Nominal Shear Strength of Cold-Formed Steel Shear Walls .../67531/metadc... · Serrette (1996)...

APPROVED: Cheng Yu, Major Professor Diane Desimone, Committee Member Haifeng Zhang, Committee Member Leticia Anaya, Committee Member Enrique Barbieri, Chair of the Department of

Engineering Technology Costas Tsatsoulis, Dean of the College of

Engineering James D. Meernik, Acting Dean of the

Toulouse Graduate School

NOMINAL SHEAR STRENGTH OF COLD-FORMED STEEL

SHEAR WALLS USING OSB SHEATHING

Chao Li

Thesis Prepared for the Degree of

MASTER OF SCIENCE

UNIVERSITY OF NORTH TEXAS

May 2012

Li, Chao. Nominal Shear Strength of Cold-Formed Steel Shear Walls Using OSB

Sheathing. Master of Science (Engineering Systems), May 2012, 77 pp., 14 tables, 16 figures,

references, 9 titles.

In the cold-formed steel construction, the oriented strand board is a common material

for shear wall sheathing. An OSB is made by using wood chips as raw materials that undergo

high temperature pressing to create a multi-larger structure material. Due to the OSB having a

high strength in shear, it is an important material used in the construction field.

The thesis is trying to verify published nominal shear strength in AISI-213-07 in the

first part. This objective has two parts: the first part is to verify nominal shear strength (Rn)

for wind and other in-plane loads for shear wall. The second part is to verify nominal shear

strength (Rn) for seismic and other in-plane loads for shear wall. Secondly, the thesis verifies

the design deflection equation for nominal shear strength of CFS shear walls with OSB

sheathing. The test specimens were divided into eight groups which trying to verify the

design deflection equation that was published in AISI-213-07 standard.

ii

Copyright 2012

by

Chao Li

iii

ACKNOWLEDGEMENT

This thesis paper could not be completed without Dr. Cheng Yu. I express my highest

gratefulness to Dr. Cheng Yu for teaching me valuable acknowledge and skills and guiding

me during the research. I am also truly express my thanks to my committee members-Dr.

Diane Desimone, Dr. Haifeng Zhang, and Dr. Leticia Anaya for their guidance in completing

this thesis. I want to thank the sponsorship of American Iron and Steel Institute and the

donation of materials by Steel Stud Manufacturers Association and Nuconsteel Commercial

Corp. The assistance of the UNT lab technician Bobby Grimes in setting up the testing

apparatus has been invaluable. I would like to thank UNT undergraduate students, Marcus

Sanchez, Roger Rovira, and graduate student, Noritsugu Yanagi, who helped prepare the test

specimens. This project could not be completed without their contributions.

I would like to thank my family for their encouragement and support while I am studying

in the United States of America.

iv

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENT ............................................................................................................. iii

LIST OF TABLES ...........................................................................................................................v

LIST OF FIGURES ....................................................................................................................... vi

1. INTRODUCTION ...................................................................................................1 2. LITERATURE REVIEW ........................................................................................4 3. BACKGROUND AND OBJECTIVES ...................................................................9 4. TEST PROGRAM .................................................................................................13

4.1 Test Setup...................................................................................................13

4.2 Test Procedure ...........................................................................................15

4.3 Test Specimens ..........................................................................................17

4.4 Material Properties .....................................................................................21 5. TEST RESULTS AND DISCUSSION .................................................................23

5.1 Summarizing Shear Walls Test Results .....................................................23

5.2 Verifying Nominal Strength of 7/16” OSB Shear Walls Tested and Nominal Strength of 7/16” OSB Shear Walls Published in AISI-S213-07................................................................................................................28

5.3 Expanding Nominal Strength of 7/16” OSB Sheathing Shear Walls Published in AISI-S213-2012 ....................................................................29

5.4 VerifyingDesign Deflection Equation in AISI-S213-07 ............................31 6. CONCLUSIONS AND FUTURE RESEARCH ...................................................38

APPENDIX: DATA SHEETS OF OSB SHEAR WALL TESTS.................................................40 REFERENCES ..............................................................................................................................77

v

LIST OF TABLES

Page

1. United States and Mexico nominal shear strength (Rn) for wind and other in-plane

loads for shear walls (2007)............................................................................................. 10

2. United States and Mexico nominal shear strength (Rn) for wind and other in-plane

loads for shear walls (2007)............................................................................................. 11

3. OSB shear wall CUREE basic loading history .............................................................. 17

4. OSB shear wall test matrix for nominal shear resistance verification task .................. 18

5. Coupon test results ........................................................................................................... 22

6. OSB shear wall test results .............................................................................................. 24

7. OSB shear wall failure modes ......................................................................................... 25

8. Recommended nominal shear strength for wind loads for OSB shear walls ............... 27

9. Recommended nominal shear strength for seismic loads for OSB shear walls ........... 27

10. Comparison of nominal shear strength for wind loads for OSB shear walls ............... 28

11. Comparison of nominal shear strength for seismic loads for OSB shear walls ........... 29

12. Expanded Nominal Shear Strength for Wind and Other In-Plane Loads for Shear

Walls .................................................................................................................................. 30

13. Expanded Nominal Shear Strength for Seismic and Other In-Plane Loads for Shear

Walls .................................................................................................................................. 31

14. Comparison of displacement of tested and displacement by deflection equation........ 32

vi

LIST OF FIGURES

Page

1. Front view of cold-formed steel shear wall using OSB sheathing ..................................... 2

2. Front view of the test setup ................................................................................................. 14

3. Close up of the top of the OSB shear wall specimen (8x4) .............................................. 15

4. OSB shear wall CUREE basic loading history (0.2 Hz) ................................................... 17

5. OSB shear wall Dimensions of 8-ft. × 4-ft. wall assembly .............................................. 20

6. OSB shear wall Dimensions of 8-ft. × 2-ft. wall assembly .............................................. 21

7. OSB shear wall test result ................................................................................................... 23

8. Ratio of deflection data by different screw spacing .......................................................... 33

9. 8x2x33xOSBx2 tested curves and estimated curve........................................................... 34








1

CHAPTER 1

INTRODUCTION

Cold-formed steel shear walls using oriented strand board (OSB) sheathing is an

important member of the cold-formed steel shear walls family. Since 1940, cold-formed

steel has been widely used in building construction and more widely used in this

development global. An OSB is made by using wood chips as raw materials that undergo

high temperature pressing to create a multi-larger structure material. Due to the OSB

having a high strength in shear, it is an important material used in the construction field.

Generally speaking, the cold-formed steel shear walls provide the following advantages in

building construction:

1. Compared with hot-rolled shapes, cold-formed steel members can be more easily

manufactured for relatively light loadings. Thus, it will cost less energy to produce there

shapes during the manufacturing process.

2. Compared to wood, the cold formed steel members can provide larger resistance

value, higher stiffness and larger ductility value. Also the cold formed steel is

non-combustible.

3. Cold-formed steel shear walls are easily to be manufactured in mass quantities and

can easily stack and be transported.

4. As the metal coating on the surface, the cold formed steel is harder to be corroded.

Also, cold-formed steel shear walls are 100% recyclable.

The cold formed steel structural members can be classified into two major types:

1. Individual structural framing members

2

2. Panels and decks

Cold-formed steel shear walls using OSB sheathing is a structural assemble used to

resist the lateral loads caused from the winds and earthquakes. The frame of the shear wall

is built by the stud and track, which are screwed at each end. The OSB sheathing is also

attached to the frame by the screws as showed in Figure 1.

Figure 1Front view of cold-formed steel shear wall using OSB sheathing

Since the early 1990s, cold-formed steel shear wall design has evolved in step with

the increased understanding of their performance. Significant advances and additions in the

provisions for these systems have occurred since their first inclusion in the 1997 Universal

Building Code (UBC). Typical lateral loads on shear walls result from either wind or

seismic demand. Design wind loads are the actual expected forces, whereas design seismic

loads are reduced based on the type of lateral system used, how many lateral elements are

3

employed in the structure, and the level of seismic detailing performed. Designing for a

reduced seismic load can significantly lower the cost of construction, but the tradeoff is

heavy damage to the structure during a major earthquake.

In previous research, the researchers mainly investigated on the cold formed steel

framed shear walls with plywood, gypsum board sheathing and steel. This research focused

on CFS shear wall with OSB sheathing. Two objectives are targeted: (1) verify the

published nominal shear strength for 7/16” OSB sheathing in AISI-213-07; (2) verify and

develop the design deflection equation for nominal shear strength of CFS share walls with

OSB sheathing. In Chapter2, the cold formed steel shear wall with different sheathing and

configuration are summarized. Chapter 3 explains the objectives and back ground. Chapter

4statesthe tests procedure, materials and configuration of specimens. Results are discussed

in Chapter 5 and Chapter 6 shows the conclusion and further study.

4

CHAPTER 2

LITERATURE REVIEW

Included in this thesis is a brief summary of previous research on shear walls using

oriented strand board(OSB) sheathing reviewed by Serrette(1996, 1997, and 2002), Chen

(2004)and Dinehart and Shenton III(1998). For an extensive literature review of previous

shear wall studies, an interested reader is invited to consult their theses. The previous

experiments and research on the performance of cold formed framing shear wall are

reviewed herein to establish the test methods and configuration of specimens for this

research.

Serrette (1996) investigated the behavior of the cold formed steel shear wall sheathed

with gypsum, OSB, and plywood with three phases. The materials include: 20 gauge stud

with 3.5-in. width, 1.625-in. flange and 0.375-in. lip; 20 gauge track with 3.5 width and

1.25-in. flange; No. 8 × 0.5-in. self-drill screw on framing and No. 10 × 1-in. Hex head

self-drill screw for the plywood and OSB; the same materials used on strap as studs and

tracks. In the Phase 1, the goal was to find out the static behavior between plywood and

OSB. The Phase 2, he made analysis to determine the weaker of the OSA and plywood. In

the third phase, comprehensive investigations were performed on the panels with OSB and

plywood, covering all fastener schedules. For the 8-ft. × 8-ft. shear wall, the plywood

sheathing has 17% greater nominal capacity than the OSB wall (7/16 in. thick). OSB walls

installed parallel to the frame has lower load and deformation capacity compared to the

perpendicular installation. For the 4-ft. × 8-ft. OSB walls, the maximum load value

increased followed by the denser of the fastener space on the perimeter. The 4-ft. × 8-ft.

5

dimension wall sheathed with OSB on one side and GWB on the other side has a capacity

increase with 6-in. /12-in. fastener schedule; however, there was no significant capacity

increase in the other fastener schedule. During the cyclic tests, for given fastener spaces,

the plywood walls performed higher load capacities then the OSB wall.

Serrette (1997) completed experimental tests on a wider scope of the steel framed

wall, which included steel sheathing, high aspect ratio walls, X-braced walls and 16gauge

and 18 gauge studs. Both static and cyclic loading tests performed. This research was done

in five phases: During first phase, the tests initiated on the 4-ft. × 8-ft. dimension shear wall

(20 gauge stud and 18 gauge chord) which covered by 7/16 in. OSB and 15/32 in. plywood

with fastener schedule 3-in. / 12-in. and 2-in. / 12-in. During the second phase, the author

tried to figure out the thickness limit to occur the shear wall system change. Phase 3 was

focused on the performance of the shear wall assembled with 20 and 18 gauge studs and 20

gauge X-brace. In Phase 4, the study focused on performance of 22 and 25 gauge steel

sheath shear wall. In fifth stage, was initiated on 4:1 aspect shear wall. Similar to the tests

involved in Serrette (1996), displacement control was applied in these tests. The result of

this research was that plywood walls can provide more ductility and load capacity.

Compared with No. 8 screw, larger diameter screws were needed for the thicker studs

(16gauge). Two significant effects should be concerned: The actual yield strength of the

strap and the eccentricity from the straps, as excessive specified yield strength may cause

the stud or connection failure. The failure of the steel sheathing walls was the bearing of

the sheet edges and the pullout of the screws from the stud.

Serrette (2002) developed performance data for cold-formed steel shear wall. The

6

scope of that research includes four aspects: 1. Reversing the cyclic result of the 33-mil and

43-mil framed shear wall with 7/16-in. OSB on one side; 2. Reversing the cyclic result of

the 54-mil and 68-mil framed shear wall with 7/16-in.OSB on one sides; 3. Reversing the

cyclic result of steel shear wall with 7/16-in.OSB sheathing on one side and simple lap at

the edges of the panels; investigate the monotonic performance of shear wall sheathed by

½-in. gypsum board with different fastener spaces and blocking configuration. In the final

result, was that the OSB wall with No. 8 screw in 54-mil framing and No. 10 screws in

68-mil framing demonstrated a ductile mode of failure at the connection. For the second

purpose, the 54 mil stud buckled because the load exceeded the studs’ capacities. The

68-mil studs recital the buckling effect. Then the peak load was decided by the screw

attaching the chords. In the OSB sheathing shear wall tests, because of the screw would

cause unzip along the joint, the steel sheet could not make effect sufficiently. In the

monotonic test of GWB, the failure depended on the fasteners along the board edge pulling

through the board.

Chen (2004) investigated the performance characteristics of various configurations

of steel frame / wood panel shear walls under monotonic and reversed cyclic loading. Chen

tested and analyzed a total of 46 steel frame / wood panel shear wall specimens using the

EEEP method as recommended by Branston (2004). The configuration of the specimens

varied in terms of wall length (610, 1220 and 2440 mm (2’, 4’ and 8’)), sheathing type(CSP,

OSB) and fastener schedule (76/305, 102/305, and 152/305 mm (3”/12”, 4”/12”

and6”/12”)). A comparative study of relative shear wall performance based on the test

results obtained by Branston, Chen and the author was presented. Chen also provided

7

information on existing analytical design approaches for shear. Finally, an analytical

method of mechanics approach to estimate wall displacement and strength was

recommended.

Dinehart and Shenton III(1998) investigated the relative performance of timber shear

walls tested statically and dynamically. Monotonic tests followed the ASTM E 564

protocol; whereas reversed cyclic tests were carried out using the SPD protocol with 0.24”.

More precisely, the purpose of this research was to evaluate and to compare the stiffness,

ductility, ultimate load and failure mechanism of the walls for the two test methods. The

testing program involved twelve identically constructed8-ft. × 8-ft. walls, four of which

were tested monotonically and eight dynamically. Half of the specimens were sheathed

with 15/32” plywood and the other half with 1/2” oriented strand board (OSB).Previous

research concluded that the failure modes observed during static tests were significantly

different than those of dynamic tests. Dinehart and Shenton III found the same results and

noted that during the monotonic tests, the sheathing tended to pull away from the frame,

pulling the nails along with it. Pull-through of the nails was only observed in a few

instances along the edges of the sheathing. The bottom sill plate split parallel to the grain at

the uplift corner, i.e. the corner in tension. Both the OSB and plywood sheathing failed in

the same manner during the monotonic tests. As for the dynamic tests, most of the damage

was concentrated in the sheathing-to framing connectors. After being repetitively bent

during the reversed cycles, nails fatigued and/or sheared at the connection between the stud

and the sheathing, or were pulled out from the stud. Nail fracture was more common than

pull out. The OSB sheathed shear walls exhibited degradation near the corners in the later

8

stages of the test, which was not observed in the tested plywood sheathed walls. Apart from

that damage type, both OSB and plywood sheathed shear walls failed in a similar manner.

When comparing the load-deformation curves of the plywood and OSB sheathed

specimens, Dinehart and Shenton III noted no major differences in either the monotonic or

cyclic regime. When looking at the static and dynamic responses of similarly sheathed

shear walls, it was observed that both ultimate loads are comparable, but occurred at very

different displacements, the dynamic tests having the lower displacements (66% less for

plywood and 58% less for OSB). The dynamic ductility, defined as the ratio of the failure

displacement to the yield displacement experienced under a dynamic test, was therefore

less than the static ductility (34% reduction for plywood and 42% reduction for

OSB).Dinehart and Shenton III were not able to conclude if these results were due to the

rate of loading or the load history (cyclic protocol).Because of the severe differences in the

measured ductility between dynamic and static tests, Dinehart and Shenton III were in

favor of the 25% reduction of the allowable shear loads listed in the UBC (Uniform

Building Code, 1994) until more thorough research is carried out. This suggestion was

made in the report where the task force investigating the Northridge earthquake

recommended that a cyclic test program be carried out to determine reasonable load levels

for light framed shear walls subjected to seismic events.

9

CHAPTER 3

BACKGROUND AND OBJECTIVES

The American Iron and Steel Institute (AISI) “North American Standard for

Cold-Formed Steel Framing – Lateral Design 2007 Edition” (AISI S213, 2007) provides

shear strengths for a limited range of options of the sheathing thickness and the wall aspect

ratio for cold-formed steel framed walls with OSB sheathing. Therefore, this research

proposed in this thesis proposal is to verify published nominal strength in AISI-213 in the

first part. This objective has two parts: the first part is to verify Nominal Shear Strength

(Rn) for Wind and other In-Plane Loads for Share Wall. The second part is to verify

nominal shear strength (Rn) for seismic and other in-plane loads for share wall. Secondly,

the thesis verifies the design deflection equation. Thirdly, this research aims to develop

design equation for nominal strength of CFS share wall with OSB.

The objectives of this thesis include:

1) To verify published nominal strength in Table 1and Table 2.

This objective has two parts: the first part is to verify nominal shear strength (Rn) for

wind and other in-plane loads for share wall. The second part is to verify nominal shear

strength (Rn) for seismic and other in-plane loads for share wall. In Table 1, the thesis and

test will focus on the 7/16” rated sheathing (OSB), and the fastener spacing panel edges are

considered by 2 inches, 4inches, and 6 inches. The aspect ratio (h/w) is 2:1.InTable C2.1-3,

the thesis and test will focus on the 7/16” rated sheathing (OSB). Also, the designation

thickness of stud, track and blocking are considered by 33 mil, 43 mil, and 54 mil.

10

Table 1United States and Mexico nominal shear strength (Rn) for wind and other in-plane loads for shear walls (2007)

(Pounds Per Foot)

Assembly Description

Maximum

Aspect

Ratio

(h/w)

Fastener Spacing Panel Edges

(inches)

6 4 3 2

15/32” structural 1

sheathing (4-ply),

one side

2:1 1065

7/16”rated

sheathing(OSB),

one side

2:1 910 1410 1735 1910

7/16”ratedsheathing(OSB)

One side oriented

perpendicular to framing

2:1 1020

7/16” rated

sheathing(OSB),

one side

4:1 1025 1425 1825

0.018” Steel sheet,

one side 2:1 485

0.027” Steel sheet,

one side 4:1 1000 1085 1170

11

2) To verify design deflection equation for nominal strength of CFS share wall with OSB.

Using the following design deflection equation analysis and compare with test data.

δ =8vh3

EsAc b+ ω1ω2

vh

ρGtsheating

+ ω15/4𝜔2𝜔3𝜔4 𝑣/𝛽 2 +

ℎ

𝑏𝛿𝑣

(Eq.C2.1-1) from AISI-S213-07

Where,

Ac = gross cross-sectional area of chord member, in square inches

b = Width of the shear wall, in feet

Table 2United States and Mexico nominal shear strength (Rn) for wind and other in-plane loads for shear walls (2007)

(Pounds Per Foot)

Assembly

Description

Maximum

Aspect

Ratio

(h/w)

Fastener Spacing Panel

Edges

(inches)

Designation

Thickness of

Stud, Track and

Blocking (mils)

Required

Shearing

Screw Size 6 4 3 2

15/32”

structural 1

sheathing

(4-ply),

one side

2:1 780 990 33 or 43 8

2:1 890 1330 1775 2190

43 or 54 8

68 10

7/16” OSB,

one side

4:1 700 915 33 8

4:1 825 1235 1545 2060 43 or 54 8

2:1 940 1410 1760 2350 54 8

2:1 1232 1848 2310 3080 68 10

0.018” Steel

sheet, one

side

2:1 390 33 (min) 8

0.027” Steel

sheet, one

side

4:1 1000 1085 1170 33 (min) 8

12

Es= Modulus of elasticity of steel 29500000 psi

G = Shear modulus of sheathing material, 77500 psi

h = wall height, in feet

s = maximum fastener spacing at panel edges, in inches

t𝑠ℎ𝑒𝑎𝑡 ℎ𝑖𝑛𝑔= nominal panel thickness, in inches

𝑡𝑠𝑡𝑢𝑑 = framing designation thickness, in inches

υ = shear demand (V/b), plf

V = total lateral load applied to the shear wall, in pounds

β = 660 for OSB

δ = calculated deflection, in inches

δv= vertical deformation of hold-downs, in inches

ρ = 1.05 for OSB

ω1 = s/6 for s in inches

ω2 = 0.033/tstud in inches

ω3 = (h

b)/2

ω4 = 1 for wood structural panels

13

CHAPTER 4

TEST PROGRAM

The test program was carried out from November 2010 to January 2012 in the

NUCONSTEEL Materials Testing Laboratory at the University of North Texas, Denton

Texas. The research verifies the published nominal shear strength of 7/16-in OSB sheathing

shear walls (nominal shear resistance verification task). In this test, the shear walls

including 8-ft.x2-ft, and 8-ft.x 4-ft.

4.1 Test Setup

The monotonic tests and the cyclic tests were performed on a 16-ft. span, 12-ft. high

adaptable structural steel testing frame. Figure 2 shows the front view of the testing frame

with an 8-ft.x 4-ft. OSB shear wall installed. All the shear wall specimens were assembled

in a horizontal position and then installed vertically in the testing frame. The wall is bolted

to the base beam and loaded horizontally at the top. For shear walls using 3.5-in. framing

members, a 5-in.x5-in.x ½-in. structural steel tubing was used for the base beam. For shear

walls using 6-in. framing members, 10-in.x5-in.x ½-in. structural steel tubing was used for

the base beam. The base beam was attached to a W16 x 67 structural steel beam that was

attached to the concrete floor slab with 3/4-in. anchor bolts at 24-in. in the center. The web

of the structural steel tubing base beam was cut-out in several locations on one side to

provide access to anchor bolts in the shear walls.

The lateral force was applied to the shear wall top via a load beam made of structural

steel T shape. The T shape was attached to the top track of the shear wall by 2 - No. 12

x1-1/2-in. hex washer head (HWH) self-drilling tapping screws placed every 3-in. on center.

14

The out-of-plane displacement of the wall was prevented by a series of steel rollers on each

side of the T shape. Figure 3show that space was provided between the rollers and the T

shape to avoid significant friction in the test. The anchoring system for monotonic tests

consisted of ASTM A490 5/8-in. diameter shear anchor bolts with standard cut washers and

one Simpson Strong-Tie S/HD10 hold-down with one ASTM A490 5/8- in. diameter

anchor bolt. For the cyclic tests, the anchoring system included ASTM A490 5/8-in.

diameter shear anchor bolts and one Simpson Strong-Tie S/HD10 hold-down with a 5/8-in.

diameter ASTM A490 anchor bolt at each end of the shear wall.

Figure 2Front view of the test setup

15

Figure 3Close up of the top of the OSB shear wall specimen (8x4)

The testing frame was equipped with one MTS35-kip hydraulic actuator with

5-in.stroke.AMTS407 controller and a 20-GPM MTS hydraulic power unit were employed

to support the loading system. A 20-kip TRANSDUCER TECHNIQUES-SWO universal

compression/tension load cell was placed to pin-connect the actuator rod to the T shape.

Five NOVOTECHNIC position transducers were employed to measure the horizontal

displacement at the top of the wall, and the vertical and horizontal displacements of the

bottoms of the two boundary studs. The data acquisition system consisted of a National

Instruments unit (including a PCI6225 DAQ card a SCXI1100 chassis with SCXI1520 load

cell sensor module and SCXI1540 LVDT input module) and an IBM desktop. The applied

force and the five displacements were measured and recorded instantaneously during the

test.

4.2 Test Procedure

Both the monotonic and the cyclic tests were conducted in a displacement control

mode. The procedure of the monotonic tests was in accordance with ASTM A370 (2006). A

preload of approximately 10% of the estimated ultimate load was applied first to the

16

specimen and held for 5 minutes to seat all connections. After the preload was removed, the

incremental loading procedure followed until structural failure was achieved using a load

increment of 1/3 of the estimated ultimate load.

One protocol was used for the cyclic tests as specified in Tables 3.The CUREE

protocol was used in accordance with the method C in ASTM A370 (2006)Table 3 and

Figure 4 illustrate the CUREE protocol was chosen for the majority of cyclic tests in this

research. The CUREE basic loading history shown in Figure 4 includes 40 cycles with

specific displacement amplitudes, which are listed in Table 3. The specified displacement

amplitudes are based on a percentage of the ultimate displacement capacity determined

from the monotonic tests. If the panel has not failed at the end of the 40 cycles of Table 3,

then additional cycles were to be added. Each progressive primary cycle added was to

include an increase of 50% over the previous primary cycle. Two trailing cycles followed

each primary cycle with an added magnitude of 75% of the primary cycle. For the CUREE

protocol, a constant cycling frequency of 0.2 Hz was used for the loading.

17

Table 3OSB shear wall CUREE basic loading history

Figure 4OSB shear wall CUREE basic loading history (0.2 Hz)

4.3 Test Specimens

The test specimen configurations for the nominal shear resistance verification task

are listed in Table 4. This task was to verify the published nominal shear strength for 7/16”

OSB sheathing in AISI-213-07 and propose to make direct comparison with the test results

of Serrette (2002) in AISI-213-07.

18

Table 4OSB shear wall test matrix for nominal shear resistance verification task

Test label Wall

dimension Stud Track Screw

spacing Test

protocol

8x2x33xOSBx4-M1 8x2 33ksi 362S162-33 33ksi 350T150-33 4" M 8x2x33xOSBx4-M2 8x2 33ksi 362S162-33 33ksi 350T150-33 4" M 8x2x33xOSBx4-M3 8x2 33ksi 362S162-33 33ksi 350T150-33 4" M 8x2x33xOSBx4-C1 8x2 33ksi 362S162-33 33ksi 350T150-33 4" C-40 Cycles 8x2x33xOSBx4-C2 8x2 33ksi 362S162-33 33ksi 350T150-33 4" C-40 Cycles 8x2x33xOSBx2-M1 8x2 33ksi 362S162-33 33ksi 350T150-33 2" M 8x2x33xOSBx2-M2 8x2 33ksi 362S162-33 33ksi 350T150-33 2" M 8x2x33xOSBx2-C1 8x2 33ksi 362S162-33 33ksi 350T150-33 2" C-40 Cycles 8x2x33xOSBx2-C2 8x2 33ksi 362S162-33 33ksi 350T150-33 2" C-40 Cycles 8x2x54xOSBx2-M1 8x2 50ksi 350S162-54 50ksi350T150-54 2" M 8x2x54xOSBx2-M2 8x2 50ksi 350S162-54 50ksi 350T150-54 2" M 8x2x54xOSBx2-M3 8x2 50ksi 350S162-54 50ksi 350T150-54 2" M 8x2x54xOSBx2-M4 8x2 50ksi 350S162-54 50ksi 350T150-54 2" M 8x2x54xOSBx2-C1 8x2 50ksi 350S162-54 50ksi 350T150-54 2" C-40 Cycles 8x2x54xOSBx2-M5 8x2 50ksi 350S162-54 50ksi 350T150-54 2" M 8x4x43xOSBx2-M1 8x4 33ksi 362S162-43 33ksi 362T162-43 2" M 8x4x43xOSBx2-M2 8x4 33ksi 362S162-43 33ksi 362T162-43 2" M 8x4x43xOSBx2-M3 8x4 33ksi 362S162-43 33ksi 362T162-43 2" M 8x4x43xOSBx6-M1 8x4 33ksi 362S162-43 33ksi 362T162-43 6" M 8x4x43xOSBx6-M2 8x4 33ksi 362S162-43 33ksi 362T162-43 6" M 8x4x43xOSBx2-C1 8x4 33ksi 362S162-43 33ksi 362T162-43 2" C-43Cycles 8x4x43xOSBx2-C2 8x4 33ksi 362S162-43 33ksi 362T162-43 2" C-46Cycles 8x4x43xOSBx6-C1 8x4 33ksi 362S162-43 33ksi 362T162-43 6" C-43Cycles 8x4x43xOSBx6-C2 8x4 33ksi 362S162-43 33ksi 362T162-43 6" C-43Cycles 8x4x43xOSBx4-C1 8x4 33ksi 362S162-43 33ksi 362T162-43 4" C-43Cycles 8x4x43xOSBx4-C2 8x4 33ksi 362S162-43 33ksi 362T162-43 4" C-43Cycles 8x2x43xOSBx2-C1 8x2 33ksi 362S162-43 33ksi 362T162-43 2" C-43Cycles 8x2x43xOSBx2-C2 8x2 33ksi 362S162-43 33ksi 362T162-43 2" C-43Cycles 8x2x43xOSBx2-M1 8x2 33ksi 362S162-43 33ksi 362T162-43 2" M 8x2x43xOSBx2-M2 8x2 33ksi 362S162-43 33ksi 362T162-43 2" M 8x2x43xOSBx2-M3 8x2 33ksi 362S162-43 33ksi 362T162-43 2" M 8x2x43xOSBx6-C1 8x2 33ksi 362S162-43 33ksi 362T162-43 6" C-43Cycles 8x2x43xOSBx6-C2 8x2 33ksi 362S162-43 33ksi 362T162-43 6" C-43Cycles 8x2x43xOSBx6-M1 8x2 33ksi 362S162-43 33ksi 362T162-43 6" M 8x2x43xOSBx6-M2 8x2 33ksi 362S162-43 33ksi 362T162-43 6" M 8x2x43xOSBx6-M3 8x2 33ksi 362S162-43 33ksi 362T162-43 6" M

19

The dimensions of the tested shear walls are shown in Figure 5 and 6. The studs were

placed 24-in. from the edge, in the center. Double back-to-back studs were used for the

boundary, and a single stud was used for the interior. The OSB sheet sheathing was

installed on one side of the wall by 7/16-in. modified truss head self-drilling screws. The

details of the components of the proposed OSB sheet walls are given as follows:

Studs:

33ksi 362S162-33structural stud,

50ksi 350S162-54 structural stud,

33ksi 362S162-43 structural stud

Tracks:

33ksi 350T150-33 structural track,

50ksi 350T150-54 structural track

33ksi 362T162-43 structural track

Sheathing:

APA rated sheathing 24/16, 7/16 inches sized for spacing, Exposure 1

Oriented Strand Board

Framing and Sheathing Screws:

#8x1/2 screw, 2 in. o.c. on the perimeter, 12 in .o.c in the field (8 x4)

#8x1/2 screw, 4 in. o.c. on the perimeter, 12 in .o.c in the field (8 x4)

#8x1/2 screw, 6 in. o.c. on the perimeter,12 in .o.c in the field (8 x4)

#8x1/2 screw, 2 in. o.c. on the perimeter,(8 x2)

#8x1/2 screw, 4 in. o.c. on the perimeter,(8 x2)

20

#8x1/2 screw, 6 in. o.c. on the perimeter,(8 x 2)

Hold-Downs:

Simpson Strong-Tie® S/HD10 hold-downs with No. 10-161-in. HWH self-drilling

tapping screws, and with 5/8-in. diameter ASTM A490 anchor bolts.

Shear Anchor Bolts:

5/8-in. diameter ASTM A490 anchor bolts with standard cut washers and nuts. Four

bolts were used for each wall assembly.

Figure 5OSB shear wall dimensions of 8-ft. × 4-ft. wall assembly

21

Figure 6OSB shear wall dimensions of 8-ft. × 2-ft. wall assembly

4.4 Material Properties

Coupon tests were conducted according to the ASTM A370 (2006) “Standard Test

Methods and Definitions for Mechanical Testing of Steel Products” to obtain the actual

properties of the test materials in this project. The coupon test results are summarized in

Table 5. The coating on the steel was removed by hydrochloric acid prior to the coupon

tests. The coupons tests were conducted on the INSTRON® 4482 universal testing

machine. An INSTRON® 2630-106 extensometer was employed to measure the tensile

strain. The tests were conducted in displacement control at a constant rate of 0.05 in./min.

A total of four coupons were tested for each member, and the average results are provided

in Table 5.

22

Table 5Coupon test results

Member

Uncoated

Thickness

(in.)

Yield

Stress Fy,

(ksi)

Tensile

Strength Fu

(ksi)

Fu/Fy

Elongation

for 2 in.

Gage Length

(%)

33ksi 33mil stud

0.0341 49.8 58.1 1.17 35%

33ksi 33mil track

0.0371 44.3 51.8 1.17 32%

33ksi 43mil stud

0.0445 52.9 76.4 1.44 24%

33ksi 43mil track

0.0442 65.6 97.8 1.49 13%

50ksi 54mil stud

0.0553 52.4 68.7 1.31 25%

50ksi 54mil track

0.0552 62.2 80.0 1.29 13%

All the coupons meet the minimum ductility requirement by North American

Specification for Design of Cold-Formed Steel Structural Members 2007 Edition

(AISI-S100,2007), which requires the tensile strength to yield strength ratio greater than

1.10, and the elongation on a 2-in. gage length higher than 10%.

23

CHAPTER 5

TEST RESULTS AND DISCUSSION

5.1 Summarizing Shear Walls Test Results

The test results for this task are summarized in Table 6. The displacements in Table 6

represent the lateral displacement of the wall top at the peak load in pounds per foot. The

definition for test label is: high of wall x width of wall x framing thickness x OSB

sheathing x screw spacing and test number, for example (8x2x33xOSBx4-M1). The safety

factor is Ω, (Ω=2.0 for wind load design, Ω=2.5 for seismic load design). Shear demand (υ)

is defined as the peak load divided by the safety factor. The failure modes for nominal

shear resistance verification task are listed in Table 7. Figure 7shows an example of an

OSB shear wall test result.

(a) Hysteresis of test result

(b) Specimen after test

Figure 7OSB shear wall test result

0 1 2 3 4 50

500

1000

1500

2000

Horizontal displacement of top track (in.)

Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx4-M1

24

Table 6OSB shear wall test results

Test label Peak

load+

Peak

load - Disp+ Disp-

Average

peak load Plf Fn/Ω

8x2x33xOSBx4-M1 2167

4.79

2167 1084 541.7 8x2x33xOSBx4-M2 2242

3.75

2242 1121 560.5


4.56

2455 1228 613.7 8x2x33xOSBx4-C1 2196 2169 4.53 2.63 2183 1091 436.5 8x2x33xOSBx4-C2 3213 1339 4.83 2.07 2276 1138 455.2 8x2x33xOSBx2-M1 2465

2.15

2465 1233 616.2


2.87

2604 1302 651.0 8x2x33xOSBx2-C1 2624 2571 3.27 3.65 2598 1299 519.5 8x2x33xOSBx2-C2 2598 2489 3.04 2.83 2544 1272 508.7 8x2x54xOSBx2-M1 4335

3.73

4335 2168 1083.7


3.38

4323 2162 1080.7 8x2x54xOSBx2-M3 5113

5.28

5113 2557 1278.2


5.39

5253 2627 1313.2 8x2x54xOSBx2-C1 5420 5584 4.41 4.90 5502 2751 1100.4 8x2x54xOSBx2-M5 6198

6.88

6198 3099 1549.5

8x4x43xOSBx2-M1 11016

2.68

11016 2754 1377.0 8x4x43xOSBx2-M2 9592

1.91

9592 2398 1199.0


1.87

9047 2262 1130.8 8x4x43xOSBx6-M1 5249

2.59

5249 1312 656.1


2.66

4639 1160 579.8 8x4x43xOSBx2-C1 11392 10800 2.80 2.60 11096 2774 1109.6 8x4x43xOSBx2-C2 9809 9695 2.48 2.06 9752 2438 975.2 8x4x43xOSBx6-C1 4944 4168 1.38 1.39 4556 1139 455.6 8x4x43xOSBx6-C2 4711 4308 2.91 1.98 4510 1127 450.9 8x4x43xOSBx4-C1 6789 5200 1.94 1.11 5995 1499 599.4 8x4x43xOSBx4-C2 6429 5708 1.94 1.89 6069 1517 606.8 8x2x43xOSBx2-C1 5622 4677 4.27 3.72 5149 2574 1029.9 8x2x43xOSBx2-C2 5671 5474 4.15 4.50 5572 2786 1114.5 8x2x43xOSBx2-M1 4337

4.17

4337 2168 1084.2


5.45

4555 2277 1138.7 8x2x43xOSBx2-M3 5480

5.57

5480 2740 1370.0

8x2x43xOSBx6-C1 2257 2087 2.14 1.99 2172 1086 434.4 8x2x43xOSBx6-C2 2136 2108 2.11 2.21 2122 1061 424.4 8x2x43xOSBx6-M1 2359

4.68

2359 1179 589.7


2.45

2054 1027 513.5 8x2x43xOSBx6-M3 2229

3.14

2229 1114 557.2

25

Table 7OSB shear wall failure modes

Test label Failure mode

8x2x33xOSBx4-M1 buckling of chord studs in compression



8x2x33xOSBx4-C1 Buckling of chord studs. Screw pulled out from the frame along the bottom portion of the chord studs

8x2x33xOSBx4-C2 Buckling of chord studs, screws pulled out from studs in the area of hold-downs

8x2x33xOSBx2-M1 Buckling of chord studs

8x2x33xOSBx2-M2 Buckling of the chord studs in compression

8x2x33xOSBx2-C1 Buckling of chord studs


8x2x54xOSBx2-M1 Hold-down failure, screw shear failure on hold-down

8x2x54xOSBx2-M2 Hold-down failure, screw shear off on hold-down

8x2x54xOSBx2-M3 OSB cracking along the vertical screw line on the chord studs

8x2x54xOSBx2-M4 OSB cracking along the vertical line of screws on chord studs and along the bottom line of screws on track


8x2x54xOSBx2-M5 OSB cracking along the vertical screw line on chord studs and along horizontal screw line on bottom track

8x4x43xOSBx2-M1 Shear of screw and screw pull out

8x4x43xOSBx2-M2 OSB cracking

8x4x43xOSBx2-M3 OSB shear cracking in the field of the panel

8x4x43xOSBx6-M1 Screw pull out from chord studs

8x4x43xOSBx6-M2 Screw tilting, bearing, and pull out from chord studs

26

Based on the monotonic test results, the nominal shear strength for wind load design

for7/16” OSB sheathing shear walls is established and listed in Tables8.The values for 6-in.

4-in. and 2-in. fastener spacing configurations in Tables 8are determined by the exact test

results. The details of the test results of nominal shear resistance verification task are

provided in the appendix.

Table 7 (continued)

8x4x43xOSBx2-C1 Screw pull out from chord studs

8x4x43xOSBx2-C2 OSB shear cracking in the field of panel

8x4x43xOSBx6-C1 Screw pull out from the chord studs and bottom track

8x4x43xOSBx6-C2 Screw pull out from chord studs and bottom track

8x4x43xOSBx4-C1 Screw pull out from chord studs

8x4x43xOSBx4-C2 Screw pull out from chord studs and bottom track



8x2x43xOSBx2-M1 The actuator reached its extension capacity, and the thicker part of the t-shape touched the roller

8x2x43xOSBx2-M2 Hold-down failed

8x2x43xOSBx2-M3 Buckling of chord studs

8x2x43xOSBx6-C1 Screw pullout from chord studs

8x2x43xOSBx6-C2 Pull Screw pull through and pull out from chord studs

8x2x43xOSBx6-M1 The screw pull through OSB

8x2x43xOSBx6-M2 Pull through of screws in sheathing on the lower south end and the screws were tilted

8x2x43xOSBx6-M3 Screws pulled through the OSB

27

Table 8Recommended nominal shear strength for wind loads for OSB shear walls

(Pounds Per Foot)

Assembly

Description

Maximum

Aspect

Ratio

(h/w)


Edges

(inches)

Designation

Thickness

of Stud,

Track and

Blocking

(mils)

Required

Shearing

Screw Size 6 4 2

7/16” OSB,

one side

(this research)

4:1 1144 1267 33 8

4:1 1107 2395 43 8

4:1 2522 54 8

2:1 1236 2471 43 8

Based on the cyclic test results, the nominal shear strength for seismic load design

for 7/16” OSB sheathing shear walls is established and listed in Tables 9. The details of the

test results of nominal shear resistance verification task are provided in the appendix.

Table 9Recommended nominal shear strength for seismic loads for OSB shear walls

(Pounds Per Foot)

Assembly

Description

Maximum

Aspect

Ratio

(h/w)


Edges

(inches)

Designatio

n

Thickness

of Stud,

Track and

Blocking

(mils)

Required

Shearing

Screw Size 6 4 2

7/16” OSB,

one side

(this research)

4:1 1115 1285 33 8

4:1 1073 2680 43 8

4:1 2751 54 8

2:1 1133 1507 2606 43 8

28

5.2Verifying Nominal Strength of 7/16” OSB Shear Walls Tested and Nominal Strength of

7/16” OSB Shear Walls Published in AISI-S213-07

Due to the summary of the test results which recommended in Table 8 and Table 9,

the comparison would be made by Table 10 and Table 11. Those tables provide the

comparison between the test results and the AISI S213 values for the nominal shear

strength.

Table 10Comparison of nominal shear strength for wind loads for OSB shear walls (Pounds Per Foot)

In the Table 10 comparison of nominal shear strength for wind loads for OSB shear

walls, it was found that the published nominal shear strength for a 33-mil framed shear wall

with 7/16” OSB sheets on one side is unconservative. The monotonic tests on 7/16” OSB

sheets by screw spacing 2 inches yielded reasonably lower strength (1267 plf) compared to

the published value (1825 plf ) of 7/16” OSB sheets for wind loads. The published value

(1825 plf ) should be recommended for a 43-mil framed shear wall with 7/16” OSB sheets.

Further investigation is required to verify the published value, which is 1825plf in AISI.

Assembly

Description

Maximum

Aspect

Ratio

(h/w)

Designation

Thickness

of Stud,

Track and

Blocking

(mils)

Required

Shearing

Screw

Size

Fastener Spacing

Panel Edges

(inches)

4 2

AISI S213 -7/16” rated

sheathing(OSB),

one side

4:1 33 8 1025 1825

7/16” rated

sheathing(OSB),

one side

( this research )

4:1 33 8 1144 1267

29

Table 11Comparison of nominal shear strength for seismic loads for OSB shear walls

(Pounds Per Foot)

In the Table 11,it was found that the published nominal shear strength for a 33-mil and

43-milframed shear wall with 7/16” OSB sheets on one side is conservative. The cyclic

tests on 7/16” OSB sheets by screw spacing 2 inches, 4 inches, and 6 inches gave

significantly higher strength (2680plf, 1073 plf, and 1115plf) than the published value for

7/16” OSB sheets for seismic loads.

5.3 Expanding Nominal Strength of 7/16” OSB Sheathing Shear Walls Published in

AISI-S213-2012

Due to the summary of the test results which recommended in Table 8 and Table 9,

the expanding nominal strength would be made by Table 12 and Table 13. Those tables

provide the additional nominal strength for the published tables in AISI-S213-2012. The

highlighted values in Table 12 and Table 13 are obtained by this research work.

Assembly

Description

Maximum

Aspect

Ratio

(h/w)

Designation

Thickness

of Stud,

Track and

Blocking

(mils)

Required

Shearing

Screw

Size

Fastener Spacing

Panel Edges

(inches)

6 4 2


sheathing(OSB), 4:1 43 8 825 2060

7/16”rated

sheathing(OSB),

( this research )

4:1 43 8 1073 2680


sheathing(OSB), 4:1 33 8 915

7/16” rated

sheathing(OSB),

( this research )

4:1 33 8 1115

30

Table 12 Expanded Nominal Shear Strength for Wind and Other In-Plane Loads for Shear Walls

(Pounds Per Foot)

Assembly

Description

Maximum

Aspect

Ratio

(h/w)

Fastener Spacing at Panel

Edges

(inches)

Designation

Thickness of

Stud, Track

and Blocking

(mils)

Minimum

Sheathing

Screw

Size 6 4 3 2

15/32” structural

1 sheathing

(4-ply), one side

2:1 1065 - - - 43 (min.) 8

7/16” rated

sheathing (OSB),

one side

2:1 910 1410 1735 1910 33 (min.) 8

7/16” rated

sheathing (OSB),

one side oriented

perpendicular to

framing

2:1 1020 - - - 33 (min.) 8

7/16” rated

sheathing (OSB),

one side

4:1 - 1025 1425 1825 33 (min.) 8

7/16” rated

sheathing (OSB),

one side (tested)

4:1 1107 2395 43 (min.) 8

7/16” rated

sheathing (OSB),

one side(tested)

4:1 2522 54 (min.) 8

7/16” rated

sheathing (OSB),

one side(tested)

2:1 1236 2471 43 (min.) 8

0.018” steel

sheet, one side 2:1 485 - - - 33 (min.) 8

0.027” steel

sheet, one side

4:1 - 1,000 1085 1170 43 (min.) 8

4:1 645 710 780 845 33 (min.) 8

0.030” steel

sheet, one side 4:1 795 960 1005 1055 33 (min.) 8

0.033” steel

sheet, one side 4:1 1035 1145 1225 1300 33 (min.) 8

31

Table 13Expanded Nominal Shear Strength for Seismic and Other In-Plane Loads for Shear Walls

(Pounds Per Foot)

Assembly Description

Max.

Aspect

Ratio

(h/w)

Fastener Spacing at Panel

Edges(inches)

Designation

Thickness of

Stud, Track

and

Blocking

(mils)

Minimum

Sheathing

Screw

Size 6 4 3 2

15/32” Structural 1

sheathing (4-ply), one side

2:1 780 990 - - 33 or 43 8

2:1 890 1330 1775 2190 43 or 54 8

68 10

7/16” OSB, one side

4:1 700 915 - 1285 33 8

4:1 825 1235 1545 2060 43 or 54 8

2:1 1133 1507 2606 43 8

2:1 940 1410 1760 2350 54 8

2:1 1230 1850 2310 3080 68 10

0.018” steel sheet, one side 2:1 390 - - - 33 (min.) 8

0.027” steel sheet, one side 2:1 - 1000 1085 1170 43 (min.) 8

2:1 647 710 778 845 33 (min.) 8

0.033” steel sheet, one side

2:1 1055 1170 1235 1305 43 (min.) 8

2:1 - - - 1505 43 (min.) 10

2:1 - - - 1870 54 (min.) 8

5.4VerifyingDesign Deflection Equation in AISI-S213-07

δ =8vh3

EsAc b+ ω1ω2

vh

ρGtsheating

+ ω15/4𝜔2𝜔3𝜔4 𝑣/𝛽 2 +

ℎ

𝑏𝛿𝑣

(Eq.C2.1-1) from AISI-S213-07

The calculated deflection (δ) can be found out from the design deflection equation.

The deflection of tested (δtested ) would be got from test figures in the appendix. Then,

Table 14 will show the comparison of two deflections. This comparison was identifying to

32

a ratio which ratio =δTested /δAISI .

Table 14Comparison of displacement of tested and displacement by deflection equation

Configuration

Peak

Load

(plf.)

Peak

Load/Ω

(plf.)

δAISI

(in.) δTest(in.)

Ratio(δTest/

δAISI)

8x2x33xOSBx4-M1 1084 541 1.083 1.333 1.23053 8x2x33xOSBx4-M2 1121 560 1.141 2.379 2.08444 8x2x33xOSBx4-M3 1228 613 1.314 1.897 1.44405 8x2x33xOSBx4-C1 1091 436 0.770 1.445 1.87587 8x2x33xOSBx4-C2 1138 455 0.822 1.429 1.73829 8x2x33xOSBx2-M1 1233 616 0.845 0.776 0.91788 8x2x33xOSBx2-M2 1302 651 0.912 1.079 1.18351 8x2x33xOSBx2-C1 1299 519 0.618 1.082 1.75086 8x2x33xOSBx2-C2 1272 508 0.653 1.057 1.61896 8x2x54xOSBx2-M1 2168 1083 1.147 1.612 1.40600 8x2x54xOSBx2-M2 2161 1080 1.142 1.022 0.89515 8x2x54xOSBx2-M3 2557 1278 1.477 1.494 1.01136 8x2x54xOSBx2-M4 2627 1313 1.541 1.240 0.80480 8x2x54xOSBx2-C1 2751 1100 1.291 1.396 1.08091 8x2x54xOSBx2-M5 3099 1549 2.002 1.796 0.89715 8x4x43xOSBx2-M1 2754 1377 1.231 0.822 0.66783 8x4x43xOSBx2-M2 2398 1199 0.976 0.634 0.64926 8x4x43xOSBx2-M3 2261 1130 0.887 0.623 0.70265 8x4x43xOSBx6-M1 1312 656 1.017 0.875 0.86019 8x4x43xOSBx6-M2 1160 579 0.821 0.640 0.77944 8x4x43xOSBx2-C1 2774 1109 0.859 0.596 0.69349 8x4x43xOSBx2-C2 2438 975 0.697 0.477 0.68452 8x4x43xOSBx6-C1 1139 455 0.545 0.228 0.41806 8x4x43xOSBx6-C2 1127 450 0.536 0.327 0.60994 8x4x43xOSBx4-C1 1498 599 0.583 0.346 0.59316 8x4x43xOSBx4-C2 1517 606 0.595 0.430 0.72234 8x2x43xOSBx2-C1 2574 1029 1.229 0.943 0.76723 8x2x43xOSBx2-C2 2786 1114 1.390 1.028 0.73980 8x2x43xOSBx2-M1 2168 1084 1.674 1.565 0.93512 8x2x43xOSBx2-M2 2277 1138 1.437 1.465 1.01933 8x2x43xOSBx2-M3 2740 1370 1.929 1.742 0.90306 8x2x43xOSBx6-C1 1086 434 0.756 0.413 0.54615 8x2x43xOSBx6-C2 1061 424 0.728 0.472 0.64816 8x2x43xOSBx6-M1 1179 589 1.255 1.076 0.85744 8x2x43xOSBx6-M2 1027 513 0.995 0.618 0.62104 8x2x43xOSBx6-M3 1114 557 1.141 0.831 0.72855

33

According to the calculation of Table 14, there is a summary shows that the average

of ratio= 0.974,the Standard Deviationδ=0.412, and Coefficient of Variance COV=42.27%.

Those numbers could give the information is the test results are very close to the AISI

deflection data. In another way, the Figure 8 will show the points that for a ratio which ratio

=δTested /δAISI by different screw spacing in inches.

Figure 8Ratio of deflection data by different screw spacing

To verify and develop design deflection equation for nominal strength of CFS share

wall with OSB, not only using the deflection data point method, but also using the

estimated drift deflections to describe analysis and compare test data. In the following

figures, the estimated curves should be compared with test curves. The test specimens

were identifying by eight groups. Those figures provide a comparison between the tests

and the AISI-S213-07 values for the nominal shear strength using linear method. From the

figures, the estimated curves are very close to the test curves.

0 1 2 3 4 5 6 7 80

0.5

1

1.5

2

2.5

Screw Spacing

Ra

tio

8x2

8x4

34

Figure 98x2x33xOSBx2 tested curves and estimated curve


0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

ce

me

nt

(in

.)

Applied Load (plf.)

8x2x33xOSBx2

Estimated

C1

C2

M1

M2

0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

cem

ent

(in.)

Applied Load (plf.)

8x2x33xOSBx4

Estimated

C1

C2

M1

M2

M3

35



0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

cem

ent

(in.)

Applied Load (plf.)

8x2x43xOSBx2

Estimated

C1

C2

M1

M2

M3

0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

ce

me

nt

(in

.)

Applied Load (plf.)

8x2x43xOSBx6

Estimated

C1

C2

M1

M2

M3

36



0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

ce

me

nt

(in

.)

Applied Load (plf.)

8x2x54xOSBx2

Estimated

C1

M1

M2

M3

M4

M5

0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

ce

me

nt

(in

.)

Applied Load (plf.)

8x4x43xOSBx2

Estimated

C1

C2

M1

M2

M3

37



0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

cem

ent

(in.)

Applied Load (plf.)

8x4x43xOSBx4

Estimated

C1

C2

0 500 1000 1500 2000 25000

0.5

1

1.5

2

2.5

3

Dis

pla

cem

en

t (in

.)

Applied Load (plf.)

8x4x43xOSBx6

Estimated

C1

C2

M1

M2

38

CHAPTER 6

CONCLUSIONS AND FUTURE RESEARCH

CFS sheet shear walls with various configurations in framing and OSB sheathing

were experimentally studied for two main goals: (1) to verify published nominal strength in

Table 1and Table 2, and (2) to verify and develop design deflection equation for nominal

strength of CFS share wall with OSB. The conclusions from this project can be drawn as

follows.

By the comparison of nominal shear strength for wind loads for OSB shear walls, it

was found that the published nominal shear strength for a 33-mil framed shear wall with

7/16” OSB sheets on one side is unconservative. Because in this test program, the revised

nominal shear strength for 7/16” OSB sheet are established and listed in Tables 7 and 8.

The monotonic tests on 7/16” OSB sheets by screw spacing 2 inches yielded reasonably

lower strength (1267 plf) compared to the published value (1825 plf ) of 7/16” OSB sheets

for wind loads. The published value (1825 plf ) should be recommended for a 43-mil

framed shear wall with 7/16” OSB sheets. Further investigation is required to verify the

published value, which is 1825plf in AISI. However, in the comparison of nominal shear

strength for seismic loads for OSB shear walls, it was found that the published nominal

shear strength for a 33-mil and 43-mil framed shear wall with 7/16” OSB sheets on one

side is conservative. The cyclic tests on 7/16” OSB sheets by screw spacing 2 inches, 4

inches, and 6 inches gave significantly higher strength (2680plf, 1073 plf, and 1115 plf)

than the published value for 7/16” OSB sheets for seismic loads in AISI-S213-07.

39

The deflection data calculated by the design deflection equation which is published

in AISI-S213-07 are very close to the tested data. In other words, the design deflection

equation is an important and successfully equation for the future deign task. Due to the

Figure 8 indicate the average of ratio between calculated deflection and tested deflection is

almost equal 1, so calculated deflection is very close to the tested deflection. Then, from

the Figure 9 to Figure 16, those points out the estimated curves are very close to the test

curves. Consequently, the design deflection equation which is published in AISI-S213-07 is

a successful and reasonable equation.

Based on the experimental study, the following detailing are recommended for

assembling CFS stud framed shear walls using7/16” OSB or thicker OSB sheet sheathing:

Published nominal shear strength in AISI-C2.1-1for a 33-mil framed shear wall with

7/16” OSB sheets on one side is unconservative.

The published value (1825 plf ) should be recommended for a 43-mil framed shear

wall with 7/16” OSB sheets.

Published nominal shear strength in Table 2 for a 33-mil and 43-mil framed shear

wall with 7/16” OSB sheets on one side is conservative.

The design deflection equation which is published in AISI-S213-07 is a successful

and reasonable equation.

Future research is recommended to verify all published nominal strength numbers in

Table 1and Table 2 and using additional nominal strength which obtained by this

research work for the published tables in AISI-S213-2012.

40

APPENDIX

DATA SHEETS OF OSB SHEAR WALL TESTS

41

Test Label 8x2x33xOSBx4-M1 Test Date: 11/12/2010

Specimen Configuration

Wall dimensions: 8 ft. × 2 ft. Studs: 33ksi 362S162-33 Tracks: 33ksi 350T150-33 Sheathing: 7/16 OSB Fastener: #8x1/2 screw, 4 in. o.c. on the perimeter. Hold-down: S/HD10S on both side, touch down

Test protocol: Monotonic

Test results Maximum load: 1084 plf Maximum load: 2167 lbs Net lateral displacement at top of wall: 4.797 in.

Observed Failure Mode: buckling of chord studs in compression.

0 1 2 3 4 50

500

1000

1500

2000


Applie

d h

orizonta

l fo

rce (

lbs)

8x2x33xOSBx4-M1

42







0 0.5 1 1.5 2 2.5 3 3.5 4 4.50

500

1000

1500

2000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx4-M2

43







0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

500

1000

1500

2000

2500


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx4-M3

44

Test Label 8x2x33xOSBx4-C1 Test Date: 11/24/2010



Test protocol: Cyclic-CRUEE, reference displacement: 3.3 in. 40 cycles

Test results Maximum +load: 1098 plf Maximum +load: 2196 lbs Net lateral displacement at top of wall at Maximum +load: 4.531 in. Maximum -load: -1084.5 plf Maximum -load: -2169 lbs Net lateral displacement at top of wall at Maximum -load: -2.632 in. Average maximum load: 1091 plf Average net displacement: 3.582 in.

Observed Failure Mode: Buckling of chord studs. Screw pulled out from the frame along the bottom portion of the chord studs.

-5 -4 -3 -2 -1 0 1 2 3 4 5-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500


Applied h

orizonta

l fo

rce (

lbs)

8x2x33xOSBx4-C1

45





Test results Maximum +load: 1606.5 plf Maximum +load: 3213 lbs Net lateral displacement at top of wall at Maximum +load: 4.834 in. Maximum -load: -669.5 plf Maximum -load: -1339 lbs Net lateral displacement at top of wall at Maximum -load: -2.075 in. Average maximum load: 1138 plf Average net displacement: 3.455 in.

Observed Failure Mode: Buckling of chord studs, screws pulled out from studs in the area of hold-downs.

-5 -4 -3 -2 -1 0 1 2 3 4 5-1500

-1000

-500

0

500

1000

1500

2000

2500

3000

3500


Applied h

orizonta

l fo

rce (

lbs)

8x2x33xOSBx4-C2

46






Observed Failure Mode: Buckling of chord studs.

0 0.5 1 1.5 2 2.5

0

500

1000

1500

2000

2500


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx2-M1

47






Observed Failure Mode: Buckling of the chord studs in compression.

0 0.5 1 1.5 2 2.5 3

0

500

1000

1500

2000

2500


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx2-M2

48







-5 -4 -3 -2 -1 0 1 2 3 4 5-3000

-2000

-1000

0

1000

2000

3000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx2-C1

49





Test results Maximum +load: 1299 plf Maximum +load: 2598 lbs Net lateral displacement at top of wall at Maximum +load: 3.040 in. Maximum -load: -1245 plf Maximum -load: -2489 lbs Net lateral displacement at top of wall at Maximum -load: -2.831 in. Average maximum load: 1272 plf Average net displacement: 2.936 in.


-5 -4 -3 -2 -1 0 1 2 3 4

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x33xOSBx2-C2

50






Observed Failure Mode: Hold-down failure, screw shear failure on hold-down.

0 0.5 1 1.5 2 2.5 3 3.5 40

500

1000

1500

2000

2500

3000

3500

4000

4500


Applie

d h

orizonta

l fo

rce (

lbs)

8x2x54xOSBx2-M1

51



Wall dimensions: 8 ft. × 2 ft. Studs: 50ksi 350S162-54 Tracks: 50ksi 350T150-54 Sheathing: 7/16 OSB Fastener: #8x1/2 screw, 2 in. o.c. on the perimeter. Hold-down: S/HD10 on both side, touch down



Observed Failure Mode: Hold-down failure, screw shear off on hold-down..

0 0.5 1 1.5 2 2.5 3 3.50

500

1000

1500

2000

2500

3000

3500

4000

4500


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x54xOSBx2-M2

52






Observed Failure Mode: OSB cracking along the vertical screw line on the chord studs.

0 1 2 3 4 50

1000

2000

3000

4000

5000


Applie

d h

orizonta

l fo

rce (

lbs)

8x2x54xOSBx2-M3

53






Observed Failure Mode: OSB cracking along the vertical line of screws on chord studs and along the bottom line of screws on track.

0 1 2 3 4 5 6 70

1000

2000

3000

4000

5000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x54xOSBx2-M4

54






Observed Failure Mode: OSB cracking along the vertical screw line on chord studs and along horizontal screw line on bottom track.

0 1 2 3 4 5 6 7 80

1000

2000

3000

4000

5000

6000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x2x54xOSBx2-M5

55







-5 -4 -3 -2 -1 0 1 2 3 4-6000

-4000

-2000

0

2000

4000

6000


Applied h

orizonta

l fo

rce (

lbs)

8x2x54xOSBx2-C1

56



Wall dimensions: 8 ft. × 4 ft. Studs: 33ksi 362S162-43 Tracks: 33ksi 362T162-43 Sheathing: 7/16 OSB Fastener: #8x1/2 screw, 2 in. o.c. on the perimeter, 12 in .o.c in the field Hold-down: S/HD10 on both side, touch down



Observed Failure Mode: Shear of screw and screw pull out.

0 0.5 1 1.5 2 2.5 30

2000

4000

6000

8000

10000

12000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx2-M1

57






Observed Failure Mode: OSB cracking.

0 0.5 1 1.5 2 2.50

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx2-M2

58



Wall dimensions: 8 ft. ×4 ft. Studs: 33ksi 362S162-43 Tracks: 33ksi 362T162-43 Sheathing: 7/16 OSB Fastener: #8x1/2 screw, 2 in. o.c. on the perimeter, 12 in .o.c in the field Hold-down: S/HD10 on both side, touch down



Observed Failure Mode: OSB shear cracking in the field of the panel.

0 0.5 1 1.5 2 2.50

1000

2000

3000

4000

5000

6000

7000

8000

9000


Applied h

orizonta

l fo

rce (

lbs)

8x4x43xOSBx2-M3

59






Observed Failure Mode: Screw pull out from chord studs.

0 0.5 1 1.5 2 2.5 3 3.50

1000

2000

3000

4000

5000


Applied h

orizonta

l fo

rce (

lbs)

8x4x43xOSBx6-M1

60






Observed Failure Mode: Screw tilting, bearing, and pull out from chord studs.

0 0.5 1 1.5 2 2.5 3 3.5 40

500

1000

1500

2000

2500

3000

3500

4000

4500

5000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx6-M2

61







-3 -2 -1 0 1 2 3

-1

-0.5

0

0.5

1

x 104


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx2-C1

62






Observed Failure Mode: OSB shear cracking in the field of panel.

-3 -2 -1 0 1 2 3

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

x 104


Applied h

orizonta

l fo

rce (

lbs)

8x4x43xOSBx2-C2

63






Observed Failure Mode: Screw pull out from the chord studs and bottom track.

-4 -3 -2 -1 0 1 2 3 4

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx6-C1

64






Observed Failure Mode: Screw pull out from chord studs and bottom track.

-4 -3 -2 -1 0 1 2 3 4

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx6-C2

65







-4 -3 -2 -1 0 1 2 3 4

-4000

-2000

0

2000

4000

6000


Ap

plie

d h

orizo

nta

l fo

rce

(lb

s)

8x4x43xOSBx4-C1

66






Observed Failure Mode: Screw pull out from chord studs and bottom track.

-4 -3 -2 -1 0 1 2 3 4

-6000

-4000

-2000

0

2000

4000

6000


Applied h

orizonta

l fo

rce (

lbs)

8x4x43xOSBx4-C2

67



Wall dimensions: 8 ft. × 2 ft. Studs: 33ksi 362S162-43 Tracks: 33ksi 362T162-43 Sheathing: 7/16 OSB Fastener: #8x1/2 screw, 2 in. o.c. on the perimeter Hold-down: S/HD10 on both side, touch down




-5 -4 -3 -2 -1 0 1 2 3 4 5-6000

-4000

-2000

0

2000

4000

6000

Displacement (in.)

Applied L

oad (

lbs.)

8x2x43xOSBx2-C1

68







-5 -4 -3 -2 -1 0 1 2 3 4 5-6000

-4000

-2000

0

2000

4000

6000

Displacement (in.)

Ap

plie

d L

oad

(lb

s.)

8x2x43xOSBx2-C2

69



Wall dimensions: 8 ft. × 2 ft. Studs: 33ksi 362S162-43 Tracks: 33ksi 362T162-43 Sheathing: 7/16 OSB Fastener: #8x1/2 screw, 2 in. o.c. on the perimeter, Hold-down: S/HD10 on both side, touch down



Observed Failure Mode: The actuator reached its extension capacity, and the thicker part of the t-shape touched the roller.

0 1 2 3 4 5 6 70

1000

2000

3000

4000

5000

6000

Displacement (in.)

Applied L

oad (

lbs.)

8x2x43xOSBx2-M1

70






Observed Failure Mode: Hold-down failed

0 1 2 3 4 5 6 70

1000

2000

3000

4000

5000

6000

Displacement (in.)

Applied L

oad (

lbs.)

8x2x43xOSBx2-M2

71







0 1 2 3 4 5 6 70

1000

2000

3000

4000

5000

6000

Displacement (in.)

Ap

plie

d L

oad

(lb

s.)

8x2x43xOSBx2-M3

72





Test results Maximum +load: 1129 plf Maximum +load: 2257 lbs Net lateral displacement at top of wall at Maximum +load: 2.141in. Maximum -load: -1044 plf Maximum -load: -2087 lbs Net lateral displacement at top of wall at Maximum -load: -1.997in. Average maximum load: 1086 plf Average net displacement: 2.069 in.

Observed Failure Mode: Screw pullout from chord studs.

-5 -4 -3 -2 -1 0 1 2 3 4 5-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500

Displacement (in.)

Applied L

oad (

lbs.)

8x2x43xOSBx6-C1

73






Observed Failure Mode: Pull Screw pull through and pull out from chord studs.

-5 -4 -3 -2 -1 0 1 2 3 4 5-3000

-2000

-1000

0

1000

2000

3000

Displacement (in.)

Applied L

oad (

lbs.)

8x2x43xOSBx6-C2

74






Observed Failure Mode: The screw pull through OSB.

0 1 2 3 4 5 60

500

1000

1500

2000

2500

Displacement (in.)

Ap

plie

d L

oad

(lb

s.)

8x2x43xOSBx6-M1

75






Observed Failure Mode: Pull through of screws in sheathing on the lower south end and the screws were tilted.

0 1 2 3 4 5 60

500

1000

1500

2000

2500

Displacement (in.)

Ap

plie

d L

oad

(lb

s.)

8x2x43xOSBx6-M2

76






Observed Failure Mode: Screws pulled through the OSB.

0 1 2 3 4 5 60

500

1000

1500

2000

2500

Displacement (in.)

Ap

plie

d L

oad

(lb

s.)

8x2x43xOSBx6-M3

77

REFERENCES

1ASTM A370 (2006) “Standard Test Methods and Definitions for Mechanical Testing of

Steel Products”American Society for Testing and Materials, Washington, DC.

2. AISI-S100 (2007). “North American Specification for Design of Cold-Formed Steel

Structural Members 2007 Edition,” American Iron and Steel Institute, Washington, DC.

3. American Iron and Steel InstituteS213 (2007). “Standard for Cold-Formed Steel

Framing -Lateral Design”, Washington, DC, USA.

4. Serrette, R.L. ,Nguyen, H., Hall, G.(1996). “Shear Wall Values for Light Weight OSB

Framing.”Santa Clara University. Santa Clara, CA.

5. Serrette, R.L. (1997). “Additional Shear Wall Values for Light Weight OSB

Framing.”Santa Clara University. Santa Clara, CA.

6. Serrette, R.L. (2002). “Performance of Cold-Formed Steel-Framed Shear Walls:

Alternative Configurations.”Santa Clara University. Santa Clara, CA.

7. Chen, C.Y. (2004). “Testing and Performance of Steel Frame / Wood Panel Shear Walls”,

Master’s Thesis, Dept. of Civil Engineering and Applied Mechanics, McGill University.

8. Dinehart, D., &Shenton III, W. (1998). “Comparison of Static and Dynamic Response of

Timber Shear Walls”, Journal of Structural Engineering.

9. UBC (1997). “1997 Uniform Building Code”.International Conference of Building

Official, Washington, DC.

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