report of a testing program of light-framed...

REPORT OF A TESTING PROGRAM OFLIGHT-FRAMED WALLS WITH

WOOD-SHEATHED SHEAR PANELS

Final Report to the City of Los Angeles Department of Building and Safety

by

Structural Engineers Association of Southern California

COLA-UCI Light Frame Test Committee

Subcommittee of Research Committee

and

Department of Civil & Environmental Engineering

University of California, Irvine

This research was funded by the City of Los Angeles Department of Building and Safetythrough the State of California Governor’s Office of Emergency Services and the Federal

Emergency Management Agency’s Hazard Mitigation Grant Program. The Research AwardNumber was “FEMA-DR-1008-8011.”

December 2001

ii

TABLE OF CONTENTS

LIST OF TABLES…………………….……………………………………………. iv

LIST OF FIGURES………………………………………………………………… v

REFERENCES..……………………………………………………………………. vi

LIST OF ACRONYMS…………………………………..………………………… viii

COLA-UCI LIGHT FRAME TEST COMMITTEE, MEMBERS……………… ix

PREFACE…..……………………………………………………………………… x

1 INTRODUCTION……………………………………………………………… 1-1

2 EXPERIMENTAL PROCEDURES………………………………………….. 2-1

2.1 WOOD FRAMING………………………………………………………. 2-12.2 LIGHT-GAUGE STEEL FRAMING………………………………….. 2-32.3 SHEATHING…………………………………………………………….. 2-72.4 FASTENERS…………………………………………………………….. 2-72.5 HOLD-DOWN CONNECTORS……………………………………….. 2-9

2.5.1 General………………………………………………………….. 2-92.5.2 Wood Frame Hold-downs……………………………………… 2-92.5.3 Light-Gauge Steel Hold-downs………………………………… 2-11

2.6 TEST SET-UP AND PROCEDURE 2-132.7 TEST PROTOCOL 2-152.8 INSTRUMENTATION 2-17

2.8.1 Instruments……………………………………………………… 2-172.8.2 Data Sampling…………………………………………………… 2-202.8.3 Data Analysis……………………………………………………. 2-20

3 RECOMMENDATIONS……………………………………………………… 3-1

3.1 DESIGN VALUES……………………………………………………….. 3-13.2 DERIVATION OF DESIGN VALUES…………………………………. 3-2

3.2.1 Derivation of Strength Design Values..………………………… 3-23.2.2 Derivation of Allowable Stress Design Values from Nominal

Strength Values………….……………………………………….3-4

3.3 RECOMMENDED USE OF STIFFNESS DATA……………………… 3-10

iii

3.4 RECOMMENDATIONS FOR RELATING DESIGN VALUES TOFUTURE CODES…………………………………………………………

3-12

3.5 EFFECTS OF NON-STANDARD DETAILS IN TEST PANELS…… 3-14

A LOAD / DEFORMATION SUMMARY …………………………………….. A-1

B LOAD-DEFORMATION CURVES ………………………………………….. B-1

C EXAMPLE OF DERVIATION OF YLS (NOMINAL STRENGTH)FROM EXPERIMENTAL DATA GIVEN IN APPENDIX B-1 ...…………. C-1

D COMPACT DISKS OF DATA ……………………………………………….. D-1

iv

LIST OF TABLES

Table 1.1 COLA/UCI Shear Wall Research Program Test Matrix…………………. 1-3

Table 3A LRFD Nominal Strength Shear and Shear Stiffness for Seismic Forces… 3-6

Table 3B ASD Shear and Shear Stiffness for Seismic Forces……….………………. 3-7

Table 3C LRFD Nominal Strength Shear and Shear Stiffness for Seismic Forcesfor Walls Framed with Cold-Formed Steel Studs………………..………... 3-8

Table 3D ASD Shear and Shear Stiffness for Seismic Forces forWalls Framed with Cold-Formed Steel Studs……………………………... 3-9

Table A-1 Mean, Coefficient of Variation of Load / Displacement Results –Groups 1 – 18………………………………………………………………… A-2

Table A-1 Mean, Coefficient of Variation of Load / Displacement Results –Groups 19 –36………………………………………………………………... A-3

Table A-2 YLS, SLS, Shear Stiffness, Overstrength Factor, µµ for Groups 1—4……. A-4

Table A-2 YLS, SLS, Shear Stiffness, Overstrength Factor, µµ for Groups 5—8……. A-5

Table A-2 YLS, SLS, Shear Stiffness, Overstrength Factor, µµ for Groups 9—12…... A-6

Table A-2 YLS, SLS, Shear Stiffness, Overstrength Factor, µµ for Groups 13—16…. A-7






v

LIST OF FIGURES

Figure 2.1 Moisture Meter Used to Determine Moisture Content in WoodFraming…………………………………………………………………… 2-2

Figure 2.2 Wood Stud Framed Shear Wall Test Specimen………………………... 2-3

Figure 2.3 Light-Gauge Steel Stud Framed Shear Wall Test Specimen…………. 2-5

Figure 2.4 Cold-Formed Steel Track……………………………………………….. 2-6

Figure 2.5 Components of a C-Shaped Cold-Formed Steel Member…………….. 2-6

Figure 2.6 Sheathing Screws Used for Light-Gauge Steel Framed Shear Walls… 2-8

Figure 2.7 Framing Screws Used for Light-Gauge Steel Framed Shear Walls….. 2-8

Figure 2.8 Detail of a Wood Framed Shear Wall Hold-down Connector………… 2-10

Figure 2.9 Wood Framed Shear Wall Hold-down Connector……………….…….. 2-11

Figure 2.10 Dapping Tool and Shear Plates for Wood Framed Shear Walls……… 2-12

Figure 2.11 Detail of a Light-Gauge Steel Framed Hold-down Connector……….. 2-12

Figure 2.12 Picture of Light-Gauge Steel Framed Hold-Down Connector………… 2-13

Figure 2.13 Test Setup for Cyclic Load Shear Wall Test at UC Irvine……………. 2-14

Figure 2.14 TCCMAR Loading Sequence for FME=0.8”………………………….. 2-17

Figure 2.15 Instrument Locations for a Cyclic Shear Wall Test…………………… 2-19

Figure 2.16 Instrumentation Samples Used During the Testing of Shear Walls….. 2-19

Figure C-1 Enlargement of 1st Quadrant of Load-Deflection Curve…………..….. C-3

Figure C-2 Enlargement of 3rd Quadrant of Load-Deflection Curve…………..….. C-3

Figure C-3 Determination of YLS Using Segments of Primary and SecondaryBackbone Curves……………………………………………………..…..

C-4

Figure C-4 YLS Values for Various Nailing Configurations…………………...….. C-7

Figure C-5 Relative Lateral Load versus Number of Fasteners………………..….. C-8

vi

REFERENCES

[1] ICBO. Uniform Building Code. International Conference of Building Officials, 1997.

[2] International Code Council. International Building Code. 2000. BOCA,ICBO, SBCCI.

[3] American Society of Civil Engineers, “ASCE Standard Minimum Design Loads forBuildings and Other Structures”, ASCE 7-98, Reston, VA, 2000.

[4] American Society of Civil Engineers, “ASCE 16 – Load and Resistance Factor DesignStandard for Engineered Wood Structures,” 1997.

[5] AWC. National Design Specifications for Wood Construction. American Wood Council,1997.

[6] Structural Engineers Association of Southern California (SEAOSC). “Standard Methodof Cyclic (Reversed) Load Test for Shear Resistance of Framed Walls for Buildings,”1996a.

[7] Structural Engineers Association of Southern California (SEAOSC). “Standard Methodof Cyclic (Reversed) Load Test of Structural Connector or Sub-assembly,” 1996b, and“Commentary”, 1997.

[8] ABK, A Joint Venture. “Methodology for Mitigation of Seismic Hazards in ExistingUnreinforced Masonry Buildings: Diaphragm Testing.” December 1981.

[9] Joint Technical Coordinating Committee on Masonry Research. “TCCMAR SequentialPhased Displacement Test Procedure,” 1987.

[10] Shepherd, Robin. “Standardized Experimental Testing Procedures For Mixed MaterialStructural Systems,” Proceedings, 64th Structural Engineers Association of CaliforniaAnnual Convention, 1995.

[11] Shepherd, Robin. “Standardized Experimental Testing Procedures For Low-RiseStructures,” Earthquake Spectra, 12, No. 1, February 1996.

[12] Andreason, K.R., Rose, J.D., 1994. Northridge, California Earthquake; StructuralPerformance of Buildings in the San Fernando Valley, Report T94-5, American PlywoodAssociation

vii

[13] Rose, J.D., 1998. Preliminary Testing of Wood Structural Panel Shear Walls UnderCyclic (Reversed) Loading, Research Report 158, American Plywood Association.

[14] Serrette, R., Nguyen, H., Hall, G. “Shear Wall Values for Light Weight Steel Framing”Research Report No. LGSRG, Santa Clara University, 1996.

[15] Comerio, M., 1995. Northridge Housing Losses, Center for Environmental DesignResearch, University of California, Berkeley, March, 1995.

[16] Salenikovich, A.J., Dolan, J.D., 2000. The Racking Performance of Light-Frame ShearWalls with Various Tie-Down Restraints, World Conference on Timber Engineering,Whistler, Canada, August 2000.

[17] Breyer, D.E., Fridley, K.J. Cobeen, K.E. Design of Wood Structures ASD. McGraw Hill,1999, 4th Edition.

viii

LIST OF ACRONYMS

APA American Plywood Association

ASCE American Society of Civil Engineers

ASD Allowable Strength Design

ASTM American Society for Testing Materials

COLA City of Los Angeles

COV Coefficient of Variation

FEMA Federal Emergency Management Agency

IBC International Building Code

ICBO-ES International Conference of Building Officials, Evaluation Service

LABC Los Angeles Building Code

LRFD Load and Resistance Factor Design

NDS National Design Specification for Wood Construction

NEHRP National Earthquake Hazards Reduction Program

OSB Oriented Strand Board

SEAOSC Structural Engineers Association of Southern California

SLS Strength Limit State

TCCMAR Joint Technical Coordinating Committee on Masonry Research

UBC Uniform Building Code

UCI University of California, Irvine

YLS Yield Limit State

ix

COLA-UCI LIGHT FRAME TEST COMMITTEE MEMBERS

Members:

Graeme Dick, SE, SEAOSC, Chair, Dick & Patel Associates, Inc.

Nick Delli Quadri, SE, City of Los Angeles

Luis Pastor Sanchez, SE, City of Los Angeles

Professor Gerry Pardoen, CE, University of California, Irvine

John Kariotis, SE, SEAOSC, Kariotis & Associates, Structural Engineers

Al Johnson, SE, SEAOSC, S.B. Barnes Assoicates

Ben Schmid, SE, SEAOSC, Ben Schmid Consulting Structural Engineer

x

REPORT OF A TESTING PROGRAM OFLIGHT-FRAMED WALLS WITH

WOOD-SHEATHED SHEAR PANELS

PREFACE

The California Office of Emergency Services and the Federal Emergency Management Agency

funded this research program to the City of Los Angeles to develop an understanding of the

probable dynamic behavior of shear panels, especially wood sheathing, attached to light-framed

walls by connectors such as nails or screws. The four principal goals of the research program were

to:

♦ determine whether shear wall systems could be modeled in their linear displacement

range as principally shear deforming systems,

♦ determine the cyclic force-displacement relationships for commonly used light-

framed walls with shear panels,

♦ provide data for the improvement of the design of lateral-load resisting shear wall

systems, and

♦ make recommendations to the City of Los Angeles if code changes are warranted by

the data and data analysis.

This report includes recommendations for seismic design Strength and Allowable values for

commonly used assemblies of wood sheathing attached to light-framed walls. The sheathing

attachments used in this research program were two sizes of common nails for wood framing and

self-drilling screws for light-gauge steel framing.

xi

This report presents recommended seismic design values for use in Load and Resistance Factor

Design (Strength) and Allowable Stress Design methods. These values were determined by cyclic

testing of laboratory-constructed specimens. Whereas the 1997 edition of the Uniform Building

Code, Table 23-II-1-1, and the 2000 Edition of the International Building Code, Table 2306.4.1,

published Allowable Stress Design values that are based on monotonic testing procedures, this

research program was structured to determine the effects of cyclic loading on wood-sheathed light-

framed shear panels.

1-1

CHAPTER 1

INTRODUCTION

This research was funded by the California Office of Emergency Services and FEMA. The funding

was limited to the task of providing experimental data for the validation of a post-1994 reduction in the

ASD values of wood-sheathed panels on light-framed wood stud walls. This reduction in code values

was made by the Los Angeles Department of Building and Safety after evaluation of observed damage

to light-framed buildings caused by the 1994 Northridge earthquake. SEAOSC assisted COLA in the

evaluation after the earthquake and the decision to reduce the ASD values. SEAOSC also assisted

with the testing by providing coordination and technical input to COLA and UCI through the COLA-

UCI Light Frame Test Committee, a Subcommittee of the Research Committee.

The purpose of the research project was to quantify the difference of load-displacement data obtained

using monotonic testing under load control from data obtained by using cyclic testing under

displacement control. In addition to using the cyclic test data to determine the nominal yield strength,

the cyclic test program data would determine an elastic shear stiffness for lateral-load resisting systems

of wood sheathing on light-framed walls. The current tables in the 1997 UBC for the ASD method of

wood panel sheathed walls have a significant number of footnotes as to the expected effects of

variations in construction methods. A limited number of test groups were conducted to study these

variables listed in the footnotes.

The test program was initially funded for 27 groups of 8’ x 8’ shear walls with three specimens per

group; additional funding allowed the test program to be extended to 36 groups of three specimens

each. A full description of each test group is given in Table 1.1, Shear Wall Test Configurations.

Eight groups - 2, 5, 27, 28, and 4, 22, 23, 29 - having variations such as sill and center stud size, 16-

inch and 24-inch spacing of vertical framing, vertical and horizontal orientation of plywood sheets,

1-2

were tested to determine the effects of these construction methods. Groups 6, 33 and 34 investigated

the effects of the application of 1/2-inch thick gypsum board to the shear wall in addition to 3/8-inch

thick plywood sheathing. The effect of the added nailing of the gypsum board passing through the

plywood sheathing, but without the gypsum board itself, was investigated. The efficiency of placing

sheathing on both sides of the shear wall as well as the effect of allowing vertical movement at the edge

stud was also investigated.

The limited funding required that the wood structural panels be confined to commonly used thicknesses

of plywood and OSB. The typical shear wall framing consisted of either Douglas Fir studs or light-

gauge steel members.

A summary of the significant data obtained from the entire test program is presented in the Appendices.

Table A.1 in Appendix A, for instance, provides a mean of the push-pull, load-deformation data for the

three specimens corresponding to a group as well as a COV for the six data points. Additionally, Table

A.2 presents the push-pull, load-deformation data for each of the 108 individual test specimens. This

data shows the bias of a maximum displacement and load on the first direction of displacement (pull)

side of the cyclic loading. The examination of the hysteretic behavior of shear panels on light-framed

walls shows that significant hysteretic damping occurs even when the cycles are defined as elastic. The

definition of elastic behavior adopted for this test program is that the YLS occurs when the load at the

last displacement cycle at an interpolated displacement level is equal to 95 percent of the load

corresponding to the interpolated first displacement at that level.

The test program’s data was not used to examine the currently used Strength Reduction Factors

applicable to shear panels on light framing. This topic was not a goal of the research program. The

means and COVs for the test data are reported.

1-3

Table 1-1: CoLA / UCI Shearwall Research Program Test Matrix

1 3/8 STR I one side 3x4 8d hand driven common 2 1/2 .135 6 12 1/2 3/42 3/8 STR I one side 3x4 8d hand driven common 2 1/2 .135 4 12 1/2 3/43 15/32 STR I one side 3x4 10d hand driven common 3 .152 6 12 1/2 3/44 15/32 STR I one side 3x4 10d hand driven common 3 .152 4 12 1/2 3/45 3/8 STR I one side 2x4 8d hand driven common 2 1/2 .135 4 12 3/8 3/8

3/8 STR I one side 8d hand driven common 2 1/2 .135 4 12 3/8 3/81/2 GWB both sides 1 5/8” drywall nails 1 5/8 .094 7 7 3/8 3/8

7 5/8 GWB both sides 2x4 1 7/8” drywall nails 1 7/8 .094 4 4 3/8 3/88 1/2 GWB both sides 2x4 1 5/8” drywall nails 1 5/8 .094 7 7 3/8 3/89 15/32 STR I one side 3x4 10d hand driven common 3 .152 2 12 1/2 1/210 7/16 OSB/RS one side 3x4 8d hand driven common 2 1/2 .135 4 12 1/2 1/211 15/32 OSB/STR I one side 3x4 10d hand driven common 3 .152 6 12 1/2 1/212 15/32 OSB/STR I one side 3x4 10d hand driven common 3 .152 4 12 1/2 1/213 15/32 OSB/STR I one side 3x4 10d hand driven common 3 .152 2 12 1/2 1/214 15/32 STR I one side LGS -1 5/8" flange #8 Bugle Head Screws 1 .168 6 12 1/2 1/215 15/32 STR I one side LGS -1 5/8" flange #8 Bugle Head Screws 1 .168 4 12 1/2 1/216 15/32 STR I one side LGS -1 5/8" flange #8 Bugle Head Screws 1 .168 2 12 1/2 1/217 7/16 OSB/RS one side LGS -1 5/8" flange #8 Bugle Head Screws 1 .168 6 12 1/2 1/218 7/16 OSB/RS one side LGS -1 5/8" flange #8 Bugle Head Screws 1 .168 4 12 1/2 1/219 7/16 OSB/RS one side LGS -1 5/8" flange #8 Bugle Head Screws 1 .168 2 12 1/2 1/220 7/8 Stucco one side 2x4 Furring Nail, 3/8 Head 1 1/2 .106 6 6 var var21 7/8 Stucco one side 2x4 1" Crown Staples 7/8 .058 6 6 var var22 15/32 STR I one side 3x4; field 2x's @ 24 10d hand driven common 3 .152 4 12 1/2 1/223 15/32 STR I horz 2x4 but 3x blocks 10d hand driven common 3 .152 4 12 1/2 1/224 15/32 STR I one side 3x4; Ply bears @ sill 10d hand driven common 3 .152 4 12 1/2 1/225 3/8 STR I one side 3x4 8d hand driven common 2 1/2 .135 2 12 1/2 3/426 15/32 STR I one side 2x4 8d hand driven common 2 1/2 .135 4 12 3/8 3/827 3/8 STR I one side 2x4; field 2x's @ 24 8d hand driven common 2 1/2 .135 4 6 3/8 3/828 3/8 STR I one/horz 2x4; field 2x's @ 24 8d hand driven common 2 1/2 .135 4 6 1/2 1/229 15/32 STR I one side 3x;3x@24;2x@mid 10d hand driven common 3 .152 4 12 1/2 1/230 15/32 STR I one side 3x;3x@24;3x@mid 10d hand driven common 3 .152 4 12 1/2 1/231 15/32 STR I one side 3x4;2x@16 studs 10d hand driven common 3 .152 4 12 1/2 1/232 15/32 STR I one side 3x4;2x@16 studs 10d hand driven common 3 .152 4 12 1/2 1/2

3/8 STR I one side 8d hand driven common 2 1/2 .135 4 12 3/8 3/81/2 GWB both sides 1 5/8" drywall nails 1 5/8 .094 7 7 3/8 3/8 3/8 STR I one side 8d hand driven common 2 1/2 .135 4 12 3/8 3/81/2 GWB one/opp ply 1 5/8" drywall nails 1 5/8 .094 7 7 3/8 3/8

15/32 STR I one side 10d hand driven common 3 .152 6 12 1/2 3/4same side Furring Nail, 3/8 Head 1 1/2 .106 6 6 var var

36 15/32 STR I both sides 3x4 10d hand driven common 3 .152 4 12 1/2 3/4

34 2x4

35 2x4

6 2x4

33 2x4

Nail & Nailing Info (in)Size Spacing Edge Dist

GroupSheathing

Thickness / Mat'l / ApplicationSill & Center Stud Nail Type

2-1

CHAPTER 2

EXPERIMENTAL PROCEDURES

2.1 WOOD FRAMING

The general framing configuration for the wood frame construction used for Groups 1-13

and 20-36 are shown in Table 1.1. The overall framing dimension of each shear wall was

8 foot by 8 foot with 2x4 nominal studs spaced 16 and 24-inches on center. Each group

of shear walls had either a 2x4 or a 3x4 for the center stud and sill plate. Two stacked

2x4s were used as top plates whereas end studs (or posts) consisted of kiln-dried Douglas

Fir 4x4s.

The lumber used for framing in all tests was Douglas Fir, which was purchased green

and allowed to air-dry using fans and stickers. The drying of the lumber was done to

simulate actual conditions typical at the time of an earthquake. At the time of the tests,

the moisture content was generally in the range of 9-19 percent, as determined by a

moisture meter. Figure 2.1 shows a picture of the moisture meter used to test the lumber.

The wall sheathing was fastened to the framing within 48 hours of testing, which

minimized any effects of moisture seasoning (drying of the timber) on the performance of

the wall. Intermediate wall studs consisted of 2x4s spaced 16 or 24-inches on center.

To conform to the emergency changes adopted in 1994 to the LABC, 3x4s were used for

sill plates and for the center stud where the wall sheathing panels butt together. This

provision is required by the LABC when the ASD shear value of the wall is higher than

300 pounds per foot of length. A similar requirement has been incorporated into the 1997

edition of the UBC when the ASD shear values exceed 350 pounds per foot of length.

2-2

The increased lumber size for the bottom plate was deemed necessary in order to increase

the bending capacity of the bottom plate when it was subjected to shear plus uplift forces

from the sheathing fasteners. It also increased the resistance to splitting along lines of

foundation and hold-down bolts. A stiff, heavy-duty hold-down was used for the wood

frame construction in the test program as described in Section 2.5.2. The use of the stiff,

heavy-duty hold-down anchor prevented the sill plate from being subjected to both cross-

grain bending and tension perpendicular-to-grain forces developed by the sheathing

fasteners if vertical displacement of the end posts were allowed.

Figure 2.1 Moisture Meter Used to Determine Moisture Content in Wood Framing

2-3

The 3x4 center stud member was required to provide sufficient lumber edge distance for

fasteners when the sheathing edge distance was increased from 3/8 inch to 1/2 inch. This

increase in sheathing edge distance was another change adopted into the LABC when the

ASD shear load for the wall was higher than 300 pounds per foot.

The above changes to the framing requirements were based on shear wall failure modes

observed in the damaged buildings in the 1994 Northridge, California earthquake. The

layout of a typical test specimen of wood frame construction is shown in Figure 2.2.

Figure 2.2 Wood Stud Framed Shear Wall Test Specimen

2.2 LIGHT-GAUGE STEEL FRAMING

Groups 14-19 were shear walls consisting of plywood or OSB sheathing attached to light-

gauge steel stud framing. When selecting steel for framing, three primary variables are

considered: cross section shape, cross section thickness, and steel strength. The most

common light gauge steel structural members in residential construction are C-shaped

2-4

studs and joists and U-shaped track. U-shaped tracks are used for sill and top plates with

C-shaped studs. Adequate connection must be provided to transfer the vertical loads

between the studs and the plates.

Other researchers (Serrette, et al) have indicated that light-gauge steel framing heavier

than 18-gauge may produce failures of the connection of the sheathing to the metal

framing that are not ductile. The current tests used 20-gauge framing to conform to the

minimum thickness specified in the 1997 UBC and 2000 IBC.

The light-gauge steel framing configuration for Groups 14-19 was identical as seen in

Table 1.1. The details for the 8-foot by 8-foot shear wall are shown in Figure 2.3. These

light-gauge steel stud walls were assembled using C-shaped steel studs (with lip returns

on the flanges) spaced at 24-inches on center. At the end of these walls, double C-shaped

steel studs (back-to-back) were attached by using No. 10 x 3/4-inch hex washer head self-

tapping screws and No. 8 x 1/2 inch modified truss screws to connect the top and bottom

track to the steel studs. The double studs were used to prevent local and flexural

buckling of the end posts. Steel studs were 20-gauge, 3.50-inches deep web with 1.625-

inch flanges and 0.375-inch lips. Steel tracks were 20-gauge, 3.50-inches wide with 1.50-

inch flanges. Figures 2.4 and 2.5 show line drawings of the track and C-shaped steel stud,

respectively. See Section 2.5 for details of the hold-down connectors.

2-5

Figure 2.3: Light-Gauge Steel Stud Framed Shear Wall Test Specimen

2-6

Figure 2.4. Cold-Formed Steel Track

Figure 2.5. Components of a C-Shaped Cold-Formed Steel Member

size of web

flange

web

depth of web

flange

web

lip

2-7

2.3 SHEATHING

OSB or plywood structural panels were used as the sheathing for most of the shear wall

groups. A limited number of stucco or gypsum wallboard walls were also tested. The

plywood or OSB sheathing consisted of two 4-foot by 8-foot panels attached to the

framing to create in-plane shear-resisting elements (shear walls) for seismic loads. The

attachment of the panels also provides lateral support for the studs about the weak axis.

The test matrix included 3/8-inch (3-ply) and 15/32-inch (4-ply) Structural I Rated

plywood and 7/16-inch OSB. In almost all tests, the sheathing panels were applied

vertically, with their face grain or strength axis parallel to the studs. The plywood

sheathing was applied horizontally for Groups 23 and 28. All joints between the panels

were spaced with a 1/8-inch gap to allow for the expansion of the sheathing due to

moisture and thermal effects as recommended by the APA.

2.4 FASTENERS

The plywood and OSB panels were fastened to the wood framing with hand driven

common nails and the sheathing was attached to the light-gauge steel framing with No. 8

x 1-inch Quadrex tapping (bugle head) screws. The sheathing and framing screws used

during the test program are shown in Figures 2.6 and 2.7, respectively. The various screw

types used in this test program were covered by the ICBO-ES Report ER-5202. The Los

Angeles Department of Building and Safety has additional requirements for accepting

screws.

2-8

All nails and screws used to fasten the panels to the framing were set such that the nail or

screw heads were flush with the sheathing panel surface. It should be noted that for

diaphragm and shear wall application, countersinking of fasteners below the surface of

the panel is not permitted by Section 2315.1 of the 1997 UBC.

Figure 2.7. Framing Screws Used for Light-Gauge Steel Framed Shear Walls

Figure 2.6 Sheathing Screws Used for Light-Gauge Steel Framed Shear Walls

2-9

2.5 HOLD-DOWN CONNECTORS

2.5.1 General

Deformation or slip of the hold-down connectors contributes directly to wall deflection in

proportion to the aspect (height/length) ratio of the wall. Specially designed, welded

steel hold-down connectors were used on both the 4 x 4 end posts of the wood stud

framed walls and the double stud end posts of the light-gauge steel stud framed walls to

limit the overturning uplift of the wall in accordance with the testing procedure

requirements.

2.5.2 Wood Frame Hold-downs

The deformation or slip of the hold-down connector causes the overturning forces to be

carried by an unintended mechanism. As the hold-down deforms or slips, overturning

forces are transferred from the sheathing to the sill plate. This uplift deformation causes

splitting of the timber sill plate due to cross grain bending. The added uplift deformation

of the end post and the sheathing causes premature failure of the sheathing fasteners at

the end of the sill plate. This unintended mechanism causes a significant reduction in the

lateral forces resisting capacity of the shear wall (see Section 3.5).

The hold-downs for the wood framed wall were designed by Ben Schmid, SE for an

earlier series of tests conducted on similar shear walls at UCI and were re-used in the

current test series. Figure 2.8 provides a drawing of a hold-down and Figure 2.9 shows

a picture of the hold-downs used in the tests.

The wood framed hold-down design incorporated two 2-5/8-inch diameter steel shear

plate connectors, as described in Part X of the NDS, and in ASTM D5933, Standard

Specification for 2-5/8-inch and 4-inch diameter Metal Shear Plates for Use in Wood

2-10

Figure 2.8. Detail of a Wood Framed Hold-down Connector

Construction. The shear plates minimize the deformation or slip between the end posts

and the hold-down connectors. 1/4-inch thick x 2-1/2-inch square, steel plate washers

were placed under the nuts on the 3/4-inch diameter bolts through the end posts.

The bolt holes were drilled to a maximum of 1/16-inch oversize in accordance with NDS

provisions. The groove and dap for the shear plate connectors were accurately pre-bored

in the end posts before the wall framing was assembled, using a special cutter head

obtained from the manufacturer of the connector with a template and drill guide. A

picture of the dapping tool and some shear plates is provided in Figure 2.10.

2-11

Figure 2.9. Wood Framed Hold-down Connectors

2.5.3 Light-Gauge Steel Hold-Downs

The hold-downs used for the light-gauge steel stud framed shear walls were classified as

strap hold-down anchors, which were specially designed at the UCI structures lab. These

hold-downs were very stiff in the longitudinal direction to limit slip and uplift as required

by the test procedure. The hold-downs were securely fastened to the steel studs with 18

No. 10 x 3/4-inch hex washer head self-tapping screws on each side of the hold-down.

Figure 2.11 provides a drawing of a hold-down and Figure 2.12 shows a picture of a pair

of hold-downs used in the tests.

2-12

Figure 2.10. Dapping Tool and Shear Plates for Wood Framed Shear Walls

Figure 2.11. Detail of a Light-Gauge Steel Framed Hold-down Connector

2-13

Figure 2.12. Light-Gauge Steel Framed Hold-down Connector

2.6 TEST SET-UP AND PROCEDURE

The wood framed shear wall test specimens were attached to the base of the test fixture

with four 5/8-inch diameter anchor bolts as shown in Figure 2.2 whereas the light-gauge

steel framed shear wall test specimens were attached to the base of the test fixture with

five 5/8-inch diameter anchor bolts as shown in Figure 2.3. The sill plate of each shear

wall was supported on a 3-1/2-inch wide by 96-inch long steel rectangular bar. This bar

was designed such that it only supported the framing of the walls. This design allowed

the sheathing panels to rotate, when the shear wall was loaded laterally, without the

panels bearing on the test fixture at the bottom.

Anchor-bolt holes in the sills and tracks were carefully located and pre-drilled using a

drill jig, to minimize bolt deformation and slip when the shear wall was laterally loaded

in the plane of the wall. The bolt holes in the sills were drilled to a maximum of

1/16-inch oversize. Square steel plate washers, 1/8-inch thick x 2-1/2-inches square,

2-14

were used under the nuts of the sill plate bolts. Figure 2.13 shows an elevation of the test

setup.

Figure 2.13 Test Set-Up for Cyclic Load Shear Wall Test at UCI

Racking shear loads were applied horizontally to the top of the shear wall test specimens

through a steel H-beam lag-screwed with 3/8-inch diameter lag screws spaced 6-inches on

center to the double top plate of the wall. The beam was placed on a 3/4-inch thick by

3-inch wide plywood spacer. The purpose of this spacer was to allow the sheathing panels

to rotate when the shear wall was loaded laterally, without bearing on the H-beam at the top

corners of the panels. The beam was restrained laterally (normal to the plane of the wall)

by pairs of low-friction Teflon pads fastened to the beam and the adjacent steel bracing

frames. This set-up allowed in-plane displacement of the wall during the test while

preventing the top of the wall from twisting outside of the load application plane.

2-15

Racking shear forces were applied with a 55,000-pound capacity programmable double-

acting hydraulic actuator (MTS Systems Corporation) which was bolted to a stiff vertical

cantilever column hinged at the base to act as a lever arm, as shown in Figure 2.13. The

hinged cantilever column system was necessary to “multiply” the actuator displacement,

which was limited to 3-inches of stroke in the push and pull directions, to achieve greater

displacement at the top of the wall. The horizontal load at the top of the wall was

measured with a load cell in the horizontal plane of the top plate and steel H-beam.

2.7 TEST PROTOCOL

All tests were subjected to fully reversing cyclic displacements following the TCCMAR

sequentially phased displacement procedure shown in Figure 2.14. This test procedure

had been reviewed and refined over a 2-1/2 year period. The final version of the test

procedure was published in 1997 by SEAOSC as Standard Method of Cyclic (Reversed)

Load Test for Shear Resistance of Framed Walls for Buildings.

The TCCMAR procedure uses the concept of the FME, which is defined as the first

significant Limit State that occurs during the test. A Limit State is an event that marks

the demarcation between two behavior states. When a Limit State occurs, some

structural behavior of the system is altered. For instance, an FME occurs when the load

resistance of the wall, upon recycling to the same wall displacement, first drops

noticeably from the original load resistance at the same displacement. The FME can be

determined from preliminary cyclic load tests on an identical test specimen. For the

shear wall test specimens in this series, the FME displacement for all tests was estimated

from prior cyclic load tests of similar configurations. Appendix A summarizes the YLS

obtained from the testing of both wood and light-gauge steel framed shear walls.

2-16

The TCCMAR procedure consists of applying three cycles of fully reversing,

displacement-controlled load at each wall displacement increment representing 25

percent, 50 percent, and 75 percent of the FME displacement. Then, the wall

displacement is increased for one load cycle to 100 percent of the FME displacement.

Next, “decay” cycles of displacement for one cycle each at 75 percent, 50 percent, and 25

percent of the maximum displacement (100 percent of the FME displacement) are

applied. This is followed by three cycles of displacement at maximum displacement (100

percent of the FME displacement) to stabilize the load-displacement response of the wall.

Then, the next increment of increased displacement (125 percent of the FME

displacement) is applied, followed by similar decay and stabilization cycles of loading.

This incremental cyclic load-displacement sequence is continued to 150 percent, 175

percent, 200 percent, 250 percent, 300 percent, 350 percent and 400 percent of the FME

displacement, or until the wall exhibits greatly diminished shear load capacity.

For a typical shear wall test, the predetermined shear wall displacements were input to a

computer, which controlled the actuator displacement. A cyclic frequency of 0.5 Hz (one

cycle per 2 seconds) was used to avoid inertial effects of the mass of the wall and the test

fixture hardware to cyclic loading. During later stages of the cyclic loading sequence,

when the wall displacement exceeded 1.6 inches, the cycle frequency was reset to about

0.25 Hz (one cycle per four seconds) to properly control the hydraulic system with the

instrumented displacement input.

2-17

Figure 2.14. TCCMAR Loading Sequence

2.8 INSTRUMENTATION

2.8.1 Instruments

Typical shear wall instrumentation included measurements of the following:

• horizontal load applied to the wall, measured between the wall and the hinged

cantilevered column

• horizontal displacement of the wall at the top plate

• horizontal displacement of the bottom plate relative to the test fixture (lateral

in-plane sliding)

• vertical displacement at the bottom end of both end posts relative to the test

fixture (uplift and compression)

-400

-300

-200

-100

0

100

200

300

400

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Cycle Number

Sp

ecim

en D

isp

lace

men

t (%

of

FM

E)

2-18

• vertical displacement of the hold-down connectors relative to the end posts

(displacement/bolt slip)

The horizontal displacement of the wall at the top plate was measured using a PSCC

Rayelco Position Transducer, otherwise known as a string potentiometer. The

transducer used for this testing program was a model P-20A (A246), with a position

sensitivity of 51.01 mV/V/in. This voltage sensitivity corresponds to an accuracy of

0.005 inch. The range of this potentiometer was 0-20 inches. To account for the cyclic

displacements of this testing program, the transducer was set to a displacement of about

10 inches at the start of each test. Figure 2.15 shows a drawing of the typical instrument

locations for a shear wall test.

The horizontal load applied to the wall was measured using a Bonded Foil Type Strain

Gage Load Cell, produced by Muse Measurements of San Dimas, CA. The load cell used

for this testing program was a model SR-4-24k with a force of 24 kips @ 2.0024 mV/V.

The other five displacement measurements (sill slip, 2 post uplifts, and 2 hold down slips)

were measured using Spring Return Linear / Position Sensor (Precision Linear

Potentiometers) produced by Duncan Electronics. The potentiometers used for this

testing program were model 604 R4K. These transducers have an accuracy of 0.002

inches. Figure 2.16 shows a picture of a precision linear potentiometer, a load cell, and a

string potentiometer.

2-19

Right Hold-down Slip

Load

Right Post UpliftLeft Post Uplift

Left Hold-down Slip

Displacement

Figure 2.15. Instrument Locations for a Cyclic Shear Wall Test

Figure 2.16. Instrumentation Samples Used During the Testing of Shear Walls

2-20

2.8.2 Data Sampling

Data acquisition for all shear walls was taken using the Strawberry Tree data acquisition

system. This system includes several components including the Strawberry Tree Data

Acquisition software, the Terminal Panels, and the Analog-to-Digital (A-to-D) Transition

Hardware. The terminal panels attached the instrument wiring to a ribbon wire. This

ribbon wire was, in turn, attached directly to the A-to-D boards within the computer

system.

Data was acquired at 50 Hz (one data point every 0.02 seconds). The data value from

each instrument measurement was recorded in columnar format with the following

arrangement: Time, Top Displacement, Load, Right Post Uplift, Left Post Uplift, Right

Hold Down Slip, Left Hold Down Slip and Bottom Plate Sliding.

2.8.3 Data Analysis

Typically the raw data from a shear wall test had to be “conditioned” before it could be

analyzed. The first step in the data analysis procedure was to manually remove the

outliers (data dropouts or spikes) in the data. These spikes were obvious errors in the

data when viewed as a spreadsheet chart. When a data dropout was located, the

erroneous value was replaced by the average of the previous point and the following

point. To produce a smooth time history curve that eliminated the data acquisition

“jogs”, the data file was then filtered using a 4th order low-pass Butterworth filter with a

cutoff frequency of 5 Hz. This filter was implemented using MATLAB version

5.2.1.1420, and was used to remove the electrical or mechanical noise in the data. A UCI

developed program was then implemented to obtain several characteristics of the load-

deformation data, including the envelope curve, the “stabilized” envelope curve, the

YLS, the SLS, and the initial stiffness of the sample.

3-1

CHAPTER 3

RECOMMENDATIONS

3.1 DESIGN VALUES

These recommendations utilize the currently reported experimental results and cyclic tests made by

others. The experimental results are rounded in recognition that a variable COV exists for each of the

individual tests and for the mean of the test groups. The COVs determined from the mean of each test

group were smaller than those reasonably expected for specimens made of hand-assembled wood

products or of wood sheathing and light-gauge steel.

The data for yield strength and deflection at the YLS was plotted on a format of load vs. deformation.

The load-displacement points for six inch, four inch to two inch spaced perimeter fasteners generally

were nearly linear in this plotting format. Providing three or six fasteners per foot at the perimeter of

the sheathing panel in lieu of providing a minimum of two fasteners per foot did not have a

proportional increase in strength. The recommended design strength for three inch perimeter fasteners

was interpolated as having a linear relationship with two, four and six inch perimeter fasteners.

The recommended Nominal Strength values for shear (V in the Tables) and Elastic Shear Stiffness

values (G in the Tables) for seismic forces for wood-based panels applied directly to light-framed wood

are presented in Table 3A. The Nominal Strength values are given in pounds per foot length for shear

and in pounds per inch for Elastic Shear Stiffness. The recommended Nominal Strength values are for

use in the LRFD method.

Recommended ASD shear values are given in Table 3B. The ASD shear values are also in pounds per

foot length. The recommended shear stiffnesses are the same as those recommended for Nominal

Strength. Section 1630.9 of the 1997 UBC requires the use of Strength Design loading and Nominal

3-2

Strength material characteristics for the determination of drift for both ASD and LRFD designs.

The recommended Nominal Strength for shear and Elastic Shear Stiffness for seismic forces for wood-

based panels applied directly to walls framed with light-gauge steel studs are presented in Table 3C

whereas Table 3D presents the ASD values.

Note that the recommended values of V and G given in Tables 3A, 3B, 3C, and 3D are based on

limiting the hold-down anchorage displacements as required by the test procedure. The recommended

values of V and G shall not be used for systems with hold-down anchorages not meeting the criteria.

(See Section 3.5)

3.2 DERIVATION OF DESIGN VALUES

3.2.1 Derivation of Strength Design Values

LRFD for wood-based light-frame shear-wall systems is a part of the Manual for Engineered Wood

Construction published by the American Forest and Paper Association and the American Wood

Council. The 2000 Edition of the IBC references ASCE Standard 16 for LRFD. ASCE-16 states,

"The in-plane shear reference resistance 'D' shall be obtained from approved tables or determined using

principles of engineering mechanics" (Section 9.4.1). Section 9.2 of the same Standard defines the

resistance factor “φz is the resistance factor for shear walls or diaphragms limited by fastener strength

(emphasis added) = 0.65.” Section 9.4.1.1 references Sections 2.5, 7.1.3, and 7.4.3.3. The lateral

strength of fasteners is discussed in Section C7.4.3 of the commentary to ASCE-16 that states “The

equations for the nominal lateral strength of a small dowel connection are based on a yield theory

for dowel connections (emphases added).” Further discussion of the lateral strength of nails based on

“a strength of materials-based yield theory (emphasis added)” is contained in Section C7.5.4 of the

commentary to ASCE-16. Figure C7.5-2 defines the yield load as the load at which the initial slope of

the connection load-slip curve, when offset by 5% of the fastener diameter, intersects the curve. This

3-3

concept of the Nominal Strength of a system is the same as the use of Nominal Strength (YLS) for the

design of steel framed structural systems, reinforced concrete framed structural systems and reinforced

masonry framed structural systems. It is consistent with Chapter 16 of the 1997 UBC, Chapter 16 of

the 2000 IBC, and ASCE-7.

The test procedure used a displacement-controlled cyclic (full reversal of displacements) protocol. The

displacement used for each set of cyclic displacements was based on a fraction or a multiple of an

estimate of the FME. The FME for a system that has ductility is the YLS. The second limit state for a

yielding system would probably be its SLS (sometimes referred to as the ultimate strength state).

The test protocol begins with three fully reversing cycles of one-quarter, one-half and three-quarters of

the estimated displacement at the FME. These displacements are followed by one cycle at the

estimated FME displacement, three cycles at less displacement and then three cycles of displacement at

FME displacement. A full description of the test protocol is given in Chapter 2, Experimental

Procedures.

The COLA-UCI Light Frame Test Committee used a reduction in applied load at the same imposed

displacement of five percent to determine the YLS and hence the yield force and yield displacement of

the system. The reduction is based on the difference in force recorded on the first cycle at that

displacement versus the force recorded on the last cycle at that displacement. This generally required

that the yield force and the yield displacement be interpolated between two force-displacement data

points.

The yield force divided by the yield displacement determines an Elastic Shear Stiffness, G, of the shear

wall system. This represents a yield stiffness that can be used for calculation of the story drift required

by Section 1630.9 of the 1997 Edition of the UBC or by Section 1617.4.6.1 of the 2000 Edition of the

IBC. See Section 3.3, Recommended Use of Stiffness Data.

3-4

The Nominal Strength shear values presented in Tables 3A and 3C are multiplied by a Strength

Reduction Factor, φ, to determine a design shear value for LRFD (strength) design procedures. The

system in-plane Elastic Shear Stiffness, G, value is used for the calculation of linear and non-linear

story drift. See Section 3.3, Recommended Use of Stiffness Data.

3.2.2 Derivation of Allowable Stress Design Values from Nominal Strength Values

Current codes allow use of both LRFD procedures and ASD procedures by modifying the loading on

the lateral load-resisting system, Section 1612.3.1 of the 1997 UBC. The concept is that the structure,

when designed by either method, will have approximately the same yield strength and elastic (yield)

stiffness.

This concept was without experimental verification for wood based shear panels on light-framed walls.

The ASD values published in the UBC were derived from monotonic load controlled testing, not

displacement controlled cyclic testing. Displacement controlled cyclic testing is considered as being

more representative of seismic loading.

The goal of having a nearly identical strength and stiffness structure as a result of either LRFD or ASD

is accomplished by deriving ASD values directly from the experimentally derived Nominal Strength

values. The ASD shear value is the Nominal Strength shear value multiplied by the Strength Reduction

Factor, φ, and divided by the load reduction factor given in Section 1612.3.1 of the 1997 Edition of

the UBC. The Strength Reduction Factor used for the determination of the recommended ASD values

is 0.65. This is the factor given in ASCE Standard 16 and the Manual for Engineered Wood

Construction, AF & PA and AWC. The load-reduction factor given in Section 1612.3.1 of the 1997

UBC is 1.4. The net conversion factor for the reduction of Nominal Strength shear values to ASD

3-5

values is 0.46.

3-6

Table 3A: LRFD Nominal Strength5 Shear and Shear Stiffness for Seismic Forces

1 Values of V and G are based on limiting the contribution of the hold-down connection displacements to the total displacement of the wall assembly, at theultimate strength limit state, to 0.15% of the wall height. The values of V and G shall not be used for wall assemblies using hold-down connectors not meetingthis criterion.

2 All framing shall be Douglas Fir-Larch or Southern Pine. Shear values for nails in framing members of other species set forth in Division III, Part III, shall becalculated by multiplying the shear capacities in the Table by the following factors: 0.82 for species with specific gravity greater than or equal to 0.42 but lessthan 0.49, and 0.65 for species with a specific gravity less than 0.42. All panel edges shall be backed with 2-inch nominal or wider framing. Panels installedeither horizontally or vertically. Space nails 12 inches on center along intermediate framing members. Common nails shall be used.

3 The values shown in the Table shall not be cumulative with other materials applied to the same wall. The values of V and G for the same material applied toboth sides of the wall shall be 80 percent of twice the value shown in the Table. Framing members at panel joints shall be 3-inch nominal or thicker when bothsides of the wall are sheathed.

4 Where Nominal Strength shear values exceed 645 pounds per foot, foundation sill plates and all framing members receiving edge nailing from abutting panelsshall not be less in width than a 3-inch nominal member. Nails shall be staggered.

5 Nominal Strength shear values shall be multiplied by the Strength Reduction Factor φ of 0.65 (ASCE16, 1997 UBC).

PANELS APPLIED DIRECTLY TO FRAMING 1,2,3,4

Nail Spacing @ Panel Edges (inches)

6 4 3 2

PANEL GRADE

MINIMUMNOMINAL

PANELTHICKNESS

(inches)

MINIMUMNAIL

PENETRATIONIN FRAMING

(inches)

COMMONNAILSIZE V(lb/ft) G(lb/in) V(lb/ft) G(lb/in) V(lb/ft) G(lb/in) V(lb/ft) G(lb/in)

400 11,000 575 13,500 715 14,500 1,025 16,0001 1/2 8d420 11,500 600 14,000 750 14,500 1,075 16,500STRUCTURAL 1

3/8

15/32

15/32 1 5/8 10d 470 15,000 660 15,500 835 16,000 1,200 17,500

1 1/2 8d 290 13,500 500 15,000 615 16,500 945 19,000OSB7/16

15/32 1 5/8 10d 370 17,500 640 19,500 780 21,000 1,200 24,500

3-7

Table 3B: ASD Shear and Shear Stiffness for Seismic Forces

PANELS APPLIED DIRECTLY TO FRAMING 1,2,3,4

Nail Spacing @ Panel Edges (inches)

6 4 3 2

PANEL GRADE

MINIMUMNOMINAL

PANELTHICKNESS

(inches)

MINIMUMNAIL

PENETRATIONIN FRAMING

(inches)

COMMONNAILSIZE V(lb/ft) G(lb/in) V(lb/ft) G(lb/in) V(lb/ft) G(lb/in) V(lb/ft) G(lb/in)

185 11,000 270 13,500 330 14,500 475 16,0001 1/2 8d195 11,500 280 14,000 350 14,500 500 16,500STRUCTURAL 1

3/8

15/32

15/32 1 5/8 10d 220 15,000 305 15,500 390 16,000 560 17,500

1 1/2 8d 135 13,500 230 15,000 285 16,500 440 19,000OSB7/16

15/32 1 5/8 10d 170 17,500 300 19,500 365 21,000 555 24,500

1 Values of V and G are based on limiting the contribution of the hold-down connection displacements to the total displacement of the wall assembly, at theultimate strength limit state, to 0.15% of the wall height. These values of V and G shall not be used for wall assemblies using hold-down connectors not meetingthis criterion.

2 All framing shall be Douglas Fir-Larch or Southern Pine. Shear values for nails in framing members of other species set forth in Division III, Part III, shall becalculated by multiplying the shear capacities in the Table by the following factors: 0.82 for species with specific gravity greater than or equal to 0.42 but lessthan 0.49, and 0.65 for species with a specific gravity less than 0.42. All panel edges shall be backed with 2-inch nominal or wider framing. Panels installedeither horizontally or vertically. Space nails 12 inches on center along intermediate framing members.

3 The values shown in the Table shall not be cumulative with other materials applied to the same wall. The values of V and G for the same material applied toboth sides of the wall shall be 80 percent of twice the value shown in the Table. Framing members at panel joints shall be 3-inch nominal or thicker when bothsides of the wall are sheathed.

4 Where the ASD shear values exceed 300 pounds per foot shear, foundation sill plates and all framing members receiving edge nailing from abutting panelsshall not be less in width than a 3-inch nominal member. Nails shall be staggered.

3-8

Table 3C: LRFD Nominal Strength Shear 5 and Shear Stiffness Values for Seismic Forces for Walls Framed withCold-Formed Steel Studs

Assembly Description 3 Fastener 1,2,4 Spacing at Panel Edges (inches)6 4 3 2

V (lb/ft) G (lb/in) V (lb/ft) G (lb/in) V (lb/ft) G (lb/in) V (lb/ft) G (lb/in)15/32 inch Structural 1 (4 ply) one side 315 16,000 500 18,000 670 20,000 1020 23,0007/16 inch (OSB) one side 265 14,500 340 18,500 430 22,000 570 30,000


2 Studs shall be a minimum 1-5/8 inch by 3-1/2 inch with a 3/8-inch return lip. Track shall be a minimum 1-1/4 inches by 3-1/2 inches. Framing spacing shallbe 24 inches maximum. Framing screws shall be No. 8 by 5/8 inch wafer head self-drilling. Studs and track shall have a minimum uncoated base metalthickness of 0.033 inches and shall not have a base metal thickness greater than 0.043 inches and shall be ASTM A446 Grade A (or ASTM A653 SQ).

3 Sheathing fasteners shall be No. 8 by 1 inch self-tapping bugle head with a minimum head diameter of 13/32- inches. Screws in the field of the panel shall beinstalled at 12 inches on center.

4 The values shown in the Table shall not be cumulative with other materials applied to the same wall. The values of V and G for the same material applied toboth sides of the wall shall be 80 percent of twice the value shown in the Table.

5 Nominal Strength shear values shall be multiplied by the Strength Reduction Factor φ of 0.55 (Paragraph 2219.3, 1997 UBC).

3-9

Table 3D: ASD Shear and Shear Stiffness Values for Seismic Forces for Walls Framed with Cold-Formed Steel Studs

Assembly Description 3 Fastener 1,2,4 Spacing at Panel Edges (inches)6 4 3 2

V (lb/ft) G (lb/in) V (lb/ft) G (lb/in) V (lb/ft) G (lb/in) V (lb/ft) G (lb/in)15/32- inch Structural 1 (4 ply) one side 125 16,000 200 18,000 265 20,000 400 23,0007/16- inch (OSB) one side 105 14,500 135 18,500 170 22,000 225 30,000


2 Studs shall be a minimum 1-5/8 inch by 3-1/2 inch with a 3/8-inch return lip. Track shall be a minimum 1-1/4 inches by 3-1/2 inches. Framing spacing shallbe 24 inches maximum. Framing screws shall be No. 8 by 5/8 inch wafer head self-drilling. Studs and track shall have a minimum uncoated base metalthickness of 0.033 inches and shall not have a base metal thickness greater than 0.043 inches and shall be ASTM A446 Grade A (or ASTM A653 SQ).

3 Sheathing fasteners shall be No. 8 by 1 inch self-tapping bugle head with a minimum head diameter of 13/32- inches. Screws in the field of the panel shall beinstalled at 12 inches on center.

4 The values shown in the Table shall not be cumulative with other materials applied to the same wall. The values of V and G for the same material applied toboth sides of the wall shall be 80 percent of twice the value shown in the Table.

3-10

3.3 RECOMMENDED USE OF STIFFNESS DATA

Current seismic design procedures require that the seismic load-resisting systems meet two separate

but inter-related criteria. The system shall have the specified elastic strength (Nominal Strength

multiplied by a Strength Reduction Factor) and a limited probable story drift. This probable story drift

is estimated as the sum of elastic displacements and non-linear displacements when the system is loaded

by dynamic forces. The summation of the linear and non-linear displacements is calculated by

multiplying the calculated elastic displacement by a fraction of the response reduction, R, factor used to

reduce the probable dynamic loading to a design seismic loading.

The experimental testing determined an elastic limit for wood-based shear panels on light-framing. The

supporting studs were either Douglas Fir or light-gauge metal studs. Tables 3A, 3B, 3C and 3D

include an Elastic Shear Stiffness, G, value for each assembly and fastener schedule. This Elastic Shear

Stiffness, G, includes all effects within the shear-resisting system that caused the displacement at the

YLS. This Elastic Shear Stiffness excludes the effect of significant vertical movement at the hold-

down anchorages. The effects on elastic stiffness of the system due to allowing limited free movement

at the hold-down anchors shall be considered and is discussed in Section 3.5 of this report.

The lateral load resisting system is designed to have a resistance capacity equal to or greater than the

factored seismic loading. The engineering mechanics formula for a shear deforming system used for

calculation of the elastic displacement of the designed system is:

V H

∆∆ =

G L

3-11

where

∆∆ = elastic displacement

V = applied horizontal loading (pounds)

H = system height

L = system in-plane length

G = Elastic Shear Stiffness (pounds force per inch horizontal displacement).

Note: The above formula is based on the limited displacement of the hold-down anchorages required

by the test procedure. The formula shall not be used for systems with hold-down anchorages that do

not meet the test criteria. (See Section 3.5).

The units of height and length of the shear wall must be the same. If the units of the applied horizontal

force are pounds, the calculated elastic displacement is in inches. The applied horizontal force is

determined from the load combinations specified for LRFD, Section 1630.9 of the 1997 UBC. All

shear panels in the line of resistance must have a common height. If not, calculations of relative rigidity

must be made to assign the lateral forces to the shear panels.

The elastic drift of the shear resisting system is increased to the Maximum Inelastic Response

Displacement by a multiplication factor of 0.7 R. This increase is in conformance with the

requirements of the 1997 Edition of the UBC. This Maximum Inelastic Response Displacement is

limited by Section 1630.10.2 to 0.025 times the story height. A parallel research project, the CUREE -

Caltech Woodframe Project, has developed data that indicates light-frame buildings with wood-based

shear panels have fundamental (elastic) periods that are significantly less than the break-point between

a code permissible story drift of 0.025 and 0.020.

This experimental testing of wood-based shear panels on light-framed shear walls found that the code

prescribed drift limit exceeds the SLS displacement that was compiled for 32 groups of assemblies.

3-12

The mean value of the drift ratio at the SLS of the 32 panels was 0.0146 times the story height (1.4

inches displacement). The standard deviation of this displacement data was 0.34 inches and hence the

COV was 24 percent. This experimental data clearly indicates that the drift limit associated with the

recommended in-plane shear values of this report should be reduced from the drift limits given in the

1997 UBC.

If the drift limit is taken as the mean minus one standard deviation of the data, the acceptable value of

story drift is slightly above 0.01. A minimal number of computations on simple systems were made

during the writing of this report. These calculations indicate that if the drift limit is reduced from the

current code value to 0.015, then the design is generally controlled by the minimum prescribed strength

for story heights of 12 feet or less and use of 15/32 inch plywood nailed with 10d @ 2 inches onto

wood studs. If the drift limit is specified as 0.01, it is likely that the drift limit will control the design

process for the shear panels with closely spaced fasteners at the perimeter of the shear panels.

3.4 RECOMMENDATIONS FOR RELATING DESIGN VALUES TO FUTURE CODES

The recommended design values for ASD given in this report are related to current code because they

use a load reduction factor (Section 1612.3 of the 1997 UBC) and a Strength Reduction Factor φ

(ASCE-16) to equate the ASD procedure to the LRFD procedure. The material Nominal Strength is a

material property and is not affected by code specified seismic design procedures.

The COVs of the mean experimental data given in Appendix A should be considered in a review of the

Strength Reduction Factor for wood-based shear panels on light frame walls given ASCE-16. The

Strength Reduction Factor in that document is that assigned to connectors. The shear panels are

attached to the framing by multiple connectors loaded by translational forces and rotational forces. At

any displacement of the system, fasteners along any panel edge may have a variation in their loading

that varies from their Nominal Strength or YLS resistance value to their SLS value.

3-13

A revision of the Strength Reduction Factor for wood-based shear panels on light framing could be

based on this experimental data even though the number of identical specimens is much less than that

required for reliability analysis. However, investigations of earthquake damage to all types of buildings

using all types of materials have found that ASD code design values used by designers and construction

variations were the principal causes of major earthquake damage. It is a common opinion in the

engineering profession that Strength Reduction Factors should include the probability of construction

error in conjunction with laboratory testing for determination of resistance factors.

It is expected that the 1997 UBC will be replaced by the IBC. The IBC describes the seismic hazard

by mapping of the United States. In the western United States, the mapping is for a Maximum

Considered Earthquake that is deterministic rather than a probabilistic-based ground motion having a

specified return period. Two-thirds of the Maximum Considered Earthquake spectrum is used for the

seismic design spectrum. This concept is based on a consensus of qualified engineers for ductility and

overstrength beyond the YLS or Nominal Strength for materials used in construction. See

Commentary to NEHRP Recommended Provisions for Seismic Regulations, FEMA 303/February

1998 for further information. The existence of this consensus implies that the basis for design material

strengths should not be entirely based on reliability analyses. Regardless of where consensus on

seismic design procedures leads, the data in the Appendices of this report represents data on the

material behavior of systems of wood-based sheathing on light framing of wood and light-gauge steel.

The data determined by this research project can be supplemented by additional testing of shear wall

assemblies. The test procedures need to be similar to have a relationship with the data contained in this

report. How this experimental material behavior is related to future seismic design procedures in codes

will not influence the material behavior determined by this research project.

3.5 EFFECTS OF NON-STANDARD DETAILS IN TEST PANELS

The research program included the testing of assemblies that are variations of typical shear panels on

light frame construction. These variations included:

3-14

Group 6 - combination of plywood sheathing and gypsum boardGroup 7 - 5/8-inch thick gypsum board sheathingGroup 8 - 1/2-inch thick gypsum board sheathingGroup 20 - stucco attached with furring nailsGroup 21 - stucco attached with staplesGroup 24 - plywood bearing on test fixture at bottomGroups 25, 26, 27, 28 -2 x 4 framing, 16- and 24-inch spacingGroups 31, 32 - 0.2 and 0.4-inch movements allowed at hold-downsGroups 33, 34, 35 - gypsum board over or opposite from plywoodGroup 36 - plywood sheathing on both sides of wall

A complete description of these assemblies is contained in the Appendices.

Groups 2, 5, 27 and 28 were related in that 3/8-inch plywood fastened with 8d nails at four inches on

center was the common characteristic. The framing of the wall varied from 3 x 4 to 2 x 4, for studs,

center stud (at splice of four by eight feet plywood sheets) and sill. Plywood was placed horizontally

on Group 28 specimens. Stud spacing varied from 16 to 24 inches on center. The mean data for each

group was compiled into a mean for these groups. The COVs for the means of these groups were as

follows:

YLS load or Nominal Strength 7.9%

YLS displacement 13.2%

Elastic Shear Stiffness, G 13.4%

SLS load 8.1%

SLS displacement 23%

The test program did not determine a significant difference in system properties for any of these

variations tested.

Groups 4, 22, 23, 24, 29 and 30 were related in that all were sheathed with 15/32-inch thick

plywood fastened with 10d nails spaced at four inches on center. The framing size of the sill and

center stud varied from 3 x 4 to 2 x 4 whereas the stud spacing varied from 16 to 24 inches on

3-15

center. The size of plywood varied from (2 @ 4 x 8) sheets, (2 @ 2 x 8 and 1 @ 4 x 8) sheets, to

(4 @ 2 x 8) sheets. Mean data for groups 4, 22, 23, 29 and 30 was compiled into a mean for

these groups. The COVs for the means of these groups were as follows:

YLS load or Nominal Strength 9.1%

YLS displacement 10.4%

Elastic Shear Stiffness, G 17.9%

SLS load 3.6%


Again, no significant differences in system properties were determined.

Group 26 was varied from Groups 4, 22, 23, 24, 29 and 30 in the fastener diameter. The plywood was

attached with 8d nails at 4 inch spacing in lieu of the 10d nails used in the comparative groups. When

the test data is modified by the ratio of code specified lateral load resistance for 8d nails to 10d nails,

the difference from the mean data for all panels fastened with 10d nails was 2 percent for YLS load and

0.5 percent for SLS load. This data implies that the nail diameter has the most critical influence on

shear wall strength.

Group 26 test data was also compared to Group 2 test data. The most significant difference in the

assemblies was the thickness of the plywood sheathing. Group 26 had 15/32-inch thick sheathing

whereas Group 2 had 3/8-inch thick sheathing. The YLS load for Group 2 was 98 percent of the

Group 26 values whereas the SLS load for Group 2 was 99 percent of the Group 26 value.

3-16

Group 36 specimens were sheathed on both sides of the wood stud framed wall with 15/32-inch thick

plywood. Both sides were nailed with 10d nails spaced at four inches on center. The ratios of strength

and stiffness data of Group 36 to the mean of all data for similar sheathing and attachment on one side

of the wall is as follows:

YLS load or Nominal Strength 156%

YLS displacement 93%

Elastic Shear Stiffness, G 173%

SLS load 179%


This data led to the recommendation in this report that the Nominal Strength shear value for sheathing

placed on both sides of a shear wall shall be 80 percent of twice the values given in Table 3A and 3B.

No specimens were tested with plywood on both sides of light-gauge steel framing.

The effects of sheathing with gypsum board and plywood sheathing were investigated by Groups

6, 33 and 34. Group 6 had gypsum board on each side of the wall. Group 34 had 1/2-inch thick

gypsum board only on the side opposite to the plywood sheathing. Group 33 simulated Group 6

with gypsum board sheathing nailing penetrating the plywood sheathing and stud interface, but

had no gypsum board. The comparative data indicates that the Elastic Shear Stiffness, G, is

significantly increased by the presence of gypsum board sheathing. The YLS and SLS loads did

not show any significant trend except that the effects of gypsum board on each side of the wall,

versus only gypsum board nails on the plywood sheathed side of the wall, significantly reduced

the displacements at the YLS and SLS. The experimental data for Group 34 was compared to

Groups 6 and 33 and to the mean data for all panels with identical thickness and fastener spacing.

The comparisons indicated that the added nails penetrating the sheathing-stud interface have

significance, principally for yield strength. The comparison for the remainder of system properties

did not support conclusive opinions on the overall effects.

3-17

Group 35 was included to provide data on the effects of furring nails used for the attachment of stucco

passing through the plywood-stud interface. YLS and SLS loads were increased. The Elastic Shear

Stiffness did not have a comparable increase because only the furring nails were added to the assembly.

The panel was not covered with stucco.

Groups 31 and 32 investigated the effects of free movement at the hold-down anchorages. The free

movement allowed was 0.2 inches for Group 31 and 0.4 inches for Group 32. The effects were not

significantly different for the free movements allowed. The Nominal Strength in shear was reduced to

about 60 percent of the mean for similar panels. A similar effect on Elastic Shear Stiffness was found.

The displacements at the YLS and the SLS were relatively unchanged. The SLS shear was unchanged.

The effects of variations in the panels did not support several of the footnotes to the shear value tables

given in the 1997 UBC. The testing supported the footnote added for plywood sheathing on both

sides of the wall. The use of 3x studding given in the footnotes to the recommended shear values for

wood studding is similar to the 1997 UBC footnotes. These are recommended for construction

quality, not for resistance shear values obtained on laboratory specimens.

A-1

APPENDIX A

LOAD / DEFORMATION SUMMARY

This appendix summarizes the load and deformation results for the 108 shear wall tests (36

groups with 3 samples per group) conducted during the test program.

Table A1 provides a summary of the load and deformation results at the YLS and SLS as well as

the Elastic Shear Stiffness, the material over-strength factor and a ‘ductility’ factor µµ defined as

Displacement at SLS

µµ =

Displacement at YLS

The results provided for a typical group represent the mean of six values – the push direction and

pull direction results corresponding to each of the three samples comprising the group.

Additionally, the coefficient of variation – a measure of the data scatter in calculating the mean –

is provided for each measurement within the group. Using Table A1, one can see that the mean

YLS load for Group 1 was determined to be 3430 lbs and the COV for the six loads comprising

this mean value was 14.0%.

Table A2 also provides a summary of the load and deformation results at the YLS and SLS as

well as the Elastic Shear Stiffness, material over-strength factor and ‘ductility’ factor µµ.

However, these results correspond to the push direction and pull direction values for each sample

comprising a particular group. Accordingly, the results of Table A2 were used to obtain the

mean values of each group provided in Table A1.

The Over-Strength Factors given in the tables are the material Over-Strength Factors obtained

from the tests, specifically (SLS Force) / (YLS Force).

A-2

Table A1: Mean, Coefficient of Variation of Load / Displacement Results – Groups 1 – 18

YLS Data SLS DataGroup Load Displacement Load Displacement

Stiffness(lb/in)

Over-StrengthFactor

µµ

3430 0.307 5470 1.370 11244 1.61 4.591

14.0% 15.5% 10.0% 9.5% 10.4% 9.3% 22.6%

4751 0.409 7596 1.800 11670 1.61 4.432

11.9% 13.5% 6.3% 13.8% 8.6% 8.1% 13.1%

3735 0.251 6747 1.740 14952 1.81 7.003

5.6% 11.0% 4.8% 18.2% 6.6% 7.0% 20.8%

4924 0.320 9145 1.887 15538 1.89 6.104

17.7% 21.1% 7.3% 11.2% 13.0% 13.3% 24.1%

4592 0.373 6689 1.209 12412 1.46 3.295

6.1% 11.3% 6.8% 6.3% 8.9% 9.1% 16.5%

5746 0.213 10367 1.054 27363 1.82 4.956

8.3% 13.0% 4.2% 15.8% 16.4% 10.4% 11.6%

2944 0.108 5554 0.559 29598 1.94 5.737

21.9% 39.1% 7.3% 17.6% 31.3% 16.6% 32.3%

1885 0.084 3104 0.356 23004 1.65 4.238

6.9% 16.6% 8.0% 25.5% 15.2% 1.8% 16.4%

9515 0.546 15176 1.879 17613 1.60 3.499

8.9% 14.8% 3.7% 5.9% 11.0% 5.6% 13.7%

4002 0.210 6081 0.998 19367 1.54 4.9310

17.3% 23.2% 10.6% 17.3% 9.0% 10.6% 23.2%

2689 0.163 4461 0.917 17339 1.70 6.3911

19.5% 35.2% 5.4% 12.1% 16.1% 16.4% 42.8%

5142 0.214 8506 1.345 24417 1.67 6.5212

10.9% 18.8% 1.8% 9.1% 11.4% 10.3% 24.9%

9502 0.391 14844 1.559 24365 1.56 3.9613

5.0% 5.3% 6.1% 19.0% 8.0% 7.5% 15.7%

2504 0.154 7126 1.547 16325 2.92 10.0714

16.3% 9.3% 4.1% 10.7% 18.0% 18.2% 11.4%

3018 0.168 9775 1.702 18174 3.29 10.4715

14.3% 18.5% 2.5% 2.9% 10.6% 14.6% 20.7%

8135 0.356 15172 1.221 22868 1.88 3.4616

8.1% 7.7% 12.0% 26.5% 3.5% 17.3% 29.5%

2137 0.146 5815 1.421 14657 2.74 9.7217

9.8% 4.1% 5.3% 10.8% 12.0% 9.5% 10.9%

3107 0.130 8521 1.368 24430 2.74 10.7318

3.6% 14.7% 7.3% 6.9% 17.3% 5.5% 16.9%

A-3

Table A1: Mean, Coefficient of Variation of Load / Displacement Results – Groups 19 – 36

YLS Data SLS DataGroup Load Displacement Load Displacement

Stiffness(lb/in)

Over-StrengthFactor

µµ

4558 0.156 16031 1.819 29658 3.55 12.0519

10.0% 17.18% 2.2% 3.0% 10.2% 12.2% 21.9%

1342 0.079 2946 0.613 20069 2.32 10.5520

26.0% 51.0% 5.2% 4.3% 38.9% 24.8% 64.4%

863 0.033 2557 0.545 27302 3.17 18.8321

23.8% 35.8% 2.8% 8.5% 20.1% 33.7% 45.2%

5869 0.358 8837 1.515 16440 1.51 4.2622

7.3% 9.0% 6.0% 8.6% 6.3% 7.3% 11.9%

5534 0.329 8956 1.462 16884 1.64 4.5723

13.0% 15.0% 5.5% 10.0% 6.4% 13.0% 23.5%

6136 0.344 10110 1.458 17845 1.66 4.2824

10.7% 8.9% 5.4% 7.2% 4.5% 6.2% 13.6%

10521 0.661 14209 1.579 16050 1.36 2.4425

15.0% 20.68% 8.5% 10.1% 5.3% 9.5% 14.6%

4840 0.344 7672 1.210 14240 1.60 3.6426

13.5% 20.2% 4.5% 6.3% 8.6% 11.3% 21.6%

4592 0.296 7109 1.158 15528 1.55 3.9227

5.2% 3.7% 8.5% 8.6% 5.9% 5.8% 10.3%

5394 0.373 8073 1.200 14632 1.50 3.3028

8.2% 14.4% 6.0% 10.0% 10.8% 8.4% 22.0%

4842 0.320 8507 1.657 15170 1.77 5.2129

7.4% 8.5% 2.0% 9.2% 7.4% 8.4% 12.7%

5829 0.405 9367 1.917 14793 1.61 4.8530

3.4% 17.4% 4.0% 8.9% 18.6% 6.4% 18.7%

3312 0.296 8954 1.478 11224 2.87 5.1531

27.0% 20.3% 3.6% 6.0% 21.7% 26.7% 19.7%

3109 0.316 8825 1.606 9973 2.95 5.1232

20.7% 9.3% 4.9% 3.3% 25.7% 22.2% 9.0%

6092 0.362 9359 1.487 16904 1.55 4.1333

9.8% 11.7% 8.2% 20.3% 8.2% 13.4% 19.1%

4029 0.168 8268 1.114 23897 2.07 6.6334

10.4% 4.9% 2.8% 8.2% 8.1% 9.4% 10.4%

8277 0.549 12060 1.536 16191 1.48 3.1235

12.9% 36.08% 5.4% 4.8% 24.7% 12.6% 35.3%

8403 0.321 16074 1.356 27271 1.96 4.6136

21.0% 33.9% 12.7% 20.3% 15.2% 17.6% 34.7%

A-4

Table A-2: YLS, SLS, Shear Stiffness, Overstrength Factor, µµ for Groups 1 --- 4

YLS SLS Shear Over-StrengthSample Load Direction Load Displ Load Displ Stiffness Factor µµ

(lbs) (in) (lbs) (in) (lbs / in)1A Pull 3644 0.326 5362 1.240 11164 1.47 3.80

Push -3325 -0.255 -5235 -1.335 13018 1.57 5.23

1B Pull 3070 0.314 4898 1.489 9787 1.60 4.75Push -2730 -0.253 -5102 -1.568 10795 1.87 6.20

1C Pull 4002 0.380 5860 1.259 10534 1.46 3.31Push -3810 -0.313 -6365 -1.330 12169 1.67 4.25

2A Pull 4937 0.447 7728 1.927 11054 1.57 4.31Push -4309 -0.416 -7137 -2.030 10366 1.66 4.88

2B Pull 4840 0.437 7261 1.940 11063 1.50 4.43Push -3861 -0.299 -7167 -1.498 12915 1.86 5.01

2C Pull 5359 0.423 8266 1.935 12656 1.54 4.57Push -5199 -0.434 -8022 -1.467 11967 1.54 3.38

3A Pull 3735 0.249 6547 1.996 15018 1.75 8.03Push -3678 -0.223 -6587 -1.485 16465 1.79 6.65

3B Pull 3899 0.289 6390 1.386 13511 1.64 4.80Push -3578 -0.233 -6691 -1.496 15371 1.87 6.43

3C Pull 4048 0.282 7251 1.978 14369 1.79 7.02Push -3474 -0.232 -7021 -2.100 14976 2.02 9.05

4A Pull 5315 0.436 9692 1.877 12186 1.82 4.30Push -5071 -0.301 -9848 -2.040 16856 1.94 6.78

4B Pull 6160 0.360 9309 1.896 17091 1.51 5.26Push -4979 -0.286 -9352 -1.485 17388 1.88 5.19

4C Pull 4469 0.291 8523 1.951 15354 1.91 6.70Push -3547 -0.247 -8150 -2.071 14352 2.30 8.38

A-5




Push -4238 -0.317 -6892 -1.257 13371 1.63 3.97

5B Pull 4895 0.395 6490 1.100 12408 1.33 2.79Push -4529 -0.338 -7267 -1.246 13408 1.60 3.69

5C Pull 4905 0.426 6619 1.178 11527 1.35 2.77Push -4652 -0.356 -6928 -1.312 13060 1.49 3.68

6A Pull 6011 0.177 9612 0.801 33909 1.60 4.52Push -5319 -0.243 -10264 -1.246 21863 1.93 5.12

6B Pull 5992 0.220 10528 1.124 27284 1.76 5.12Push -5075 -0.214 -10556 -1.197 23726 2.08 5.60

6C Pull 6355 0.241 10318 0.973 26347 1.62 4.03Push -5722 -0.184 -10929 -0.983 31050 1.91 5.33

7A Pull 2852 0.113 5859 0.528 25341 2.05 4.69Push -2339 -0.097 -5170 -0.660 24154 2.21 6.82

7B Pull 4200 0.180 5579 0.514 23333 1.33 2.86Push -2618 -0.071 -5275 -0.432 36826 2.01 6.08

7C Pull 2871 0.064 6199 0.527 45158 2.16 8.29Push -2788 -0.122 -5243 -0.694 22780 1.88 5.67

8A Pull 2021 0.092 3378 0.395 22091 1.67 4.32Push -1910 -0.096 -3091 -0.433 19854 1.62 4.50

8B Pull 1948 0.072 3292 0.330 27241 1.69 4.61Push -1887 -0.100 -3066 -0.447 18839 1.62 4.46

8C Pull 1908 0.071 3133 0.330 26895 1.64 4.65Push -1637 -0.071 -2664 -0.201 23101 1.63 2.84

A-6




Push -9563 -0.510 -15293 -1.900 18737 1.60 3.72

9B Pull 10382 0.684 15607 2.004 15181 1.50 2.93Push -8237 -0.537 -14179 -1.847 15349 1.72 3.44

9C Pull 9154 0.481 15256 2.005 19051 1.67 4.17Push -10509 -0.594 -15732 -1.773 17695 1.50 2.99

10A Pull 5074 0.267 7325 1.053 19024 1.44 3.95Push -4247 -0.257 -6242 -1.310 16541 1.47 5.10

10B Pull 4102 0.204 5748 0.863 20113 1.40 4.23Push -3250 -0.152 -5706 -0.943 21361 1.76 6.20

10C Pull 4110 0.222 5849 0.831 18475 1.42 3.74Push -3230 -0.156 -5620 -0.990 20688 1.74 6.34

11A Pull 3152 0.236 4433 0.908 13355 1.41 3.85Push -2052 -0.101 -4034 -1.010 20311 1.97 10.00

11B Pull 3084 0.172 4574 0.718 17910 1.48 4.17Push -2432 -0.128 -4592 -0.983 18993 1.89 7.68

11C Pull 3225 0.224 4727 0.881 14425 1.47 3.94Push -2192 -0.115 -4407 -1.001 19039 2.01 8.69

12A Pull 4860 0.196 8408 1.422 24740 1.73 7.24Push -4349 -0.166 -8333 -1.533 26176 1.92 9.23

12B Pull 5788 0.240 8602 1.258 24129 1.49 5.24Push -5153 -0.253 -8428 -1.383 20348 1.64 5.46

12C Pull 5778 0.255 8518 1.269 22695 1.47 4.98Push -4927 -0.173 -8751 -1.207 28411 1.78 6.96

A-7




Push -9797 -0.389 -14766 -1.389 25207 1.51 3.57 13B Pull 10034 0.400 15811 1.681 25088 1.58 4.20

Push -9074 -0.399 -14735 -1.881 22758 1.62 4.72 13C Pull 9850 0.394 15091 1.724 25022 1.53 4.38

Push -8831 -0.413 -15459 -1.628 21366 1.75 3.94

14A Pull 2839 0.152 7465 1.412 18738 2.63 9.32Push -2519 -0.139 -7532 -1.484 18122 2.99 10.68

14B Pull 2911 0.165 6941 1.383 17677 2.38 8.40Push -2478 -0.139 -7011 -1.510 17827 2.83 10.86

14C Pull 2518 0.175 6909 1.690 14374 2.74 9.64Push -1760 -0.157 -6898 -1.804 11210 3.92 11.49

15A Pull 3531 0.191 10009 1.631 18497 2.83 8.54

Push -2944 -0.138 -10019 -1.731 21301 3.40 12.52 15B Pull 3167 0.183 9351 1.678 17330 2.95 9.18

Push -2639 -0.137 -9718 -1.759 19262 3.68 12.84 15C Pull 3404 0.210 9846 1.670 16188 2.89 7.94

Push -2425 -0.147 -9707 -1.742 16464 4.00 11.82

16A Pull 8451 0.352 12513 0.769 23986 1.48 2.18Push -8735 -0.372 -13735 -0.901 23452 1.57 2.42

16B Pull 8298 0.375 16446 1.409 22129 1.98 3.76Push -7360 -0.318 -17418 -1.576 23175 2.37 4.96

16C Pull 8703 0.387 16030 1.456 22465 1.84 3.76Push -7267 -0.330 -14891 -1.216 21999 2.05 3.68

A-8




Push -1998 -0.142 -6150 -1.518 14070 3.08 10.69 17B Pull 2252 0.150 5756 1.467 15010 2.56 9.78

Push -2367 -0.145 -5695 -1.118 16324 2.41 7.71 17C Pull 2120 0.151 5664 1.460 14000 2.67 9.64

Push -1803 -0.152 -5419 -1.531 11861 3.01 10.07

18A Pull 3256 0.142 8566 1.372 22942 2.63 9.67Push -3096 -0.120 -8930 -1.440 25800 2.88 12.00

18B Pull 3086 0.131 8956 1.381 23557 2.90 10.54Push -3219 -0.101 -9159 -1.388 31871 2.85 13.74

18C Pull 3014 0.157 7796 1.442 19192 2.59 9.18Push -2972 -0.128 -7722 -1.187 23218 2.60 9.27

19A Pull 4944 0.172 15922 1.807 28677 3.22 10.48

Push -4251 -0.142 -15640 -1.904 29918 3.68 13.40 19B Pull 4947 0.170 15650 1.786 29064 3.16 10.49

Push -3795 -0.110 -16504 -1.834 34500 4.35 16.67 19C Pull 4634 0.184 16191 1.743 25183 3.49 9.47

Push -4776 -0.156 -16281 -1.837 30608 3.41 11.77

20A Pull 1522 0.117 2775 0.579 13008 1.82 4.95Push -1131 -0.064 -2867 -0.611 17671 2.53 9.55

20B Pull 1793 0.117 3061 0.593 15324 1.71 5.07Push -992 -0.030 -3053 -0.616 32631 3.08 20.26

20C Pull 1626 0.108 3131 0.624 15048 1.92 5.77Push -989 -0.037 -2794 -0.655 26729 2.83 17.70

A-9




Push -949 -0.038 -2530 -0.613 25277 2.66 16.32 21B Pull 1011 0.044 2629 0.513 23064 2.60 11.69

Push -724 -0.020 -2463 -0.508 35388 3.40 24.81 21C Pull 957 0.047 2549 0.523 20557 2.66 11.22

Push -1028 -0.033 -2518 -0.520 31362 2.45 15.86

22A Pull 5318 0.338 8359 1.662 15718 1.57 4.91Push -5781 -0.330 -9351 -1.443 17534 1.62 4.38

22B Pull 5982 0.398 8351 1.673 15024 1.40 4.20Push -5468 -0.326 -8769 -1.487 16750 1.60 4.55

22C Pull 6326 0.395 8573 1.340 16032 1.36 3.40Push -6338 -0.361 -9619 -1.487 17580 1.52 4.12

23A Pull 5618 0.335 8960 1.657 16755 1.59 4.94

Push -4249 -0.239 -8712 -1.539 17764 2.05 6.43 23B Pull 5868 0.329 8844 1.319 17851 1.51 4.01

Push -6253 -0.353 -9937 -1.490 17733 1.59 4.23 23C Pull 5981 0.389 8650 1.263 15388 1.45 3.25

Push -5234 -0.331 -8634 -1.504 15816 1.65 4.54

24A Pull 5889 0.342 9878 1.368 17227 1.68 4.00Push -5421 -0.319 -9736 -1.525 16975 1.80 4.78

24B Pull 6875 0.379 10360 1.288 18159 1.51 3.40Push -6472 -0.337 -10663 -1.501 19225 1.65 4.46

24C Pull 6762 0.380 10685 1.541 17789 1.58 4.05Push -5397 -0.305 -9338 -1.528 17693 1.73 5.01

A-10




Push -9250 -0.561 -14556 -1.592 16479 1.57 2.84

25B Pull 10511 0.620 13567 1.320 16951 1.29 2.13Push -10210 -0.646 -13985 -1.605 15798 1.37 2.48

25C Pull 10197 0.649 13158 1.550 15706 1.29 2.39Push -13576 -0.926 -16472 -1.822 14655 1.21 1.97

26A Pull 4903 0.374 7519 1.147 13108 1.53 3.07Push -4641 -0.290 -8074 -1.330 16009 1.74 4.59

26B Pull 5611 0.442 7980 1.247 12698 1.42 2.82Push -4431 -0.297 -7684 -1.244 14937 1.73 4.19

26C Pull 5535 0.395 7677 1.156 14009 1.39 2.93Push -3919 -0.267 -7100 -1.136 14677 1.81 4.25

27A Pull 4403 0.304 7124 1.266 14504 1.62 4.17

Push -4465 -0.277 -7074 -1.171 16114 1.58 4.23

27B Pull 4316 0.301 6286 1.049 14342 1.46 3.49Push -4889 -0.293 -8159 -1.176 16679 1.67 4.01

27C Pull 4851 0.308 7050 1.030 15732 1.45 3.34Push -4629 -0.293 -6966 -1.255 15800 1.50 4.28

28A Pull 5270 0.442 7243 1.226 11918 1.37 2.77Push -5163 -0.336 -8298 -1.197 15381 1.61 3.57

28B Pull 5807 0.429 7980 1.002 13551 1.37 2.34Push -5161 -0.339 -8431 -1.179 15246 1.63 3.48

28C Pull 6055 0.382 8591 1.219 15864 1.42 3.19Push -4908 -0.310 -7899 -1.378 15832 1.61 4.44

A-11




Push -4928 -0.299 -8727 -1.397 16499 1.77 4.68 29B Pull 5148 0.346 8386 1.659 14894 1.63 4.80

Push -4812 -0.300 -8609 -1.719 16022 1.79 5.72 29C Pull 4480 0.338 8393 1.803 13258 1.87 5.34

Push -4391 -0.289 -8629 -1.786 15223 1.96 6.19

30A Pull 5988 0.423 9147 2.053 14155 1.53 4.85Push -5808 -0.374 -9166 -1.694 15535 1.58 4.53

30B Pull 6029 0.467 8989 2.040 12911 1.49 4.37Push -5523 -0.401 -9364 -1.732 13768 1.70 4.32

30C Pull 5938 0.477 9506 2.085 12438 1.60 4.37Push -5688 -0.285 -10030 -1.898 19951 1.76 6.66

31A Pull 3722 0.295 8751 1.389 12639 2.35 4.72

Push -3001 -0.274 -9211 -1.533 10951 3.07 5.59 31B Pull 4302 0.281 8935 1.386 15295 2.08 4.93

Push -4200 -0.410 -9339 -1.557 10243 2.22 3.80 31C Pull 2368 0.284 9042 1.421 8353 3.82 5.01

Push -2280 -0.231 -8451 -1.580 9864 3.71 6.84

32A Pull 3732 0.313 9365 1.545 11931 2.51 4.94Push -2620 -0.314 -8123 -1.583 8345 3.10 5.04

32B Pull 2845 0.367 8969 1.690 7748 3.15 4.60Push -2215 -0.320 -9055 -1.576 6932 4.09 4.93

32C Pull 3783 0.305 8859 1.592 12414 2.34 5.22Push -3458 -0.277 -8581 -1.651 12469 2.48 5.95

A-12




Push -6335 -0.377 -9371 -1.310 16795 1.48 3.47 33B Pull 6476 0.401 9691 1.778 16157 1.50 4.44

Push -5138 -0.279 -10094 -1.297 18393 1.96 4.64 33C Pull 6279 0.378 8834 1.768 16601 1.41 4.67

Push -5611 -0.377 -8109 -1.067 14900 1.45 2.83

34A Pull 4391 0.177 8255 0.957 24760 1.88 5.40Push -4158 -0.171 -8583 -1.112 24374 2.06 6.52

34B Pull 4464 0.174 8446 1.237 25606 1.89 7.09Push -4111 -0.165 -8213 -1.091 24977 2.00 6.63

34C Pull 3614 0.154 7904 1.141 23467 2.19 7.41Push -3434 -0.170 -8209 -1.144 20199 2.39 6.73

35A Pull 8931 0.657 10965 1.468 13599 1.23 2.24

Push -7540 -0.466 -11751 -1.623 16185 1.56 3.48 35B Pull 7162 0.327 11906 1.479 21922 1.66 4.53

Push -7923 -0.397 -12615 -1.622 19953 1.59 4.08 35C Pull 10090 0.870 12644 1.470 11600 1.25 1.69

Push -8016 -0.577 -12483 -1.557 13887 1.56 2.70

36A Pull 11004 0.463 17797 1.293 23750 1.62 2.79Push -8239 -0.256 -18292 -1.495 32177 2.22 5.84

36B Pull 8577 0.333 13668 0.984 25766 1.59 2.96Push -6001 -0.190 -13490 -1.104 31620 2.25 5.82

36C Pull 9528 0.432 16634 1.661 22080 1.75 3.85Push -7069 -0.250 -16568 -1.601 28229 2.34 6.39

B-1

APPENDIX B

LOAD / DEFORMATION GRAPHS

This appendix depicts 15 of the load-deformation plots for the 108 shear wall tests (36 groups

with 3 samples per group) conducted during the research program. These 15 configurations were

chosen to provide a glimpse at some of the processed load-deformation data for a variety of shear

walls. The enclosed graphs depict the load-deformation influence due to a variety of shear wall

configurations including nail spacing, ‘sheathing’ type (plywood, OSB, gypsum wallboard,

stucco) and thickness, framing (timber, light-gauge steel) condition and hold-down fixity. Note

that all 15 graphs are plotted to the same scale in order to provide a direct comparison among the

different configurations.

Each load-deformation graph is further annotated with the First Backbone and Last Backbone

curves. The First Backbone curve connects the points on the load-deformation curve that

correspond to the maximum load measured when the shear wall is subjected to a predetermined

displacement level – some fraction or multiple of the FME displacement – for the first time in

the cyclic displacement protocol. The Last Backbone curve connects the points on the load-

deformation curve that correspond to the maximum load measured when the shear wall is

subjected to the same predetermined displacement level – again, some fraction or multiple of the

FME displacement – for the last time in the cyclic displacement protocol.

Note that the remaining 93 load-deformation plots, plus a wealth of additional data too

voluminous to include in this report, can be obtained from the two compact disks that contain all

the raw and processed data for this research project. See Appendix D for descriptions of the data

contained on the compact disks and how to obtain a copy of the data.

B-2

City of LA - Shear Wall 1A8'x8' - 8d Hand Driven Common @ 6"/12" - 3/8" Str I

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B-3

City of LA - Shear Wall 3A8'x8' - 10d Hand Driven Common @ 6"/12" - 15/32" Str I (4 ply)

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B-4

City of LA - Shear Wall 7A8'x8' - 1 7/8" Drywall Nails @ 4" / 4" - Blocked 5/8" GWB - Both Sides

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B-5

City of LA - Shear Wall 8A8'x8' - 1 5/8" Drywall Nails @ 7" / 7" - Unblocked 1/2" GWB - Both Sides

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B-6

City of LA - Shear Wall 9A8'x8' - 10d Hand Driven Common @ 2"/12" - 15/32" Str I (4 Ply)

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B-7

City of LA - Shear Wall 11A8'x8' - 10d Hand Driven Common @ 6"/12" - 15/32" OSB

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B-8

City of LA - Shear Wall 13B8'x8' - 10d Hand Driven Common @ 2"/12" - 15/32" OSB

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B-9

City of LA - Shear Wall 14A8'x8' - #8 Bugle Head Screws @ 6"/12" - 15/32" STR I (4ply) - 20 ga Steel

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B-10

City of LA - Shear Wall 16A8'x8' - #8 Bugle Head Screws @ 2"/12" - 15/32" STR I (4ply) - 20 ga Steel

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B-11

City of LA - Shear Wall 17A8'x8' - #8 Bugle Head Screws @ 6"/12" - 7/16" OSB - 20 ga Steel

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B-12

City of LA - Shear Wall 19A8'x8' - #8 Bugle Head Screws @ 2"/12" - 7/16" OSB - 20 ga Steel

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B-13

City of LA - Shear Wall 20A8'x8' - 7/8" Stucco w / 3/8" Head Furring Nails @ 6"/6"

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B-14

City of LA - Shear Wall 21A8'x8' - 7/8" Stucco w / 1" Crown and 7/8" Leg Staples @ 6"/6"

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B-15

City of LA - Shear Wall 25A8'x8' - 8d Hand Driven Common @ 2"/12" - 3/8" STR I (3 ply)

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B-16

City of LA - Shear Wall 32A8'x8' - 10d Hand Driven Common @ 4"/12" - 15/32" Str I (4 Ply), Hold-down nut backed off .40"

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C-1

APPENDIX C

EXAMPLE OF DERIVATION OF YLS (NOMINALSTRENGTH) FROM EXPERIMENTAL DATA GIVEN IN

APPENDIX B

See Appendix B for the definitions of the First Backbone and Last Backbone curves plotted from

the test data. The YLS is defined as the point on the First Backbone curve where the load difference

between the First Backbone curve the Last Backbone curve is 5%. The YLS defines the Nominal

Strength.

Figures C-1 and C-2 represent, respectively, an enlarged plot of the data for the first and third

quadrants of the load-deformation data for shear wall sample 4B. The point of the maximum load

and its displacement at the first cycle to that displacement is shown as point i whereas the load and

displacement corresponding to the last cycle of loading to that same displacement is shown as point

m. Points j and n are similarly established at the first and last cycles to the next higher displacement

in the test protocol sequence.

A computer program written by Dr. Gerard Pardoen (LINYSLS) searches the load-displacement

data, such as shown in Figures C-1 and C-2, to find pairs of points that bracket the YLS. The "less

than 5 percent difference" in load between the First Backbone curve load and the Last Backbone

curve load at the same approximate displacement is represented by (i, m) and the "more than 5

percent difference" between the curves is represented by (j, n). The recorded data displacement

points of the first and last cycles on the Backbone curves are not identical because of the inability to

precisely control pre-programmed displacements.

C-2

The slopes of the straight lines corresponding to segments of the First and Last Backbone curves

shown in Figure C-3 are given by mF and mL respectively. The intercepts of these sloping lines with

the load axis, where deflection is equal to zero, are bF and bL respectively. The subscript F refers to

the First Backbone curve whereas the subscript L refers to the Last Backbone curve. The loading at

any displacement x on the First Backbone line is yF whereas the loading at any displacement x on

the Last Backbone line is yL. This load can also be determined by yF = mF x + bF for the First

Backbone line segment and by yL =mL x + bL for the Last Backbone line segment.

The slopes of the straight lines representing the segments of the First and Last Backbone curves can

be expressed in terms of the force F and deformation x at the four key points i, j, m, n as

mF = (Fj-Fi) / (xj-xi) mL = (Fn-Fm) / (xn-xm) (C-1)

The ordinate intercepts of the straight lines representing the segments of the First and Last

Backbone curves are

bF = (Fi xj –Fj xi) / (xj-xi) bL = (Fm xn –Fn xm) / (xn-xm) (C-2)

The interpolation scheme objective is to determine the displacement ∆ that corresponds to a force on

the Last Backbone curve that is 95% of the force on the First Backbone curve. It is a relatively

routine matter to determine this displacement ∆YLS by expressing the ratio of yF / yL = 95%. Thus

∆YLS = (bL – 0.95 bF) / (0.95 mF- mL) (C-3)

Knowing ∆YLS the force at the YLS can be determined from

FYLS = mF ∆YLS + bF (C-4)

Using the First and Last Backbone curves from a typical load-deformation plot, one can determine

∆YLS from Equation C-3 whereas FYLS is determined from Equation C-4.

A displacement ∆YLS and a force FYLS are determined from both the "push" and "pull" load-

displacement plots from specimens A, B and C. These values are given in Table A-2. The mean of

these six values and the COV is given in Table A-1.

C-3

City of LA - Shear Wall Tests8'x8' - 10d Hand Driven Common @ 4"/12" - 15/32" Str I (4 Ply)

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City of LA - Shear Wall Tests8'x8' - 10d Hand Driven Common @ 4"/12" - 15/32" Str I (4 Ply)

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Figure C-1 Enlargement of 1st Quadrant of Load-Deflection Curve

Figure C-2 Enlargement of 3rd Quadrant of Load-Deflection Curve

C-4

Figure C-3 Determination of YLS Using Segments of First and Last Backbone Curves

Determination of YLS

0

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Shear Wall Deflection (inches)

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Load = 0.95 Load at YLS

YLS

Segment of First Backbone Curve

Segment of Last Backbone Curve

∆∆

C-5

Groups 3, 4 and 9 are assemblies of 15/32-inch thick Structural 1 plywood nailed to wood studs

with 10d common nails. Groups 4, 22, 23, 29 and 30 are related in that the materials used in the

assembly are identical in wood products and diameter of nails.

Figure C-4 shows the relative load-displacement values for the YLS values given in Table A-1.

This figure assumes that the experimental data given for Group 3 and 9 are anchors for this line.

"All data" shown in this figure is the mean for Groups 4, 22, 23, 29 and 30. This data strongly

indicates that the number of fasteners per foot at the perimeter of the panel is the most significant

parameter for determination of Nominal Strength (yield strength) and Elastic Shear Stiffness. This

parameter was used as the criteria for smoothing the relationship of perimeter nailing and YLS

given in Table 3A. Similar relative load-displacement plots were made for 3/8 inch thick plywood

on wood studs, OSB on wood studs, OSB on steel studs and plywood on steel studs. Similar near-

linear relationships anchored by the values of least and greatest number of fasteners per foot were

found and used for smoothing the Nominal Strength shear values given in Table 3A and Table 3C.

Similar data analyses were made for the strength limit state data. A consistency of load data for

number of fasteners per foot at the panel perimeter was found. The data for displacement at the SLS

did not have a rational relationship of SLS displacement versus spacing of perimeter fasteners.

The load of the YLS versus the number of fasteners per foot at the perimeter of the panel is plotted

in Figure C-5. The data derived from the testing indicates that the load (shear per foot) does not

increase in a direct relationship with the number of fasteners per foot, however, the increase in load

has a linear relationship with the number of fasteners per foot. A recommended Nominal Strength

shear value for fasteners spaced at 3 inches on center was interpolated from similar plots for each

assembly.

C-6

The recommended Nominal Strength shear values were rounded and adjusted to eliminate values

that were judged irrational by engineering principles. For example, the experimental Nominal

Strength in shear for 3/8-inch thick plywood (Group 25) nailed with 8d @ 2 inch spacing had a

higher Nominal Strength shear value than 15/32-inch thick plywood (Group 9) nailed with 10d at 2-

inch spacing. The recommended Nominal Strength given in Table 3A was adjusted to have the

more reasonable relationship shown in Figure C-5 for perimeter nail spacing. Further, a comparison

of Group 26 and the mean of Groups 4, 22, 23, 29 and 30 indicates that when the Nominal Strength

of Group 26, nailed with 8d nails, is increased by the ratio of the strength of a 10d nail to an 8d nail,

Group 26 Nominal Strength varies by six percent from the mean Nominal Strength of 15/32-inch

thick plywood nailed with 10d.

C-7

15/32" plywood, 10d Nails

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6

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10

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∆ ∆ @ YLS (inches)

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Group 3

Group 4

All Data

Group 9

Figure C-4 YLS Values for Various Nailing Configurations

C-8

Relative Lateral Load vs Number of Fasteners

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Number of Fastners per Foot

Rel

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oad

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Group 3

Group 4

All Data

Group 92.55

1.78

1.40

Figure C-5 Relative Lateral Load versus Number of Fasteners

D-1

APPENDIX D

COMPACT DISKS OF DATA

D.1 INTRODUCTION

The data and some documentation for the City of Los Angeles-UC Irvine test program arecontained on two compact disks. Some of the items on the compact disks include:

• A CD Guide file that briefly describes the contents of the CDs and the project itself• A README file that describes the project goals, specimen construction details, test

matrix, test data and DATA CD layout• An 11-page description of the Test Protocol and Test Setup• The Final Report to the City of Los Angeles (this report)• The source code listing of a computer program to calculate the YLS and SLS values• Four UC Irvine Master of Science Theses:

o Eric Freund – “Performance Comparison of Plywood vs. OSB Shear Walls”o David Larsen – “Experimental Cyclic Tests of Timber Shear Walls Utilizing

Plywood and Gypsum Wall Board Sheathing”o Neal Shah – “Shear Resistance of Oriented Strand Board and Plywood-Sheathed,

Light-Gauge Steel and Wood-Framed Stud Walls”o Amie Smith – “Exploring a Yield Limit State for Timber Shear Walls”

The set of two CDs can be obtained directly from the Department of Civil & EnvironmentalEngineering at a cost of $40. One must have access to MS Office to read the spreadsheet(EXCEL) and text (WORD) data. To order the two CDs, send a check made out to the “Regentsof the University of California” to:

COLA/UCI Data CD4167 Engineering GatewayDepartment of Civil & Environmental EngineeringUniversity of California, IrvineIrvine, CA 92697-2175

Sections D.2 and D.3 depict, respectively, the print version of CD Guide and README files.

D-2

D.2 CD GUIDE

CD Guide

Welcome to the COLA-UCI Light-framed Shear Wall Research Project Data CD. The followinguser's guide will explain the contents of the disc as well as provide information about the projectitself.

The goal of this joint venture project between the City of Los Angeles and UC Irvine was todetermine some fundamental characteristics of shear walls with different sheathing, nailing andmaterial configurations. The tested wall configurations were specified by the SEAOSC Testingand Standards Committee and the tests took place at the UC Irvine Structures Test Hall using theSEAOSC Committee on Testing Standards shear wall test protocol. There were 36 different wallconfigurations tested which translates into 36 wall groups. Each group consisted of threespecimens with the same configuration resulting in a total of 108 shear walls tested.

Although the sheathing, nailing and material specification for each group varies, the basicconstruction of the frames was kept constant. The whole of the project entailed 108 8-foot x 8-foot fully sheathed shear walls. For framing members, both light gauge steel and timber wereused. Sheathing materials included plywood, OSB, gypsum wallboard, and stucco. Thefasteners used were hand driven common nails, drywall nails and bugle head screws in a varietyof sizes. The hold-downs were designed by the SEAOSC test committee to meet test methodrequirements.

The material configuration of each group is more thoroughly defined in an Excel Worksheetentitled "Summary_Tables_&_Curves.xls" that is located in the Group_Data folder on this CD.The wall frames themselves were constructed in an identical manner save the specified size ofthe sill and center stud. The timber construction utilized 4x4 kiln dried posts at the ends of theeach wall, 2x or 3x4 sills and center studs and 2x4 top plates and field studs. The 3x4 memberswere all ripped from 4x4 posts at the UCI Structures Test Hall. The frames were assembledusing 20d smooth bright box nails through the sill and 16d green vinyl sinkers through the topplate. The specified sheathing was attached with the given nail size and spacing, differing foreach group. The framing configuration for the light-gauge steel groups also consisted of thetypical 8-foot x 8-foot wall. The vertical studs were 20-gauge, 1-5/8 inch flange studs spaced 24inches on center. The posts consisted of two studs back to back with a channel attached to themto aid in resisting compression failure of the posts. The top plate and sill were comprised of on20-gauge, 1-5/8 inch flange channel. The sheathing fasteners were No. 8 bugle head screws.

The following parameters were measured for every shear wall test; displacement at the top of thepanel, force applied to the top of the panel and sill sliding displacement. Where possible, upliftof the end posts relative to the ground and motion of the hold-downs relative to the end postswere recorded also. The SEAOSC Test protocol, which contains a picture of the test rig setup, isincluded on this CD. The data was recorded at a frequency of 50 Hz and in columnar formatwith each row having a time step.

D-3

The data CD contains three folders, ASCII_Data_9911, Group_Data_9911, and Technical papersas well as the SEAOSC Test protocol. The ASCII folder contains two types of data files, .f and.b. The .f files contain all the data collected for each individual test and the .b files contain thelocal peak points (envelope curves) of the cyclic data in chronological order. The labeling of thefiles consists of an LA_XYZ.b or .f. The XY is indicative of the group number (01 through 36)and the Z is the specimen designation (A, B, or C). The Group_Data folder contains four typesof Excel data worksheets. The CoLA_TestInfo_Sheets is a file that contains detailed informationregarding each sample's configuration, unique properties, test conditions and comments. TheCOMPLETE_DATASET_GXY files include the .b and .f files along with plots that demonstratethe data findings for each specimen. The variables XY in the label indicate the group number(i.e. G01 is Group 1). The Group_Plots_XY files are simply the plots from the CompleteDatasets without the spreadsheet data. Finally, the file that contains a comparison of the YLS,SLS, and group plots for all 36 groups as well as the wall group configurations is in theSummary_Tables_&_Curves.

D-4

D.3 README FILE

COLA Shear Wall Groups 1-36

Goal

The goal of these shear wall tests was to provide some fundamental characteristics of shear wallswith different sheathing, nailing and material configurations. For the first four groups allframing characteristics were held constant, only the plywood sheathing and the nail size/spacingwere changed. The groups immediately following those involved the use of gypsum wallboardand groups 14-19 used light gauge steel framing with various sheathings and screw spacing. Thesubsequent groups experimented with placement of the sheathing as well as stud spacing. Allpanels were tested at the UC Irvine Structures Test Hall using the SEAOSC Committee onTesting Standards shear wall test protocol.

Specimen Construction

The general framing configurations for shear wall groups 1-4, 10-13, 22, 24 and 25 wereidentical. Each was 8'x8' and had studs spaced at 16” o.c. Each frame consisted of 2 - 4x4 endposts, 1 - 3x4 sill, 1 - 3x4 center stud, 2 - 2x4 top plates, and 4 - 2x4 field studs. The 4x4s werekiln dried to ensure straightness and quality. The 3x4s were made by ripping 4x4's. Care wasexercised when cutting the 3x4's from the 4x4s in order to remove wood defects. The frameswere nailed together with 20d smooth bright box nails through the sill and 16d green vinylsinkers through the top plates. The sills were drilled to 11/16" for the 5/8" anchor-bolts (4 ea; 12'& 40" from each end) using a drill jig to ensure proper hole location. On occasion the sills werepredrilled for the framing nails to avoid sill splitting. The posts were drilled and dapped toaccept the shear plates for the hold-downs. The hold-downs used were designed by Ben Schmidand fabricated from heavy 3" structural channel (designation C3x6). Groups 5-8, 20-21, 23 and26 were framed similarly except a 2x sill and a 2x center stud were used. Groups 14-19 were also8'x8' but these walls utilized 1-5/8" flange light-gauge steel framing members.

Test Matrix

The test matrix was designed to establish the baseline behavior of 8'x8' shear walls for differentsheathing and nailing configurations. The sheathing used was 3/8" Str I, 15/32" Str I, 7/16" OSB,15/32" OSB, 1/2" GWB, and 5/8" GWB. The nails used were 8d and 10d commons, 1-5/8" and 1-7/8" drywall nails, and No. 8 bugle head screws per the UBC. A more complete descriptionof the test matrix and specimen details is given in the Excel file

“WorkbookSummary_Tables_&_Curves.xls".

It can be found in the Group Data Folder on the Data CD.

D-5

Test Data

The following parameters were measured for all tests:

Displacement at top of panel - Panel DisplacementForce applied to top of panel - LOADSill sliding displacement - Sill Slip

Where possible, the following parameters were also measured:

Uplift of the end posts with relative to the ground - Left Post UpliftRight Post Uplift

Motion of the hold down relative to the end post - Left HD SlipRight HD Slip

Data was recorded at 50 Hz, the data is recorded in columnar format with each row having a timestamp.

DATA CD Layout

The Data CD contains the following folders:

ASCII_DATA_9911GroupData_9911

ASCII_DATA_9911

This folder contains two types of data files:

LA_XYZ.f - all the data collected for a particular testLA_XYZ.b - local peak points (envelope curves) of the cyclic data in chronological order,

in "S" - Curve Order (largest displacement to smallest), envelope curve, degradedor "stabilized" envelope curve ("4th excursion")

XY - is the group number (01 thru 36)Z - is the specimen designation (A, B or C)GroupData_9911

D-6

This folder contains the following file and types of files:

A summary file with tabular detail data, tabular summary data and group envelop plots

Files with plots for a single group (plots only)

Files (very large) that contain complete sets of data and plots for a single group

Summary_Tables_&_Curves - a summary file with group plots, group average YLS(yield limit state) and SLS (strength limit state) and specimen detail data - YLS and SLS

COLA_Test Info_Sheets - a file with detailed information about sample configuration,sample properties, test conditions and comments

Group_Plots_GXY - files that contain plots only for group "XY"

Complete_Dataset_GXY - files that contain a complete set of data and plots for group“XY’

report of a testing program of light-framed...

Documents