8000 sf SOG & cols, sects. 5 & 6 fl.l

4/16 S Framing sects. 4 & 5 & cols, sects. 7 & 8;

place steel sect. 3; cast sect. 1 of fl.l

& cols, in sect. 7 & part sect. 8

kill 57 60 s Framing sect. 5; place steel in sect. 4; cast sect. 3 & cols, sects. 7 & 9

4/18 55 68 s Framing sects. 5 & 6 fl.l & cols, to fl.2;

place steel in sect. 4 fl.l & cols, to

fl.2; cast cols. B8, B9, C9, D9, E9 to

fl.2

4/21 55 71 s Framing sects. 6, 7 fl.l & Cols, to fl.2;

place steel in sect. 5 fl.l; strip sect.

2 fl.l; cast sect. 4 & bal. of cols, to

fl.l & 3 cols to fl..2

kill 55 74 s Framing sects. 7 & 8 fl.l & cols, to fl.2;

strip sect. 2 fl.l; place steel in sect.

6 fl.l & cols, to fl.2

kllZ 61 77 s Framing sects. 8 & 9 fl.l & sect. 1 fl.2;

place steel in sect. 7 fl.l; cast sect.

6 fl.l, bal. of SOG & part of cols, to

fl.2 under sect. 2

4/z4 61 78 s Framing sects. 9 & 10 rl.l; place steel

in sect. 8; cast sect, 7 of fl.l & part

cols, to fl.2 under sect. 2; strip sect.

3 fl.l

4/25 62 77 s Framing sects. 9 & 10 fl.l; place steel

in sect. 9; strip sects. 2 & 3 fl.l;

cast sect. 8 fl.l & part cols, under

sect. 3 to fl.2

B-4
Table B.l - Cont

.

Ambient Condition

Day

Low

Temp.

(F)

High

Temp.

(F)

Weather

Code

Construction

Activity

R Framing bulkheads in sect. 9 fl.l & cols,

to ri.z; strip sects, i cx d rl.i; cast

cols. AlO, BIO, CIO, DIO, FA, F5 , E5A to

F1.2

4/29 57 62 C, S rrammg sect, lu ri.i a sect, i ri.z;

place steel in sect. 10 & cols, to

fl.2; strip sects. 1, 3 & 5 fl.l; cast

sect, y ri.i e< cois. Ay, t,iu, riu, CiU

to fl.2

57 63 R Framing parapet fl.l & sects. 1 & 2 fl.2;

strip sects. 1, 3 & 4 fl.l; cast cols.

A8, G7, G8, G9, B3, C2 , C3, D3, E3

5/1 R Framing sect. 2 fl.2; strip sect. 3, 4

& 5 fl.l; cast cols. G4-G6, A7 to fl.2

J 1 ^ 62 71 S Framing sects. 2, 3 fl.2 £i parapet wall

top of ramp, strip sects. 5 & 6 fl.l;

place steel in sect. 1 of fl.2; cast

sect. 10 fl.l & cols. B2, D2, E2 , A6

,

B6, C6, C5 to fl.2

-5/

J

61 82 S rrammg sects, z, j xx.z, strip sects.

5, 6 fl.l; cast sect. 1 & cols. F2, F3,

35, A5, A4, A3 to fl.2

5/6 62 86 S Framing sects. 2-4 fl.2 & cols, to fl.3;

place steel sect. 2 fl.2; strip sects. 7,

8 fl.l; cast cols. CI, Dl, G2, G3 to fl.2

X nr^ic Ain T^in no r^in Fin "Pin GIO, F9, E9, D9 to fl.3

5/7 65 80 S Framing sect. 4 fl.2 & cols, to fl.3;

strxp sect. -7 rx«X) pxHCc fateex xn bccu.

3 fl.2; cast sect. 2 fl.2, N parapet (? ramp, cols. A9, B9 , C9 , G9, A8, B8, C8,

D8, E8, G8 to fl.3 & cols. Bl, El, Gl,

Fl to fl.2

5/8 67 78 R Framing sect. 1 fl.2 & cols, to fl.3;

strip sect. 9 fl.l; cast cols, Al, A2

to fl.2

5/9 49 57 S Framing sect. 1 fl.3 & cols. sect. 2 to fl,3; place steel sect. 4 fl.2; strip

sect. 9 fl.l; cast sect. 3 fl.2, cols,

under sect. 2 to fl.3 & ret. wall ftg.

B-5
Table B.l - Cont

.

Ambient Condition

Day

Low

Temp

.

(F)

High

Temp

.

(F)

Wpn CaCk t*L. 1iL 1 pc t^ Code

Construction

Activity

5/12 67 83 S Framing sects. 1 & 2 fl.3; strip sect. 10

fl.l; cast sect, 4 fl*2-& cols, under sect.

3 fl.3; strip sect. 1 fl.2

5/13 71 90 C Framing sects. 2, 3 fl.3; strip sect. 1 fl.2 & basement; place steel in sect. 1 fl.3; cast cols, under sect. 4 fl.3

5/14 71 90 S Framing sects. 2-4 fl.3; strip sect. 2 fl.2; cast sect. 1 fl.3

5/15 55 76 S Framing sect. 4 fl.3 & cols. sect. 1 to

fl.4; strip sect. 3 fl.2; place steel

sect. 2 fl.3; cast cols, under sect. 1 to fl.4

5/16 71 85 S Framing sect. 1 fl.4; place steel sect.

3 fl.3; cast sect. 2 fl.3

5/19 74 86 C Framing sects. 1, 2 fl.4; place steel

sect. 4 fl.3; strip sect. 4 fl.2 & garage;

cast sect. 3 fl.3 & cols. sect, under fl.4

5/20 64 72 C, R Strip & move cols, from sect. 2 to 3 under

fl.4; strip bal. fl.2 garage area;

5/21 62 71 R

bill 64 88 S Framing sect. 2 fl.4; strip sect. 1 fl.3;

cast sect. 4 fl.3 & cols, under sect. 3 to fl.4

5/1-i 71 89 S Framing sect. 3 fl.4; strip sect. 2 fl.3;

place steel sect. 1 fl.4; cast cols. sect.

4 under fl.4

5/27 64 85 S Framing sect. 4 fl.4; strip sect. 3 fl.3;

place steel in sect. 2 fl.4; cast sect. 1 fl.4

5/28 71 82 S Framing sect. 4 fl.4 & ret. wall (§ ramp;

place steel sect. 3 fl.4; strip sects.

3, 4 fl.3; cast sect 2. fl.4 & cols. sect.

1 under fl.5

B-6
Table B.l - Cont

.

Ambient Condition

Day

Low

Temp.

(F)

High

Temp.

(F)

Weather

Code

Construction

Activity

J / /y 68 88 S Framing sect. 1 fl.5; place steel sect.

4 fl.A; strip sect. 4 fl.3; cast sect.

3 fl.A & cols. sect. 2 under fl.5

J / jU 68 81 S Framing sects. 1, 2 fl.5; strip misc.

on fl.3; cast sect. 4 fl.A & cols,

sect. 3 under fl.5

6/2 76 90 S Framing sects. 2, 3 fl.5; place steel

sect. 1 fl.5; strip sect. 1 fl.4; cast

cols, sect 4 under fl.5

6/3 79 91 S, C Framing sects. 3 & 4 fl.5; place steel

sect. 2 fl.5; strip sect. 2 fl.4; cast

sect. 1 fl.5

68 82 S Framing sects. 3, 4 fl.5; strip sects.

3, 4 fl.4; place steel sect. 3 fl.5;

cast sect. 2 fl.5 h cols. sect. 1 under

fl.6

Weather Code Notation :

C : Cloudy

R : Rain

S : Sunny

W : Windy

SN: Snow

B-7
Table B.2 Concrete cylinder test data

Test

No.

Date & Time

Molded

Type

of

Mix

Cone

.

Temp.

(F)

Air

Temp.

(F)

Slump

(in)

Cylinder Strength

(psi)

5-day 7-day 28-day Location

1 2/26

11:55

A* 60 35 4-3/4 - 3320

3420

5440

5280

Footings column

lines AlO, 11

2 2/27

2:20

A 68 40 3-3/4 - 3920

4080

5880

5740

Footing D9

3 3/4

1:40

A 60 42 4 4120

4140

5860

5660

Footing BIO

4 3/6

2:15

65 50 4 - 3900

3720

4780

4600

5 3/7

1:35

A+

1% cal.

75 64 4 - 4040

3920

5240

5140

Footings G7

,

H7-I7

6 3/10

1:15

c* 72 62 4 _ 2800

3000

4240

4420

W wall col, line

10 to C line S,

set 1

7 3/10

3:30

B* 74 63 5 3140

3040

5060

4960

Footings D5, D6,

D6A combination,

set 2

8 3/11

1:10

A 65 35 3 3640

3540

4600

4720

Footings C1-C3

9 3/12

3:05

A 67 34 4 3720

3580

5560

5500

Footings F3, H3,

13

10 3/12

12:55

A 63 42 5 - 3000

2940

4600

4760

S wall between

C & H lines

11 3/18

2:20

A 69 46 3-1/2 3360

3420

5000

4880

Footings C4, D3,

D4, D4A, E5A,

E6A, set 2

12 3/19

3:30

A 70 66 4-3/4 3460

3320

5140

5000

Footings C4a,

F2, Gl, G2, HI,

H2, 11, Is

13 3/20

2:25

B+

4.2 oz. AEA

72 56 4 4180

4240

5960

5820

W wall from col.,

line 10 to 6 & SE wall from col

line G to 9 linei

14 3/25

9:40

B+

4.2 oz, AEA

59 47 4 4000

4140

5660

5660

E wall between 9 and 2 line, set

1

B-8
Table B.2 - Cont

.

Test

No.

Date & Time

Molded

Type

of

Mix

Cone.

Temp.

(F)

Air

Temp.

(F)

Slump

(in)

Cylinder Strength

(psi)

5-day 7-day 28-day Location

15 3/25

12:05

B+

11.2 02 AEA

H 3900

4000

5320

5500

Crane pad , set 2

16 3/26

8:30

B+

4 oz

.

AEA

56 42 4-1/2 - 4780

4640

5280

5060

Sect. 1 SOG,

set 1

17 3/26

12 : 20

B 58 47 3

- 4460

HOUU

5740

jy zu Wall line 3 to

18 3/27

9 : 25

B 62 48 5-1/2 - 4240 5280 Sect. 2 SOG,

set 1

19 3/27

1:45

B 62 58 4-3/4 - 3600

3640

4640

4500

G line to NE

20 3/28

9:40

B 68 45 4-1/2 4280

hXoU / 1 Qfl 6040joOU

Sect. 3 SOG,

set 1

21 3/28

1 n • 40

B 70 53 3

- 4240 6200

AnDUDUAn W wall 1-3,

set 2

22 4/1

1 • 40

B 62 70 4

- 3080

3360

5060

4940

W wall 3-6 N

A-D wal

1

23 4/2

3:35

A 64 70 4 — 3640

3460

5320

5180

Cols. CIO, Cll,

D10-D12, ElOE12 Fll F12

Gil, G12 below

floor 1

4/3

9:20

61 4 - 3640

3680

5040

5100

Sect 4 SOG,

set 1

25 4/3

12:15

B 70 69 5 3040

A 7 on 4880

Cols. Hll, H12,

111, 112 below

floor 1, set 2

26 4/7

9:45

B+

4 oz. AEA

68 64 3 3180

3040

4280

4180

SOG sect. 5,

set 1

27 4/7

2:40

A 62 72 5 3400

3260

4940

5100

First floor cols

C8, C9, C12, E9,

F9, FIO, G9, GIO

H9, HIO, 19, 110

set 2

B-9
Table B.2 - Cont

.

Test

No.

Date & Time

Molded

Type

of

Mix

Cone

.

Temp.

(F)

Air

Temp.

(F)

Slump

(in)

Cylinder Strength

(psi)

5-day 7-day 28-day Location

28 4/8

8:55

B+

4 oz. AEA

68 60 5 - 3000

3080

4380

4420

Sect. 6 SOG,

set 1

29 4/8

11:15

B+

4 oz. AEA

70 72 3-1/2 3420

3460

5440

5240

Cols. C9, D8, E8,

F8, 110, set 2

30 4/10

9:10

B+

4 oz. AEA

66 60 3-1/2 2980

2940

3900

3960

Sect. 7 SOG,

set 1

31 4/10

2:45

A 73 68 3-3/4 3580

3500

4540

4820

Cols. B6, B7, C7,

D7, E7, F6, F7,

G6-G8, H6, H7

below floor 1,

set 2

32 4/11

9:25

B 61 60 4 - 3360

3280

4780

4540

Sect. 2 floor 1,

set 1

33 4/11

11:30

B 67 70 4 3360

3420

4960

4780

Cols. B5, C6, C6a

C6b, C7a, Da, E5a

E6, E6a, 14-17,

set 2

34 4/15

9:25

6+

4 oz. AEA

64 50 3-1/2 - 3900

4140

5040

4940

Sect. 8 SOG,

set 1

35 4/15

12:30

B 62 53 4 3420

3280

4640

4500

Cols. B4, C4-D4A,

C4, C5A, D5, E5A,

E6A, F5, G5, H5

,

set 2

36 4/16

8:30

B+

4 oz. AEA

57 50 4 3580

3580

4540

4420

Sect. 1 floor 1,

set 1

37 4/16

12:35

B+

4 oz. AEA

62 50 4 3180

3260

4640

4500

Cols. B2, B3, C2,

C3, D2, D3, E2,

E3, F3, G3, G4,

H3, set 2

38 4/17

8:20

B 62 59 4 2860

2760

3000

3080

4600

4500

Sect. 3 floor 1,

set 1

B-10
Table B.2 - Cont

.

Test

No.

Date & Time

Molded

Type

of

Mix

Cone.

Temp.

(F)

Air

Temp.

(F)

Slump

(in)

Cylinder Strength

(psi)

5-day 7-day 28-day Location

39 4/17

3:50

A 66 60 3-3/4 3260

jlZU

4680

/Bon 4oZU

Cols. Bl, CI, Dl,

El, Fl, F2, G2,

H2, set 2

4/1

1:20

A fi4 7n A JZOU

3360

^ 9 ftn 5180 D9, E9, story 1

A/91

8:25

R 64 A 979n

2840

jZoU

3140

A4/hU 9 /i n 4080

^e^ot L f 1 nnr 1 set 1

42 4/21

12:55

B+

4 oz. AEA

70 69 4 2900

2840

3720

3580

Floor 1 cols. 10,

11, 12, 13, HI;

floor 2 cols. C8,

D8, E8, set 2

43 4/22

8:15

A 66 64 4 2440*

2720*

3180

3120

3680

3960

Sect. 5 floor 1,

set 1

44 4/22

12:40

A 72 74 4 - 3120

3180

4000

4120

Cols. F8, F9,

set 2

45 4/23

8:45

B+

4 oz. 66 73 4-3/4 2400

2680

3000

2940

3780

3900

Sect. 6 floor 1,

set 1

46 4/23

12:10

B+

4 oz. AEA

70 76 4 3000

3000

4120

4000

Cols. 7B, 7C, 7D,

7E, 6E, set 2

47 4/24

9:10

A 70 66 4-1/2 2400

2440

2840

2800

3920

4200

Sect. 7 floor 1,

set 1

48 4/24

12 : 15

A 72 78 4 3000

2980

4340

4600

Cols. D6A, C7A,

E6, E7, set 2

49 4/25

8:57

B+

4 oz. AEA

70 67 4 2120

9 1 60

2620

ZHOU 9 ARn

3720

i6fin Sect. 8 floor 1,

set 1

4/9 S 12:40A 79 6Q 4 3180

3120

4540

4380

Floor 2 rol«? B4

C4, C4A, C5A, D3,

D4, D4A, E4, E5,

set 2

51 4/28

11:40

A 62 58 4 3180

3180

5240

5320

Cols, AlO, BIO,

CIO, ElO, F4, F5,

E5A below floor 2

B-11
Table B.2 - Cont

.

Test

No.

Date & Time

Molded

Type

of

Mix

Cone.

Temp.

(F)

Air

Temp.

(F)

Slump

(in)

Cylinder Strength

(psi)

5-day 7 -day 28-day Location

52 4/29

9:45

B+

4 oz

.

AEA

64 54 4-1/2 2500*

2380*

3040

2980

4720

4640

Sect. 9 floor 1,

set 1

53 4/29

3:10

A 64 67 3-1/2 - 2720

2840

4880

4960

Cols. A9, ElO,

FIO, GIO below

floor 2, set 2

54 4/30

12:30

A 65 63 4 - 3420

3320

4560

4760

Cols. A8, B3, C2,

C3, D3, E3, 07,

G8, 09 below

floor 2

55 5/1

12:10

A 70 68 4

- 3180

3360

4760

4780

Cols. A7, 04-06

below floor 2

56 5/2

9:00

B+

4 oz. AEA

70 69 4-1/2 2840

2760

2900 4540

4280

Sect. 10 floor 1,

set 1

57 5/2

12:15

B+

4 oz. AEA

72 77 4 3400

3580

3640

3580

4780

4960

Sect. 10 floor 1,

set 2

58 5/2

2:15

B+

4 oz. AEA

72 76 4 3220

3040

4280

4280

Cols. A6, B2, B6,

05, 06, D2, E2

below floor 2,

set 3

59 5/5

9:00

B+

4 oz. AEA

71 75 4 2580

2580

2900

2980

4200

4200

Sect. 1 floor 2,

set 1

60 5/5

1:00

B+

4 oz. AEA

77 86 4 - 2980

2860

4240

4120

Cols. A3-A5, B5,

F2, F3, set 2

61 5/6

1:15

A 78 84 5 3080

3000

4640

4540

Cols. 01, Dl, 02,

03 to floor 2; cols. AlO, BIO,

010, DIO, ElO,

FIO, 010, F8, F9

to floor 3

62 5/7

8:50

A 75 77 3-3/4 2580

2500

3360

3500

4640

4500

Sect. 3 floor 2,

set 1

B-12
Table B.2 - Cont

.

Test

No.

Date & Time

Molded

Type

of

Mix

Cone

.

Temp

.

(F)

Air

Temp.

(F)

Slump

(in)

Cylinder Strength

(psi)

5-day 7-day 28-day Location

63 5/7

1: 30

A 78 81 4-1/2 3360

3320

5320

5100

Cols. Bl, El, Fl,

Gl to floor 2; cols. A8, A9, B8,

B9, C8, C9, D8,

E8, F8, G8, 09 tc floor 3, set 2

64 5/8

11:00

A 70 65 4 3680

3600

5140

4960

Cols. A1-A2 to

floor 2

65 5/9

9:25

A 64 62 4 2720

3000

3420

3360

4420

4280

Sect. 3 floor 2,

set 1

66 5/9

12:00

A+

h% cal

67 68 5 3400

3400

4820

4720

Cols, below floor

3, set 2

67 5/12

8:15

A 73 75 5 2660

2680

2840

2800

3720

3640

Sect. 4 floor 2,

set 1

68 5/12

12:20

A 80 85 5 2660

2660

3860

3820

Cols, below floor

3 sect. 3, set 2

69 5/13

1:45

A 85 85 4 3120

3120

4240

4080

Cols, below floor

3

70 5/14

8:10

A 81 75 5 2200

2260

2540

2680

4640

4500

Sect. 1 floor 3

71 5/15

1:00

A 70 76 5 3420

3320

5240

5100

Cols, below floor

4 sect. 1

12 5/16

9:35

A 73 70 4 2980

2800

3320

3400

5320

5180

Sect. 2 floor 3

73 5/19

7:45

A 70 58 4-3/4

2680 3460 5100

Sect. 3 floor 3,

set 1

74 5/19

1:30

79 77 4-1/2 3360

3360

4600

4680

Cols, below floor

4 sect. 2, set 2

75 bill

8:15

A 74 75 4 2620

2620

2720

2660

4240

4080

Sect. 4 floor 3,

set 1

76 bill

11:35

A 74 76 4-1/4 3000

2940

4140

4200

Cols, below floor

4 sect. 3, set 2

77 5/23

12:10

A 77 75 4 2760

2760

4080

4120

Cols, to floor 4 sect. 4

B-13
Table B.2 - Cont

,

Test

No.

Date & Time

Molded

Type

of

Mix

Cone

.

Temp

(F)

Air

Temp.

(F)

Slump

(in)

Cylinc

5 -day

ler Str€

(psi)

7-day

;ngth

28-day Location

78 5/27

9:15

A 71 65 5 2660*

2720*

2840

2900

4140

4320

Sect. 1 floor 4

79 5/28

9:15

A 75 68 5-1/4 2720

2620

3080

3000

4540

4380

Sect. 2 floor 4,

set 1

80 5/28

11:20

A 76 80 5 3280

3400

4780

4600

Cols, to floor 5 sect. 1, set 2

81 5/29

9:00

A 76 78 5 2940

2900

3120

3120

4600

4540

Sect. 3 floor 4,

set 1

82 5/29

2:25

A 77 79 4 3140

3180

4120

4180

Cols . below floor

5 sect. 2, set 2

83 5/30

10:00

A 80 76 5 3000

3040

3400

3180

4420

4640

Sect. 4 floor 4,

set 1

84 5/30

12:15

A 80 82 4 3220

3360

4780

4600

Cols, below floor

5 sect. 3, set 2

85 6/2

1:00

A 83 87 4-1/2 3600

3540

5000

4860

Cols, below floor

5 sect. 4

86 6/3

8:20

A 78 76 4-1/2 2760 * 2840 * 3040

3000

4420

4280

Sect. 1 floor 5

87 6/4

8:20

A 78 75 4 2660

2660

3080

3000

4640

4500

Sect. 2 floor 5, set 1

88 6/4

12:00

A 77 79 7 3080

2860

4540

4780

Cols, below floor

6 sect. 1, set 2

Field cured and tested at six days

2 Note: 6" x 12" (28.27 in ) cylinders molded in accordance with

ASTM C-31 and tested in accordance with ASTM C-39.

Mix types (by weight)

Type A B C Cement 564 564 564

Fine Aggr. 1170 1070 1070

Coarse Aggr. 1970 1970 1920

UNITS;

1 in = 25.4 mm

1 psi = 6.9 kPa

°C = (5/9) (°F - 32)

1 oz = 28.3 g

B-14
APPENDIX C

Selected Data on Shoring Systems

C-1
SELECTED DATA ON

WACO SHORING SYSTEM

Complete shoring towers have been tested both at testing laboratories and

at the Waco testing facility. All tests are witnessed and certified by an independent testing laboratory. All tests are conducted in compliance with

the Scaffold and Shoring Institute testing procedures.

The "Hi-Load" frames are manufactured of electric resistant welded high

strength structural steel tubing having the following properties:

1) Yield Strength = 50,000 psi

2) Tensile Strength = 75,000 psi

3) Elongation in 2 in. is 23 percent

Properties of the frame leg material are as follows:

1) Outside diameter D = 2.375 in

2) Wall Thickness t = 0.154 in

3) Area A = 1.075 in

4) Moment of Intertia I = 0.666 in

5) Section Modulus S = 0.561 in

-6) Radius of Gyration R = 0. 787 in

The failure (see Test #1) occurred in the plane of the connecting crossb races. The resulting test loads can be equated to the Eulers column design load.

Additional tests and testing programs were initiated to determine the effect

of screw and staff at various extensions. The results of all these tests are shown in Tables 1 and 2. These Tables reflect a 2^:1 minimum safety factor

as required by the Federal Occupational Safety and Health Act and the S.S.I.

Test //2 (as illustrated) was performed on a three 6'-0" frames high tower

which contained four staff and staff attachments with interchangeable heads

at the top and base plate at the bottom of the tower.

Properties of the Staff Extension Material are as follows:

1) Outside Diameter D = 1.900 in

2) Wall Thickness t = .132 in

3) Area A = . 733 in

4) Moment of Inertia I = .288 in

C-2
5) Section Modulus S = .303 in

6) Radius of Gyration R = .627 in

The staff which slides inside the legs of the top frame of the tower is

supported by a pin which is placed thru the staff and supported on the

staff attachment "Speedset."

Failure of the tower was confined to the top Staff Extension. The failure

of the staff was short column failure which can occur in either plane. The

ultimate load can be equated with the Euler's column design load.

Table 2 is a result of extensive testing of the "Hi-Load" frames with

staffs. The table reflects a minimum 2J:1 safety factor as recommended

by the Scaffold & Shoring Institute and OSHA.

C-3
oHM

P4WMWI X!CMII x;

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EnO

h3

CO

woxioa doi Ko iNmisnrov ivioi ooI ooI CM o O O o O 1 in 1 m 1 m

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.H iH vf <• o o O o o 1 vO r 1 <r <r CM

CM rH <r -3-

<u• u " o

^3

Q)W3W

0)

CM

13d

cfl m

CM

i-t <JCOp, *» 0) ".D P <J- MKT d

•H

)-l (U

OJdHd <!

rH o o- o

<J 14-1 :s o

in

,dM

p

d

•H

O S -H

4-1

J-l CO H d d -H

COd 6 o o

cj o I uo

•H 0) X >O = ^ O CO

COuO rH

4J <r

rJ<+e ^H o o

•P o o n) PQ >4-l -3 >>

+J O. 0) O M-i H cfl CO

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COiH oI uo

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m CO rH to CM CO O 0)

CJ bO QJ d d d 4J

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-S ^

to (U •H rH

4-1 to d ^

OJ o S rH

4-1 rH

to Cfl d

•n 0) T3 >

(Ua

cfl rH ^

to to g CO o o

rH

U

rH CJ o

CM

to -a

too

rH

CO to O U-t

CO rH ^

Q) •Hm

•H

4-1 M

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13d

to . to (U OJ to u to

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d

CO o

rH CO

cfl 4J (U O ^ H H

(U rH >O ^4

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cfl CO

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tU > > <u O rH

to QJ

tU

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0) CM a o

tuod

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t3 tu Xl ^

CO QJ

^4 &

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to CO

4-1 o to rH QJ I 4J in

r-H rH

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C4H

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C-4
TABLE 2. Allowable Load on Staffs 4805-XX (lb)

STAFF

EXTENSION

NUMBER OF FRAMES HIGH

1 TIER 2 TIERS 3 TIERS A TIERS 5 TIERS 6 TIERS 7 TIERS 8 TIERS 9 TIERS

I'-O' 9100 8600 8100 7800 7500 7400 7300 7200 7000

2'-0' 8500 7500 6900 6550 6200 6050 5900 5700 5500

3'-0"

4'-0"

7300

6500

6500

5550

5700

4600

USE 3 FRAME HIGH VALUES FOR 4 THRU 9 FRAMES HIGH IF

TOWER IS SECURELY BRACED IN BOTH DIRECTIONS WITH

2x6 TIMBER LACING AND 4432-00 NAILING PLATES AT A

MAXIMUM SPACING OF EVERY THIRD FRAME UP THE TOWER.

5'-0' 6000 4750 3800

NOTES

;

1. All values reflect a minimxim 2^2:1 safety factor.

2. Consult with WACO Engineering Department for situations not covered.

3. Use the above loading for tower combinations of 4144, 4145, 4146, 4124, 4125,

and 4126 frames.

4. Staff extension is the sum of the screw and staff adjustment top and bottom.

5. All tests were witnessed and certified.

C-5
TEST #1

1'/4x1 '74x1/8 ANGLE IRON X-BRACE (typ.)

4'-0" STUD SPACING ON X-BRACES

4411-00 CONNECTOR

\ (typ.)

Ult. Ld. = 26,750 lb./leg

TEST #2

480X-XX STAFF

SPEEDSET

4452-OX STAFF AHACHMENT

FRAME LEDGER

FRAME LEG

VA"^VA"y]/B"

ANGLE IRON X-BRACE (typ.j

Ult. Ld. = 13,438 lb./leg

C-6
0

0

PLATE mOED

C-7
#4145-00

Wt. 54 lbs. SHORING FRAME ASSEMBLIES

c-8
ALUMA BEAM DESIGN DATA

STANDARD LENGHTS

Imperial

10 ft 6 12 ft 0 in

14 ft 0 in

16 ft 0 in

18 ft 0 in

21 ft 0 in

Metric

3.20 m

3.66 m

4.27 m

4.88 m

5.49 m

6.40 m

Bolt Slot accepts 1/2-in

standard square head, hex

head, or Aluma bolts.

2.0 4.0

1 _L

6.0

SPAN (ft)

8.0 10.0

c-9
MAXIMUM REACTIONS & CONCENTRATED LOADS

REFERENCE

Strength of Alum'n

Alcan 4th Ed'n

Strength of Alum'n

Alcan 4th Ed'n

(with F.O.S.=2.2)

CSA S-157

CP. 118

REACTION WITH

FULL BEARING

kips kN

23.1 103

10.5 46.7

14.4 64

10.7 47.7

REACTION WITH

PARTIAL BEARING

kip s kN

11.6 51.6

5.3 23.4

7.5 33.4

CONCENTRATED

LOAD

kips kN

22.2 99

10.1 44.9

13.9 62

SECTIONAL AND ELASTIC PROPERTIES

IMPERIAL

Overall height 6.50 in.

Base width 5.00 in.

Width, inverted top hat section 3.20 in.

Cross sectional area

2 (excluding 2" x 2" nailing strip) 2.65 in.

Nominal weight

(including 2" x 2" nailing strip) 4 lb. /ft.

Distance of neutral axis from base 2.749 in.

(when beam is clamped or loaded)

L Moment of Inertia I 16.882 in. x-x

I Moment of Inertia I 2.657 in.

y-y

Section Modulus Sx-x

about the lower chord/flange 6.141 in^"

about the upper chord/inverted top hat section 4.50 in.

Section Modulus S 1.063 in.'

y-y

Radius of Gyration r 2.518 in. X Radius of Gyration r 1.00 in.

Modulus of Elasticity E 10.2 x 10

METRIC

165 mm

127 mm

80 mm

1710 mm^

6 kg/m

69.8 mm

703 cm^

110.6 cm^

110 cm 73.75 cm-^ 17.42 cm^

psi

63 . 9 mm

25.3 mm

7.04 X 10^ kN/cm^

C-10
ALUMA BEAM STRUCTURAL PROPERTIES

IMPERIAL METRIC

Torsion Constant J = 0.027 in. 1.124 cm

Warping Constant H = 28.0 in. ^ 7519.0 cm^

Slenderness Ratio (local

buckling Bottom Flange) X = 60 60 = m, M = 4.5

t

Maximum Buckling Stress

Bottom Flange F^, = 26 ksi 17.93 kN/cm

Maximum B.M. (local buckling

Bottom Flange) M = 160 kip in. 18.08 kN.m

Maximum Permissible - Bottom M = 72.5 kip in. 8.19 kN.m

Flange (F.O.S. 2.2)

Slenderness Ratio: (buckling A = 73 73

due to Lateral Instability,

with 4'6" long cantilever)

Maximum Buckling Stress - F^ = 19 ksi 13.10 kN/cm

Lateral Instability

Maximum B.M. - Lateral M = 116.7 kip in. 13.18 kN.m

Instability

Maximum Permissible B.M. - M = 53 kip in. 5.99 kN.m

Lateral Instability (F.O.S. 2.2)

Slenderness Ratio (local buckling A = 14 14 - top cbord)

2 Maximum Buckling Stress - F = 37 ksi 25.51 kN/cm

top chord

Maximum B.M. (local buckling - M = 166.5 kip in. 18.81 kN.m

top chord)

Maximum Permissible B.M. - M = 76 kip in. 8.59 kN.m

top chord (F.O.S. 2.2)

C-11
SELECTED DATA ON

ELLIS WOOD POST SHORES

ALLOWABLE LOAD CHARTS

FOR 4x4 SHORES

20

18

16

14

12

10

8

A

8

C

2 3 4 5 6

ALLOWABLE LOAD (kips)

TEST RESULTS

Load per Deflection

,

shore 2 clamps

(kips) per shore

(in)

1 0

2 .005

3 .021

4 .063

5 .127

6 .172

7 .213

8 .249

9 .319

10 .449

NOTES

CO

I—oCL W

t/J Qo

oo

77777777777T

Allowable Load Charts:

Curve A: Braced both directions at third points

Curve B: Braced both directions at mid-point

Curve C: Unbraced

Chart is for vertical loads only.

Every shore should be braced against lateral movement.

Allowable maximum value of 6000 lb. per shore is based

upon a safety factor of 3 against failure of the

mechanical mechanism of splice joint.

Chart is based upon allowable unit stresses of 1500 psi

for wood members of fir or yellow pine, free of knots.

Chart is based upon approved engineering standards, but

does not compensate for unusual conditions. The final

accepted supporting framing should be approved by a Registered Professional Engineer.

Test Results :

* The tests were made with ELLIS clamps on No . 1 Douglas

Fir ELLIS sticks; clamps were driven down with a carpenter's hammer before the load came on.

* The ELLIS jack, as is, will lift 1400 lb. with a 3-ft

.

piece of pipe slipped on the handle, the jack will lift

3000 lb.

* Shores were 11 ft. long and were tested under increasing

loads of up to 20,000 lb. without breaking. There was very slight deflection at 6,000 lb. and progressive

deflection up to 20,000 lb. (see test results above).

* ELLIS method assures a 2:1 safety factor.

U U.S. GOVERNMENT PRINTING OFFICE ; 1983 O—380-997 (2432)

C-12
NBS-114A (REV. 2-eo) U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Orgsm. Report No, 3. Publication Date BIBLIOGRAPHIC DATA

SHEET (See instructions)

REPORT NO.

NBS BSS 146 February 1983

4. TITLE AND SUBTITLE

Evaluation of Construction Loads in Multistory Concrete Buildings

5. AUTHOR(S)

S.G. Fattal

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

The Occupational Safety and Health Aaministration

U.S. Department of Labor

Washington, DC 20001

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 82-600579

r I Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most si gnificant information. If document includes a si gnificant

bibliography or literature survey, mention it here)

Construction loads in a multistory flat plate concrete building were measured

using strain-gaged metal shores and an analog recorder. The instrumented shores

were placed within an interior bay of the third story under the formwork for the

fourth story floor slab, and loads on the shores were measured continuously

over a 24-hour period during the casting and partial curing cycle of that slab.

The loads on some of these shores, when subsequently used as reshores in the same bay, were measured during an 8-hour period which included the casting of

the fifth story floor slab. A time-lapse camera, operating synchronously with

the load data acquisition system, gathered simultaneous photographic evidence

of the construction activities during load monitoring periods. This report

presents a complete documentation of the field data in compact form for subsequent use in related studies. The load data is interpreted and compared with

construction load and design provisions of current standards.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

concrete buildings; concrete casting; construction loads; construction standards;

falsework; field measurements; flat plate; floor slab; formwork; instrximented shores;

load measurement; multistory construction; shored construction.

13. AVAILABILITY

Pn Unlimited

I I For Official Distribution. Do Not Release to NTIS

[Xn Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

031 Ofder From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

139

15. Price

USCOMM-DC 6043-P80



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PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register. The Register

serves as the official source of information in the Federal Govern- ment regarding standards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended.

Public Law 89-306 (79 Slat. 1127), and as implemented by Executive Order 1 1717 (38 FR 12315, dated May II, 1973) and Part 6 of Title 15 CFR (Code of Federal Regulations).

NBS Interagency Reports (NBSIR)—A special series of interim or

final reports on work performed by NBS for outside sponsors

(both government and non-government). In general, initial dis- tribution is handled by the sponsor: public distribution is by the National Technical Information Service , Springfield, VA 22161,

in paper copy or microfiche form.
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