DESIGN CONSIDERATIONS FOR SHEAR LINKS IN ECCENTRICALLY ... · Eccentrically braced framing has been...

REPORT NO.UCB/ EERC·83/24NOVEMBER 1983

- -~ -_._._.- --

EARTHQUAKE ENGINEERING RESEARCH CENTER

DESIGN CONSIDERATIONSFOR SHEAR LINKS INECCENTRICALLY BRACED FRAMES

by

JAMES O. MALLEY

EGOR P. POPOV

COLLEGE OF ENGINEERING

UNIVERSITY OF CALIFORNIA • B.rk.ley, CCilifornia

Il",OOUCEO ITNAT10NAl TECHNICALINFORMAliON SERVICE

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DISCLAIMERAny opinions, findings, and conclusions orrecommendations eKpressed in this publication are those of the authors and do notnecessarily reflect the views of the NationalScience Foundation or the Earthquake Engineering Research Center, University ofCalifornia. Berkeley

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£PORT OOCUII£NTATION IL tIP'OIn' ItO. . II. l.rB8i19rts6PAGE NSF/CEE - 83037..........--- .. ~e=r .1983Design Cons~derations for Shear links in Eccentri ca llyBraced Frames ..

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The performance of an eccentrically braced frame depends to a great extenton the behavior of short beam segments called active links which. through bendingand shear. transfer the axial forces in the diagonal braces to other braces or tocolumns. The sensitivity of link behavior to the imposed loading history. thelink-column connection detail. and the web stiffener design and details are discussedin this report. The results of twelve full size shear link specimens are ~resented.

Each of the specimens was designed to investigate specific shear link responsecharacteristi cs. Four specimens were tested with stiffener details which differedsignificantly from those of previous experiments and early design applications.Another set of four specimens were designed and tested with widely varying lOodinghi stori es. A set of four specimens which employed conventional moment resistingconnection details were also tested. Test conclusions and design recommendationsgenerated by the test results are presented. A practical method for web stiffenerdesign is developed. A design procedure for eccentrically braced ·frames which employshear links is outlined.

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DESIGN CONSIDERATIONS FOR SHEAR LINKSIN ECCENTRICALLY BRACED FRAMES

by

James O. MalleyResearch Assistant

University of California, Berkeley

and

Egor P. PopovProfessor Emeritus of Civil Engineering

University of California, Berkeley

Report toNational Science Foundation

Report No. UCB/EERC - 83/24Earthquake En&ineerin& Research Center

University of CaliforniaBerkeley, California

November 1983

ABSTRACT

Eccentrically braced framing has been gaining acceptance in seismic applications because

this system can provide both high elastic stiffness and large energy dissipation capacity. The

performance cf an eccentrically braced frame depends to a great extent on the behavior of short

beam segments called active links. Through bending and shear. active links transfer the axial

forces in the diagonal braces to other braces or to columns. These short beam members pro

vide the primary energy dissipation mechanism for properly designed eccentrically braced

frames.

The results of previous experimental and analytical research has provided a good deal of

information on the cyclic behavior of active links. This work has demonstrated that short

active links which yield in shear (shear links) can dissipate more energy than longer active links

which yield primarily in bending (bending links). However. some aspects critical to the

economical design of an eccentrically braced frame which employs shear links have yet to be

addressed. includina the sensitivity of link behavior to the imposed loading history. ttte link

column connection detail. and the web stiffener desip and details. These three important con

siderations of shear link behavior are discussed in this report.

The results of twelve full size shear link specimens are presented. Fach of the specimens

was designed 10 investigate specific shear link response characteristics. Four specimens were

tested with stiffener details which differed sisnificantly from those of previous experiments and

early design applications. Another set of four specimens were designed and te~led wilh wid~ly

varyina loadins histories. A set of four specimens which employed conventional moment resis~

iog connection details were also tested.

The qualitative and quantitative results of these experiments were compared and analyzed

usina enel'lY dissipation capacity as a mlijor parameter. Test conclusions and desian recommen

dations lenerated by the lest results are then presented.

-ii-

A practical method for web stiffener desipJ is developed. This method considers both the

axial force and bendiq rigidity requirements which shear link web stilfeners must satisfy. An

example of this stilfener design method is liven in an ADpendix.

A desian procedure for ;;ccentrically braced frames which employ shear links is outlined.

Based on the results of this and previous investigations. and the common practices of seismic

desian. this procedure attempts to summarize the ~r considerations of shear link design.

This procedure includes recommendations on the determination of structural confiauration.

member sizes, link-connection details, and web stUfener sizes and details. The suuested con

nection and stilfener details are illustrated.

-iii-

ACXNOWLEDGIMENTS

The authors aratefully acknowled&e the suppon of the Nationa! Science Foundation.

Grant No. CEE 81-07217. which provided the funds for this res-~rch. The opinions expressed

in this report an: those of the authors and do no: necessarily reflect the views of the National

Science Foundation.

Many people made significant contributions to the completion of this project and the

preparation of this report. Gail Feazell prepared the ftaures presented in this report. Wes Neigh

bour provided the technical expertise necessary to perform the experiments reported herein.

The suggestions and comments provided throulhout the project by Keith D. Hjelmstad helped

to form many of the conclusions and recommendations presented in this report. The authors

greatly appreciate the contributions made by these individuals.

The authors also acknowledge the suggestions concernin. web stitfener desian provided by

the Sacramento branch of the California Office of the State Architect and one of the author's

<J.O.MJ colleques at H.J. Dqenkolb Associates.

Filures A.I throuah A.4 were reproduced with the permission of the Royal Aeronautical

Society. Their cooperation is appreciated.

-iv-

Table of Contents

ABSTRACT ,.. , , , ..

ACKNOWLEDGEMENTS ,......................................................................................... iii

TABLE OF CONTENTS .. iv

LIST OF FIGURES .. vi

LIST OF TABLES ix

CHAPTER I INTRODUCTION I

1.1 Prim:iples of Earthquake Resistant Design I

1.2 Typical Structural Steel Framing Systems 2

1.3 The Eccentrically Braced System 4

1.3.1 The Development of the Eccentrically Braced System as a FramingAlternative. 5

1.4 Scope and Objectives of this Investigation 6

CHAPTER 2 THE EXPERIMENTAL SYSTEM 11

2. I The Modeling Assumptions of the System I I

2.2 The Test Setup 13

2.3 Instrumentation 13

CHAPTER 3 DESIGN OF TEST SPECIMENS 1'7

3. I Common Features of the Tests 1'7

3.2 Material Properties 1'7

3.3 Stiffener Detail Tests 18

3.4 Loading Program Tests 19

3.5 Erld Connection Detail Tests 20

CHAPTER 4 DISCUSSION OF TEST RESULTS 32

4.1 General Discussion of Specimen Behavior 32

4.2 Special Features of the Different Tests 34

4.2.1 Stiffener Detail Tests 34

4.2.1.1 Specimen 17 34

4.2.1.2 Specimen 21 35

4.2.1.3 Specimen 26 35

4.2.1.4 Specimen 27 35

4.2.2 Loading Program Tests 36

4.2.2.1 Specimen 16 36

4.2.2.2 Specimen 18 36

4.2.2.3 Specimen 20 37

4.2.2.4 Specimen 24 37

4.2.3 End Connection Tests 38

-v-

4.2.3.1 Specimen 22 384.2.3.2 Specimen 23 394.2.3.3 Specimen 2S 394.2.3.4 Speci.nen 28 39

CHAPTER 5 - ANALYSIS OF EXPERIMENTAL RESULTS 585.1 Elastic Behavior 585.2 Inelastic Pre-Buckling Response 60

5.2.1 Inelastic Displacement Contributions .. 60

5.2.1.1 Shear Displacement Contribution 605.2.1.2 Support Contributions in the Inelastic Ranae 61

5.2.2 Link Moments and Aanae Strains 62

5.3 Control of Post-Buckled Behavior .. 62

5.3.1 Delayina Bucking 635.3.2 Controlling the Location of Buckling 635.3.3 Developing Multiple Panel Buckling 63

5.4 Failure Modes of Shear Links 64CHAPTER 6· EVALUATION OF LINK PERFORMANCE 72

6.1 Energy Dissipation as a Measure of Structural Performance 726.2 Design Recommendations 75

CHAPTER 1 • WEB STIFFENERS IN SHEAR LINKS 807.1 Experimental Results 807.2 The DeSil" of Shear Link Stiffeners 81

7.2.1 SprJCina of Web Stiffeners 81

7.2.2 Sizins Shear Link Web Stiffeners 827.2.2.1 Axial Forces in Web Stiffeners 827.2.2.2 Riaidity Requirements of Shear Link Web Stiffeners 85

1.2.3 Detailina Shear Link Web Stiffeners 88

CHAPTER 8 - A DESIGN PROCEDURE FOR SHEAR LINKS IN ECCENTRI-CALLY BRACED FRAMES 93

8.1 Determination of Structural Confiauntion 938.2 Determination of Member Sizes 9S8.3 Desian of Link Connections.. 98

8.3.1 Link-Column Connections 98

8.3.2 Link-Brace Connections 998.4 Desiln of Shear Link Stiffeners 100

CHAPTER 9 - SUMMARY AND CONCLUSIONS 1069.1 Summary 106

9.2 Conclusions 106BIBLIOGRAPHy '" 109APPENDIX A.I DERIVATION OF THE REQUIRED STIFFENER RIGIDITYRELAnONS"IP 111

APPENDIX A.2 AN EXAMPLE OF SHEAR LINK WEB STIFFENER DESIGN 116

Fil. 1.1

Fi,. 1.2

FiB 1.3

FiB. 1...

Fi•. l.S

FiB. 2.1

FiB. 2.2

Fia·2.3

Fig. 2.4

Fia· 3.1Fia.3.2

FiB. 3.3

FiB. 3.4

FiC.3.S

Fia. 3.6

Fia.3.7

Fi,.3.8

FiB. 3.9

Fia.3.10

Fia. 3.11Fia. 3.12

Ft•. 3.13

Fia. 3.14

VII.3.lS

Fia.3.16

VII. 4.1

FII.4.2VII. 4.3

FiB· .....

FiB. ".SVII. 4.6

F'1I.4.7

FiB. 4.8

VII. 4.9

-vi-

LIST OF FIGURES

Moment Resistina Framing for a 16 Story Frame

Two Possible ConfiBurations for a 16 Story Concentrically Braced frame.

One Possible Confi.uration for a 16 Story &centrically Braced Steel frame.

Two Arranaements of Eccentrically Braced Framina Studied in Early JapaneseResearch (8, 10).

Four Alternative Arranaements of Eccentrically Braced F'ra'llinl [1l).

The Active Link Model Extracted from Two Possible iJroMYpe Confiaurations1121.

The Experimental Setup [121.

Location of Linear Potentiometers and LVDTs Used in the Instrumentation ofthe Specimens.

Location of the Strain Giles Used in the Instrumentation of the Specimens.

Typical Section and Connection Details of the Specimens.

Connection Details of Specimen 17.




-Control" PrOlfam of Incrementally Increasina Displacements UsedThroUlhout the Experimental Invcstiption.

Section and Connection Details of Specimens 16 and 18.Loadil1l History Employed in Experiment 16.

Loadil1l History Employed in Experiment 18.

Loadil1l History Employed in Experiment 20.





Stiffener Details Employed In the Experiments.

Connection Details Utilized in the Experiments.

Typical Load vs. Displac:ement Curve for a Well Stift'ened Shear Link.

Symmetrical Bucklinl Mode of Shear Link Webs (13).

Typical Half Cycle for a Shear Link Durina Postbuckled Response.

Orientation of Web Bucklina at Different Stales of Half CYcle.

Force-Displ-eement Hysteretic Loops of Specimen 17.

Photo of Specimen 17, a W18x40 Section with Two 1/2 in. Thick Stiffeners. atthe End of Testifll.

Force·Displacement Hysteretic Loops of a Similar Specimen (S~cimen 9 (13))with Two-Sided Stift'eners.

Force·Displ-eement Hysteretic Loops of Specimen 21.

Photo of Specimen 21•• WI8x40 Section with Two 112 in. Thick Stilfeners. atthe End of Testina.

Force-Displacement Hysteretic Loops of Specimen 26.

Fig. 4.11

Fig. 4.12

Fig. 4.13

Fig. 4.14

Fig. 4.15

Fig. 4.16

Fig. 4.17

Fi•. 4.18

Fi•. 4.19

Fi•. 4.20

Fig. 4.21

Fi•. 4.22

Fig. 4.23

Fig. 4.24

Fi•. 4.25

Fi•. 4.26

Fig. 4.27

Fig. 4.28

Fi•. 4.29

Fia· 4.30

Fia·4.31

Fia·5.1

Fia·5.2

Fia. 5.3

Fia·5.4

Faa. 5.5

Faa. 5.6

Fia. 5.7

Fia. 5.8

Fia·6.1

-vii-

Photo of Specimen 26, a WI81140 Section with Three 3/8 in. Thick Stiffeners,at the End of Testin•.


Photo of Specimen 27, a W18x40 Section with Four 3/11 in. Thick Stiffeners, atthe End of Testina.

Photo of the Failed Flanae Weld of Specime". 27.


Photo of Specimen 16, an Unstilfened W18x60 Section, at the End of Testina.


Photo of Specimen 18, an Unstilfened W18x60 Section, at the End of Testina.


Photo of Specimen 20, a W18x40 Section with Two 1/2 in. Thick Stilfeners, atthe End of Testina.

Foree-Displacement Hysteretic Loop of Specimen 24.

Photo of Specimen 24, a W18x40 Section with Two 1/2 in. Thick Stilfeners, atthe End of Testing.



Photo of Distorted Bolt Holes of Specimen 22.Force-Displacement Hysteretic Loops of Specimen 23.Photo of Specimen 23, a Wl8x40 Section with Two 1/2 in. Thick Stilfeners, atthe End of Testina.

Foree-Displacement Hysteretic Loops of Specimen 25.


Foree-Displacement Hysteretic Loops of Specimen 28.

Photo of Specimen 28, a W:8x40 Section with Three 3i8 in. Thiele Stilfeners,at the End of Testina.

Simple Analytical Model of the ExperiMents.

Refined Analytical Model of the Experiments.

Plot .'f Fixed End Slip vs. Shear Used to Determine the Lateral Support Displacenient Stiffness, K 4'

Plot of Fixed End Rotation vs. Shear Used to Determine the Rotational Support Stiffness, K 8-

Plot Comparina the R~rded (Solid Line) and Acljusted (Dotted Line) Displacements of Specimen 20.

Plot Comparina the Recorded (Solid Line) and Acljusted (Dotted Line) Displacements of Specimen 16.

Suuested Stilfener Spacina for Shear Links with the Web Fillet Welded to aShear Tab.

Suuested Stilfener Spacina for Shear Links with the Web Iolted :0 a ShearTab.

Plot of Normalized Enel'lY Dissipation, )., vs. Cumulative Ductility, 4c., forSpecimens With Dilferent Loadina Conditions.

FiS.6.2

FiS.6.3

FiS. 7.1

FiS. 7.2

FiB. 7.3

Fig. 7.4

FiS·7.5FiS. 8.1

FiS.8.2

Fig. 8.3

Fig. 8.4

Fig. 8.5

Fig. 8.6

Fig. 8.7

FiS. 8.8

FII. A.lFil. A.2

FiS. A.3

FiB. A.4

FiS. A.S

-viii-

Plot of Normalized Enel'J)' Dissipation, A., vs. Ductility, II, for Specimens WithDifferent Stiffener Details and/or Spacinl.

Plot of Normalized Energy Dissipation, A., vs. Ductility, ,.,.. for Specimens WithDifferent Connection Details.

Plot of the Averase Axial Strain in Each of the Stiffeners Employed in Specimen 20.

Free Body Diqram For Determinina Stiffener Forccs Usinl Tension FieldTheory.

Assumed Distribution of Axial Stresses for Two-Sided Stiffeners.

Assumed Distribution of Axial Stresses for One-Sided Stift'eners.

Three Possible Details for Connection of Stilfeners to Shear Links.

Alternative Arranaements for Eccentric Bracina Showing Possibie Location ofArchitectural Openinas [I Il.Proper Configuration of Framina to Limit the Axial Forces Introduccd Into theActive Links.

A Simple Eccentrically Braced Frame and Its Collapse Mechanism II Il.Typical Moment-Shear Interaction Diasram for Wide Aange Sections.

All-Welded Link-Column Aanae Connection with Fillet Welded Web ShowinaSuaested Stiffener Spacing.

All-Welded Link-Column Aanae Connection with Full Penetration Web WeldShowinS Suaested Stift'ener Spacina.

Bolted Web, Welded Aanae Link-Column Aanae Connection Showina Suggested Stiffener Spacil'lJ.

Sugested All-Welded Link-Column Web Connection Showina SugestedStift'ener Spacina.

Critical Bucklina Stress Factor vs. Stift'ener RiBidity for ~ - 1.0 (23).

Critical BucklinS StreA Factor vs. Stift'ener RiBidity for ~ - 3.0 (231.

Critical Bucklina Stress Factor vs. Stift'ener Riaidity for ~ - 1.5 (23).

Critical Bucklina Stress Factor vs. Stift'ener Ripdity for ~ - 2.0 (23].

Plot of Minimum Required Stift'ener Riaidity ,. T Which Develops the Maximum Elastic Critical Stress ( K ) for Different Values of Panel Aspect Ratio (~).

Table 3.1

Table 3.2

Table 3.3

Table 5.1

Table 5.2

) able 5.3

Table 5.4

Table 5.5

Table 6.1

-ix-

LIST Of TABLES

Properties of the Steel Used in This Investiaation.

Section Properties of the Specimens Used in This Investigation.

Summary of Test Specimen Details

Experimental Contribution of Shear Disp:acemel't Duril1l Linear Cycles.

Experimental Contribution of Shear Displacement During Inelastic Cycles.

Plastic Moment Capacities of the Sections Used in This Investigation.

Maximum End Moments Resisted by the Specimens.

Maximum Straim for Each Aanae Gille of Specimen 16.

tnergy Dissipation of the Test Specimens.

CHAPTER 1 - INTRODUCTION

1.1 Prbad,les .f Eart....ake R.eslstant Deslp

Structures located in seismic regions must be designed to resist inertial forces caused by

earthquake induced support excitations. The nature of earthquake around motions causes the

support excitations to be unique for every seismic event. Also. durilll a seismic event the sup

port motions of different structures vary widely due to local soil conditions. Furthermore, the

specific composition of each structure determines the mapitUde. location. and dura!ion of the

inertial forces. As a result of all these factors. the possible future inertial forces caused by

earthquake ground motions cannot be determined with accuracy.

Due to the uncertainty involved in determinina seismically induced inertial forces. the

structural eqineer must rely on satisfying the basic requirements of earthquake resistant

desiJn. Three limit states comprise the fundamental philosophy of seismic desi&n.

First. serviceability requirements dictate that the structure should resist r"lalively frequent

minor earthquakes without damaae. Generally. structural damBIe is avoided by providina the

structure with enouah Itrenath to remain elastic throUlhout the minor events. Sufficient elastic

stiffness must be provided to prevent excessive deflections and thereby preclude the occurrence

of non-structural damqe.

The ICCOnd requirement of earthquake resistant dcIiIn considers the structural respoDIe

durina the less frequent moderate earthquake. Durina the moderate event. the structure

should not undel'lO any structural damale. But•• limited amount of non-structural damqe is

allowed. To meet these requirements. the structure can undeqo minor inelastic letivity in crit

ical reaions. The resultina deflections can become Iarp cnoup to C8U8C lOme non-structural

damqe. since in this intermecUate limit state the COlts incurred to provide structural stifl'neta

- 2 -

sufficient to reslrain deflections below the limit of non-structural damage may be much greater

than the expenditure required to repair the resulting damage.

The final requirement of earthquake resistant design is that the structure should not col

lapse during the most severe earthquake. Both structural and non-structural damage may occur

during this rare event. Inelastic structural behavior is allowed, since for the vast majority of

str'Jctures the costs necessary to resist major earthquakes elastically becomes prohibitive. Ihe

underlying motivation for this requirement is to prevent structural collapse and minimize the

possibility for loss of life. To meet this requirement, the structure must be able to dissipate

large amounts of energy through inelastic deformations. In general, structural systems which

exhibit stable hysteretic loops perform well under the large inelastic cyclic loadings of major

earthquakes.

1.2 Typical Struetunl Steel FrRmlnll Systems

By proper application of these three requirements, the ltppropriate structural system can

be devised. Because of its excellent strength and ductility properties, structural steel has been

used for many applications, especially those involving high and medium rise buildings. In the

past, structural engineers have utilized two types of structural steel framing for these applica

tions: mOlnent resisting fames and concentrically braced frames.

Moment resisting frames, depicted in Fig. 1.1, are by far the most widely used structura'

steel framing system. From an architectural standpoint this system is advantaaeous since there

arc no obstructions between columns. The capacity of this system to dissipate energy during a

ml\ior earthquake is provided by inelastic action at beam-column joint locations. Use of the

~trong column-weak beam approach causes the formation of plastic hinges in the beams near

the column connection. Tests on moment resisting beam-column subassemblages demon

strated the stable non-deteriorating hysteretic loops desirable for enel'lY dissipation purposes

1i6l. With proper detailing, the moment resisting frame can be expected to provide sufficient

ductility and energy dissipation capacity in the event of a major earthquake. This confidence in

- J -

the desirable inelastic behavior of the moment resisting system has led to reduced code lateral

force requirements for these frames 1311.

Moment resisting frames also have disadvantages. First, the elastic stiffness required to

limit deflections and thereby prevent non-structural damage during minor earthquakes results in

member sizes larger than thuse necessary for other framing systems. This can result in

increased material costs and story heights. Second, the larg, beam end moments inherent with

this system often result in substantial shearing deformations in the column panel zones. These

panel deformations can contribute signihcant amounts to the story drift, resulting in increased

p-~ effects. Often these panel deformations are reduced by the addition of costly web doubler

plates.

The second widely used framing system is the concentrically braced frame, a~ shown in

Fig. 1.2. In this system, a set of diagonal braces are provided to increase the lateral stiffness of

the frame. The braces are located so that member centerlines intersect at the joints, effectively

forming a vertical truss. The intrinsic stit'fness of braced frames orten makes them economi·

cally advantageous for the shorter plan dimension. Architecturally, such frames are less desir·

able than moment resisting frames because of the obstructions produced by the braces.

The seismi.: resistance characteristics of concentrically braces frames differ significantly

from those exhibited by moment resisting frames. The braces cause the system to resist lateral

forces primarily through axial forces in the members. This results in smaller beam bending

moments and therefore smaller member sizes. Consequently, some savinp in material costs

may be realized. Also, panel zone shearing deformations are insignificant due to the small

bentting moments at the beam ends. The excellent elastic stiffness properties of such systems

makes the concentrically braced system quite efficient for resisting minor seismic events.

In contrast, the inelastic behavior of such systems is suspect, even thouah the damqe

caused by the 1976 Managua earthquake demonstrated that stiff buildinp with sufficient ductil

ity can exhibit desirable performance. Caution should be exercised in adopting such a system

because repeated buckling of the diqonal braces causes a rapid decrease in the brace capacity

· 4·

(4). This causes pinched hysteretic loops for such systems duriOI inelastic load reversals (17).

The severity of the pinching depends on the slenderness ratio of the brace, with lower KII r

values exhibiting better hysteretic behavior. The slenderness ratio of diagonal braces is typi

cally quite high, so rapid deterioration of the systems' energy dissipation capacity can be

expected. Building code provisions recognize this undesirable behavior by requiring a larger

lateral force coefficient than that of moment resisting frames. Also, in highly seismic regions

the Uniform Building Code requires a moment resisting system capable of resisting 25 percent

of the lateral forces for all structures taller than 160 feet UIJ.

Thus. neither of the traditional structural steel framing systems efficiently meets all of

three of the principal requirements of earthquake resistant design In the past structural

engineers have often employed both systems to meet all three requirements. As an alternative

to providing a combination of the traditional systems, a hybrid system which can satisfy both

the elastic stiffness and energy dissipation criteria has been gaining acceptance. This system is

the eccentrically braced frame.

1.3 The Eeeenttiall'y Rnced System

In eccentrically braced frames, the axial forces in the diasonal braces are transferred to

columns or to other braces by bending and shear in a portion of the beam called the active link.

as shown in Fig. 1.3. By offsetting the braces in this fashion the maximum force that can be

imparted to the brace depends on the shear capacity of the beam. With this limitation on brace

forces, the braces can be designed to avoid the deleterious effects of cyclic buckling. The active

links provide the primary energy dissipation mechanism for the system. The length of these

links determines the dominant mode of inelastic behavior. Shorter links generally dissipate

enerlY through inelastic web shear stTlAins. while longer links dissipate eneTIY in a manner simi

lar to moment resisting frames. through inelastic flange normal strains. In addition. the elastic

stiffness of the system approaches that of the concentrically braced frame for low to moderate

eccentricities [I11. Properly designed eccentrically braces frames can therefore meet both the

- 5 •

elastic stiffness and ultimate ductility requirements of earthquake resistant de-sign.

1.3.1 The D.nlopnK'nt of the E~ntrlc.lly Braced Syst~m 0;. a Framinl Alternatln

As early as 1930 the eccentric bracing system was proposed as a method to resist wind loads

1271. The interest in this system for seismic applications has developed recently. Early Japanese

research demonstrated thaI eccentricall) braced K frames. such as that depicted in Fig. 1.4a, can

dissipate large amounts of energy without excessive lateral deflection [81. Other studies in Japan

effectively made use of inverted Y braces such as that shown in Fig. 1.4b (10).

The initial research of Roeder and Popov [241 demonstrated the excellent stiffness and

dissipative capacities of systems braced similar to that depicted in Fig. 1.5(a). This research

also showed that the excellent cyclic shear yielding properties of shon active links require

proper restraint to control web buckling. Further. this investigation presented the first set of

recommendations for the overall design of an eccentrically braced frame. The encouraging

results of this early research led to f"rther study and the earliest design applications.

Manheim extended the work of Roeder and Popov to the split K eccentrically braced sys

tem of Fig. Uk) (18). This work also developed an analysis and design procedure from limit

analysis techniques, and presented a method for analyzing overall frame stability and the effects

of beam lateral torsional buckling.

In addition to developing a program for the preliminary design of eccentrically braced

frames, Kasai USI studied the response of V-type bracing, such as that shown in Fig. !.S(d).

The critical importance of active link behavior to the energy dissipation capacity of the

entire system motivated further study of link properties. In this research Hjelmstad isolated the

link element to investigate local response characteristics 1121. This research included a series of

fifteen tests designed to investigate both links which yield primarily in shear and those which

yield in bending. The ~or conclusions obtained from this study included the following: t.)

Shear links achieve greater ductilities and dissipate more energy than bending links. 2.• Strain

hardening in shear links can increase the ultimate shear capacity well above the yield value.

Bending links do not benefit as significantly from strain hardening. 3'> Web buckling greatly

- 6 -

deteriorates the energy dissipation capacity of active links. 4.1 To delay and restrain web buck

ling, stiffeners should be provided. Equal spacing of shear link stiffeners was found to be

optimum. The minimum ~tiffener spacing for shear links should be on the order of 20 to 30

I., where I. is the link web thickness. 5) The post· buckling behavior of shear links depends on

the stiffener spacing. The post·buckling life decreases with im:reased web stiffening.

1.4 Sc:epe and Objeethes of this (n,"estlaation

A good deal of information has been developed from the four investigations cited previ·

ously. From this research, the elastic, inelastic, and energy dissipation characteristics of both

entire eccentrically braced frames and the critical active links is now better understood. But,

some of the considerations critical to the economical design of eccentrically braced frames have

yet to be investigated. Many of the details required for shear link design have not been studied

explicitly. In an effort to investigate the critical response parameters, earlier studies employed

overly conservative design details in many cases. In this investigation a deliberate effort was

made to find more efficient detailing procedures that might provide significant Cosl economies

without seriously inhibiting shear link behavior. The possible cost economies, Ihe importance

of providine; adequate seismic connection details, and the critical significance of shear link

behavior combined to mOlivate Ihis investigation.

The specific design considerations investigated included the following:

Whot impacts do varied loadinx histories hoW! on the ~rformallCe of the links?

2. Who' are the most efficient stiffener detoils considerinx both economy and structural ~rfor.

monce?

3. How do lhe typical connection detoils affecl the ~rformance o/shear links?

4. Whot types and magnitudes of loads do the wt>b stjfff>ners resisl? How should the stjff"ners be

desiglWd to resist tMSR loads?

• 7 •

5. Whot are the performan.'e choracteristics of shear linb connected to the web ofa column?

A series of twelve specimens were designed, tested and analyzed to investigate the design

lllnsiderations listed above. From the results of these tests. recommendations are given for

~hear link design. A method for stiffener design is developed such that a complete shear link

d<,~ign method can be presented.

r7l

'rrfir

r"r

r7

),

~

MO

ME

NT

RE

SIS

TIN

GF

RA

MIN

GS

YS

TE

MC

ON

CE

NT

RIC

AL

LY

BR

AC

ED

FR

AM

ING

SY

ST

EM

S

Fig.

1.1

Mom

ent

Res

isti

ngF

ram

ing

for

a16

Sto

ryF

ram

e.

Fig.

1.2

Tw

oPo

ssib

leC

onfi

gura

tion

sfo

ra

16S

tory

Con~cntrically

Bra

ced

Fra

me.

(0)

EC

CE

NT

RIC

KB

RA

CE

(b)

INV

ER

TE

DY

BR

AC

E

1>

Fi•.

1.3

One

Pos

sibl

eC

onfi

gura

tion

for

a16

Stor

yE

ccen

tric

ally

Bra

ced

Stee

lF

ram

e.

Fig.

1.4

Tw

oA

rran

gem

ents

(,fE

ccen

tric

ally

Bra

ced

Fra

min

gS

tudi

edin

Ear

lyJa

pane

seR

esea

rch

(8,

101.

(0) (b)

-10-

(c ) (d )

Fig. 1.5 Four Alternative Arrangements of Eccentrically Braced Framing lit J.

• 11 •

CHAPTER 2 • THE EXPERIMENTAL SYSTEM

Research into structural enaineerina topiQ pnerally takes one of two forma. The ftnt

method, the analytical approKh, utilizes a mathematical formulation of the structural problem.

But, in ~ome cases structural problems are so complex that tbe cost of obtainina meaninaful

results solely throuah analytic:al techniques bec:omes prohibitive. In tbele instances it bec:omel

necessary to use experimental techniques.

The aoat of any type of structural research is to acxwately model the real system. In

experimental research tbis entails developina an experimental system that captures as many of

the important features of the Ktual system u poesible. Put research on eccentrically bnced

frames U.,241 cooc:entratod on the aJobal properties of the entire framed system. A recent

investiption [J 2,13] fOCUled on the local response of the critical component of the system, the

Ktive Unka. The experimental model UIId in Ibis investiption wu extraetod from the two pol

able prototYJle conftaurations mown in Fla. 2.1.

1.1 Tile M..... """."...• ., tile s,.a.

DeIi.nlnl an experimental system involves makina lOme simpUf'yina aaumptioDa.

Rational julti8cation of these IUUJIlptiODl is _ntill if the tests are to provide reIU1ts tbat

doeely correlate with the perf'ormmce of an ICtual structure.

The .-unptions employed in the experimental system developed for tbiI inYelliplioD

were .. rolknn (12,13]:

1. 77w ~.. oj ,. ;,1Ik~ /btId ....'IUI ",."".. A two inch thick Itee1 plate at .-dl end

connected the ll*imens to the teItinI ......tuI aM provided hit)' .............

Thia conditioD is present in the lCluai .,.... Iince the iit\t is ...... COIltipou to •

ftIIion of low sbeu, or direct.ly CODDeCteel to a column.

- 12 -

2. If IrtOrwlfl coltll«tiolr ws pro~1MtJ lit bot" 'rub 0/ tM liltk. In aU cues, fun penetration or

flUet welds connected the beam Danael to the end plates to provide the required moment

continuity.

3. Ywlt/lrrg WtI.S COlUtTlllrtet/ 10 tM link rqion. This assumption wu nel:ellaIY in order to test

the link separately from the ;est of the frame. Previous experimental researc:b on frame

subusemblaaes [18.24] demonstrated that the amount of inelastic behavior in ~ODl

ICliacent to the links il neaIilible wben compared to that within the links.

4. TIw linJa wrr ioGMd wit" II eo"""ltt sMar /'ora. Since durina seismic &tivity the load

from the eccentric tnte is likely to be much &reater than the distributed Door lOId, the

link in the prototype structure hu a nearly constant shear force alona its lenath.

S. TIw Iiltks wrr IIIIJ)«ted 10 rr~r. CUf'WlIIn wit" ~UQI ~NJ IfIOIWItI1 This condition it not

Ktually present in the prototype structure until it bu underaone several inelutk cyck.

un It is believed that the inelutic behavior caU8el redistribution of streaes tbrouab

plutiftcation, 1eIdina to the assumed condition. A current investiption i. studyina the

validity of this assumption.

6. TIw kit linJa wrr ItOI Iotldtd wit" 11'0' 1IJdai/Orta. The development of laqe uiaI forces

in the IICtive IinltI can Iilni&.nUy reduce their eDelJ)' dissi.-lion caplCity. Therefore, it

is adVrtlltlpous to locate the IICtivc linu such that they are' not required to axially trlllllfer

:up seismic forces to the bnces. TbiI can be ICCOmplisbed tbrouah judicious locatiOll of

the Inces. or throUlb the ute of llIraIlel 1Itberin1 beIma. An inveltiption presenUy II!

proIJ'eII is Itud)'irll the efFects of oW fote:el OIl link reIPODIe.

To provide stability aDd to impoee the CODdition of zero end rotation. IIDa1I uial forces

were iJnpoed on the syItem. This created IliIbtty unequal end momenta in tbe links. But, the

uial force .. pnera1ly small enoqb that its efFect on the performaoc:e of the specimeas ..

DelUlibie.

- 13 •

2.2 TIM Telt Set-.,The testina apparatus, depicted ~n POll. 2.2. was desianed to provide the system with the

modelina usumptions listed above. All the specimens in this series of tests were 36 in. lona.

18 in. deep wide Oanae lCCtions. As noted earlier. tbe links were welded to .....e end plates.

Each end plate wu in turn attached to • still' steel usemblqe by sixteen 1 1/4 in. diameter

A490 bolts. The -fixed" end of the testina .pparatus was ~nnected to ......e concrete reaction

block by means of twelve 2 in. diameter prestressed steel rods. The wfreewend of the specimen

was .ttached to • riaid system of steel pl.tes. A 3S0 kip loadina ram transmitted the shear

fon:e. while a sidearm with. 12S kip tmlIducer provided the axial load required for system Sla

bility lOCI zero free end rotation. The IMds were applied to the specimen in the plane of the

web centerline. The eccentricity of the axial sidearm was SS in. from the center of the 1POCi

men. while the !08dina ram wu positioned .t the center of the test link. Support for the lllU

sive IoIdina arm wu provided by two Teflon lined support pedestals. The frictional resiItance

of the suPportina system was insipifk:ant.

2.3 lun-tat'"

All of the teat data WII monitored by • Nell' biah speed data lCquisition I)'Item. The

information wu recorded on mqnetic tape so tbat subsequent data analysis could be performed

with • CDC 6400 computer. The iDJtrumentation DIed to record the teat data included ao.cs

cella. linear potentiometers. linear variable difl'erentill transformers (LVDT). and linin .....

The shear and u:iaI forces imputed to the specimens were measured by tranlducers,

located u shown in Pia. 2.2. The accuncy of the data obtained from the 350 kip and the 12S

kip transducers were ± 1.0 kip lOCI ±O.S kips respectively.

Linear potenticr.neters. located u shown in Pia. 2.3. measured many of the important

specimen dilplacemeGts. Four potentiometers mouured the lateral dilpl8cement of the free end

or the specimen. Axial displIcemmtl and free encl rotations of the epeeimeaI were recorded by

IDOther set of four potentiometers. In the ftrst four teats these instrumentl were alto UIeCl to

- 14 -

measure out of plane web diaplKementa. The reIOlution of the potentiometers wu %0.001 in.

Previous tests usma this test sct-up revealed elastic: link stUrnesscs on the orck:r of one

balf of thai expected from Timosbenko shear beam theory [13l. This wu in part due to lick of

complete end ftxity. In the lint four tests. a I)'Stem of sil[ LVOTs were UIed to measure the

displac:ementa of tbe fixed end, u sbown in 1711. 2.3. Two LVOTs measured lateral displlce

menta wbile the other four determined tbe fixed end rotation. The relOlution of these instru

ments wu %0.0001 in.

Axial flanae strains were measured by means of uniaxial SR-4 post yield strain Illes,

located u shown in Pia. 2.4. In the lint four specimens, three Illes were provided in each

(;.)mcr. Sinalc Pies located 3.S in. from each comer wer<: employed in the otber tests. Strain

rOleltes, compo8ed of three uniuial ...... recorded the web sbear "~Wns. In the first four

tests, eac:b panel contained a centrally located rOlette on both sides of the web. Only one panel

shUI' strain wu measured in this manner durina IUbeequent tests. Osa" were also centrally

located on both sides of tbe web stift'enert to meuure their axial skin strains. The ....

adhesive limited the maximum strain measurement to approximately eltht per cent. Since tem

perature eB'ec:ts were nealec:ted, strains were aaumed to be ICCUrate to ftf'ty mic:rostrain.

, - Y'

SP

EC

IME

N

CO

NC

RE

TE

RE

AC

TIO

NB

LO

CK

~ Mc1P

=qJp·

~.

~

~ n--

--II

'"

If1-

(0)

(bJ

(c)(H

II

II

II

H)

FiB

·2.

1T

heA

ctiv

eL

ink

Mod

elE

xtra

cted

from

Tw

oP

ossi

ble

Pro

toty

peC

onfi

gura

tion

s11

2).

Fig.

2.2

The

Exp

erim

enta

lS

etup

It21

.

·16·

----f

----1

_. - - - LINEAR POTENTIOMETER

I------ LVDT

+ WEB LINEAR POTENTIOMETER'l-

I

~--L_

+ + +

+ + +

+ + +t--- r~

I

T,*' 1

I,

Fig. 2.3 Location of Linear Potentiometers and LVDTs Used in the Instrumentation ofthe Specimens.

- UNIAXIAL GAGE

.... , ROSETTEIr-- -

123 1,87_... ..........

.... ~ ....~ ....~

• , I

I I

'4"i"6 ..........12 II 10

I.- .....

FiS·2.4 Location of the Strain Gages Used in the Instrumentation of the Specimens.

·17-

CHAPTER 3 • DESIGN or TEST SPECIMENS

Due to the eucourqina results of the eu1ier investiptions on KCeotric:al1y br.ced frame

IUboIemblqes, the \lie of this fraDlint system is beiq repeatedly Idopted in practice, even

thouah investiption conceminl many of tbe important considerations of shear link desian ue

not yet complete. Since the perforJDal1':e of shear links is vital to the utisflCtory performance

of the entire system, a leriell of further tests were desiped to determine the efFects of IC*1inl

history, stifFener details, and connection details on link I'flIPODIe.

3.1C............' .. T...

Before discusIina the desian of 1l*i6c: specimens, the common futures of ail the speci

ment should be noted. The desip of the specimens followed the AISC SpeciftcatioM III for

IUCh detlils II weld si1.e, bolt si,.e and number, boit bole si,.e,IPICiDI, ecIp distance, etc. I!.Ich

of the specimens WII an 18 in. deep, 36 in. lona rolled wide tJanae lec:tion. The bIIic end plate

connec:tion detail employed all-around fUlet weIdI. Some tests were deIiped to in'Wlltiple typ

ic:aI end connection detsill UIed in practice. In all c:uea. the stiffeners were poIitioned OIl only

tide of the web. The stUl'enen were connec:ted to the link by fun &eDIth IWet welda. Fit- 3.1

lIhowI a spec:imen with tJpic:aI details.

3.2 ........ Pnllrt*

The Iarp ineIIIdc stniD demIDd which can be iIIlI'OIed on Ibear IinkI durinl a extreme

IeiImic event requirel • biIbIY duc:tile material, suc:b II mild c:arboD 1teeI. Therefore, A36 IteeI

wu elDen for thOle tells. The relevat propertiea of the atee. are IiJted in Table 3.1. TbiI data

were obtained from manufKtunr'. mill ....... Coupon .... were DOt c:ouideIed DeCUIIIY,

Iince compuiIons were made from normali,.ed valuea of the tell feU...

• 11 •

The !leCtio.. "hosen for the testa included two cUll'erent 1eCtiolll, Wl8xo4O and Wllx60.

The reuolll for cboosiq these leCtioDl wu twofold. Thele 1eCti0ftJ are typical beam W.ea for

multi-ltory bral:ed frame construction, and when lDIde 36 in. IODl to ftt into the available

apparatus they exhibit the detired shear link behavior. The buic: properties for thole lIOCtiona

are lilted in Table 3.2. Since deviation of the actual dimensions from the. liven in the AISC

Manual 11 ] were neaIiaible, the nominal values were UIed tbrouabout tbiI invesdption.

3.3 StlSeeer DetaIl T•••

The larae displKementa demanded of abear liDb in ecc:entrica11y brlCOCl frames can Quae

web buc:k1ina problems. Web buctlinl should be prevented. since it severely reduces the

enerpo diaai.,.tion ~ly of • link. The addition or web ,tlff'eners delayS the initiation of web

bucklina and improves the poatbucklinl behavior or shear linb. In aU the previOUI reaean:h

112,13], the web denen were pllc:ed on both IidIlI 01 the web, ud Met we1ded to both

Oanaes II weD II the web. While aufDdent to meet the dener structural requirements, tbis

detail is not the moet economical. A aeries of four testa were therefore deIlped to in,....tipte

the eft'ects of lea expensive atifl'ener details on the per(ormance of shear linb.

The eft'ect of providina one-tided web denJ.na ... invellipled in Specimen 17. In tbiI

specimen, the 1/2 in. one-sideclllift'eoen were welded to both fIanpI as well u to the web, U

mown in Pia. 3.2. In prevlOUI leila, the two-llided ltift'eoen were 3/1 Ill. thick 112.13].

8ec:aUle of the excellent performance of tbiI specimen, III or the aucxeediDi teala Ud we"Iliffened on only ODe tide.

The COIl of providinl web llil'eaen CIIl be further reduced by reluina the requirement

of weldina the llift'eDen to both beam .... as wen as 10 the web. Specimen 21 employed a

1impU6ed detail which required the two 1/2 In. tbic:k ltift'eoen to be COIUlflCled to the web and

ODe fIuJ&e only, as mown in PIa. 3.3. Tbe ltiffeaen on oaelkle tenDlnaled. diIlance k from

the outer edp or the fIaap, (See AISC UJ MaaUII). Both deaen were welded to the lime

Oanae. It may be more 1dYID..... to alteraate the .ttameat old... to ..., but

- 19·

this could callie fabriQtion problems. Moreover, bucklina of tbe lop t1Inae is pnerally rei

tnined by the conc-ete dock.

The webs of two specimens, 26 and 27, were reinforced with stil'eaen whicb were not

attlthed to either of tbe link fJanaes. In Specimen 26, depicted, in Pia. 3.4, the three stift'eners

reduced the eft'oc:tive panel width to lea than 9 in. The four stiff'enen employed in Specimen

27 reduced tbe panel width even furtber, as shown in Pia. 3.5. In these two tests the stifFeners

were 3/8 in. thick.

3.4 LeMI.. Pnpaa Tnt.

All of the tests in previous rele&J'('h [12,13] employed I ICMdina history of cyclic ditpIace

menta increasina incrementally until failure. The IoMiDI biatory used as the -control- proaram

for thete testa was quite similar to that UIed previously. F'trIt, I few linear cycles were per

fonned to chock the instrumentation. After the linear cycles, the control proarun included I

cycle near the expected yield displacement. The next cycle bepn the incremental portion of the

IoIdinI history. Two cycles were performed at cUsplacement levels of :0.5 in., :t: 1.0 an.. : 1.5

in., etc. until failure of the IJ)CCimen. ThIs IoDna history is shown in Pia. 3.6.

Since in the inelastic ranae structural responte is dependent on prior toAd and displace

ment history, it ... CODIidered oecc.sry to inYeltipte me eft'ects of VUJiDI the IoIdiaI bit

Ioriea. Of' the twelve tests, • total of four bad bdiDa bistorieI wbic:b varied aipiftcantty from

the control propam.

SpecimenlI6 and II were WllDO.ec:tioaa with DO web stUf'eninI. .Ibown in Pia 3.7.

In the IodD& for Specimen 16, the initial c:yc:les were two Iaqe dilplM:ement pu'" in the

aame direction. After tbeae laqe pulses, the tJpic:aI inl:remental cyc:Uc propam WII followed

until failW'O. ThIs IoIdiaa bJatory II Ibown in fiI. 3.•. Nine complete cycIee with : 1 in. di.

.-:omenta were employed It the belinniq or the IoadinI pnJIJ'IIIl for Spedmea II, uibowa

in Pia 3.9. n- nine CJdeI dilsipated the IIIDe IIDOUIlt or eDeIIf .. 1ft ideIltical previoul

I)*imen (Spedmea • [12,13]) wbich CIDPIoJed the iDcroIDeatai ....... biItorJ. After u-

- 20-

cydea, two linear cydea were followed by two eye1elat ~2.S In. displacements. The ftaa1 cycle

bad a 4 in. diaplM:ement.

All of the rcmaininalPOcimel1l were WI8140 1eCtioaI. The loediq biJtory of Specimen

20, with two 1/2 in. thick denera, Ibown in Faa. ).2, itlbown in Pit. ).lo. To inveltiple

the detrimental effeas of impoGna two cyclel at NCb dilplac:ement level, this IPOCimen

underwent ooIy one cycle at achlevel after the ftrst iiI c:yc:les. In an effort to demoDJUate the

displacement C81*ity of shear linb, Specimen 2. was tested under moootollica1ly applied loed

ina. TbiJ specimen wu displaced 7.2 in. to the limit of the test tet-up, aftd then unloaded aftd

Iwded in the reverse direction to pnerate I laqe hYlleretic loop.

3.5 I .. e..-t... DetaU T....

The perf'ormaIlCe of dift'erent end c:oanection detaill under Iaqe cyclic 10edI baa boon Itu

died previously (21). TbeIe testa indicated that all welded COIUlflCtiona ..nerally perform betler

tban hybrid c:onnectionI with welded fIInps aftd bolted we". The repetitive nature of the by.

terebc loopa demounted the exceUeat eDeIJY diIIi~tiOD ~t)' of tbeIe connections in typi

cal moment reliltiDI fram•.

In lOme eccentrically braced 1YSteIDI, one eocl of the abeer link retion it I c:onnec:tion to I

column. In lOme rapecIa, the deformation c:barKterilticl or Ibear linb under c:ycljc: loedI

dUl'er from thole or beams in moment reIiICinI (ruDeI. The Ibear linD diaipate eDeIV pri

marily throUlh ..... yieIdinI of the web. TbiI INMIe or ODIIIJ dillilNltioo varieI conIidersbly

from that of beIJIII in II10IDIDI ..tina rramel, which mainIr dillilNlte eneqy throuah ftuura1

yieldina of the ..... Mono...., the web boeMi,. pbeDcMMnoo. typica1 of Ibear linD it DOt

......ly encountered. TbeIe unique apocta of ..... liak behavior, coupled with the impor

tance or beun-column CODMCtion inceptty, 1ecl to the inVelliptioD of different c:olumo-Unk

details.

Pour ..,edmenI were _iped to inftldple tJPicIJ beam-e:olumn connectioIl det8i1I. A

COIUMICtioa detail with ..... CODDeC:teeI by fun penetration 8eId weIdI. and the web bolted to a

·21 •

Ibop welded shear tab ia the predominant detail for Itee1 CODI1J'Uction in California due 10 its

COlt economy. Specimens 22 aDd 21 employed tbiI detail. III specimen 22, depicted in Pia. 3.11,

four 1 in. diameter A325 bolts provided the couectioD betweeD a 1/2 in. thick abear tab aDd

the web of the link. FiDet weldl on both sides attKbed the Ibear tab to tbe end plate. Two 1/2

in. web ltift'eners provided the web restraint. The deners were lII**1 equally from the bolt

line. Specimen 21 was identical to Specimen 22, except that tbree stift'eners were welded to the

web only. Tbiltpecimen is shown in FII. 3.12.

Another typical c:onatruetion detail ia the all field welded coanection in whicb the web ia

ftllet welded to • Ibear tab wbicb WII shop welded 10 the column fJadae. While beiq sli&btly

..~ eft'ective than the bolted web~n, tbiI detail provides a der mode or shear

transfer. ~ shown in FII. 3.13, ~pecimell 23 was of tbiI type, with a welded web c:onnection to

a 1/2 in. sbear tab. The atiff"ner detaill were identical to tJu.e of Specimen 22, witb two fully

welded deners ..-ed from the bolt line. Two 3/4 in. diameter erection bolts were added to

limutate the Ktual conatruction detail more accurately.

In the IricI floor ayateDil aeoerally encountered in bi&b rile buildinl construction, one alIo

eocounten beIm·to-c:olumn web c:onnectiODl. Teats a' 1Ierk.y and al Lebi&b University

12CM) indic:Ited tbat the commonly UIed coonectioaI of this type do nol perform in •

IUftk:iently ductUe manner. Flanp weld railwu caUIed by me. cooc:entratiOIlI were alia

obIerwd in tbeIein~ To inveltipte the behavior of tbiI Iype of Unit coaaectioa••

....... (Spedmea 25) .... rlllricated and teIteCl. In tbillI*imen, Ibown in Pia. 3.14. 1/2

In. IIUI'.. plata were wekIed to. W14xl93 IeCtioIl in the pIaDe of the link'" and web.

Fun penetration welda coaaected tbeIe platea to the Iinit. Two fun, weAded ltift'eoen were

..... eqUlllr from the .. or the column ....

Table 3.3 II preICIIlteel to 1IiIIlIDIM.e lOme of important propertieI of the 1I*imeDI. The

Idea. detaUa and end CODDeCtioDI identiled in tbiI table are ref'enaced from Pip. 3.15 and

3.16.

Table 3.1

-22-

Section UJ' utI ."(ui) (Ui) <in.lin,)

18x60 .... 67 0,2418x<40 48 64 0.26

Properties of the Steel Used in This Investigation.

Section A d I. 6, IfIlL 2 ) ( Ill. ) ( IlL ) (IlL) ( IlL )

WI8x60 17.60 18.2" O,41S 7,SSS 0.69SW18x40 IUO 17.90 0.31S 6,015 0.S2S

Table 3,2 Section Properties of the Specimens Used in This Investigation.

-23-

T.. Specimen Section No. 01 ~HiItorr Slilrener I ColUlllClion

Feature Number 'aMIl DetailI

Detail

16 W lidO I wac lniu.! DiIpI. . 3.16Ca)

LoedinI H. II W 11160 1 Nine 1 in. US mm) CycleS 3.16!.)tory 20 W 11140 3 One Cycle .1 £ad! Level 1IS<.) 3.I6Ca)

24 W 11140 3 Moaotonic 3.IS<') 3.16Ca)

3.1S(.)I

3.16<')17 WIII40 1 ,SdeDtr 11 W 11.40 1

Two eyelet .t £IdI DiJpI.lI5(b) I 3.16<')

Details 2CI W 11140 4Level. IncreuinI in 1/2 3.1S(c) 3.16(b)

21 W 11.40 4in. 03 mm) lnaemcnts

l.151c) 1I6(b)

22 W 11140 3Two CydeI .t £IdI DiIpI.

3.15Ca) 3.16(c)

Coanec:don 2J W 11.40 3 3.ISCa) 3.16(1,)

Details 25 W 11140 3Level. IncteaIinI III. (IJ

l15Ca) 3.16(d) I

21 WI1I4O .. mm)1I2111.lnaemIlats31S(c; 3.16(c) II .

Table 3.3 Summary of Test Specimen Details

·24-

II

WI8x40

A

A

If+-.. --- 3611----~1SECTION A-A

fig. 31 Typical Section and Connection Details of the Specimens.

fig. 3.2 Connection Details of Specimen 17.

-25·

1---- ,... -f~..-----+.I3~12·:36·

Fig. 3.3 Connection Details of Specimen 21.

4 @ ak": 34"~I


-26-

- .......--.......I.....--.....~lfol..P---..........I....--~."

5 @ 6:; =34"


Fig. 3.6

4

-4

25 27

21 23

17 19~

13 15

A Ai

9 II

AAA1.~

I A \ ;

2 V

VV\I

46

8

10 12 Y~14

\,....Ie 20

22 2'1

26 28

CYCLE NO.

·Control" PrOiram of Incrementally Increasing Displacements UsedThrou&hout the Experimental Investilltion.

-27-

WI8x60

3611-------.,~

Fig. 3.7 Section and Connection Details of Specimens 16 and 18.

4r-----------------------:3 25

\

\

23

22 24

21

2018

2

~ZI&J

~ 0 1J-----II"---~~_+I_~"-4-_+_+_+___\o-+__+_4__+_+_t__+__+__i

~..JQ.fI)

o-2

-

26

-4 L.- ....... ~~_=__:__=__-'-------'-------'

CYCLE NO.

Fig. 3.8 Loading History Employed in Experiment 16.

-28-

4

23 27

2Z--~Zl£J~

0l£J(,)c:(..J~(/)

Q-2

24 ?8

-4CYCLE NO.

Fig. 3.9 Loading History Employed in Experiment 18.

3 2321

19

2 17

I~-Z....ZI&J~

0I&J0Cl..J~(/) -IC

16

-2 18

2022

-3CYCLE NO.

Fia·3.10 Loading History Employed in E"periment 20.

-29-

I-1 ~_2_~_"_ ....~....----.l~l'-. ~I

," 3":3 @ 11:. =33~


7" I"4 «t ail =334


·30-

<t.I


Fia.3.14 Connection Details of Specimen 25.

I =3/8"t sl

(a )

t I =1/2 IIsf

( b)

-31-

(c )

Fig. 3.15 Stiffener Details Emilloyed in the Experiments.

(0 ) (b) (c)

-* .. -1',:;1iI~

III

(d)

Fig. 3.16 Connection Details Utilized in the Experiments.

- 32 -

CHAPTER 4 - DISCUSSION or TEST RESULTS

The specimens fabricated to meet the desian requirements diIcusIed in the previous

chapter were tested in the ~xperimenta1 apparatus described in Chapter 2. Since the respoue of

all the links follow a similar pattern. a leneral dilcussion of link behavior will be praentl=d.

Special features of each test will then be commented upon. The force-displKement hysteretic

loops and a photOlJ'8pb of each failed specimen are included to aid in understandinl the resulta

of the experiments. It should be noted that the initial excunion to any specifled displacement is

defined to be the positive direction for all the fon:e-diJpllcement curves. This cbapter is

intended to live a qualitative discussion of the test results. Quantitative analyses of the tests

will be discuued in sublequent chapters.

4.1 G....... Dbcaalo• .,S~DMa._The buic features of shear link respoDIe to tarae overiOllds are common to all ave

links. A typical displacement curve. shown in POll. 4.1 (from Specimen 26) t will be used u an

aid in delcribinl these buic f.turel. The initial elutic rePon. is Ibown by the line between

points A and B of this ftaurc. This retion exhibited the expected linear responae with a Itift'DeIS

near that predicted by Timolbenko beam theory. First yield occurrecI at a dilpbament of

approximately 0.20 in. at a .hear near the theoretical yield shear of Y, - fT,dt.l~ (Pt. C).

Because or the cyclic 10IIdiDI prOlflJll. the apecimeDl did not exhibit the yield plateau and IU~

lOquent Itnin bIrdeDiDI cbanlcteristica of teDIion tests on mild carbon steel. Unloedina fol

lowed a Pith essentiall, parallel to the eIutic ltil'neaa. all IbowIl by the "on betweell points

D and E. DUJ'iDI this loediDa process the apecimeDl dilliPited a considenble amount or DDeru.

Rove..... lodaa coatinuecl olutk:ally until the onset or)'ieldina in tbe opposite directioD. The

Bau'Cbinpr dect was clearly preent u the IOIlds approICbed the new muimum cfiIpI8cemeftt

- 33-

(Pt. F). Tb.la efFect became more pI'OIIOUIIC:ed u abe ... PI'OII'llleli The cyc:lic gture tI the

10IIdinI bistory, coupled with iDcreuina dilpllcementl, ~uced aipiftant IUaiJl bardeniDI in

the specimens. The specimens \1OIDIIlonly reacbed IoIdina peakJ (Pt. 0) SO percent bi&ber thad

the initial yield load. The specimens emibitecl -..tiaUy kinematic Itnin bIrdeninI, with e....

tic reboundl of approximately twice the yield Ibear before the oawet or the llauninpr dec:\.

Before web buctliaa occurred, IUCCellive 10Id peaks to the ume diJplatemeot level inc:reued

lliabtly (Pts. Hand O.

After the web buc:tled. the bebavior of the linb cbanpd COMiderabiy. Web bucklina of

shear links senerally followed a cyc:licalsymmetric:ll mode. depieted in Fla. 4.2 (I3l. To meet

compatibility requirementl. tbis type of buckled confIauratioG mUlled pincbina ftaap diIplace

mentl. Strea conc:entrationa induced by the one-Iidecl ltift"ener welda milled bucIdiDI to take

pIIce towIrd the llift'enedlide or the web. In poenl, only ODe puel1.oDe exhibited 1ian16c:lnt

buclI:lilll, althoulb in lOme c:a-. multiple peael buetUDa did occur.

AlOlJl with ...... web dilplacemeata. web bucklinI caUIed aubetanlill uial lborteDilll of

the linb. Peak out-of-pIaDe dilpllcementl were 3.25 in. for unalift'eaed webl and 2.5 in. for

webl with two 1tiIf...... PeU: uiallborleniDI Vlluea were OIl the order or 1.0 in.

Tbe 0lIIOI or web buctIina initiated the deterioration of link pert'onIIIDCIe. AI Ibown by

paintl J and IC ift Pia. 4.l, IUCCIIlIIive POlka 10 the I11III clilpbalDlllt tIIlc:nM.1l1fter buctllq

AIIo. the~t CUrveI Ibowed • _1'kMt drop iD ItreIIIth Won "'IIial.. capa

city, u Ibown br poUlt L. TbiI pbmomeDon II WUIIrated more apedIcaIly ift Pip. 4.3 aDd 4.4.

PiIure 4.4(a) the initiallJ budded coaftauratioa. llevenal of the load eaUlld ID

UDlllped buckled Iimilar 10 that of PIa. .....(b). At tbla poiDt the ... CMliDI ClPldtJ

...-cI ill miDialum poUlt. poUlt b iD f'ia. ".3. Wbea. the lOId revenal wu completed. the

buckle bad formed iD the compIemeotarJ dinIcdotl. u IbowD in PIa. .....(c). Once the new

buckled lbape bid formed. IeIIIioD IeId actioa IimiIIr 10 dlat of • Pratt truII mIde PGIIible the

QIlKity mer- IbDn br poiDt e ill fiI. ".3.

·34·

ContiJlued ..... cUlpilcement qcIina ftnaUy caUNd mate.. teuiDI In the 1InkI. TIUa

material tearIna wu COIIIidered the flilurc point ~ the Il)eCimeDi. Por the UDIIift'ened tpeci

mens. teariDi took pIIce Dell' the c:eoter of the web rePon due 10 material fatipe from levere

web curvature revenala. In the dened specimeas. the teariaI took pIIce II'OWId the perimeter

~ the a-kJed panel. CenaiD 1PICimeDI. tbouab. failed due 10 connection flilure rather tbaII

web web teariaa. This type or flilurc occurred in a IUdden manner, while material tearina toot

pllce lI'Idually.

".2 S.... r.t1IrM., .... m..-t T..

Virtually all the bak: r.turel mentioned above were exhibited by the difFerent ll*imeas

tbrouPout the teItina MQUODCe, but, the decree varied CODIiderably. ThOle variatiOlll mate it

..-ible 10 compare the elective.- or Ihear IInkI with cWr«eot detaiJa or 1oIdinI1UstorieI. In

this lOCtion, qualitative COIJIIlIriIOU will be diIcuaecl. Later chapten win explicate the quantita

tive c:ompaUona. From tbeae COIJIIlIriIOU, concJUIioDI and deIiID roc:ommeDdatiOlll can be

detennilled.

".2.1~ DetaIl T.....

4.1.1.1 Sp«11IWtt 11. Tbe .ecti..... ~ oae--Iided denen WII ftr1t iaveItipted in

Specimen 11. ItemarkaWY. the bJIteretic IOClIII for tlUlPOdmen, depicted In Pia. 4.5, are virtu

Illy identical to thOle ~ ID earlier spec:imen wbicb bad lWIHided ...... IbowD In Pia. 4.7

(13]. Even the poll buc:kliDI bebavior or the two 11*1 proved 10 be IlDI.'.inIlJ Iimilar, •

comperiIoa or the two 8prea indicates. Tho oaly ... cWr the two e:utVeI it Ibat

the yield ItreDIIh or Sped... 17 .. IflPIODmately 20 t tbaII that of the earlier

II*fmeD. Tho fKf that tbeIe two 1PId.... bebaved IImoIt IdeaticaIIJ led 10 ... coacIUIlon

tbat IUlk:ient 0DHided ...... it atrueturaI1J equivalent 10 that ofd", OIl both IideI of

abe web. Tho faUed IPIdmea, In wbic:h bucIdinIlnitialed durinI the IICOIId 2 in. crde. II

Ibown in Pia. 4.6.

• JS •

4.1.1.1 Sp«ime" lJ· Spedmen 21, I W llx40 leCtion with two .tift"eoen. wu deIiped to

invatipte the perfOfllWlCe of Ibear liab with the one-aided .tift"eaen welded to only one

flanae. The responae of tbiJ apec:imen is IhOWD in Jrll. 4.8. Prior to bucklina, the behavior of

tbiJ specimen wu almOit identical to that of Spedmen 17. Once bucldina occurred durina the

IOCOnd 2 in. eycle, the capacity reduction of this specimen wu more rapid than that of Speci

men 17. The ·:urvet aIIo show that there is I smaller increue in 10id due to realipunent of tbe

buclded Reid for the specimen with .tift'enen welded to ooIy ODe Danae. But, Specimen 21 wu

Ible to undel10 two full eyelet more than Specimen 1" due mainly to the fact that web buck

liDI in two panels placed lea levere local Itrain requirements on this apecimen. As shown in

rll. 4.9, Specimen 21 failed by tearina near I panel comer in whieh tbe stilfener wu not

welded to the flanae.

4.1.1.J Spec/me" 26-1be favorable performance of Specimen 211ed to the decision to try

denen cut IWI, from bcIth 8anpa. AI POll. 4.10 shows, the W18x40 leCtion with three

Slifl'eDen used in Specimen 26 performed quite well. Tbe clotel, II*Od .tilfen"rs delayed

bucldina until the second 2.S in. <:ycle. DeIaYina web bucldinl allowed the web to continue to

Itnin harden, permittinl tbiI apecimen to reach I 10Id of 213 kipI, 10 Dill above the expected

yield, and 2S killl above the peaks of previoUi II*imeDI with two ltill'eners. TbiI tarae UIlOUIlt

of Itrain blrdenioa aIIo caused yieldiq in the 112 in. abear tab. This apedmen !eIiIted only

ODe and one-balf eyelet after web bucklinl. indicatinl that an increued number of web

ltiJl'enera tonell to reduce the PGltbuc:ldial life of Ibear liob. With the ODIIt of bueklioa. the

end of 0DIl of the ltill'eoen pulled lway from the web 8llet weld. Thil10II of we'd intelritJ led

to bucklinl ICI'OII this dener duri... the failure eyde. Tbe ...... dilplacementl of this

dener may be Men in Pia. 4.11. Weldina the dener to the Oanp woulcl have eliminated

the ~bility of the initial weld pUIJ-out wbieb led to this failure mode.

4.1.1.4 S/1«iIIW" 17- Thia Wllx40 apecimen identical to Spec:imea 26, except that

IDOIber Itiff............. to reduce the pueI Ib' Sipiftc:ant buddi,. .."., took place dur-

iq tbiI tell, U Pia- 4.12 demoDItntei by the IadI: or pincbina in the bJltereail1oopl. The

-)6-

lidded ltil'ener permitted tbiI IPeCimen to IUIiD buden more tllaD Specimen 26. The max

imum ... resiIted WIt 23. kips, which is almost twice the yield shear. A auddon fnc:ture or

one of the full penetration t1anae welds cauted failure of the II*imen at the end or tbe IeCODd

2.5 in. cycle. Inspection of the fractured weld showed that weld defects in the beat 1I'ec:ted

".one call1ed the failure. A phololfapb of the weld is shown in Fia. 4.14. One caD DOte lIIat

web and fIaDae strain Iwdeniq enabled the end momenta to exceed the theoretical pIutic:

moment e&l*ity or the aection. The ludden failure exhibited by this IPICimen iDdicated that

COo clOIC a stUfener ...ana may contribute to this u.ndeIirlbie failure mode. After the weld

failed, the ll*imen wu 10ided in the oppoeite direction to a displacement of S in. Even an.

the loa of one flanae connection, the lint continued to reIiIt tremendoul 10IIdI. Fiaure 4.13

!bows the residual dilpllc:emenl. Note the apparent IIIck of web bucklina of this .,.amen.

••2.2 ....... Pr...... T....

4.1.1.1 Sp«I." 16- The loIdinI prDII'aIIl for the lIIIItift'ened WllDO leClion UIed in

Specimen 16 WIt deIianed to callie web buc:tJinI duriDI the initial CYcle. AI f'iI. 4.15 .....

the Initial c:yc:Ie exhibited a yield plateau IimiJar to that~ of IDODOlODk tenlion teItI

OIl due:tiJe 1tee1I. The peak load occurred duriDi this initial c:yde. '!'be 1atIe IbeIr forces PD

erated IDOIDeIlti wbic:h cau.d 101M c:l'UIbinI and IPIlliDI or the coocrete reactiClIl block. '!'be

el'ect of this \%\IIbiaa on link dilpbaments will be diIcuIIed in the next cbapter. Sip'fbDt

to.cI C&l*ity reduction due to web bucklina caUIed piacbiaa of the bJateretic Ioope. Despite

tbiI pindlina eft'ect, this IPIdmen dillipeteet a ....t deal of eMI'I1 after the initiatioa or buct

lina. TbiI appean to De cbncteriItic of IinkI with thick UllltUl'ened ..... The fdad II*iJDeD

ilshown in Pia- •.16.

4.2.2.1 s"cimefl 18- The UDlCift'ooed W18x60 Iection for this teat .... IUbjoI:tod to aiDe

1UCCIIIi.. one inch c:ydea, aeneratiDI the IoId cIiIpblcement curve shown In PIa. 4.l7. The iai

tiaI eXCUllioa exJUllited 1)'ieId plateau IimiJar to dill of Spedmen 16. In the ... loM .......

IDd tbe four complete qdea which preceded buclrlinl. the b.JttereIiI 100pI were virt.u,

- 37 •

identic:al. The cbancteriltic dip in tile poItbuckied curve duriDa to.d revenal did DOt occur

dunna the 1 in. cydel due to tile wmpuativcly lmall muimum dilplM:ements, At the concha

lion of the ninth cycle. a linear cycle to appromnately one-half of the yield load wu performed

to meuure the relidual elutk Itiffneas. The Imall amount of byltereail exhibited by thil

apecimea Ibowed that it retained itl elutic Itil'DeII even after levere iDelutie deformationa. A

limilar lublequent c:yc:le to tbree-quartera of tbe yield Ibear demonstrated the increasina

BlUlCbinaer eft'ectI at larp deformations. Fiaure 4.18 depictl the material tearina whicb caused

the apecimen failure after a .. in. poaitive diaplacement. This filure alia points out tbe c:ompar01

dvely small amount of.. cIiItreII that occ:urred at Iarp diaplacementl of tbiJ unstifl'ened,

tbic:k web Ibear link. S ICC:Mdina pbOkJlnpba of atiffenod apecimeftl with thinner webs diaplay

larp local ftanae diaplacementl in the !llIion of the buckled panel.

4.1.1.J Spec'''''' 10- The initial c:yc:le to U in. did not buckle tbil adened Wlb40 _.

lion. As Pia. 4.191bows. the sec:ond cycle caused a sJiabt amount of web buc::tlina. tbOUlb this

did not lill'ikandy deteriorate the Iiak capKity durina later cyclel. The web ltil'enina res

trained the pclItbuckled piacbina of the bn\ereIiIloope exhibited by the unltiffened IPecimena.

C7diDI oace at each clisplacement level allowed tbiI ll*imen to retain lood C&&*ity to a diI

plKement of 3.5 in. 8MtIrlina occ:urred in all tbree panela. tbouah the bucklina in the center

PIIM1 predominated. Applic:ation of only a IiDIIe cycle at eacb clilpll«r;Jent level and multiple

.-.1 bflCktinl c:ombined to aUow this ll*imeo to dilliptte a tremendous lIDOunt or oDefl)'.

The material teariaa in a corner of the center panel is Ibown in Fla. 4.20.

4.1.1.4 ",.",." 14- In~ 24•• moootonic bIdina biItory was irnpcMed OD •

Wllx40 IICtioa with two full, welded deaen. As depicted in PIa. ...21. tbiltpOCimen exhi

bited a rielcl ......... FiI'It buckli • of the II*imea occumd just beJond • displacement of .1.5

in. The tIIUiIIlum load of 119 kipI ... only llilbtly above &bat of the peab for cyclicllly

a.ded aped..... with ideatbl cletaill. Tb1I peat load occurred just after bv'*Una. at a diI

..........t ...... 3.25 In. TIle 1PId- reIiItaace clropped GIll, IUtbd, • tile dilplacemeat

Iave.tld be10Dd tbiI point. At a~t of 6 in. tile tell ... delayed becaUle of •

- 31 -

constraint in the apparatus, causina a drop in the told due to strea reluation. On removiDI

the mecballical interference in the apparatua, the applied cIiIplacement was continued to 7.2 in.,

readUna the limit of the Ioadina ram. At the maximum displacement the Il*Unen still reIiated

a lOIld of 172 kips. Upon load reveru1, the ll*imen did not resist as Jaqe • force as that in the

positive direction, tbouab the 160 kips peak wu ItiU well above the yield shear. This spec:imen

1110 .... IUbjected an additional 6 in. cycle, which it not shown ira 1711. ".21. Du.rina tbiI cycle

no yield plateau .... oblerved, with the load increuiDa moaotonicalIy to 162 kips. The !old wu

then revened, IIChievina I maximum lIbear of 148 kips, before CODclusioD of the test. The

failed specimen, as shown in FII. 4.22, bad IeYere buckliq ill the two exterior panelJ and

minor buckUna in the center. Also, this ftaure IbowI the extremely Ie¥ere llanae bucIdiDt

which allowed the IPIlcimen to lICbieve the IarIe dilpla:ementl.

".2.3 E.. CeueetIM T....

4.2.1.1 Sp«1." 14- The bolted web. welded ftanae CODIleCtion utili:r.ees in Specimeo 22

bas become a common~on detail in California. This Wllll40 specimen bad two one

IIded ltitI'enen. The h,.teretic reepome of thia type or connection iJldudei bolt slip at IarIe

eJdic loIIdI. The tnt slip in tbiI IPOdmen occurred !oar. Ifter the initial )'ieldinl, durina the

IOCOnd one inch cycle. Tbereafler, bolt Ilipptp root place MIl' the initW Jield IoIId. As Pia.

4.23 shows, the prebuckled I"eIPOftIO of tbia IIPOCimen .. quite similar to tbIt of previoul teItI.

Aller the lpecimen buckled duriDa the IICODd 2 in. cycle the 10M Cll'lYiaa~ty doterioratecl

tipiftc.mtJy. ....skUIII occurred in the panel coalainiaa the bolted COIlIIedion. The bolt bo.

were .vereIy cIiItorted by the slipptIe 01- 1M bolts, a1thou1b the boIli tbelrAhei not

.verelY dem ...... Fllure ".25 cIispl8JI the distorted boIII. Tbc bolt IIiPPIIC tnalferred ....

portion of the IbeIr to the specimen fIanpa. 1'beIe fIaap ...... fon:el Initiated IeIriaI at the

web-ftaap juDctioo MIl' the ftanp weld. The ftDaI failwe of the IIPIdmen I'IIU1ted from •

fIInp Ibear failure... IbowD in PIa. ".24. The mode 01 failure exhibited by tIUI ...._ WI

ideatkal to IboIe cf bolted CODDeCtioDI teIted previoullr 121J.

- 39 -

4.2.3.2 Specimen 23- Another common beam-to-column flange connection is the connec·

tion with a shear tab fillet welded to the beam web. This detail was investigated in Specimen 23.

a W18x40 section with two one-sided stiffeners. The load-displacement curve for this specimen

is shown in Fig. 4.26. Before the initiation of buckling the response of this specimen was very

close to that of Specimen 22. But. the more efficient shear transfe' mechanism allowed Speci

men 23 to regain more load following buckle realignment than Specimen 22. It is interesting to

note that this specimen buckled in the center panel. away from the column-link connection. In

the all-welded case the shear was transferred at the fillet weld. effectively reducing the web end

panel width. In the bolted web case. the shear is transferred at the bolt line. which results in a

larger effective end panel width than that of the fillet welded web connection. In general. buck

ling is preferred in interior panels, since end panel buckling may lead to sudden connection

failures. Specimen 23 failed by web tearing in an interior panel. as Fig. 4.27 shows.

4.2.3 J Speci~n 25- Since connection to the column flange is not always possible, Speci

men 25. a W18x40 section with two one-sided stiffeners. tested the connection of a shear link

to a column web. Initially, this specimen performed quite well, as Fig. 4.28 indicates. The lack

of ability to regain previous loads during postbuckhng behavior can be noted. The shear link

property of energy dissipation throulh inelastic web strains rather than flange yielding appears

to have prevented any problems with the flange connection. The column stiffener plates pro

vided to transfer the flange forces to to the column showed no signs of distress, while the web

plate was slightly bent about 2 in. from the full penetration web weld. The specimen buckled in

all three panels. as Fig. 4.29 shows. This fact made possible the large displacements which this

specimen resisted. While one test cannot be considered conclusive. the nature of the shear link

eneru dissipation mechanism and the results of this test implies that connections to column

webs do not appear to seriously impair shear link behavior.

4.2.J.4 Specimen 18- The bolted web connection of Specimen 28. a W18x40 section.

included three web stiffeners. The added web stift'ening delayed the initiation of buckling and

allowed for increued strain hardening. SliPPllle of the bolts initiated during the one inch

- 40-

cycles. The short flat reaions near one inch displacements in Fia. 4.30 depicts the bolt slippaae.

Bolt slippaae continued to occur until a small tear initiated at the web-Dallle junction near the

full penetration flanae weld. After the bolt slip occurred on the next cycle, the specimen failed

suddenly. It appears that the bolt slip transferred larle shear forces to the Danaes, causina the

1/2 in. thick flanle to shear 011' just outside the heat all'ected lone of the weld. This specimen

showed no web bucklin., and reached cyclic displacements of only 1.5 in. before failure. The

failed specimen is depicted in Fia. 4.31. The small displacement capacity and the abrupt failure

exhibited by the bolted web connection of this sP"'Cimen demonstrated the possible deficiencies

of this detail for links with larae ductility demands.

.41·

200

100

~-0:

0~I&JXen

-100

-200

-4 -2 o 2

DISPLACEMENT (IN)4

Fig. 4.1 Typical Load vs. Displacement Curve for a Well Stiffened Shear Link.

Fig. 4.2 Symmetrical Buckling Mode of Shear Link Webs [131.

-42-

SHEAR

DISPLACEMENT

Fig. 4.3 Typical Half Cycle for a Shear Link During Postbuckled Response.

(0 ) ( b) (c)

Fig. 4.4 Orientation of Web Buckling at Different Stages of Half Cycle.

-43-

200 r--------------.-----------------,

100

~ 0 ~--+l_-_+_-_+_--_t_ ---,f--~_+-__+-~-~--f_---____i

&&.I%fit

-100

-200 L-__---'- ......... ...I...-__~'_____~ __'

-3 -2 -I 0 I 2 3

DISPLACEMENT (IN)

Fig. 4.5 Force-Displacement Hysteretic Loops of Specimen 17.

Fig. 4.6 Photo of Specimen 17, a WISx40 Section with Two 1/2 in. Thick Stiffeners. atthe End of Testing.

·44-

3.02.0-1.0 0 1.0

DISPLACEMENT (IN)

o t-----+-+--f---I---+-I---+--+--+-------,f-+--+-'-----1f-----+-+----i

100

200 r---------~------__,

D:~W:I:en

-100

--

Fig. 4.7 Force-Displacement Hysteretic Loops of a Similar Specimen (Specimen 9 (13))with Two-Sided Stiffeners.

-45-

42oDISPLACEMENT (IN)

-2

100

200 ...------------

-100

-200 '----_---'__.-...__.....0.-__"'--_--'__--'-__.....0.-_----'

-4

Fig. 4.8 Forl:e-Displacement Uysteretk Loops of Specimen 21.

Fig. 4.9 Photo of Specimen 21. a W18x40 Section with Two 1/2 in. Thick Stiffeners. atthe End of Testing.

-46-

-4 -2 o 2DISPLACEMENT (IN)

4

FiB. 4.10 Force-Displacement Hysteretic Loops of Specimen 26.

Fig. 4.11 Photo of Specimen 26, a Wl8x40 S«tion with Three 3/8 in. Thick Stiffeners.at the End of Testing.

r--~--~---.-- ._-

-47-

..._._---------

200

100

~-ll:

0Clw%UJ

-100

-200

-4 -2 o 2DISPLACEMENT (IN)

4

Fig. 4.12 Forre-Displaccment Hysteretir Loops of Specimen 27.

Fig. 4.13 Photo of Specimen 27, a WIS)(40 Section with Four 3/8 in. Thick Stiffeners. atthe End of Testing.

-48-

Fig. 4.14 Photo of the Failed Flange Weld of Specimen 27.

-4':J·

300 ..-------------~------------,

150

~ 0 1----I----+----I---.I-----HI-I-----+-------jJ+-----,f_~f_--+_--_lUJ%en

150

-300 '-----.........---.....-----~---~----~-----'-3 -2 -I 0 2 3

DISPLACEMENT (IN)

Fig. 4.15 Force-Disl'lacement Hysteretic Loops of Specimen 16.

Fig. 4.16 Photo of Specimen 16, an Unstitfened Wl8x60 Section, at the End of Testing.

-50-

4-, 0 I 2

DISPLACEMENT (IN)-2-3

-300 ~----'~---"'---"'--~-----'-------~-~-4

150

-150

300

~ 0 ~----~-+--+---+-----,U--~--M-----+----_~l&J%:en


Fig. 4.18 Photo of Specimen 18, an Unstiffened W18x60 Section, al the End of Testing.

-51-


-2

100

200 .-------------~------------,

-100

-200 1--_---""__--'-__-...-__.1...-_---'__--"-__~_ _'

-4

FiB. 4.19 Force-Displacement Hysteretic Loops of Sp~cimen 20

Fil.4.20 Photo of Specimen 20, a W18x40 Section with Two 112 in. Thick Stiffeners. atthe End of Testing.

·52-

zoo ~--,--------------------_._-----,

~-_.~---~,

. I

100

-~....a: ac~

:J:(/)

-100

-200 _L.I--O~-----'Z~--'3~--'4~--5---6--"""7--"'8

DISPLACEMENT (IN)

Fig. 4.21 Force-Displacement Hyslcretir Loop of Specimen 24.

Fia· 4.22 I'hoto of Specimen 24, a Wlh40 Section witli Two 112 in. Thick Stilfeners. atthe End of Testing.

-53-

200 r---------.------r-------------,


-2

-200 <-- ---'-__--.4-__...L-__""'""-__-4--__'--_---'

-4

100

.....~

0::0C

IAJXf/)

-100


Fi•. 4.24 Photo of Specimen 22, a W18x40 Section with Two 1/2 in. Thick Stiffeners. atthe End of Testing.

.54·

Fig. 4.25 Photo of Distorted Bolt Holes of Specimen 22.

-55-

200 r-------------r--------------,


-2

100

-100

-200 L-_---L__...........__""""-__L--_----" ~_ ____I

-4


Fig. 4.27 Photo of Specimen 23. a W18x40 Section with Two 112 in. Thick Stiffeners. atthe End of Testing.

-56-

200 .-------------.------------

2oDISPLACEMENT (IN)

-2

100

-100

-200 L--_--'-__~__""""____.L..-_ ____l____'___.........._ __'

-4

Fig. 4.28 Force-Displacf:ment Hysteretic Loops of Specimen 25.

Fig. 4.29 Photo of Specimen 25, a WI8x40 Section with Two 1/2 in. Thick Stiffeners. atthe End of Testing.

200

100

x-Q: aC[ILl%en

-100

-200

·57-

-4 -2 a 2

DISPLACEMENT (·IN)

4

Fig. 4.30 Force-Displacement Hysteretic loops of Specimen 28.

Fig. 4.31 Photo of Specimen 28. a W18x40 Section with Three 3/8 in. Thick Stiffeners,at the End of Testing.

- 51-

CHAPTER 5 • ANALYSIS or EXPERIMENTAL RaUL1'8

CMpter 4 dealt with the results of the twelve teItI in a qua!itative lDaIUler. Thae reaulll

enabled the development of IOIDC buic coDdUliofti reprdiq the behavior of shear IinkJ. The

data coUec:ted by the instrumentation provided qumtitative information reprdina IIJlIlcitk:

aspects of the tests. In this chapter. this leal data are UIed to anaIV.e the four ltllea of shear

link response: elastic, inelastic: pre-buck1ina. post-buctlina. aDd failure. The nellt cbapter wiU

concentrate on eneqy diaipetion clwlcteriltic:l u a meaure of link performance. Evaluation

of tbe qualitative oblervationa and tbe quutitative anaIYICI provides the basil for conclusions

aDd recommendations for shear link deIiJn.

5.1!...& ......

The elatic: reIpoDIC of • beam II UIuaIIy anaIV.ed UIina the Bernoulli-Euler-Navier

bypath_ that initially IlOrIU1 aDd pIaIIe IflCtioDI remain DOI'IDa1 and pIaDe after deformation.

AI the lenath of the beam deerelnl. Ibearlna def'onnationI become .'hnt and the buic

theory becomeI _ accurate. In TimoIbeako beam theory. IbeariDI deformatiOlll arc

.ccountecl for by _"mi... that a coutant avenp ... ItreII ada on an "oc:tive shear area,

A '. For wide Danae lIeCtions. the ..... ... II pftwally taken u the area of the web,

OIl the above .... the elutic~tI~ Ibeu Iinb due to ...., can be taken u:

(5.1)

In tbiI equatioD. /I introducel the cootributioD 0( DuiaI del'ormaIioaI to link dilpllcementl.

Tbe term /I IIIPPI'ODmateIy:

(5.2)

• 59 •

For the analytical model of these experiments correspondina to Fig. 5.1, the displacement due

(5.3)

Assuming a value of E/G-2.50, the values of 13 for the W18x60 and WI8x40 sections

used in this investigation are l.SI and 1.26, respectivel~. For these 13 values, the theoretical

contributions of shear deformation as a fraction of the total, 213/1 +213, are 0.75 and 0.72,

respectively.

Web shear deformations integrated over the specimt.'\ length determine the specimen dis-

placement due to shear. Using the simple model depicted in Fig. 5.1, the shear displacement

contribution during the linear cycles of each experiment are listed in Table 5.1. As this table

shows, the shear contribution to the total deRection is on the order of 0.50 when the model

shown in Fig. 5.1 is employed.

The actual end fixity of the specimens was not complete. Throughout the tests, the "fixed"

end at the riaid concrete reaction block side slipped and rotated Slilhtly. A refined model of the

prevailing conditions at the fixed end is shown in FiB. 5.2. This diaaram shows that a lateral

displacement suppon stiffness, K 6, and a rotational suppon stiffness, K 8t can be introduced to

obtain a more accurate formulation. From the test data shown in Figs. 5.3 and 5.4, the values

of K & and K., are estimated to be 4400 k/in. and 8,200,000 k/rad, respectively. Therefore, the

true stiffness of the system, K', can be defined as:

1 IlL---+-+K' K K& K.,

In this equation, the member stiffness, K, is liven by:

and the link displacement, v, for the refined link model becomes:

(5.4)

(5.5)

- 60-

(S.6)

From the values determined for tbeIe 1eItI. it wu calcu1ated tbat the support diIplIce-

menta contributed IPProJtimately 23 per cent or the toIa1 dilplacement iD the linear elutie

raqe. Usioa the more reftned model depicted in Pia. 5.2, the Ihw cHspl8cement contribution

.... .,.m cU;ulated. TbeIe values, Jisted in the rilbt column or Table 5.1, are quite cJoee to

tile 72 per cent contribution expected (rom TiftlOlhento beam theory. Therefore. it seems lIIal

the elutic stift'JleSI or Ihw IiJtkI iD eccentrically bnced (rames c:aa be anaJp.ed quite lCCurstely

usilll Timosbenko beam theory.

5.2 I.....tk Pn allCkU.....,....

DurinI an extreme leismic event, a properly cIeIipecI eClCOntrically braced frame wiU

caute the shear links to undel'lO extenlive inelastic deformations. The inelutic pre-bucklioa

Itqe is imPOl'Wlt to consider for two reIIOIII. First, molt or the eDeIJY cliIIipetiOD cx:curs duro

ina this response pbue. The amount or eDelJ1 dillipaled aner web bucldiq is usuali)' quite

small for linb with IUJBcient web atiJl'enJq. Second, the iDeIutic behavior o( the link prior to

web bucklinl is important. u this is taitly _meet in pIutic anaJ)'sis medlodI. AI'let. the

occurrence of web bIaIina. the bebavior of the link iI uareJiabIe and dUlcuJt to model analyti

cally.

5.2.1 I D1 t e..trIIIdrIu- The prilDll')' )'ieldiJII mecbanilm exhibited

by a link fOrllll the buis for the diItinction between shear and bendina 1iJW. Sbeir Iinb yield

primarily by inellltic .-rma IIreIIeI in the web. In beDdiDI linkI, normal Itreaea in the

ftanaea dominate the inelutic bebavior. Durina IDeIutic 1'flIIlC)DIe, therefore, sbearina displace

_II predominate in ..... Iinb, and beDdinI diJpilcemenll predominate in bendina 1iDb.

in tbU in"eItiption CUl be PPf.a.d a:

·61 •

(5.1)

In this equation, ",,(x) Is the dUplIcement due to Iheu Itrains,

(5.8)

The displ8cement due to flexural strains, "bl , Is

(5.9)

The displacement due to support movements in Eqn. 5.7 Is ".(x) .

The ,,_ term in Eqn 5.7 wu evaluated numerical1y lIIina the data collected from the web

strain PlOt. Table S.2, liItI the ave,. contribution or Ibear to displacement in the iDelutic:

ranae prior to bucklina. After buc:klina oc:aarrecl, the .. readinp did Ilot acc:urately detennille

Ibear displacement. Since the webe of Spec:imens 16 and 18 buctled durina the initial c:ycle, the

results from tbeIe tests are not included in the table. TbIs table clearly abows that the shear dis

placements contributed the ,.;or compooont to the liDk deflection in the ineJutic: ranae.

5.1.1.1 Support CoItIri6lltkHu I" 1M llWltutk R"",r· In the eIutic ranae, the suppon

stilf'nea contributed up to 23 percellt of the total specimen displacement. The support

stiJf~ were nearly linearly elutic: u Pial. S.3 IDd 5.4 cIemonJtrate. The support displace

ment contribution therefore bec:ame DCIUIible durina tbc laqe IneIutic: displacement cydea.

POllure 5.5 Is I plot c:omparina the rec:orded specimen dilplacel1lOllt with the actual dilpl8cemcnt

acUUIted for support conditions. AI this ftaure 1bowI, exc:ept for the linear c:yc:1eI It the start of

the test, the differeoce between acUUIted and recorded dilpllcemellts wu inclilcernible.

ne above result applied to all spec:imens except Spec:imen 16. 'ibis heavier -=tion

c:autee1 IP8Uiaa of the concrete I'IICtion bIoc:k dUl'illa thia tell POllure S.6 IbowI the eft'ect orthis IPaIlinI on the acUUIted displacement. Althoulb this elI'ect ... recopi.•.abIe, it did not

sipiftcwndy dect tbc J1lIPOIIIC or the 11*1..... TbiI problem WII endic:ated. IDd further

- 62·

spallina of the reaction block did not oc:c:ur in any of the lubla(uent IeIlI.

5.2.2 Llak~...... ,..... S......... AJthouab abear deformatiol1l dominate tbe

relIPOlIlIe of Ibear !inks. flexural actions alIo play an important role. AI Fia. 5.1 abows. for tbe

link model UIed beret the relationship between end momeDt aDd lIbear was AI VL/2. Due

to larae amounll of ItraiD bardenina, the apecimel1l usuaUy reaiated momenll above the nomi·

nal plutic moment, AI,. Table 5.3 liatl the values of AI, baed on the plutic modulus values,

Z. for the W18x60 and W18x40 leCtiona ( 123 ill. 3 and 71.4 in. 3 respectively), and the actual (

fTY - 48 laO and nominal VIllues ( fT, - 36 bi ) of yield streaes. Table 5.4 !iSlI the values of

meuurecl maximum end momenll reIiIted by the apecimcna. AI can be ICeD from this table, in

all c:ueI the linD resisted bendinl momenll in excell of the nominal values of AI,. For weD

ltift"eDed webe, these DlOIDeDlI even exceeded the values of AI, bued on fTy - 48 bi. It

Ibould be noted, however, that the pIutic: moment must be reduced aince the webe fully yield

(13). The correIpoaetinl values of AI~ - fTy.,(d-',) for fTy - 48 bJ are alIo liven in Table

5.3. Since the end momenllliven ill Table 5.4 are above AI;' lOme strain bardeniIlI must have

occurred in the ftanaes u weD u the webe. ADalYlii of the lIanIe strain data verified this con

dlllion. The maximum ftanae IItIiDI at CIdl PIe location for Specimen 16 (See Fia. 2.4 for

lIP 1ol:ationa) are Uated in Table 5.5. These valUCl Ibow that Iaqe iIlelutic ItrIina developed

.... the endI of the links. (The yield strain was approximately 1700 111./;11.) The fIaDp strain

diatributionl were quite Iimilar to thole found in III eartier inveatiptiOD (13), .bowiq III

almoIt IiDear variation of Oanp IlOI'IIII1 ItfIiIl from the maximum value at the endl of the

apecimeu.

5.3C...... ., ..................

The deve10pmeDt of web ,""Clrlilll matCl Iaqe local ItrIinI .. reedinp erratic. Qua1ita

tive apectI of poll-buckled bebavior are DOMtbe1eII 1ip1ftcant. The cbarIcteriItk:I of PQIt

bucIded bebaYior depend dinedy OIl the link ..... detaiJI. Proper detaiUnI' of the link cu

therefore enaure the deIired poIt-buddinI behavior. In this aectioIl tbtee upectI of web

- 63 -

bucklinl that can be controUed throup proper deIip will be dita1aed: 1.) deWyi. 1JuckJJ.. 1.)

co"I1OHi. tM locatio" 0/buclclill6. aNi J.J dewlopi. "",blpltt pa.' buckli",.

5.3.1 DelaJl...1Iddlq. The ftrst and forell108t objective of ItifFeniq the link web is to

delay the ouet of bucklina, since the eMIlY diaipative capecity of Ibear links is patly

reduced by buctlina. The II*ina of stift'eners is the macial consideration in delayina bucklinl.

Earlier research (12) praented a let or relationshipa between the stifl'ener ..,.ana and the

enellY dissipation capacity before the initiation of bucklina. Theile relationship' demonstrate

tbe sipiftcant inc:reue in enellY diIIipation caplCity which can be reaii,.ed by emploYma dOlely

II*Cd stifFenen. As Specimen 27 demonstrated, tbouab, reducina stifFener II*ina below ur

lain limits tends to lad to abrupt failures, causina the specimen to 'Ole its ability to withstand

larae deformations. 8ued on the completed work, the minimum sPlQna for stifFenen providina

elullent eneraY dissipation caplcily appears to be about 2Ot•.

5.3.2 c.trew.a ............., ....... The lIlO8t desirable location for the develop

ment 01 • web buckle is an interior panel of the Ibear link. Bucklinl in the web panel adJaeent

to the column should be avoided since it can lead to premature link-c:olumn connection failure.

Protection of the connedion panel ,.one is acc.:omplisbecl by proper location or the ltift'enen. In

the web connection detail shown in Pia. S.7, the shear is transferred to the shear tab Ilona the

Met weld. Por this calle the still'enen can be spICed (rom the ereetion boll line, U shown in

this ftaure. Sinee the panel width is reduced by the shelr tab, web bucklina is likely to occur in

an interior penel.

Slippqe may occur Ilona the boll line of bolted web lIleat lint-to-c:olumn connectionI

due to larp shear forces. To protect the panel '.oDe ICUlcent to the column in tbiJ calle, it is

advisable to II*C the stifFeners from the column flCe rather lbaD the bolt line, U Pia. S.'

shows. The .... approech can be adopted for the link-eolumn CODDeCtioD with fuD peDetnlion

web welds.

5.3.3 M In pneral, the bucklina pbeoomenon

depends on plate topolOl)' (paneI1i."", initial imperfections. etc.), IIIaIeriaI propertiet. ud the

- 64-

boundary conditions. TypK:aUy, b\alina occun iD ODIy one pe~l of shear tina. Once one

peDel belins to buckle, the displacement capeclty etemended of the other pueIa is redlKlOd. But,

lipifkant bucklina occurred in multiple poels of equal Ii~.e in four of the twelve apec:imens

detailecl in this investiptioo. Therefore, to induce multiple puel bucklina the denen should

be equally .PICed center-to-eenter.

5•• r....... M.... ., SIIear Llw

Typically, the ftnaI r8iJure of the IPOCimens wu caused by material tear1na due to severe

reversals of web plate curvature. In unstiJrened wet. this occurred near the center or the buck

led reaion, wl1ile in stift'ened webe, this teuina took pIKe U'OUIld the perimeter of the buckled

penel ~.one. These types of failure did not produce catutrophic results. Si,nifbnt buckiiDI pre

ceded the final material tearina, and the teuinI took piece P'ldually; larp loads could still be

resi.ted throuahout the tearinI process.

Reduced stiffener .pecina delays bucldinl aod permits larp iDa'CUel in 10ld resistance

due to strain hardenina. The increued Ibear force required .....r momeDt resistallce of the test

specimens. Specimen 27 demOllllrated that without exceUent weld iIltelrity, • IUddeD weld

failure can take piece in an exCflllivel)' stifFened 1POCimen. To avoid this type or failure, the

stiffener IPIcina should not be lea thin 20,•.

Table 5.1

Table 5.2

-65·

Specimen ~6.. ~6.....(felt rauJlI) &cl. end roll.)

17 49 7221 45 6822 52 1523 51 1425 SO 1326 52 1521 48 1121 49 72

Experimental Contribution of Shear Displacement During Linear Cycles.

Spet'meo ~A .....

17 1921 1222 IS23 952S 1326 9227 972. 93

Experimental Contribution of Shear Displacemenf During Inelastic Cycles.

Table 5.3

-66-

M, M, M,Section ( II-la. ) ( II-la. ) ( II-ill )

(" y - 36k.tJ) (tT y - 41k.fI) CtT, - 48 k.r/)

Wllx40 2120 3760 2630Wllx60 4430 5900 4420

Plascic Moment Capacities of the Sections Used in This Investigation.

Specimen Free End Fixed EndM--. M. M,.. M_(k·la) (k·la) (Il-ln) (k-iII)

16 4120 4520 S040 496017 3030 3320 3520 3290II 4270 4390 ~ 47SO20 3220 3220 3~ 355021 3300 3240 ~ 3SSO20 3520 2510 ~ 343023 3210 3300 3430 344024 3450 ~ 3120 319025 3060 3390 3300 341026 3530 35SO 3900 402027 3940 3960 3940 414021 3620 3510 3210 3520

Table S.4 Maximum End Moments Resisted by the Specimens.

Table 5.5

-67.

Specimen 16

Gaae No. Maximum Strain( a/IlL )

1 261002 203003 146004 27900S 132006 117007 26100

• 179009 13200

10 2230011 640012 6900

Maximum Strains for Each Aange Gage of Specimen 16.

-68-

.....'""~ T.......~~~ V

~....... I-_...... ".:::::-- -!............... -9

............" I

" I"" I"'~~:dFig. 5.1 Simple Analytical Model of the Experiments.

Fig. 5.2 Refined Analytical Model of the Experiments.

-69-

0.25 ,------------~----------__,

200100-100 oSHEAR (K)

Plot of Fixed End Slip vs. Shear Used to Determine the Lateral Support Displacement Stiffness, K:.,.

-0.25 ~_---'____....__~__~__.....___...._ __J

-200

005-zCl.:::;en0 0Z&lJ

0&lJ~u.

-0.05

Fig. 5.3

0.002 ,------------,-------------,

200100oSHEAR (K)

100-0.002 L..-_.........__........__.......__.l.....-_---I.__~__........._ ___J

200

-0 0.001C'Q.-~~

i 0

0ZI&J0I&J -0.001)(

~

Fig. S.4 Plot of Fixed End Rotation V5. Shear Used to Delermine the Rotational Support Stiffness. K...

2

-70-

15

17

2123

z

IZW

~OI'--+--+--+-+++++-+-f--4~--;-f--+-+-+-+-+-+-+-+------i(,)<I-Jn.6 -I

16

Fig. 5.5

-2

-3

18

20

22

Plot Comparing the Recorded (Solid Line) and Adjusted (Dotted Line) Displacements of Specimen 20.

4r--------------------------..

-4

3

23

22 24

25

I

Fig. 5.6 Plot Comparing the Recorded (Solid Line) and Adjusted (Dotted Line) Displacements of Specimen 16.

Fig. 5.7

FiC. S.8

-71-

....__.....~_E_Q._..._E~

Suggested Stiffener Spacing for Shear Links with the Web Fillet Welded to aShear Tab.

~..EQ. EQ. EQ.

~I·II •I

,.I •I.

~.....

"

Sugested Stiffener Spacina for Shear Links with the Web Bolted to a ShearTab.

- 72 -

CHAPTER' • EVALUATION Of LINK PERfORMANCE

Prom a strueturailtaDdpoint, sbear linb can be -Ined to ablorb a tremendous amount

of eDeIV and exhibit a ductile failure. But, lIince DIlDy lim are required for typiQI applica

tions, the cost of sucb • link becomes important. It it _ntial, therefore, to RlCb a balance

between the ltrUetural I'CIPODIe cbancteriltica and cost. Only tbroUlb sucb a procell c::an

rational desip recommendations be DUlde.

'.1 It..., DIal...... u. M.... ., Stnet...........

The concept of eccentrica1ly brIced frames for .iImic applications IUOqly depeDda on

the ability of the active IiftkI to dillipaae Iarp amounts of eMIlY duriq iDelutic J'CIPOIUC.

Eneru diJaipation c:aplcity therefore becomes the primary buiI for qUUltitative link com·

pWon.

The kMld VI. dilpllcement CUIWI preIeIlted in CbIpter 4 depicted the reIPODIC clwIc:.

teriatlm of the taMed ..-:imeu. The f'unctiona11y important eDellY diaipatod by the active link

it the area encIoaed by the bJ*retk: too.,. 01 thole curvea. Pormally, the eneav dillipatecl,

ED. CID be uPI'8IIIC1 u:

E -Jp(I)dl (6.n

In dUI equatioD. • it the nladve II*imeD eDlI dilpl8cemeat. and P(I) it the..force in the

IPIldmen.

To mate lMIIIi"ut CODduIioaI J'eIIfC1inIeDeI'IJ dillipatioD. it waI DeCeIIuy to make

~ wbk:b ICCOUDted 'or dil'ereIlt IIIIIeI'iII PI'OI*ties IDd member Ii1.ea. TbiI waI done

.., nonaaIi." the ....., clilllpeted '" the link with the eoerv wbic:b would have been diIIi·

pated '" 1ft w.J eIIIto-perfectJ, pIMdc liDt with the IUDe JieId loIld and """meDt _ the

·73 -

llCtuai specimen. Por the tpedmem with differeDt kwldiDa propama, the DOI'lMli.,.ed eDeI'I1, ~,

it plotted qaiDIt cumulative ductility, U. in Pia. 6.1. Por the eilbt spec:imeDi whic:b were

subjected to the 1liiie IoIdinIleCluence, the normali:r.ed eneqy it plotted qaiut ductility, p., in

F.... 6.2 and 6.3. 1'beIe 1lOI'IIIIIi:r.ed eneqy dillipetion valuea are deftnecl u:

~ _ 1'_11)' diu/tM1td by IQt -/,.,.

'Mtr db6ipaw by equ/Wllelll ~1tuto-pltmiC ."",,,,

11' - IlUMttlUoII p/ p.', for liB CJIC~'

(6.1)

(6.2)

(6.3)

Table 6.1 it Il1o preIeIlted to provide comperiIoo of tbeIe eiabt Iimilar specimeDi. The

enet'IY dillipetion meuurea in tbiI table are: E.,. the total eneqy dillipeted before the '.Iure

C)'C1e, Ei, the total eneqy dillipated before the ftrst buc:tliDa cycle, E.,-Ei, the total eDlqy

dillipatecl after bnckIl'll, and A_ the muimum value of normali.,.ed eneqy dillipetiOD

obtained by eICb 1I*imeD. This table aIIo incIudeI the maximum diJpllcemeDt ductility, 14_

IDd the cumulative ductility, J:p..

1. For tItt 0'JIr qf 1oIIIIi• ... ill tItat ..,,__ ",.",.,., .,.,., ",., lim CGII tlJIIIpIIte"",.11-0/~.,., ,..""." 0/ tItt 1otMIi. 1tIIIot'y.

,."",.", .. 0/ ctIIIIICl(y. SiDce the hcoima Dam Record fA the 1971 SaD PemaDdo

l!artbquaa Ibowed that loaI pUea eM. occur durinl a .... eartbqUlb, tile ..... liDb

lDlJ be required to witbltlDd ... IIlODOIOIlic dilpllcemeDq. Tbe ..mil mSpecimen 24

indicaIe \bat tbe Iinb caD _t IUCb • Iaqe ductUllJ cIemgd,

- 74 •

4. From II Jlnlctlnl ",,"'1tI, /If'OIJI'rly t*sipNI OM-1JdH Itt/lnwn tw ~.", 10 two-lJdH

ItIJ1eMrl. Both lite pn.budcIft/ 11l1li posI-bfICIcW raptHUft wen WrtrMIUy /de1ll1cG1 for tIw o~·

skIN 11l1li two-sided rp«llrWrtS w/tll otlw,.,,. iM",IcIIIt*",//s. [" ,illter co.. lite ItfIPMn IfIIIIt

I» prollidhl with ~C;'III tDdIIIltn".m a1lll1»1IdI". ,.idity to jWIy e",1op lite littk '1tBD dis·

$/ptltioll CfI/Jflcity. A method for .i~DI Ibear link web stiJfeaers it liven in Chapter 7.

S. St~II"S 1101 wldH to both .", /III"Ift • 1tDt c•• " littk's '1fInD dissipation /»fin

buckli.. IIlthotclr lite postbuclcW CtIfItIcity Is~ "" owrall ductility CtIPIJcity is "01

.,.tly~ by lUi. swlt II .iL 77w J108I-buckW ,.,.y dJu/pGtiOll CtIPtIclty Is jlutlwr

mIrJud If lite It~.rs air ItDt COlllt«I«J to ,,,.,JI"•.

6. AII·wlt*d Ilttk-colll"", COlllt«tlolU altiblt m:eu,1Il per/Omttl,,". Propn'fy t*JIptd "NI fabrl

Cd_ dll-Wlt*d ,NI COlUl«tIoIu t*wlop tIw }l.U "'IJIICity 0/Jlwr /l1I1cI.

7. BoW wb. wlMd.llll. coIIMCliOu IIIlI)' I» .tlf/tM:lOry I" temu 0/etttrD diu/ptltion coptl

cll)l for IOIIW dpfJl/allioIII. "" pn-buckW /1l1li mode,." ~.1Il tq10IIM 0/ lite bollH

wb COIUWlIo" Is co"".",» III .,of lite flIJ·wlded COIIIIICIkJ". Howw" /IIJ#y It~Md wbs

""'Y I» fWl"lMI to __lop "". IIwdr jbrca wIrIcIt. allf t:tIfM bolt slip. 7'Iri8 bolt MIp trrI~,

d poniolf of lite "",IietI slwG, 10 dw./lll"," wIrJcIt '.IIIY~ '-'''' pmrttIttft /Gillin 0/.

IIttk-co"""" COIUt«IioIf.

8. ~ clolt Itl/lt., .-1". aI" IIdd 10 "",. ./II11ura bdw • IlfhIdtltJII D/ wb bfM:Jc

II".. ~ IIIftDIIIItS 0/ IMItutk .,.,.,.", CWIIGtS ItI'tIIII ""'"1. wllielt alII ownl1aS

witts 1I1III1ftuI1O MIdI" wid./II11IIm.

9. Butd 011 O. ,."."" it",..""., dw COIfII«tiOll of /I littk 10 lite colluM w6 lion IfOI

JiptficollttY "Ier ".~1fttIeof tIw Iillk. 0.. III ". tWIIItW Itf/fttaI 0/ tJu. COIf/WwtItioII,

dw flMrD "'110" ctI/I«ity /$ ",.~ mlIIcN __ • iotMIJ."."". 77w ....tiN

fXIIIIIC/Iy Irdllca ,.,.. ,.,.. .,''' ,.,.1Mt:IcW fq1t)IW. Ho.... * _I",.~

_ dw dtIctiIJty in ItDt .db_ lower .11 COIIIVtCtIoIu qf1/. III coIIuu./III",.

It mwt be empbui_ that all cl the IiDkI tested were au.:hed to ~tiaIl1 riIid .Ie·

IIIIIDIlta at both ... CautioD mUll tbenf'ore be .urdIed ill extnpoIatiaa the CODdUlioDl tilted

·75 .

above to situations where column panel 7.ones eJ.hibit flexibility or inelutic action.

'.2 0.11...........tIN.

Bued on the c:onclusiolUl listed in the previous leCtion, and appropriate consideration of

cost fllCtorS, the followiftl desip recommendations for shear links in oc<:cntriwly brlaKl

frames can be prelented:

1. OIlINid«J &td!erwr, Ctlll ,. ~mpIoyH to delay ~b buckling in ,_r lillla of modertlte dept'"

&UCh 11& tho. IUH ill tlte. rJlIIrrlllWllu. Since the structural performance of one-sided and

two-sided stiffeners were found to be almost identical, cost considerations suaest the usc

of one-sided stift'enen, althouab u shown in Chapter 7. one-sided deners require more

material than the two-sided onel.

2. TM ",/IIi"",,,, ••r IPtIci,. ill &Mar lillia mould ,. 201•. Spaci". .~." "1$ tIta" 20t.

CtI" precipitate ...,." 'O"lI«Iio" faibln&.

3. W~b ~.n may I» welded 10 Ollly OMfta. oJ lite link. For the lpecimens telted, one

Iided stift'eners welded to only one fJaop performed quite adequately. althouab they ue

slilhtly lea eft'ective than the fully welded detail. To provide stability apinst fJaop buck

lina. the stiffeners should be welded to the bottom Danae. The top ftanae i. lOIDetWhar res

trained from buc:kliftl by the floor I)'stem, thoUlb this resistanc:e may be diminished by

cracltiftl of a concrete !Jab duriftl1arJe dilp1llcement cycles.

4. ..4" t111-wltkd IittJc-eollmr" COIIMCtioIf Ihofdd ,. .-dP lillla with 1tIf6r ductility ....".

The all-weldecl connec:tion appears to be more reliable, since the bolted web connection

bu • I"lIter propensity for sudden failures duriDI laqe dilplKement c:yc:1ea. AU-welded

liJlk-eolumn connec:tiona are therefore preferable for liJlkl whicb ue likely to experience

laqe inelutic deformatlolb.

5. For lillla with »w or ".".",,, tluctility ....... boW wb. wlt*tl/III,. COlllttCtiolU IIIlO' I»

""".,.. Bolted web c:onnec:tions appeII' to exhibit IltilfKtorJ per(0I1DIDCe UJlIeaa 1arJe

iDeIutic del'ormatioaa ue 1JDpoM.

- 76 -

6. S., Ulfla 11IIO' .,~ to ". eoIwM ... ""'/6 ct1IIMdloll rItouItJ ., .",IW tICCOI'dl".

10 tJte ~"'tIo", jbr typktJl ".".11I raisII". ftafltft. The larIe shear to moment ratio

preeent in the linb does not caute the IuJe moments wbic:b can reault in fIanp weld

failures. The problem studied by the iDveIlipton at Lebiab University (6) may therefore

be more critical for I)'pica1 IDOment-reIiItiDa COIlIleCtiou tban it it for shear linb. AIl

welded linlt-oolumn web COIUlectiODI lie recommenclecl for liDb with Iaqe ductility

demand.

-77·

Specimen Number E70T Er. Eror-Er. ~111111 11-.- ~II-iII-Ia.> <II-ill'> <II·in,)

17 6870 2910 3960 0.993 46.1 52521 U90 4010 4580 0.991 58.5 75122 7040 4ISO 2890 0.977 51.0 57623 7070 4100 2465 0.991 46.1 52'25 7890 2980 4920 0.934 58.5 69326 10800 7300 3500 1. liS 66.0 70027 7520 7520 0 1.140 46.1 52528 2SSO 1550 0 .910 31.9 237

Table 6.1 Energy Dissipation of the Test Specimens.

-78-

1.2

1.1

\

\\

\ 24

1.020

-....-.....0.9 ....,

'-

'----16

0.8 ----....'------18

0 0 Ill-200 400 600

FiB. 6.1 Plot of Normalized EnerBY Dissipation. ~. \IS. Cumulative Ductility. 4£. forSpecimens With Different Loadinl Conditions.

.19-

1.0t----

27---------26

#'"~

""."".

/"".

/

0.7

0.8

0.9

~---L.---'----.JL..---....---------~JI.o w ~ ro

Fig. 6.2 Plot of Normalized Enel1JY Dissipation, A, vs. Ductility. p.. for Specimens WithDifferent Stiffener Details and/or Spacinl.

1.0t----

o 20 40 60

Fil.6.3 Plot or Normali1.ed Enerv Dissipation. A. VI. Ductility. "., for Specimens WithDifferent Connection Details.

-10-

CHAPTlt 7 - WEB STlfRNEU IN SHEAR LINKS

The bene8t1 derived from ltil'enina the .... of.. IiDb lllve bleD delllODltJ'atecl by

experimefttal relUlti (,;~ twefttJ-eilbt ..,ecimeas. Delayed buck1htl aDd hxnued -ru diaipe

don capllCity directly reIU1t from ..b deaiDl. The extent to wbidl tbeIe bene8t1 are reaIi,.ed

dope" Oft the inteIritJ of the deoen.

In all previous reteIIdl and earl, IPPlk:atioaI of tbe eccentrically brIcecS I)'ICem. ltitrener

deaip hal been accompIjIbed without beneftt or • rational method. Even thou'" tbeIe previ·

OUIIy doN,ned ltitfenen have performed quite ldequately•• more ratioDal practicalltifl'enef

deIip method is .-r)' to euure proper perfOl'lDlDCe of futun appIadona.

1.11...............

In the testa preIeIlted 1ft tbiI report the ••oen .-e 1i.7.od Ulina the ruuItI of previous

IftYeltiptioal • • pdde. 1ft 1ft .on to ualp.e their requiremefttl in Ibeu linU, ltitl'ener

IU'aioI were IDOIlltored durinI the ..... Prom tbeIe .....tI uiaI ItrainI were plotted I8d com

pared. A repl'ellDtative plot II pr-.nted in Pia- 1.1.

CompIriIoD II the ltifl'ener Itnin pIota for tbe dUl'ereat .... rauIted in the foUowial

coadUlioDl:

1. 77w .,..,. .." lIlWIM/{)I _aMI 'lor 10 "..,~.

2. ~ 11wkJJ"" ••...,. aIIIl IINhI hi "..-... .. 'ittbI ".",qt.,._...M

IIifIinwr "",,11 TIlt .... IIXItII~ ...... """ below~ iIwI". dtJI ,." qf

1otMJi",.

3. Ora budcII",~ • ".,." ...,.WM.. 10 tift COIItIJIMIioIf qftIJdII/ II."."..--.

- II -

AlIo. it Ibould be noted that the ..... Ilift'ener strains tx:eurred iri Specimen 20. wbicb

exhibited excellent poIt-bucklina behavior. It INma then that lOme Jieldina 0( the Idenen

does not aerioully detrICt from the poet-bucklina behavior of the lintl.

7.2 Tile Del'" .,S.., Lin~...

The delay and control of web bucklillllDd the relultina increued ..., link enel'lY diui

pation c.pKit)' can be ecbieved by the addition of web ltift'enen. The deaip of tbeae denen

can be separated into three 1tapI: 1PICiIII. Ii~DI. IDd detailiq.

7.2.1~ ., W.. St.....• The relatiODlbip between oneru dilliJ-tion capecit)' IDd

web stifl'ener IPICiIII wu ItUdiecl by Hjelmstad IDd Popov U21. Bued on ftf'Ieen tell JPeci

MeDl, the)' propOIOd the follcnriDi empirical relationlbipl:

tl Ei--90-910-'. E.

tl EO--94-1410-'. E.

(7.n

(7.2)

Tbe ..,.11eal .... dilDlDlioD. fl. and the web tIIic:t.-.. ' .. are the topoIap:aj ............ in

tbeIe equatioal. The ~I'IJ di.....tioD parameten are Ei, t"e tota1 enerv dillipatecl prior to

budd_, E., the eIIItic eaeru IltOred bJ the link It JieId. and EO, the...., abIorbed duriIII

the ..... prebuctliDl cycle of In eQel'imelll

Eq. 7.2 it iDteaded to Mdmate the required d for IDODOtoaic ..... bit-

torieI. The -.db 01 the IDODOtODic tell (Speclmea 24) tecI ia tbiI report provide IOIDO

corroboration for tbiI relatioDlhip. SiDce the tell Il*iIDllll UIed to aeaerate Eq. 7.2 were

IoIded qdicaIIJ with incremental1J iDcreuiDI dilpllcemeDta. the IDOIIOtOGic bur)1iDl eaeru,

EO, .. probIbIJ overeIli-ted It II IlbIJ, therefore, that Sq. 7.2 it c:oa.-vatiWl, and illUboo

jIct to futun rniIioa.

- 12-

Without the raultl ol • _riel of iDelutic dJQIIDic: ....,.., the Ibear link eDeI'lJ dillipe

tioo requirementl must be approximated by OItimatiDa the ductility demancl. With the ductility,

"', deflDed in Sq. 6.2, and "'/, deflDed .. the ductility dftnencIed in the i- th cYcle of • IoIldiDI

history, the followinl relatiODlbipl result for an e1uto-perfectl, plutic material underloinl

predomiDately Ibear deformatioas (12):

(7.3)

(7.4)

The illt. ntio c:boen mould be the amaUer of'the valUfl1 liven by EqJ. 7.1 and 7.2. It

the reaultinl tilt.. ratio II .. than 20, the eneru dillipatioll demandI Oil the Ibeu IinkI may

be unattainable (12), therebJ requirina reYiIion or the beullection. StUl'oner SI*iDI bued on

tbeIe equatioaa IbouId delay web buc:Idina and therelore allow the Iinb to meet their ellel'lJ

7.2.2 .... SIIeIr Llak W" lei...Once the ltiJl'ener II*iIII bu been determined,

......t uialltrqth to develop the IiDk web teDliollIeld IICIion. Second. the d .... must

be riIid enouIb to prevent buctliDa of' the whole IiDk web ... IinIle panel.

The AISC Spedflcatioas UJ provide dIIip equationa for web ltifl'eaen in plate IiJden.

Wbile Ibear Iiak web d .... mUll 1ItiIf, requiremeotl reau1ti111 from IimiIar CODIideratioaI

ol"" tbIIe equatioaa CIDDOt be \lied here IiDce they are baed on eIIItic lOIutioal. The

iDellItic Dature of .... Oak web buddiDl mabI In eUd lOIulion for the Ii1.iaI ol the

..... extmMIJ c:ompiex IDd iDqncticII for cIeIiID appIicalioaI. AD approximate method

mUll tberefore be deviled for &be ... or .... link web 1tiJI'....

1.2.2.1 bIIIl FtJtr:a /It W. Sti/IIItA ... The AISC dIIipa equatioal for &be required uiaI

IInaItb of ........... are .... OIl tbe wort ol ..... [31. T:.Me equatioaI were derived

·83·

from teosion field theory, U depic:ted in Pia. 7.2. Tension fteld lCtion is uWotoUi to. Pratt

Trusa in which principal tensile stre_1et u the dlqonal member, the beam flaqa act u the

upper and lower chords, and the stiffeners act u the vertical struts. AI iUUllJ'ated in F"1I. 7.3,

the stift'enera develop compressive lue.s. The AISC equations bued on Ibis theory apply for

the elutic cue, where the ratio of the lirder depth to tbe web tbic:kneas is Iuae (ea.

dlt.. - ISO). Since the rolled sections used in eccentrically braced fnme appliQtiooa have low

d/t.. ratios wbic:b can lad to inelutic web budcIiDa. the tension fteld theory must be modified

for shar link stifl'ener clesian.

The &pproKb followed here is similar to the formulation preleDted by Adams. Itrenl7.,

and Kulak [2J. Por the system depicted in Pia. 7.2, Y" the shear due to tension field action, is:

(7.S)

where a, is the diaIonal tension streII, " and II ue the beilbt and width of the web panel,

respectively, and 8 is the anale between the cIiqonal tension and boriY.ootal. Since tbe tension

fte1d wiJl orient itleU' in the most efBcient nwmer, the muimum Y, c:aJl be found by

dift'erenliatinl Eq. 7.S with respect to 8, and .ttiq the derivative equal to Y.ero. This pr0

cedure yieIda the followina equation:

(7.6)

CoIIIideriaa vertical equiUbrium of the free body depicted in Pia. 7.3, the muimum Dial force

(7.7)

IlecaUie of the eDeDsive straiD blrdeDiDa exbibited by well ltdfeDld experimeJltal shear

Unb, a, '*l be reuoaably ueumed to be approximately equal to a II' the ultimate tenIile ItreII

· 84 -

of the steel. Using this conservative assumption in combination with Eqs. 7.6 and 7.7 results inthe following expression for the axial force in shear link web stiffeners:

<7.8)

Experimental shear links indicated that local stiffener buckling generally does not occur,

and that stiffener yielding does not reduce their energy dissipation capacity (See Section 7.]).

Therefore, yielding of the stiffeners will be allowed and local stability considerations will be

ignored in the determination of the required stiffener area. Assuming a web participation equal

to half the flange width, as shown in Fig. 7.3, the area required of a pair of two-sided stiffeners,

Au. becomes:

(7.9)

For one-sided stift'eners, Fig. 7.4 approximates the stresses necessary 10 maintain static equili-

brium assuming a fully yielded condition [3J. In this case, the required area of one-sided

stiffeners, A~. is approximately:

(1.10)

In Eqs. 1.9 and 7.10, F. is the stift'ener axial force given by Eq. 7.8. tTy is the yield stress

of the sfiffener material. bf is the flange width, and I", is the web thickness. Even though over

twice as much stiffener area may be required, one-sided web stift'ening may be more economical

than the two-sided detail because of reduced welding costs.

Web stiffeners Me usually detailed so that they do not protrude outside the longitudinal

edge of the beam Oanaes. For stiffeners which just reach the ed&e of the flanges, the required

thickness of two-sided stiffeners, I". is:

- .5 -

A., ---• b,- I"

For sti6eners provided on only one aide of the web, the required tbicknal. I~. bec:omea:

. A~t.-2-

b,t"

('.11)

(7.12)

In either cue, the stiffener tbi<:knea sbouId not be 1_ than t", the thickn_ of the web.

".1.1.1 RI6H111y R.Jnmellll 0/Slnr LiNe Wtb S~.,,- For I limply IUPported plate of

width -I- and beiaht -b-, with one transverse stiffener. Timoshenko (30] stated the riaidity

requirement of web stilfeners this way:1/1M r/PIJly of1M .111' " 1101 Aflkwlll, 1M IItCUMd MI~' 0/1M bllclclN pIIl~ rull tlCrolllite flute.r. Gild 6udcJJJtI 0/ tM pIG. II tICtOIffIJtJlfied by beltdl", 0/ tIw rib. By llllutqwlltI~ of tM rl6k11ty 0/I. ,/6 w mtly ji_/Iy ",,~ "'11 co1tdJlJolt III wltlch ttlClt itaV' 0/1Mpill" wiN buc/de III a rrcur",.., pIG. willi siIfrIIfy IIIIIIJO'fWJ... 0/t1JmellJio", al1 aPlll 6 "ItdtIw rib will nmtlill llrtIillrl.

The web stiffeners must therefore form nodal linea fOl the web plate. If the stlfl'enen ue

not riIld eooUlh to form theIe nodal IineI. the efl'ective puej si~.e increases, caUlina silnifk:mt

reduction of the link eneqy dillipauon capCty. The deners mUll therefore be rilid eoouab

10 tbat the whole link web does not buckle u • sinlle panel. In the late pbues or the experi

ment, Specimen 16 exhibited a tendeN:}' for this type of reIPOftII. u may be dia:cmod from

the photoltftpd in Pia. 4.11.

The required lti6eoer riJidity in the elutk: bucklina cue bII been studied extenlively

Iince the 19301. Tbrouah an eocl'lJ method. TimoIbenko ftrIt demoped a theory for the cue

or one or two Itlft'enen (30). Wana (32] extended TllllOlbeakc/s theory, livina cn.arams for

three and four ltil'enen, mel iDftDitelJ IoDI plates. In 1949, Stein and Fnlich concluded that

the resulta obUineci by TimOlbenko and W.... were ~Cive (21). For the infloitely

loa&. limply supported plate problem, they dneloped a lOlution by minimi.'.iDI the 1YItelDl'

potendal eDeIIY UIiDI the lAIranIiaft multiplier method. 8ued on thit epproIlCb. the,

preeented charts for the required Itil'DOII u a fuoctioD ~ the critical Itrea for difFerent poel

.apect 1'IIiot. In the earI1 IHO.. Rockey and Coot exteDdld the tbeorJ ~ Stein IDd Fralidl

-16 -

for the cae of clamped klaaitudinal edaea [23).

All of the elutic IOlutioDi for the required ritidity of web ltifFeners [23, 28, 30, 32) relate

the critic:a1 IbeIr buctlina Itrea to the non-elimenlioau .....ter, ~, u • function of the plate

upect ratio. ~. This stifFener riaidity puameter is de8ned u:

- EJy--(I/)

(7.13)

In this equation, E is the elastic: modulus. I is the stifFener moment of inertia, II is the smallest

panel dimension, aDd D is the plate dnea fKtor. This fador ill defined u:

t~D - E 12 (l - ..2)

The .. term in tbiI equation is Po_n'l ratio.

(7.14)

Bleich [S) used the raults of Stein and FraIicb to determine the minimum deoer riIi

dity required to obtain the larpst aitic:a1 shear Itrea u • function of the panel upect ratio. ~.

With ~ deflDed u the ratio or the larpr to IIDIIIer panel dimension, the required riaidity, ~...'

was poetulated to be:

(7.15)

This relationship results from • IOlution wbicb ....... that the JonaitudiDal ... of the plate

are limply supported and therefore free to rotaIe. Rockey and Cook (23) developed an analo

lOus lOlution for the cue in which the loqitudinal edaes _ ....med to be ftxed qaiJIIt rota

tion. U..... procedure similar to that employed by 8leicb, the foUowiDa relatioDlbip can be

~ for tlUs c:.e:

(7.16)

The derivation of tbiI relatioDlbip is "Yell in Appendix A.l. Note that Eqs. 7.15 aDd 7.16 apply

for 1< i <5.

-17 -

n.e.c relatiODlbipe aU pertain to the problem of elutic: Ibear bucklina. The «:omple:l

nature of ioea.ue plate buddina problema makeI tIIeoreticaI IOlutiona for the reqWred bendiDI

rilidity of Ibear lint denen impnctical for deIiIn purpoees. An approximate method will

therefore be prtl8ented wbic:b modiBeI the elutic lOIution to 8CCOUIU for ioelutk effects.

M.aonnet and Maquoi U9] attempted to account for the inelutic; effects by CODIerva

tively recoaunendina that the dener riaidilY required to keep the ,tiff_,. stJ'ailbt in the

pOItbuckied ranae be obtained by multipl)'ina the required rilidity for the elutic: cue by • flC

tor of 410.5. This recommendation .... received lOIfte juati&atioo from both anaIytic:a1 (7) and

experimentaJ [22) IllIeaIl:h 00 plate Iirden IOlIded to c:ollapee. While this reteartb did not con

sider the cyclic: IoIdinp which sbear Iinb are desipled to resist, it is believed that thie recom

mendation illUftkientlJ COIIIeI'Vative for deIip appIicationi.

Since Ibear links are relatively short aDd Iatenlly bnIl:ed at both ends, the Banaes of the

usuaJ roUed leCtiona would appear !o provide "'lftcaat rettraint aIoaI the Iona.itudinal edps of

the web. Eq. 7.16 rather than Eq. 7.15 II tberel'ore Idopted for the desipl of shear link web

stiffenen. Moreover, Iince in _mic deIiID lOme dIImaae to the Iinb &:Ill be tolerated at

extreme overlolda, the lower MaIonoet aDd Maquoi multiplier of 4 II taken. The resultinl

(7.11)

ComblDatioD or Eqa. 7.13, 1.14, and 7.17 produces the (oUowiaI equation for the required

ltUreaer moment aI Inertia:

I J :;,.,

,.. - "'''120 - .,3) ('.II>

FollowiDI the UIUII pqctice Ul, 1,.. call be lakeD about III axil in the plane or the web

for both 0DHided and t1JOoIided d .... TIUI prICtice hllpliciU, "'m. IOIDI pertidpatioG

." the beIm web in the rlPditJ ol oae-liclecl .....

· II·

If the stift'eDell are lllin aaumed to just racb the lonIitudinaJ edp or tile ftanpa, the

required tbickDea of two-Iided ltift'eDell, I", becomes:

(7.19)

The required thickness for one-llided deners. I~, is:

(7.20)

AI remarked earlier, it is not recommended to UN • stifl'ener tbiclcnea lea than the

beam web tbiclmea.

An exampl" of the Ibear link defter deIian. method prelented above iJ liven in Appen

dix A.2.

7.2.3 """.11. S.... Llak W. sa....... The ftnal step in mear link web stiffener

deIip is the speci8cation of proper details. In put reIOUCb and desip applk:ationa, the web

Itlft'enen have been fitted to allow Met weldina to both fIanps u well u to the web, u mown

in Pia. 7.S(a). The experimental resultl indicated, however, that only. IIDd reduction or

eaeI'IY dillipation tapKity oc:c:urs for Iinb with ltilrenen wbic:b are not fully weIdecl. It there

fore appears poIIible to relax the requiremeDti of fitted ltift'enen. If tbiJ limpler detail iJ util

i.,.ecI, the stifFeners should terminate a diJtance "k- (u deftned in the AISC Manual [1J ) below

the top beam Gaaae, U Ibown in Pia. 7.S(b). In IUCb cues it appears reuooable to weld the

ltitfener to the bottom fIaaae, aDd depend on the concrete floor to ldequately reatnin the top

.. from buckIiJII. TbiI UIUIDPtion may not be justifted in lOme applic:aIiona, since the poe

sible c:nckiDI or the loot llab durinI a m.;or aeiImk: event may reduce tbiJ reltraint. Undel

aucb circum...neat fitted ltift'enen (Pia. 7.S(a» may become IdviJable.

Pitted ltift'enen may IIIin be awided wilen two-sided ltift'enen are employed. In this

CAlI equal relUliDt for the top aDd bottom beam call be prcMdecl by weIdiaI the

deaers on oppoIite IideI of the web to dUl'erent ulbown in PIa. ?S(e).

·19 •

In all .-., the d .... ftUet weIdIlbouid be contiDuout, fullleaatb welda OIl both IideI

of the ltil'enen.....tiDa AISC SpecifbtionJ lor minimum and maximum Ii,.e.

Fig. 7.\

Fig. 7.2

-90-

10000 .----------.-----------

z 5000a0:I-

~~2

0Z

~

\

a ~0:l-ll)

-oJ~ -5000x~

~-'0000200 400 6000

DATA RECORD

Plot of the Average Axial Strain in Each of the Stiffeners Employed in Speci·men 20.

v. ...f

J rh

1" Vta

(a)

a/2.

, Fsa/2.

AI~~A A II ••

--·-N.A.----

V1 tV12_Twl2Tw/2~

T+~T~ ____.T

( b)

Free Body Diagram For Determining Stiffener Forces Using Tension FieldTheory.

-91-

III

{

I

~bf~~~~PLAN

.F,

8

Ij1 "III-

... .......

t.A.....

II If-- n . .----

A

tI~"--bf--~

tat

.lT

SECTION A-A SECTION B-B

Fig. 7.3 Assumed Distribution of Axial

Stresses for Two-Sided Stiffeners.Fig.7.4 Assumed Distribution of Axial

Stresses for One-Sided Stiffeners.

-92·

(0) (b) (c)

Fig. 7.5 Three Possible Details for Connection of Stiffeners to Shear Links.

·93 -

CHAPTER 8 - A DESIGN PROCEDURE FOR SHEAR LINKSIN ECCENTRICALLY BRACED FRAMES

The experimental work reported here and in earlier investil8tions h.~ demonstrated that

properly desianed shear links can dissipate a areat deal of enerlY and u1derao larae displace-

ment ductilities. The results of this research on ca:entrically braced sl~ei frames tosether with

common desian practice leads to a procedure for the desian of shear link.s. The basic procedure

includes the followiDJ steps: J.) Determination of structural cor.qun~lon, 2'> Determination of

member sizes, 3.) Design of link connections, and 4'> Desian and detailina o~ web stiffeners.

Once the ec:centrically braced framin. system bas been selected, the enaineer must first

choose an appropriate structural conquration. The Oeltibility of brace location inherent to this

system allows the desianer to choose from a number of arranaements to meet both architectural

and structural requirements. This ftcltibility can result in fewer obstructions to the functional

requirements of a buildiOi than would oa::ur with concentric buana. Fia. 8.1 [l I] shows the

location of possible architectural openinp for four alternative framina lIChemes.

It is advantaaeous to locate the active links such that they are not required to axially

transfer the lalJe lateral forces to the braces. Judicious location of the links, as shown in Fia.

8.2, or the use of parallel I8theriOi beams, can minimize this problem. The effect of axial

forces on shear link behavior has not yet been fully investipted, and is the subject of current

research.

After the brace conftauration has been ICIec:ted, the appropriate ca:entricities must be

chosen. This is a critical step in the efBcient desiIn of an ca:entrically brlCCd frame since the

amount of ca:entricity provided determines both the elastic: stiffnea of tt.e frame and the

- 94 -

ductility demand on the active links. It is at this point in the desian process that the engineer

can satisfy both the drift and ductility requirements of seismic design.

Drift control requirements are satisfied by providing the structure with sufficient elastic

stiffness. As the length of the active links increase, the elastic stiffness of the frame of the

frame decreases, in the limiting case reaching the stiffness of a mom~nt resisting frame. An

earlier investigation IJ 1) demonstrated that for a simple structural configuration, as in Fig. 8.3,

there is little in,rease in elastic stiffness when the ratio of elL >0.5. As the e/L ratio

approaches zero, the frame stiffness increases toward that of a concentrically braced frame.

This work also showed that neglecting the effects of shear deformations in the links leads to an

overestimate of the elastic frame stiffness for ell < 0.5. Conventional elasti;; analysis pro

cedures which include the effects of shear deformation in the links are sufficiently accurate for

design applications.

Structural ductility requirements of seismic desian dictate that the structural configuration

limit member ductility demands below the available supply. Earlier research using rigid-plastic

analysis methods (II] demonstrated that the active link ductility demands in eccentrically

braced framing systems are reduced as the eccentricity of the braces is increased. The collapse

mechanism for a simple eccentrically braced frame shown in Fia. 8.3(b), illustrates this point.

The collapse mechanism of this system leads to an approximate geometrical relationship

between the structure and active link deformations:

8L-ye (8.1)

The structure deformation measure, 8, can be interpreted as an ultimate story drift index. The

angular deformation requirement of the active link, y, measures the averaae shear strain for

shear links, while for bending links 'Y is the plastic hinge rotations.

Since the eccentricity, t', is usually much smaller than L in eccentrically braced frames,

the links must underao Jarae displacements to meet the story drift. TheBe localized reaions are

therefore required to dissipate I....e amounts of eoerl)' during inelastic response, makina their

- 95 •

performance critical to the prooer functioning of an eccentrically braced frame during a major

seismic event. It is apparent that in a moment resisting frame, where e-L, the ductility

demands on the beams are much smaller.

Minimum (I values of 0.01 S to 0.020 have been recommended by ATe 03·06 129] for

highly seismic regions. Smaller (J values are required in regions of lower seismicity. Sinc~

seismic loadings can produce complete load reversals, recommended }' values should br deter

mined from cyclic experiments. The results of previous experiments and those described in

this report indicate that properly designed shear links can attain ')I values of up to ±O.lO for

cyclic loading and 0.20 for monotonic loading. Once the values of L, 9, and y, have been

specified, the minimum eccentricity, e, can be estimated using Eq. 8.1. Relationships similar to

that of Eq. 8.1 can be derived for other eccentrically braced configurations.

Determination of the maximum eccentricity necessary to meet elastic stiffness (drift)

requirements, and the minimum eccentricity needed to limit active link inelastic demand form

bounds for the length of the shear links. A suitable eccentricity within these bounds must then

be selected.

1.2 Dete..l.atlo. 0' Meml»er Sizes

Because of the importance of providing the desired energy dissipation mechanism during

extreme overloads, preliminary member sizing should be performed using plastic analysis tech

niques. The system of lateral forces employed in this initial sizing can be determined by apply

ing a load factor to the equivalent static lateral forces specified in a building code 129,31 J.

Several procedures have been sugested for determining the member forces and moments for

the desired collapse mechanism [15,18,241.

Roeder 125,261 used the moment balancinl technique [9,141 to determine preliminary

member forces. This procedure is based on the concept that if a structure is desi&ned for any

moment diqram which satisfies statics, the assumed loadinp will be a lower bound for the

strenath of the structure. Ir the desian also exhibits the desired collapse mechanism, the upper

- 96 -

bound solution will also be satisfied.

Roeder's approach makes an assumption of the proportion of the story lateral shear

resisted by the brace and then solves for the forces and moments in the beams, such that the

plastic hinges form in the desirt:d locations. The remaining story shear is then distributed to the

columns and the column moments are determined. The resulting unbalanced column end

moments are then adjusted by moment balancing methods until all the nodes of the frame are

in equilibrium, satisfying statics and thereby achieving a lower bound solution.

Manheim's method [18) is an upper bound approach to satisfy the desirel' collapse

mechanism. This method equates the internal and external work based on an assumed distribu

tion of shear link strength. Once the required strength of the links has been determined, the

remaining member forces can be determined from statics.

Kasai (15) noted that both of these preliminary member sizing methods may encounter

difficulties in obtaining acceptable column design moments. Roeder and Popov (26) observed

that the columns may be in single curvature over multiple stories, resulting in large column

sizes. Also, unless the initial assumptions are quite accurate, these two approaches may require

a number of iterations to obtain an acceptaole solution.

A third preliminary design method was developed to provide more acceptable column

design moments without requiring any assumptions concerning the distribution of story shears

or beam strength. Kasai 115] obtained a statically and kinematically admissible solution based

on the desired collapse mechanism. In this method the location of column inflection points are

assumed to ensure that the columns are in double curvature under any fixed loading condition.

The resultina force and moment distribution forms both an upper and lower bound solution to

the plastic design problem, and inelastic activity is confined to the appropriate locations.

Once a satisfactory set of desian forces and m'Jments in all the frame membt'rs has been

determined, the preliminary sizes can be chosen using the recommendations of Part 2 of the

AlSC Specification III. In choosina appropriat~ beam sections it should be noted that energy

dissipation data from previous tests indicated that shear hinae behavior is preferred over

·97·

moment hinge action [12,131. A shear-moment interaction diagram for a wide flange beam

[2,12,181. as shown in Fig 8.4, can be combined with consideration of static equilibrium to

ensure shear rather than moment link behavior. The M;, V;, and M, terms for this figure are

given by the following equations [12,131:

(8.2)

(8.3)

(8.4)

In these equations, the section properties, d, I/o I .. , bf , and Z are the beam depth, flange

thickness, web thickness, flange width, and plastic section modulus, respectively, such as given

in the AISC Manual [I). The terms CT y and 'T y are the yield stresses in pure tension and pure

shear, respectively. Using the von Mises yield criterion, 'T y - CT"t.[j.

Satisfying statics of the assumed link model (See Section 2.1) results in the following rela-

tionship:

2Me--V

(8.5)

The existence of a rapid change in slope in the shear-moment interaction diaaram at (M;,

VpJ is characteristic of wide flange sections. The balance point locates where the entire web

yields in shear while the flanges yield simultaneously in uniaxial tension or compression. Using

this point of the shear-moment interaction diaaram, the Ualanced length for a section, b', can

be defined as:

(8.6)

Active links should therefore act as shear links if e < b'. The test results to date indicate that

shear link action continues to predominate for lenaths up to approximately e-1.1Sb·,

(8.7)

- 98-

Combining this experimental observation with Eq. 8.6 results in the following simplified expres

sion for the maximum length of a shear link:

. 4 I;bm.. :::: bf -r~

To attain the desired shear link inelastic response characteristics the beam sizes chosen should

therefore have a b';'.. greater than e. the eccentricity provided.

It should be noted that Eq. 8.7 was developed from experimental data which simulated

links with reverse curvature and equal end moments. such as shown in Fig. 2.1 (c). For the

links illustrated in Figs. 8.1 (b). (c). and (d). in the elastic range of behavior larger link

moments tend to develop at the column ends than at the brace ends. Whether these moments

equalize under severe cyclic loading has not yet been fully established. This topic is the subject

of a current experimental investigation. If an elastic analysis indicates that M; will be reached at

the column face before the initiation of shear yielding. either the eccentricity should be

reduced. or an alternative section should be selected.

The preliminary design of columns and beams in eccentrically braced frames should fol-

low the basic provisions of Part 2 of the AISC Specifications [l], with the following

modification. Since significant strain hardening of shear links has been observed in experimt .".

an additional safety factor should be used in the design of braces to preclude the occurrence of

brace buckling. The previously recommended safety factor of 1.5 appears to be reasonable [24].

A comparable factor should also be considered in the design of the columns.

Since current building codes (31) ue based on elastic analysis techniques. the plastically

desianed frame should be checked at working force levels. Satisfaction of both elastic drift and

member size requirements should be ensured. If the elastic design requirements result in

increased member sizes. the plastic design procedure given above should be rechecked to

ensure that the desired inelastic behavior will occur.

- 99 -

8.3 Destin or Link Conn«ttons

8.3.1 L nk-Column Conn«tlons- The structural configuration of eccentrically braced

frames frequently are such that the active links are located in the portion of the beam adjacent

to the supporting column. In this instllnce the integrity of the beam-column connection

becomes critical for developing the dissipation capacity of the active links. The designer must

therefore understand the nature of the inelastic response of the frame to adequately detail the

link connections. Without sufficiently ductile connection details the active links may not be able

to withstand the large displacement requirements which they could be subjected to during

extreme seismic events.

Eq. 8.1 demonstrated that the ductility demand on active links can become quite large as

their length decreases. Since these shorter links yield ill shear. the link-column connection must

be able to develop the full yield shear capacity of the links. The increased shear capacity of well

stiffened links. up to 75 per cent above the initial yield level. must be recognized in the con

nection design.

The lest results described earlier showed that all-welded link-column connections can pro

vide the reqUired shear capacity and ductility. As Specimen 28 showed. in bolted web. welded

flange connections the larBe shear forces can cause bolt slippage which can lead to premature

brittle flange failures. To avoid such failures, all-welded shear link connections. which can

achieve large energy dissipation and ductility, should be employed. A detail such as that shown

in Fig. 8.5 was found to sustain a large number of load reversals in the inelastic range. A satis

factory alternative detail which provides for a more direct transfer of shear forces is shown in

FiB. 8.6. If an analysis shows that the ductility and energy dissipation demands on an active

link are moderate. the bolted web, welded flange connection shown in FiB. 8.7 can be expected

to perform adequately.

Since shear links must resist large end moments (See Section 5.2.2), the link flanaes must

be connected to the columns with full penetration welds in all cases. In fabricating anyone of

these connections in order to minimize residual stresses, the flange welds must be made before

- 100-

final attachment of the beam webs.

Similar details can be used for the connection of active links to column webs. But. previ

ous research showed such connections to be less ductile than those to column Danges 1201.

Lehigh University investigators [61 recommend eJltending the connecting plates beyond the

column Danges to decrease the possibility of weld failure. as shown in Fig. 8.8 for links with

large ductility demands For links with moderate ductility demands a detail with a bolted web

similar to that shown in Fig. 8.7 should be satisfactory.

8.3.2 Link-Brace Connedlens- The link-brace connections must be designed to develop

the full yield capacity of the shear links. including the anticipated strain hardening of the

material.

The link·brace connections shown in Figs. 8.5 through 8.8 illustrate a typical detail for

braces composed of a pair of angles. A similar detail can be adopted for tubular braces. The

gusset plate detail consists of two plates welded into a T section in order to stiffen the connec

tion and to provide better alignment of the weld centroid. AnClher detail. in which the braces

are welded directly to the; link Danges. has also been used in design applications.

Since active links are susceptible to lateral torsional buckling. the link ends at the eccen

tric braces must be laterally supported. A link-brace connection which is T-shaped in plan. as

shown in Figs. 8.5 throuah 8.8 tends to reduce 11l~ load induced to the lateral bracing beam

(18).

.... Desll_ of Shear LI.k SttfreHh

The design of shear link stiffeners should follow the recommendations liven in Section

7.2 of this report.

·}Ol·

(01 (b) (el (dl

Fig. 8.1 A.lternative Arrangements for Eccentric Bracing Showing Possible Location ofArchitectural Openings II)].

FRAME I

I

·102-

PLAN

I FRAME 2

FRAME I FRAME 2

FiB. 8.2 Proper Confiauration of Framina to Limit the Allial Forces Introduced Into theActive Links.

I- L

(a )

e

-103·

rIIII

/"i8'

( b)

y

Th

1

BALANCE POINT

Fig. 8.3

Fit. 8.4

A Simple Eccentrically Braced Frame and Its Collapse Mechanism 111].

v

Vp

V. r. ~_~::::~:::::==~p

M

Typical Moment-Shear Interaction Dilllram for Wide Ranle Sections.

Fig. 8.5

Fig. 8.6

-104-

---I----~_._ _ _< BOTH SIDESOF GUSSET

EO. EO. EO. EQ .

....--- e ---.-t

All-Welded Link-Column Flange Connection with Fillet Welded Web ShowingSuggested Stiffener Spacing.

BRACE ON THIS LINE

........-_.......:..L.-...__--<. BOTH SIDESOF GUSSET

EQ.

~---e

All-Welded Link-Column Flanae Connection with Full Penetration Web WeldShowina Suuested Stiffener Spacina.

P T 8BFLG

k

EQ. EQ. EQ. EQ.

14--- e

-lOS-

BOTH SIDESOFGUSSET

Fig. 8.7 Bolted Web, Welded Flange Link-Column Flange Connection Showing Suggested Stiffener Spacing.

BOTH SIDESOFGUSSET

IIII

Fig. 8.8

EQ. EQ. EQ EQ.

....---e----.t

Suggested All-Welded Link-Column Web Connection Showing SuggestedStilfener Spacing.

• 106 •

CHAPTER 9 - SUMMARY AND CONCLUSIONS

9.1 Summary

Eccentrically braced framing can exhibit both excellent elastic stiffness and large eneray

dissipation capacity. These characteristics make eccentrically braced frames a viable alternative

to the more conventional structural steel framina systems in seismic regions. Previous studies

[l8, 24] demonstrated the overall behavior of frames with different bracing systems. A recent

'1tudy (13) analyzed the local behavior of the crucial active link elements.

The results of these previous inve~tigations provided a lood deal of information on the

cyclic behavior of active links. However. some upects concerning the practical desian of an

eccentrically braced framing system had not been addressed, includina the sensitivity of link

behavior to the imposed loadina history, the link-coiumn connection detail, and the web

stiffener details. The purpose of this investiption was to examine these aspects of the desian

problem.

To investipte these aspects, a series of twelve full-me specimens were desiped and

tested. These tests &pin demonstrated the excellent enel'l)' dissipative capacity of shear links.

Analysis of the test results provided the information necessary to make desian recommenda

tions considering both economic and performance characteristics. A method for stiffener sizins

was developed and I procedure for shear link desian was presented.

t.%c .

The m~r conclusions of this investiption are:

• 107.

I. Timoshenko Shear &am Theory clo~1y approximates the linear elostic behavior of shear links.

Shear displacement effects should be considered in elostic analy~s 0/ecantrically braced frames

employing shear links.

2. For the type ofloading u~d in the~ eX/Nriments. proflt'rly designed and «tailed shear links can

dissipa,€, farg€, amounts ofrnergy rf'llQrdless of the loading history.

3. Monotonic rrlarive end displacements of up to 10 /Nr cent of the link If'ngth can be resisted

without Significant loss ofcapacity. This conclusion demonstrates that shear /inks can meet the

Iorge ductility demand which may result from long puisR ~Ismic disturbances similar to thai

recorded during the 1971 San Fernando Earthquake.

4. P,oflt',1y iksigned one-sided web stiffening sl4fficiently deloys and restrains web buckling. The

u~ of one-sided web sttffeners can provide significant cost economies due to reduced welding

rrquirements.

S. Web stiffeners need not be connected to both link flanges; the sti/hners can be terminated a dis

tance k (sn AISC Manual (1) from Ihe tup of the UPf't'r flange. The rfll/('rete .floor supported

by the beam trUly be Munted upon to provide the neceSS/lry restraint against flange buckling.

However, thiS restraint IS not entirely reliable. since it may be r('~ by cracking of the slob

during a ~ismic event The sti/hners should be welded to the lowerfla~ to provide buckling

restraint.

6. Sti/feners should be designed for axial forces and bending IIi/fness. TItP use of tension field

theory provitks a method for the axial fora design. Bending IIi1fness /Wluirenwnts can be

ellimated by modifying previOUSly QlIQilabie elastic buckling solutions to ac:courrt ./Or the ineJallic

nature ofSMar link web buckling.

7. From e~ dissipation and failure mode considerations, the minimum spacing for stiffeners in

shear links should be 20t... qual spacing of IIi1feners should be used with II mod;/ied panel

zone si~ for panels atlaanl to the beam-column CO"n«IitHr. Fur a web wlrich is fillel welded '0II shear 1Gb, spacing of lhe Slilfrners should ~in from 1M er«Iio" boll line. For boiled andJWJ

f't'If/!lralio" wlded co"neclhHU, lhe lIi/hners should be spacedfrom 1M/aCt' o/IM coburur.

• 108·

8. All weldH connections deowlop the fUll capacity of shear links. This detail is ret:OmfMnded /or

links wi,h kJ~ ductility tkmands '0 propkle assurance QgainSl abrupt connection failuri's.

9. lJlUlf'r cyclic loading, well s,iI!enM webs deW!lop a grea' tkal of Slrain hardening which

increases tM War capacity of the link cignjficanlly. For welded jlangt'. boiled web conneclions.

boll sliptJQgt' Il'a,,*rs a kJrge pol'lion of Ihis incl't!Qsed SMa, to 1hI' jlangt's. "nding 10 cause of

fJ"malUre jlaflg(' failures. This type offa jure mode makl's this conn«,ion undl'sirab/(' for links

with kJ~ ductility demands. ThI' bolted web deUlil should perform adeqUtlIi'1y jor sMar links

wilh moderate ductility demands.

10. &sed on one expt',i""nt. it apt1Hrs that shea, links connected 10 the column web can diSSipatt'

a kJrge amounl of eM'KJI. The shear link web yielding reduct's flange /orces in Ihl' fMmbl'r.

diminishing lhe possibility 0/ weld failures.

- 109 -

BIBLIOGRAPHY

(1) AISC. Specification for the Design, Fabrication and Erection of Structural Steel Buildings,with Comm.:ntary, Manual of Steel Construction, American Institute of Steel Construction, Chicago, 1980.

(2) Adams, P.F., Krentz, H.A., and Kulak, G.L., Limit State Design in Structural Steel,Canadian Institute 01Steel Construction. 1979.

(3) Basler, K., "Strength of Plate Girders in Shear", Journal 01 the Structural Division, ASCE,October, 1961, pp. 151-180.

(4) Black, R.G., Wenger, W.A., and Popov, E.P., "Inelastic Buckling of Steel Struts UnderCyclic Load Reversal", EERC Report 80-40. University of California, Berkeley, October.1980.

(5) Bleich. F., Buckling Strength of Metal Structures, McGraw-Hili, New York. 1952, pp.409-418.

(6) Driscoll, G.C., and Beedle. L.S., "SulSestions for Avoiding Beam-to-Column Web Connection Failure", A1SC Engineering Journal, Vol. 19, No. I, 1982, pp. 16·19.

(7) E.C.C.S. - I.A.B.S.E.: Liege Colloquium on Stability of Steel Structures, April 1977, pp.273-278.

(8) Fujimoto, M., Aoyagi, T., Ukai, K., Wada, A., and Saito, K., "Structural Characteristicsof Eccentric K·Braced Frames", Trans AU, No. 195, May, 1972.

(9) Gaylord, E.H., "Plastic Desisn by Moment Balancins", Steel Structures Symposium, Univ.of Illinois, Urbana, October, 1966.

(10) Hisatoku, T., ct. aI., "Experimental Study on the Static Behavior uf;ie Y-Typed Bracings", Report of T.kenaka Technical Institute, No. 12, August, 197t

(I1) Hjelmstad, K.U., and Popov, E.P., "Some Characteristics of Eccentrically Braced Frames",Journal 01Structural Engineering. ASCE, in press.

(12) H;elmstad, K.D., and Popov, E.P., ·Cyclic Behavior llJld Design of Link Beams", JournalofStructural Engineering, ASCE, in IJress.

(3) ffjelmstad, K.D., "Seismic Behavior of Active Beam Links in Eccentrically BracedFrunes·, Ph.D. Thesis, University of California, Berkeley, June, 1983.

(14) Home, M.R., "A Moment Distribution Method for the Analysis and Design of Structuresby the Plastic Theory", Proceedings. Institute of Civil Engineers 3, No. I, April, 1954.

(IS) Ka:;ai, K., "A Plastic Design Method for Eccentrically Braced Frames," Dept. of CivilEngineering, University of California, Berkeley, CE 299 Report, 1983.

(16) Krawinkler, H., Bertero, V.V., and Popov, E.P., "Inelastic Behavior of Steel Beam-toColumn Subassemblages", EERC Report 71-7. University ofCalifomia. Berkeley, 1971.

(11) Maison, a.F., and Popov, E.P., "Cyclic Response Prediction for Braced Steel Frames·,Journal of the Structural Division, ASCE. 106, No. ST7, Proc. Paper 15534, July, 1980, pp.1401-1416.

(IS) Manheim, D.N., "On the Desisn of Eccentrically Braced Frames", D. Eng. Thesis, Department of Civil Engineering, University of California, Berkeley. February, 1982.

(9) Massonnet, Ch., and Maquoi, R., "Recent PI'OIres5 in the Field of Structural Stability ofSteel Structures", I.A.B.S.E. SutWys, S-S/78, May, 1978, pp.1J-16.

(20) Popov, E.P., and Pinkney, R.B., "Cyclic Yield Reversal in Steel Building Connections",Journal olthe Structural DiviSion, ASCE, Vol. 95, No. STJ, Proc. Paper 6441. March. 1969,pp. 327-352.

- 110 -

(20 Popov, E.P., and Stephen, R.M., ·Cyclic Loading of Full-Size Steel Connections", StulResearch lor Construction, Bulletin No. 21, American Iron and Steel Institute, New York,N.Y., Feb., 1972.

(22) Regional Colloquium on Stability of Steel Structures, Budapest, Hungary, October, 1977,pp.219-229.

(23) Rockey, K.C., and Cook, I.T., ·Shear Buckling of Clamped Infinitely Lonl Plates Influence of Torsional Rilidity of Transverse Stift'eners·, Aeronautical Quarterly, Vol. XVI,February, 1965, pp.92-95.

(24) Roeder, C.W., and Popov, E.P., ·Inelastic Behavior of Eccentrically Braced Steel FramesUnder Cyclic Loadings", EERC Report 77-18, University of California, Berkeley, August,1977.

(25) Roeder, C.W., and Popov, E.P., ·Eccentrically Braced Steel Frames for Earthquakes·,Journal o.fthe Structural Division, ASCE, Vol. 104, No. sn, March, 1978, pp. 391-411.

(26) Roeder, C.W., and Popov, E.P., ·DesiJn of an Eccentrically Braced Steel Frame", AISCEngineering Journal, 3rd Quarter, 1978.

(27) Spurr, H.V., Wind Bracinl, McGraw-Hili, New York, 1930.

(28) Stein, M., and Fralich, R.W., "Critical Shear Stress of an Infinitely Long Simply SupportedPlate with Transverse Stift'eners", N.A.C.A Technical Note 1851 (949).

(29) "Tentative Provisions for the Development of Seismic Regulations for Buildings", ReportNo. ATe 03-06, Applied TcehnolOlD' Council, Palo Alto, Calif., 1918.

(30) Timoshenko, S.P., Theory of Elastic Stability, McGraw-Hili, New York, 1930.

(3)) Uniform Building Code. 1981 Edition. International Conference of Building Officials, Whittier, Calif.

(32) Wana, T.K., "Bucldil18 of Transverse Stift'ened Plates Under Shear", Jourllill of App!it!dMechanics. (ASME), Vol. 3, No.4, 1941.

- 111 -

APPENDIX A.I DERIVATION OF THE REQUIREDSTIFFENER RIGIDITY RELATIONSHIP

Bleich (5) used the results obtained by Stein and Fralich (28) to postulate a relationship

between the required stiffener rigidity. :y ffq' and ~, the panel aspect ratio (See Eq. 7.15). The

solution presented by Stein and Fralich assumed that the longitudinal edges of the web plate are

simply supported. Since shear links are relatively short and laterally braced at both ends, the

flanges of the rolled sections used in eccentrically braced frames appear to provide significant

restraint along the longitudinal edges. A relationship similar to that given by Bleich should

therefore be developed for the required stiffener rigidity when the longitudinal edges of the web

plate are fixed against rotation, corresponding to the above case.

Rockey and Cook (23) obtained an analytical solution for the critical ela, :.; buckling stress

factor, K, as a function of the stiffener rigidity. "I T, when the longitudinal edges are fixed

against rotation. The results of this solution were pruented in a series of graphs for different

aspect ratios, some of which are shown in Figs. A.l through A.4. The CTIBT term shown in

these figures is the ratio of the torsional to bending rigidity of the stiffeners (231. The max-

imum value of 0.769 is for a thin walled circular tube stitrener. For the single plate stiffeners

used in eccentri<:ally braced frame appli<:ations the C rlBr ratio is near zero.

In the derivation of Eq. 7.5, Bleich used the results of Stein and Fralich [28) to determine

the minimum value of )' T which would develop the maximum critical buckling stress, for

different panel aspect ratios. He then developed a relationship between these values of "I T and

the corresponding aspect ratios.

A similar approach is followed in the derivation of Eq. 7.16. For six panel aspect ratios,

includilll those given in Figs. A.I through A.4. the table presented with Fia. A.S lists the

minimum value of )' T which allows the web to develop its maximum elutic critical shear stress

- 112 •

for a CrlDr ratio of zero. This ficure plots these values of Yr apinst ~2. From this araph. the

followina equation relatins the stift'ener bcndina riaidity to the panel aspect ratio is obtained:

:y,." - 16~2 - 8 (A.l)

This equation. also plotted in Fig. A.S. is givcn as Eq. 7.16 in thc dcrivation of the required

shear link stift'ener rigidity. Note that Eq. A.l applies for elastic shear bucklina of the web plale

when 1< 13 <So The recommendations of Massonnet and Maquoi 119] can be used to account

for the inelastic nature of shear link web bucklins.

-Jl3-

~ 12

10

\ 0.769 CrIST'-- 0.20

0.10O.O~

0.01o

LONGITUDINAL EDGES CLAMPED

o

Fig. A.I Critical Buckling Stress Factor vs. Stiffener Rigidity for ~ - 1.0 [231.

60

~

40 Cr/~ lDNGlTUDtNAL EDGE CLAMPED

IT1JIIIII]}a ~ I---J I-d/3

20

260

~

Fia. A.2 Critical BuckJina Stress Factor VI. Stiffener Rigidity for ~ - 3.0 1231.

-114-

24

~ CT/BT ~ITWNAl.EDGES CLAMPED

[]]I]}~ L- 213d

80 35 45 55 6

)"r

Fig. A.3 Critical Buckling Stress Factor vs. Stiffener Rigidity for ~ - 1.5 1231.

40

30X

20

LONGITUDINAL. E:DGE CLAMPED

FiB. A.4 Critical Buckling Stress Factor V$. Stiffener Rigidity for j - 2.0 1231.

·115-

IJ YT

1 81.5 302 702.5 8S3 130S 400

100

-2o 0'--llO.1--..Io.---....IO-----------I20~--~{$

200

300

400

Fig. A.S Plot of Minimum Required Stilfener Rigidity ,. T Which Develops the Maximum Elastic Critical Stress ( K ) for Different Values of Panel Aspect Ratio (~ ..

- 116 -

APPENDIX A.2 AN EXAMPLE OF SHEAR LINK WEBSTIFFENER DESIGN

This example is given to illustrate the procedure for shear link web stiffener designpresented in Section 7.2.

Given: A Wllx50 section of A36 steel shear link. Assume that the stiffener spacing hasbeen determined from an inelastic dynamic analysis, or an estimated ductility demand. asa/I.. - 2S.

The followins section properties of a W IRx50 section are required for shear link sliftenerdesign [II:

I .. - 0.335 in.

d - 17.99 in.

b, - 7.495 in.

If - 0.570 in.

h - d - 21f - 16.85 in.

The required stiffener spacins is therefore:

Q - 251.. - 25 (0.355) - 8.815 in.

The followins material properties have been assumed:

a y - 36lai

a,,-60lai

., - 0.30

Desll. 'or Adal FMUS (See Sect".1.1.1.UUIi.. the values assumed above. by Eq. 1.6, the maximum panel shear, V, , is developed

when:

. "" ( 1 (8.815)/(2)(16.85)] v,san"", - - - ...,.==~~~:;.=;~~

2 JI + «8.87S)/06.8S»2

sin9 - 0.517

For an ultimate tensile stress, a". of 60 ksi, by Eq. 1.7, the force in the stiffener, F"

is:

F. - 6O(O.3S5)(8.815)(O.517)2

F. - 50.5 kips

The area required for two-sided stift'eners, A•• becomes:

.A _ SO.S _ (1.49S)(O.3SS) _ 0.0124 in. 2

• 36 2and the thic:tnea, I., is therefore:

- 117 •

0.0724I" - 7.495 _ 0.355 - 0.01 in. < I ..

The thickness required of two-sided stiffeners for axial forces will therefore be controlled by thethickness of the link web.

For one-sided stift'~ners. the required area. A~. is:

A~ - 2.4[(50.5)/(36) - (7.495)(0.355)/2) - 0.174 in. 2

and tne thickness of one-sided stiffeners. I~ becomes:

(0. I74)lSi - 2 7.495 _ 0.355 - 0.049 in. < I..

The thickness required of one-sided stiffeners for axial forces is also controlled by the thicknessof the web.

Deslln of Shear Link StUrelien for BeHlnl RIII.lt, (See Section 7_1.1.1)

The panel aspect ratio. ~. is:

~ - h/a - 06.85)/(8.875) - 1.90

By Eq. 7.1 7. the required stiffener riaidity. y...,. is:

Y..., - 640.90)2 - 32 - 199

The stiffener moment of inertia. I...,. is liven by Eq. 7.18. as:

I _ (8.875)(0.355) JO 99) _ 1.22 in. 4

... 120 - 0.32>

The thickness of two-sided stiffeners, I.,. is therefore:

I. - o2)(1.22)1 (1.49S) J - 0.206 in. <'..Since the thickness of two-sided lo>tiifeners required for bendina rilidity is also less than I ... thestiffeners sizilll is controlled by the web thickness. Two-sided stiffeners should therefore be3/8 in. thick.

For one-sided stift'eners. the required thickness, ,:,. is:

I~ - (24)(7.22)/(7.495») - 0.412 in.

The size of one-sided stift'eners is therefore controlled by the bendilll riaidity desian. and1/2 in. thick stiffeners should be chosen.

-119-

NOTE: Ih_ro in pa....nth•••••r. At::c...lon N"'r....~qned by the IIAUonAl T.cllnical tntonMUon Servic.; ~he," lro

followed by I prl". code. Copie. or the r.port• ..y be order.d rro. the NAtionAl ~chn1cIl IntOnl&t10n S.rvic•• 5285Port ~YIl ~d. Spr1nqfi.ld. Vlrqin11, 22161. Acc•••10n Nu.ber••hould be quot.d on ordlr. for r.port. (PI ._- _0_)

and rllOittance _t Icca.pAny .ach order. Reportl without th.. 1ntonlltion wer. not .vulablo It t,.. or pr1ntinq.Thl ee-plet. Illt of EE-e report. Ifroa EZRC 67-1) il Iv.ilAbl. upon requ..t fro. the E.rthquake Enq1n••rinq RI••arehCent.r. ~nlv.r"ty or Californll. "rkli.y, 47th Str.et and Koft-&n Boul.Vlrd. R!cn.ond. Cllifornll 94804.

UC5/EEAC-77/0i ·PLUSH - A Coaput.r Pr09r~ for Probablllltlc Finlt. Element An.iYll. of S.,.mic SOlI-Structure InterIctlon,· by M.P. ~ Or9&nilta, J. Ly.mer and K.B. Seed - 1977 IPaBl 177 6511A05

:JCB/tE'RC-77/u2 "Soll"5tructure Interaction Ef~.c-t. &e t.he HumbOldt Bay ;'0-..1" 'r1.ant. In tr.. Fern4ale tarthqu.4l<. of ';..&r.e7, 1915.· by J.E. Valer., H.B. S.ed. C.F. TI.i Ind J. Ly..... - 1977 (pa 265 7951A04

vea/EEP-c·77/,3 "InUu.nc. of Sample DlIturbMIce on Sand Re.pon•• to Cycllc Loadlnq." t:y K. Morl. H.B. S..ed 5nd :.K.Chan - \977 (PI 267 352)A04

CCB/EERC-17/04 ·S.il.o109l".1 Studies of Stronq ~tion Record_.· by J. Shojl-Tah.rl - 1977 (PI 26~ 6S;IAI'

:Jca / EERe-7 7/06 "!leveloplng :o1ethOd<>109l•• tor Evalwotinq the EarthqUAk. Safet)' of ExlSunq Buildlnqs." by ~. 1 -B. Bre.l.r; No.2- B. Br._ler. T. Okada and D. Zlolinq, No. 3 - T. Okada .nd B. Bres~er; ~. 4 • ~.~.

Bertero and B. Ir•• l.r - 1977 (PB 261 354)AOB

~CB/E£RC-77/01 "A llter.t~r. Survey - Transverse Strenqth of ~~Qnry W.lls," by Y. umot., R.L. ~Y•• , 5.~. :hen ar.dR.~. Clouq~ - 1911 (PS 277 9JJ)A07

UCBlEERe-77/0e "CRAIN-TAlIS; "Col\\puter pr09r,... for In.l••tle Earthquako "'••pons. of Thre. Clmenllona! 6ulldlnq.... by~. Gu.nd.laan-I.rael ana G.H. powell - 1977 (PB 270 693)1.07

"JCB/EERC'-i"';09 "SU&WALL: ~ Spec.L41 ?·JrPOSf. rlnlte Element Computer Program f:lr .?r!kc~~cal Elas~l= Analj.'s13 wd ce~lgr:

of Structural Walls With Substr~c~ure Optlon." by D.Q. Le. H. Peterscr. ~nd E.P. popov - 197~

(PB no ~671A05

'JCB/E£Re-77/10 "Exparl...nUl £voluuion of SOl,1Il1C oeuqn ~thod. ror Bro.d e,11nancI1 Tal\l(. .... by D.P. elouqh(PB 272 2801A13

ueB/EERC-77/11 ·Ear~hquako Enq1n.erlnq a.••arch at Berkol.y - 1976," - 1977 (PB 273 S07lA09

UCB/EERC-17/12 ·Autout.d o.llqn of E.r~hquake a..i.tant Multl'tory Steel Bulldi.nq fr!I".·'s." by N.D. :.Io.1l<.r. Jr .• l3~1

(PB 276 526> 1.09

Uell/ElRe- 7III ·COncr.te Confined by Recunqular Hoop. Subjocted to A,u.1 !.O.do, .. bj J. Vall"na•• V. v. a.rtero andE.P. Popov - 1977 (PB 275 165)1.06

veB/EERC-77/14 ·S.lO~lC Str"n Induef>d in the Ground Durlnq Earthqu.k••• • by Y. Suql~ura - 1977 (pa 264 20I1A04

UCB/EERC-77/1~ ::n..uqned

t,1C!/EERC-"/L6 "Compu~,,·r t\J.ded OptL:ftWft =>eslqn ~t Ouctlle ReLnforcec2 Concretlll ~nt Reslstlnq Frames." .::y S.''';.zeq.)••kl and V.V. 8e[~ero - l~77 ,pa 28~ 1)1l~07

VCB/EERC-77/l7 ·Earthquake Sl~ulltlon Te.tlnq of I Stepplnq Frame with En.rgy-Absorbing Devle••• • by J.M. ~.ll)' andD.F. T.ztoo - 1971 (PB 271 506IA04

VCa/EERe-77/iB ··n.l••t1c Beh.vlor of Eec.ntrlC.lly Ir.ced Steel Fr.... under cyclic Loadlng•• • by C.~. ~ed.r and~.P. Popov - 1917 (PI 275 52&IA15

UC8/EERC-77/1~ "A Slmplified Proceaure tor E.timet1nq Earthquak.-Induced Deforsotlon. in DeIIl. and Embankment.... by F.I.Kakdbi and H.B. Sled - 1977 {PIS 27& 820lA04

UCI/EERC·7'I.O -Th. Performance of Earth oea. durinq E.rthquak••• • by K.I. Seed. F.t, Klkdi.i and P. d. Alb. - 1977(PI 276 121lA04

uC8/EERC-77121 ·Dyne&1c Pll.Uc Analyei. Ullng St.... Mlultant F1nit. El._nt Fonou1.tlon." by P. L~UI\'rva'lt .ndJ.M. ~lly - 1977 (PI 275 453)A04

UCB/EERC-77/22 ·P,...hlUn.ry Expen_nt.l Study of S.i..1c Uplift ot a St.el Fr._." b~ R.I'. Clouqh .nd A.A. Huckelbn<lqe1977 (n 278 7UIA08

UC8/ttRC-'7/2) ·Earthquake Su-u1ltor T••t. of. Nine-5bory St..l Fr... w1th Col~1 Allowed to Upllft.· by A.A.Huck.lbridq. - 1977 (PI 277 944)A09

UCl/EERC-77/24 ·Nonl,n••r 5oi.l-Structuz. Int.ract13n of Skew Hlqhway 1<1dq••• • by M.-C. Chen end J. PlnZl.n - 1977(PlI 276 176iA07

llCB/EERC-77/25 ·S.illOic Anelyli. of en Off_hor. Structur. Sl&pporte4 OIl pU. P'oundetion•• • by D.O.-H. t.iou ...d J. Pen.ien19'7 tn 28J 180)A~

UCi/EEJe-71/26 "Dyneaic Stiftn••• "*trlc•• for KaIoqaneou. Vl.00elaatl0 Half-'l...... • by G. DaIqupca and A.~. Chopra 1977 CPB 279 6S4:A06

Prece<lng page ~ank

Reproduced frombest available copy -120-

\,lCB/EE.-:-70 f27 ·11 Practical sott Story EArt!\quuI IIololtion Systlm," by J.M. Kally, .1.'1. E1~ln'l.r He :.;. :Jer,'lAm _13-- (PB r6 3UlA07

UCB/EERC-1i/28 NS.ll~ic Safety ?f EXlltinq Bu~ld1n9' and I~centiv•• fo~ K&zard Mltl1etl0n In San ~r£nC1SCO: AnExplorator~ Study," by A.J. ~Iltsnlr - 1977 (PB 291 ~'Q\AOS

"CII:EUC-77/2~ .. Dyn....1c M&lySlS of Ulctr?hydnuHc Sh&k1nq T&I>ll.," by D. Ru, S. ,;j-~~~'-Hay&t: .nj·' 7al<..huni197~ (PB 2112 5;;~)A04

"JCB/EERC-77,30 "An Approach for [:nprovlnq ~.l.mlC' - ~.lst..nt hhavlor of Rel~!O[':.1j, :cno::rete ::1:-:rlor J:H:':.ts," cy8. ~lun>c. V.V. 3er~ero And •• ? popov - "9~O IFB 290 ~~J)A06

UCB/EERC-7J3./;)1 "Tne DeveloptMtnt of Energy-Absol"::anq Devlces :01' '\S.l,. fl1.C Base I solat.lon ';yl-:'l!l!"H;." c'/ :. -"'. ~~i:"/ .anda.F. 7"'00 - 1978 1P9 284 978)AO~

UCB/EERC-78/02

:JCS.•ERe- 78/Q 3

"Effect of Ten.lie Pre5trl.n ':m t.he Cyclic Response ~f Str',Jetural Steel Connect: -~.:;.

and ~o ~ukhopadhyay - 19,3

"Experim.ntal ~.ults of an Earthqu~. Isol.~lon 5ystem ~s~nq ~at~ral R~ber ge~'

E.d>"qer and J.~. Ke1:y - l,oS ;PS 281 ?861A04

·'Selsmi.:: gehaV1Qr or ':"a:'l L.lqUld Storage Tanxs," by A. SlW4'" 1'178 'fB ':6~ ;1");. .. ..:.

"JC!l1 EERC,'8/06

otHvsteretl.C BI@naV10r of R~.1nfr)rc@d ':'ar.cr,~t.~ Col~ns SubJ~CL@j to HIgh o\Xla~ "'nd : ...by 3.w. Zaqa~l@skl. 'l.V. B~rt~ro "'r.d J.G. Bouwkamp • 19~8 (PB 2B3 ~5~lA13

"Three Dlmenslon41 Ir.ellstlc Fr3me Elements :or -::ae ~~SR-~ ?roqr.l::'l," b':' A. i'lah.:..,~.H. Powell - 1976 (PB 295 755lA04

?.oW :"f.":

';:SI EERC-7S/09

UCS/EE.C-78/10

'JCS/EER(.-78/ll

UCII/£ZRC-78/12

UCB/EERC-78/13

UCB/E£RC-~8/1S

tlCII/EERC· 78/16

UCB/£ER:-78/17

tJCB/EEAC-78/18

UCB/EEIlC- 78/19

UCB/....,.c·78/20

UCB/EEItC-78/21

tlCB/UR:-78/22

tlCB/UIIC-78/23

UCI/a:~C-78/24

UCII/!UC- 71/25

"Studi.es of St.:uct.~ral Responie to £a.rthqu;'i<e ::;round ~·1Otlon." by ~ ..:;,. Lope:t a.nd ~.K. :::~opr4 • 1:"0(?B 2B2 1901A05

"~ :..a.bor,J,tor"! 3tlJ~'I ;)f <:he rLl,lld-Structure Int;~r~C'1;.lOn o! ';l.lbmE:r,;tj 1'u.ks :1n:i =,Hs~or.s l!'l E~r-:.:,q'.Ja.j,(,-as."

by R.C. Byrd - 13~a ,PS 2R4 957\~0a

"SeiillllC Per!ormance of ~nstru=t'Jral and 5e-:ondar'l Str-..lc:.urll Elemt-nts.'· :.y 1. 3ax3!f"'CJto - :~-~

(PB8l 154 593lA05

"Mathematical ~1Od.ll inq of HystereSls Loops E.::.r Relnforced ~oncret. Columns," by S. '144a t.3.. 'r. 3pr"ol.iland J. Plnz>en - 1976 (PB 298 274lA05

"o.maq.lbllity in Exuhnq 8U1ldi"9S," by T. Ble""as and B. Bresler - n~8 (PB ao 166 3~8)~05

"Dynamic Behavior of I. Pedestal &Ase ~ltistory BUllding," bi' R.M. Stephen, E.t.. Wllion, ~•. ';. E<O'J'Wr;,I:npand ~. Button - 1978 (PB 286 6S0lAJ8

"SelsmlC Response of aridqes • Case Studi@..... by R.A. rmbsen. V. ~utt. and oJ. PenZlen - i979(PB 286 SOIIAl~

MA Sub.~ruct~re Technl~ue for NonlInear St4tLC and ~namlc AnalysLs,M by o.~. Row ~nd ~.H. Powel: 1978 (PB 288 177lAIO

"S.1••1C Risk Studles !or SAn Francisco and for the Gre.t~r San FranclSco Bay Ar~a," by :.S. Jllve~ra 19~8 IPB 81 120 115lA07

"Strlnqtll of T>_r Roof Conn.ctlon. Subjectld to Cyclic LoAds," l>v P. ~ii1I<a", R. L. ~Yel ind R. Ii.Clouqll " 1978 (KeD-OOO 14911~7

"a..pon•• of K-Braced St••l Fraae Mod.l. to Lateral Load.,M by J.G. Bcuwkamp. R.M. Stephen 4ndE.P. Popov - 1978

"Rational Des>qn Me~hods tor L.911t Equi~nt >n Structurls Subjectld to Gr~~d Hot>"no" byJ.L. Sac~ and J.~. Kelly - 1978 (PB 292 35711104

"Test>nq ot a Wind Restra>nt !or Ase ••alC Bas. llOlat>on," by J.M. Kelly &nd D.E. Cllitty - 190BIn 292 8331A03

"APOLLO - A Co.puter Proqr.. for the An.lysia at Por. Pre.sure Gener.t~on and Di.s~pat~on Ln Horl~ont.:

sand Layer. Durinq Cycl1e or &lr~hquakl Loadinq," by PoP. ~rtin >nd ~.n. Sled - 1978 (PS 292 B3SIII04

HOp~i..l o..iqn of An Earthquak. [solation 3Ylt.m," by M.A. Bh&t~i, K.S. P11ter an~ E. Polak ... 1378(PB 2S4 7J5IA06

"MASH - A COMputer proqr.. for the ~R-Lin.ar Analyaia of Vlrticllly Propaqat>nq Sh.ar _aves 1"Korj&nn~ally Layered Depoait.," by P.P. Mar~in and H.B. Seed - 1978 (P8 293 1011,\05

"Inve.tiqation ot the Elaatic Cheracter••tica of a Thre. Story Steel Frame uaing Syste. Ident.ficat>onby I. !CAIya UIcI M.D. _i".,. - 1971 ,n 296 225)"06

Reproduced frombest available copy -121-

~CB,EERC-~8/~6 "Stud~•• of StrQnq ~round ~t~on ~n TaIwan." by Y.M. Kilunq. B.A. BoL~ &nd J. P.nz~.n - ~~:8

,PB 298 436)1.06

''':CB,EE~--~, ",:.,..=1.:...: to.,1.1.r.q Teats of '1asonry 51.n~le 'Pl'US: VolulIMI 1 - H.~':Jht ":':' "'lldth R.tlO ot 2," oy P.>.. i'!lc&lqo.~.~. ~&Y.I. n.O. ~c~lv@n ~nd R.~. ::ouqh ~ 1978 lPB 216 2tl\~O~

~":9 EE~C·-~~:1 ''':'/cl.:.: ~.d.:.nq Tests ~f '1ss.:lnr( 31r.qle Plfl[S; \'oJ.'.1me 2. - He.:.~t'.t ':0 '''11t.;'' !'atlo ct ... by 5.-.,:. :~en.

P.A. Hld41~o, R.~. ~Y@5. P.W. ::otiqn and H.'. ~cNl'le~ - 19i~ I?B ~~6 2121AD9

:":C9/EtRC- ":''?/01 "Hyseeret..1 =aehaVlor of !..lqhtwelqht Ft.eln!orced ~ncr.t. geUl-(:"l;JllJJ'l SlJba.seatllaqes.·· bV ~. F~rZ.1.nl.

t.P. Popov and V.V. S.r~.ro - ~~cll 1979(PB 298 26711.06

::CB/EERC-i'9/02 "':'he i:)e".lopment of a :"IAt.~eaat1c:al Pit)del 1:0 Pred1.ct the Flexural R8spana. of bl..ofor:ed concrete &eatr.ato cycl~c Loads, U.lnq Sy.te~ tdentlti=.t~on," by J. Stanton. H. ~cNlv.n • Jan. 1~~9(P8 ~95 87SJA1J

'..-:9/EERC- 79 / O) ''!.In••1'' snd ~nL.ne..r E..rth~·.lak. Re:;pon•• of Sl.Dlple TorSionally COupled SYIt.e.," by':".:'. K4n .l.ndA.K. Chopra - Feb. 1979{PB 298 26~IA~6

';C3/E,EP.c ... 7']/J4 "'" ~.them.tl.:.1 ~dei .'f ~onry for Predictlnq lCS I'...i.n...r SelSnu..; Response C"ilracterlst~:3." :)'iYo ~nq. and H. D. Mc~"en • feb. 1979 (PB 298 2661 AC6

::~/EERC ... ':"9!"!5 "~ch&nl.C'aJ. &ehaV1Qr ,~t ~._qt.tw.1CJht Concrete Cantin.oj ~y :.lfferent Type. o! Lateral Ftelnf:lro:ement.,··~Y M.A. Manrlque, V.V. l~:tero and E.P. Popov - May 19i9(P! J01 1l4)A06

·cC3·EERC·-JI)~ "S~.. t.: T.lt Te.t. o! .' ":Ill :'jllndn:al Liq'J.d Stanq. Tank," :y R.W. Clough and A. N,wa - r.b. 1979(PB 301 1671AOE

'...'C3/E:E:Fl:C ... 7~;J7 "The 0.519" of .:iteel E:1oerqy Abaorblnq Restralnerl and 'n\elr Incorporation ln~ ~uc1.e.. :- Pt?ver Pla.nt:.!t~r Enhanced S.fe~y= Vt.-lu.me 1 - SUIIIft&ry Report," by P.~. Spencer, v.r. z.&ckay, and E.R. Pl.rJeer ...Feb. 19791'JCB(EEPC-7~/011NJ9

·~·.:9'E'E?C-"'9 1~8 "The Deliiqn of Steal Enerq'r' Absortanq R•• trainers and ~.lr Incor?Qcltlon lnto ~uc:lear Power Pl.sntsfor Enhanced S&te~y: lJ:Jl1Jme 2 ... nte 3lRvelopment ':Jf Anal,'sel t')f Re&c't~r S/'stem Plplnq,""$lmr le 3:isterr.s"by ~.C. I.ee, J. Penz.len, A.IC. C'!opra and K, .suZUkl "COmpl~x SystelP.s" by G.~. Powell. E.:". Wllson.~.~. Clouqh and ~.;. Row - reb. 1919{UCB/EEPC-19/081A10

;:~/;:ERC-"'9/:;9 ·'nt. oesiqrl of Steel tnerqy AbIOrblnq P.estralners and 'n1elr Incorporation into ~ucll!.r Pcr.rer Plmt~

for Enhanced iatety: lJol'J.lfte ) - Ev.h....tlOn of C:otNnC!rclal Steels," by \oJ.S. -:Wen, R.:·L:L ?llo~·x,

~.O. IUtel\1•• /I. F&ral, T. ·)hhuh., J. Tcpla.ky. S.J. HartllWln. ·J.F. ZAckay and E.R. Parl<er •hb. 1979 (UCB/EEIlC-79/09J 0\04

:JC"3"'EERC-'7~/lu "The oes1.qn ot Steel Energy Absorbinq ~.t.rAin@rs dlnd 'ft1e1.r Incurporat1. l!'ltO NucL.ar Power Plant..for EM.anc.d Saf.ty: Vol.,.,. 4 - A IlI!vi .. of En.rqy-Absarlunq o.V.CU." oy ~ .14. K.lly and~.s. Skinner - Feb, 19 79(UCB/F.ERC-79/10lA04

UCB/EE:RC-"'9/11 "COns.rvatislI\ In StJmlNtion Rul•• for Clo••ly Spaced Hode.," cy J.M. ;<elly and J.L.. s.C'~-,..1Il - l'W.y1979(P!l lOI ]2811.03

·JCB/EEPC-19/12 "Cyehc Load.nq T•• ts of )4a.onry Hnqle Purs: Vol ..... 3 - He.qht to W,dth Rauo o! J.5," byP.A. H,dal<J> , ~.L.~ay•• , ~.D. 14c~li~n and R..... Clough - ~y 1979(PB 301 321lA08

:':CB/E£IlC·":'9/13 "cycliC aeh.vior ;,t Den•• COurse-GrAined ~tl!["1.s.1s in Ralation to the Seisl1U.c St.lbll1.t'l of Ca.1'S," byM.G. san.r)•• , '.B. S••d and C.K. Chan - Jun. 1~79(P8 301 3731~13

UC9/EERC-79/14 "S.1SUUC Behavior jf Reinforced Q)nerete Interi.or 8e&ftt-Col~ 3ub•••entllagel," by S. V1.·.,.thMiatep••E.P. Popov and v.,. S.rt.ro - June 1979(PI ]01 32&lA!0

~CB/EERC-7'j/15 "OptilUJ. Oedqn of Localiz.d Nonll.ne..r Sy.t.... wH.... Dual !'ado", ,nee Cri teua Qlder EuthqllAk.Exci~ation•• " by ~.A. Bhatt1 - July 1979lPS SO 167 l09lAC6

UCB/EERC-79/16 "OPTOYN - A General Purpos. Op~iB1z..t~an Proqran for Prob1... w.th or w\thout Dyn...c Conatra.nta."by M.A. Bh..tt1, E. Polak and K.S. P••~.r .. July 197.(ps RO 167 091lACS

UCB/EEIIC-79/17 "ANSR-II. AnAly.1. of ~nline&r Structural lie. po..... U.en ~ual." by O.P. Ibn&u and G.H. Pow.llJuly 1979 (PS 110 113 lOll ADS

IlQ/EERC--"/18 "Soil StrllCture [nt.r&<:~ion in D1lferent S.Ua1C EnYiro....nu.· A. "=_I:-MAe8O, J. Ly._r, J.-C. Olenand H.B. S••d - Auqus~ 19791P1 80 101 520IA04

UCB/EEIlC-79/l'i "AlUlA ,.,eleb tor EArthquake Gl'OUAd :olOt1onl." by /I.K. Chanq, J.II. 1Ooi1a~ow.k1. R.F. NAu. R.M. Oliver.and K.S. Pilt.r - July 19791 .. 301 166)A05

UCB/EEIlC-79/20 "Hy.teret1c: leh.vior at 1lI!1ntore.d Conc:rete Structural 1I&l~I." by J.M. VAll....... V.V. lertero andE. P. l'op:>Y - ""'lust 1979(PI 80 165 90S) Al2

L'CII/EERC-19/21 "Studie. on Hi9l!-Freq....ney Vibr.t1..... of lui1dinql - 1: ",. O:>IUll'l Eff.~." by J. l.IIbli.l&r - "lI9118t 1'j79IPB 80 lSI 553) A03

tCI/EEIIC-79/22 "Effec:u of GaUralized toadinq. On Bond 1Ie1nforc:inq e.n Ellbedeled in Conf1ned Concrete lloc:kI." byS. V1w..Ch.....tePA, E. P. I'Op:>Y &lid V. V•••rtel'O - Auquat 1979 (PB Bl 124 0181 Al4

lICI/DRC-79/23 "Shaldnq Table Study of S11191e-StDry Muoftry 110..... IIbl.- I: ~.~ Structu.res and 2.· by P. GIilk.an.R.L. Maye. ~d R.W. Clouqh - Sepe. 1979 lHUO-OOO 176])"12

LQ/DRC-79/24 "Shut..., Table Stu4v' of li...,l...StDry _-.y 110..... 11121_ 2, !Mt S~r1ICtuno. 1 and 4." br P. GW.kan.R.L. Map• .and R.II. Cl""'lh - ..~. U?9 (IMl-OOO lU6lAlZ

i lD/URC-79/Z5 "Shakiftq Table Itu4v' of U""l...ltory MuoftIY 10_. _1_ 3, l-rv. 00nc:1..1_ .and "_dat1ona."by R.II. Clouqh. Lt.. ~• .and P. Gii1Itan - Sept. 1919 (IIUO-OOO 18]71Al)6

-122-

UOlfttRC- '79f26 "~OO_n4&tl01l. tor a U.S .-J.p&I\ Cooper.Uve Re•••rch Proqru t:tl14Z1l1q t.arge-Scal e Teeung ,ecl14 t,....by ;].iL-J.p&I\ Pl&llning Group - S.pt. 1979('1 )01 4071A06

liCB'EERC-79;2' "Earttlqualte-Induced Llquet.cuon _.r Lake l\II4lUtlan, G,..t...la." by H.B. Se.d. I. "r.."go. C.K. Clan,.... ::oom.z-M.l..o &lid R. ~rant ~....eoh - Sept. 1979 (NUFlEC-ClU 3411 A03

UC5. EE~-"~,2S "Inf1ll Pan.ls: Th.lr Influence on S.ls_ic Respons. of BU1ldlnq•• " by J.~. Axley and '.V. 3erterOSept. 1979(PI 80 163 3711 AlO

UOl,EEAC-'9ng ")0 'l'ru.. Bar El_nt (!'ype 11 for the ANSR-I! Progr...... by O.P. ~r.dkar and ;.rl P""eU .. ';OV. 1979:!'!! 80 169 7091 A02

:Jal/EERC-~9130 -20 1.__C01....., El_nt l'!'Ype 5 - Parall.l El ....nt Th~ryl for the AHSR-n Program." by D.G. ~,~.H. Po",.ll &lid D.P. Mondkar - :lee. 1979(PI 80 167 2241"J3

U:BfEEPl:--9:J1 "3C Be._C..:ll\llllll El...nt ('!"/pe 2 - Parallel El....nt Theer/! for the MSR-n Prog..... " by .... lUahl.G.H. ~.ll .."d D.P. Mondkar - Dec. 1979(PI 80 167 2l61A03

t:Cllf EERC· 7913. -On Re.pon.e of Structur•• to Stationary Excit.tion." by A. Der Klureghlan - Dec. 1979(PI 80166 ngl;>'o)

UCB/EERC-79133 "Undaturl>ed Sa:nphng and Cyehc Lo.d Testinq of oanela." by 5. Su,qn, H.ll. oeeo and :.~. :oan::lec. 1';o79("DA :)87 2981A07

~C!I'LERC-"9/14 ":nterac:tlcn [(tect.;)! Simultan.:>aa 'TOrsIonal and Compr.'llOn&l C'/Cll': Loadlnq =f ~.nd.·· oyP.M. "jr~~fln and ~.N. K,:)usron - [)@c. 13i9\ACA ]92 352),\,15

'JC8; [ERC-"C I 1')1 "E'ar~hq'jal<e Fl.espons'! of C:)ncrete -;ravltv DUO's tnc~'-JdLnQ H·rdr'">dv1""I.n'llc 5nd F'':'l.Jn1"t.::.?:. !nterJ.ctlonE!!ects," by A.K. Chopra. ? :~4kr£ba:tl And S ~l.Jptl - ~4n, li8~lAC-AC8~2971A12

C':9/EEFl:C ... .,,:',02 "J(ock~nq Response of ?lqlj BlOCKS to Eartnq'.lai<III!I,' by ': • .5, '{un, r\.'!. :nopra and ;, Penzlen'" "':a.r.. i:tovI r:'8H!:" 1~6 0(.2 i ).(14

UCBfEERc-ao/ ~4

UCB/EERC-AOf1S

';(3. EERC-aOn6

UCBiEERc-eO/~7

UCI/EERc-aon8

"Opel-mum rnelaS':lC o.slqn of Selsml:-ReS15,=ant. ?e:.n!.,rced C,..)ncret:.e FrU"~ ';t.r'.J~t.\,;,re!l," 0'/ .i. iI. ZagaJ@skland '1.'f. Bertero - JaR. 19~0(PB80 164 6351A06

"!ttect.s of Amount &lId Arran<;Jement of ';II.Il-Panel Relnforcement <:In ii,st.aret.le BenaVlor of ~eln:orced

,:oncrete ...111," by R. 1111'1, a.nc! '.1.',/, eertero - reb. 198CI~88~ l~ 525lAG9

"Shak1.nq TAbl. Re•••r':h \In Concret.e Dam "'\Odel.,·· by ~, N1WI and R.ilI. Clouqh - Sept.. l-j8,:;(r8l3:' ~;;" 30di';"';'

"'!'he D@Sl'}" of Ste.l Ene!'qy-At.50rclr.; Rest.ralners And ~he:.r In:orpoca-t.l.:Jn lnto ~l.Jcl~ar ?o....e[" ;:-:'ants forEnhanced SAfety ('_'o1 1A): ?lpi.ng wlth Energy AbsorbJ.nq Restrai.ner.: Pa.rl.~_et.er St.-..:dy on :;r\4l1 ~ ...·stE.m5,"by I~, H. Powe 11, C. :)uCI'hour llan and .:. Sl!'nOns - June 1180

•• In.last.lc Torsi-onal Response of St.ruct.ures Subject.ed t.o £a.rt.hq',,1Ake :lround :-1Ot1.ona." by 'i. 'iAmaZaklAprll 1980(P1l81 122 3271"08

"Study ot X-Brac.d Steel F'rame Structures Und.r Earthquak. S1mul.tl0n," by Y. Chan...t - Aprll 19.0(P88l 122 3351All

UC8/EERC-80/12

UCB/EERC-aO/13

UCB/EERC-60f10

UCI/EERC-80fll

\1Ca/IERC-80f17

UCI/EEIlC-801l8

UCI/EEAC-80/14

UCI/EEIlC-80/1S

UCI/EEIlC-80f16

UC8/EERC-80/~9 "Hybrid !1Od.lllnq ot Soil-Struct..re Interactlon." by S. Gupta, T.~. Woll. J. Penzan and c.o. 'tenMay 1980(P881 122 )191A07

"~n.l'.l Appllc&bJ.lJ.ty of III ~nl1.n •• r "1Odel of a One Story Sit•• l Frame." by B.I. SVe1n_son andH.D. MeNiven - :i4y 1980(P181 124 a77 ....06

"A core.n-F'unctlon :1ethocl for ·~.ve Interactlon "'lth • SUbl!lerged SOdy." by W. Kloka - Apnl 19~u

(P881 122 269)AC7

"Hydroclyn_lc Pr.ssure and ;>.dded :la.. for Axis.,....,.trie Boclce•• " by F'. :.&llrat - May 1'?eO(PB81 122 HJ)~~

"'l'r.atlMlnt ot ~n"LI~.ar Drag F'orees Aetin1 or. Offahore Pbtfor1ll5." by I. V. Deo and J. Penuen~y 1980(P18l .5) 413'''07

"20 Plane/Axlaymmetrcc Solid El.ment (Type 3 - El.atic or El.stlc-P.rtectly Pla.tic) for the ANSR-I'Proqra.," by D.P. ~ndkar and C.H. Powell - ~uly 1980(P18l .22 350'A03

.~ Re.ponae Spectcu" Method tor Randa. Vibration•• " by A. Der Klur.qhian - Jun. 1980 (PB81 122 30l1AO)

·Cyclic Inel••tic luckling of 'l'Ubul.r Steel Ir.c..... by V.A. ZAyaa. E.P. Popov and S.A. MAhlnJune 1960(PI81 124 8851AlO

·Dyrla.ic Re.po".. ot Sl"'Ple .....ch OUla Includinq Hyc!rodyn_lc Inuraction.· by': .5. Porter andA.K. C~a - July 1~O(PI81 124 OOOIAll

·Experi.-ntal Te.tlnq ot a FrictIon Da8ped " ••ismic Ia.e lsolAtlon Sy.teM with rail-sat.Charact.ri.tic.,- by J.M. Kelly. ~.E. Beuck. and ~.S. Skinn.r - July 1980IP881 1~8 59S)"04

UCI/EERC-80/l9 ·The c..iqu ot Ste.l Enerqy-Absorbinq Re.trainer. and their Incorporation into Nuclear Power Plant. fortAh&nced S.f.t1 (~l lit, Stocha.tic Sei.mic Analy.e. of Nucl.ar ~r Plant Structure. and PlpinqSYlt... Subjected to Multiple Suooort Excitation•• " bv ~.C. Lee and J. Penzl.n - Jun. 1980

UCI/E!RC-80/20 "Th. o..i9n of St.el Enerqy-Ab.orblnq Ra.traln.r~ .nd their InCOrporation illtn Nuele.r Pover Pl.ntlfor Enhanced Saf.ty IVol lCI, N~rical ~thoa tor Dyn..ic Subatructure An.lY.la.· by J.~. D1Ck.n.and E.L. Wilson - June 1980

UCI/E!IlC-'30/21 ·The o..i9l\ of UHl Enarqy-Ab8Clrbinq Re.train... and thur Incorporation into Huclear Pover Plantotor Enhanced 5.f.cy (vol 21: Devel~t and te.ting ot ...tralnc. tor Nucl.ar Piping Sy.t.... " byJ.M. ~lly and M.S. Skinn.r - Jun. 1980

UCI/ElJC-10/22 ·3D SOli4 11...nt (Type 4-ll••tic or fl ••tic-Pert.etly-Plaltlcl for the ANSa-II Progr... • byD.'. Mandkar and G.H. Powell - July 19801PB81 123 2~2)A03

UClIIaJIC-80/2J ·Gap-rUet1011 11_t (Type SI for the AIlSa-II PrOOlr_.· by D.P. Mandkar and C.H. 1'oW11 - July 1980(...1 122 21SIA03

;"'C9 ;:EW;-, ].I

. :3 F.E?~-~: J,

C':3, EEP:-.,,"'I JIi

-123-

:""CS/~ERC..a'J/~4 "'0°-gar RestrJ.lnt Element IT..,p. 11) for the ANSR-II Proqr&ll!f" by C. JuqhO'JcllAn .and G.H. P?Wel~

cul, 1990U'B81 112 29JlAOJ

:"C9/EE~C"-!J:;/,,5 "':'estlnq or • ~~.t..Jr.l P~b~r 3 .... Iiolatl.on Syat•• by an Expio.lovely SUllulated E.rt.hq'.J..k.... ty:.~. K.lly - Auqu~t 1980,PB81 "01 J60JAC4

\.:C8/[ERC-';Ol.2€l "Input Identlh,c&tion ~rom Str:.JctaraJ. ':lbrat1.or.•l Response," by Y. Hu - Auqult 1980(1'881 152 3':S)AC5

:,,;':8,'EER::·.,):.. ";>lcllC' Inela!t.lc Sehavlor :,! :;te.:' )t'!shcre St;.r'Jc';\lr••• " b',t '-l.A. Zaya... S.;". ~..r.1.n s.r'.d t.P. ?opovAugust. 198~\?B81 196 ld~I~15

_:8. EER: .. a"),::et "£ha,unq Table T••t~nq of 4 ReLn:o["ced :oncr.~e :ra.:r.. ·... Lt.~ 8.l.&Xlal Re.pons.... by ..,.~. CllV&)Ctober 1980lPB81 154 J04'A10

'JCB. EERC-;;n 29 ":lynamlo Properues of • Twe1ve-Stc.ry Pr.,f.bnc.Ud p~.l Bulld~nq,· by •. ~. Bol.lwk"'~, J.? l:Olleqq...anj R.~. Stephen - October 1980.'Ba: :J~ 1"81~06

:"C9,EER('-'1;) ];~ ··'.J'1nU\lC rrQp.r~l•• of an El.qht.-St.ory Prefabcl.cated Pan.l 91.l1.1d1.nq," 0'/ J.:4-. BouwkAll'lF • .l.r. Kol1eqqerand R,~. S~eph.n - Jctober LQ8CI?B81 200 31JI~05

:':C9,.~t~':-~0, 31 "Pred .... ctlve :lynuu.c ~.spor.•• ot Pinel "'1pe Str'.lctutel:Jnder E4rt.hquakes," b:r .=.F .•. ,:. ~ne!' ar.d:.~. Bouwk~'F - OCtobe( l~8JiP8dl l52 3l~IAJ4

·.:~9,'EtF.::-~·jI32 "":'he ')es1CJ:-:' ot Steel ~nl!rqy-Absorblr.g P.eStr.lners .nc the~r ::ncorpor.tlon lnto ~;·..C'leJir ?o ....er Plan':5for Ennar,ced :5afet·,. (Vel 3': :'eStlnq ot ~ ,m.":'t:-r:li: Steel~;,.n :"ow-':,cle Tor:ilona.. ['.J.t:":jUt." [;1

~ . .:"~"'''-·r. LR. parker, f. ~·cnqew...r1 and ~.,. Dr':)r:,

d;.:-o:\.:-~ 'J 3 "":'nl:: ""' ....:d.. ..:i!l at Steel. t:ner;",'-M.D~Gr::l1n; Reltralners !n~ t:"1elr :nc'Jrpor.t1.on lnt.o ~\lcle.r L ..... .:;::( ?J..sntstoe £nhanced ~.fcty ,vol ~): 3~.i<L:"lg Tab1. '!'.ests :It ?l?ln~ :'jstt:of"lS w:.tn Energy-Ahsorblnq ?..e~tr,], ..neri."by .:i.F, .itlemer and W.:;,;odden - Sept. L9BO

'''r~e :'es.gn ':If 3tl!!eL Ene!'qy-AL'sOrblnq Re!itr&l:l~rS ar,j thelr Incort";or.J.t.lon .lnt.o :Jucl ••r ~ower PlAnts~or Enhanced S.fet., I VQ! 5) : 5~r.I'l'I.ari' Report." by P. Spencer

"f.xperlm'!tnt3.1 '!'e!ltlnq of a.n E:nerQy-Absorb1.nq e...e: lsol4.t1.on syst.em,·' b'~' ::.'1,. Kel:y, ~~ . .:i. S,kl;.r.er s.r.3K.E. e.'Jcke - OCtOb(:I ~98c.{PB81 13.j, 0":'2)"04

"SlmuJ.4tlr,q .fond AnalyzL,q Art.lflcJ.&l SOn-Stat1.0n.srj' Eartl1qua.ke ;round 1otlons," by P.r, ~Jau. ? •..,. Jl.:.'/er.nd K.5. P"ter • 0ct~b.r 1980(PB81 153 397lA04

L'CB/EERC-dO,!); .. t4rt:hqu..k~ [email protected]:.~g at Berkele'j - 1~80." - ';.pt. l'-1tt i)(PBu.1. ; ... j; "J-4)A09

·.:,:6,-EERC-ar:.:'/J8 "Inelastlc S€!lsmJ.C AnllY~lS at :...tr'le Pinel Bl.aL:hr:q•• " by v. 5cnclcker ann :;.H. fowel.1 - 5ept. 1980'?1l81 154 338) ~lJ •

r;'.-S/EERC-dO/39 "~n..nHc Response or ElftbanluMne. Concrete-Cravitj' and ArCh ~Ut5 Includl.r.g Hydrodyn&lflll; Irt~r.ct1.on,"

by J.F. Hall .~d A.K. C~opr. - October 1980lPB81 152 324lkl1

~Cel[[RC-~0/40 .. InO!luuc lluckl1nq of st••l .itr·Jts 'Jnder Cycllc lD.d Rev.rsal,· by P, ~. chck, .~. A. W.,nqer andE.P. Popov - OCto~r 198CIP1l81 15~ 3121A08

'';CBiE:ERC-aC/.&l "tnfLJence of 51.te :-h••.·.cterJ..tlc. on BUJ.l(hnq oamaq. During the October 3. 1974 u.~ E&rt.~quaj(e.'· byP. RepHU, , 1. .:<ranqo and H,B. 3••d - S.pt. 19BoltBa1 11;1 'J9)~05

'..,;c8/F:EP.C-~O/"Z "EvaluAt.:.on af '" Shakl.nq Table -:'.St Pr~qrsm an Respon:lie 8ehavlor ot a Two Stary Reln.for:-ed ':oncrete?f&Jne." by';.:'!. Blondet, R.W. -:louqh and S,A. ~a}lln

LiCB/!:.ERC-eC/4J "~odeLJlnq of S01i-Str'.J,cture Int.er.sction by Finite an::! Ir.f1.n.1te E:el'!l~:1t~." b'i F'. ~~edln4 •Dec.mber 1980lPB81 229 270lA04

~CB/EERC-81/01 "Control of S.iamie Reapona. of P1pinq Syat... and Oth.r Struc~ur•• by ea•• Isol.tion," .dit.d by J.~.

Kelly - Januu., 1981 (P1Ill1 200 7JSI~OS

:.JCB/UPC-81/02 ·OP'rll$I'. - M Int.racti". Soft_n SV.t•• for Opt.i_l o..i9" of StatlC.Uy an4 Oynaa1c.lly l.Oa4edUnac:tur•• with Nonlin.... Re.pon... • by M.A. Bhatti, V. Ci.... t and K.S. PiatAr - January 19811'881 218 85111009

UCB/Z!RC-Bl/03 ·~ly.i. of Local Variation. Ln Fr.. Fi.ld S.i.ale Ground MOtion~." by J.-C. on.n. J. Ly...r and K.B.seed - January 1981 (AD-M99508lAll

UCB/UIlC-81/04 ·l".lal~ic Struetural ~linq of Sneed Ofb""r. 'l.do.... for 5eilllic Loading.· by V.A. ZAy.. ,P.-5 ••• Shinq. 5.10. Mahin and E.'. Popo~ - January 19BIIP882 llB 7771A07

UCBIEEIlC-81105 "Dynallic lIe.pon.. of Liq' .:qui~nt. Ln St.ructur••• " l)y A. Der K1uraqhJ.an. J. L. kckMn and B. Nouroaid - Apr11 1981 ('881 21~ 49711004

t1CB/EERC-81/06 ·Pr.liaJ.nary !xpari_ntal InYl.Uq.Uon of • Broad .... Liquid Storaqa Tank.' by .1 .G. BouwkAJnp, J. P.Kolleqqer and a.M. S~.ph.n - ~y 1981"S82 l~O J8SI~03

UClJIEERC-81/07 "TIle SeiaJUc 1le.11tant DeI19" of ReinforCed Concnt. COupled Structural WAllI.· by A.E. Aleun and 'I, II •..rc.ra - June 19B1l'1.2 ~13 3581A11

UClJ/EEIlC-Bl/08 'TIle IIn4rained 1"'.ri"9 Ile.iatanc. of Cohe.iYe SoUl at ~rqa o.tocaaUona,' by 1I.It, P\,l.. Uld H.B.seed - A...,...t 1981

uc:a/UIC-81/0t 'lxper18antal ....."'1or of a Spacial Plpi1\9 .,._ with Staal 1nar9J' llbeo.....r. lubjac:ted to • It.1laC.dDilt......t.1a1 lIi.-1c Input," by I.F. Sti~. W.G. aocIden and .1.11. bUy - July 1981

-124-

UC&/EEIIC-81/10 -Evalution of Seiaaic De.i"" Provision. for Ra~ in the United SUte•• " by ••1. SveJ.D8son. R.L.Rayes and H.D. MeNiven - August 1981 CPB82 166 0751a08

UCB/E£1IC-81/11 -'!'«>-Di_n.iona1 Hybrid ltocSeUi.n9 of Soil-Str1Ic·~e Inunction." by T.-J. TeonCJ. s. CuptA and J.'en&ien - Auqust 1981(PB82 142 1191A04

t1CB/EEIlC-81/12 "Studie. on Effects of Infills in Sei_it" ,,",.1s~t IVC Con.truction." by S. &rokk..n and V.V. Bert.ro septe~r 1981 (;B32 166 1901aO~

UCB/EEIlC-91/13 -Linear ltocSel. to Pr.dict the Nonlinear Seilllllic "havior of a On.-Story 5t_l Fr_.- by H. Va1d...r ..on.A.H. Shah and H.P. MeNiv.n - Sept.-ber 1981 (P882 138 79311107

U<;;8/EEIl<;;-81/14 "TLUSH: A CClIIIputer Pr09rU for the Thr••-DJ.mendOll&l Dyn&l!l1t" ......aly.u of Earth Du•• ," by I. llAc;awa,L.H. Mejia, H.8. se.d and J. Ly._r - septelllber 1981(PB82 139 940)1\06

UC9/EEIlC-91/lS -Three Di_nsional DynAmic Response Ana1y.is t. Earth Dams." by L.H. Mejia and H.8. Seed - Septpnber 1981(PB82 137 2741A12

UCIl/EERC-81/16 -Experim.ntal Study of Lead and Elut......r1c Duoper. for ea.. IsolaUOft Syst.lI1s.- by J.t!. !(aUy ar.dS.Il. Hodder - October 1981 (PI82 166 182)A!)5

UCB/URC-81/17 -'nM! Influence of .... Isolation on tbe Sal.-iC "spons. of Liqht S.condary Equi"",el\t ,- by J .M. ICally April 1981 (P1I82 255 2661A04

UCB/EERC-8l/l8 -Stwli.s on Evaluation of Shakinq Tal:lla lIe_pon.. _ly.i. I'roc.dur••• • by J. tlarcial Blondet - Nove"r1981 (.892 197 "8)Al!)

UCB/EERC-81/19 -DELICHT.5TRUCT: A COMpUt.r-Aided o..i9ft Envir~nt for Structural Enqineerin9.- by R.J. Ba11in9.It.S. Piner ."d E. Polak - Decelllber 1981 (P382 2la 496)A07

tIC8/EEIIC-81/20 -OpUmal oes1;n of Sei_ie-Re.istant Planar StHl rr_a,- by R.o!•••111n9. V. Chllli'i.. It.s. Piner andE. Polak - Deceaber 1981 (P892 220 1791A07

UClI/EEIIC-82/01 -o,n_ic "Mvior of czouncS for Se.u.ie Ana1yala of IoUe11M sy.~," by T. $ato and A. Del' !U.ure~hilln January 1982 (P882 218 9261A05

Dal/EEIIC-82/02 -Sbakinq 'fable ~.te of a TutNlar se-1 rr_ I1Dael.- by Y. Ghanut and Jl. W. C10. - January 19e:'Pal2 220 1611AOl

UQ/DIlC-82/C3 "'!lavior of a 'ipin9 Sya~ Uftder Seisa1c ExcitatiDn. bper~nta1 In....t.i9ati''''. of a Spatial .1...n9Iyste. .upported by Mchanical Shock Amstors ...d .tee1 ErIervy AbllOrbin9 Devic.s under Seismicbcitatian.- by s. 5C'-loSe". H.-II. Lea end •• G. Go4cSeD - llay 1912 (...3 172 544IJlQ9

UCII/ZEIIC-e2/lM -_ Approac.... for ~ ~c Analyai. of Lar.,. scnctural syu_," by E. L••11_ - June 1982('183 148 080IA05

UCII/EEIC-U/05 -lIodel Study of Eff~. of 0DAge OIl t:M Vu.raUca Propertie. of 1_1 Offsllon P1.tfo~.- by1'. Shahrivar and J. C. IIoUWItup - .1_ 1982 ePen 148 742lAlo

UCII/EDIC-e2/C6 -State. of the Art and Practice in ~ Opt;'" Sei.-ic De.i9ft and Analytical ......-.. 'rediction ofIVC Fr__ll Stnact..... - by A. E. Aktan and V. V...n.ro - July 1982 ('B83 147 73611105

DCII/I:EIlC-82/01 "Further Stlldy or tIM Earthquake "IIJIlIIIH of • 8ftlad Cylindrical Liquid-Stor• .,. TaDII 1lode1.- byG. C. llanos and a••• Clouqh - July 1982 (PBS3 lC7 7441All

DCII/EEIlC-82/08 -An BYaluatiOll of the De.iCJl\ and Analytical seu.l.c ".pen.. of a ....n Story "inforced ConcAtePr_ - _11 Structure, - by F. A. OIarney .ncl V. v. Bertero - July 1982(n8! 157 6Z811lO9

DCII/EERC-82/09 -F1uid-Structur. Interaction.: Added Mas. CoaputatiOll. tor IDcCla;lresaibl. nud.,· b,y J. 5.-11. ltuo "'"'Ju.t 1'112 e",l 156 281)1\07

0C1I/U1lC-82/l0 -Joint-()peni"9 Nonlinear Mechanisa. Interfac. SMarecS Crack ltocSel." by J. S.-H. Xuo AUCJ\let 1982 1.183 149 195)A05

DCII/EEIlC-82/11 -Dynaaic ".pon.. Ana1yaia or 'l'eClli 0-," by a.•. Clouqh. a. It. Stephen all4 J. S.-B. Xuo A\I9IlSt 1982 (Pal3 147 4961All6

ac:lllb:llC-821l2 -Predictlan of t'" ..ia.l.c: IIespor.••• of J/C rr--COu1l1ecS Wall Structure•• " by A••• AkUft. V. Y•..nero aDd ". 'lazu - AUC)1ISt 1982 4P883 149 2011'lO9

uc:B1EE1lC-82/U -Prelimnary "port on the SlUIRT 1 ItrOft9 JIIotiOll Array in Tai...n. - by •• A. Iolt, C••• toll, :J.Pend.n. Y••. Teai ancS Y. T. Yall - A\l9Ust 1982 '1M' 159 400IAlO

uc:B1El:1lC-I2/lt -Shal<inq-Table StlllSi•• of an Eccentrically X-Braced 510..1 SUuC~un," by It. I. Ya"9 - "ptellber1982

uc:B/EEIlC-U/15 -n-. hrfo~e of .tah....y. in Earthquakes.- ~ C. ibM. J. W. Axley ancS V. v...nero - ..pt....r1982 (PM, 157 691)1107

uc:B1D1lC-U/16 ",.". Behavior of .lIbIwrgecS l'lu1tip1. 1o,11.s in Earthq..lle., - by •• -Go LillO - ..pt.. 1"2 (PM3 151 709)""7

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UCB/!EIlC-83/11 ·Etfee~e of c:..nc"~. Typ8. and Loadi..., condltion. oa Local 1oII4-IUp "laUon.bipe.· by A. D. Cowell.1:••• .....,., and V. V. "rUro - saPta8lNI' 191~ 'PM3 153 5771AD4

UCB/!EIlC-83/18 ·....,haIlic:aJ. IlahAviol' of IbMI' ..11 V.l'Ucal Boundaq .......1'8, All EJql8rl_tAl IrilranipUon.· byII. t'.......... and v. V. "rUro - OCtGbar 1HZ ' ..83 159 7641Ilo05

1I01EE1tC-8U19 ·EJql8r~bl St\l41a. of ~U-."PPOrt ..bali.. Loa4iA9 en Plpi", aye~._.· by J. II. blly andA. D. Coooall - .........r IH2

1IO/EE1lC-82/30 ·co.n.raUaad 'lutic II1nqa COftc:apta for 3D ..-0.1.... E1e...." •• • by •• '.-a. Olen and G. II. PoVall llovelaber 1982

tICIl/EEItC-82/21 • AIlSa-III , Genel'al 'urpo.. co.putel' 'rovr- for lIoft1in....r structural Aft.1y.b.· by c. V. O\acJhollrHan....s G••• Powl1 - IIonaIber 1982

llOI/!EIIC-II~/~3 ·SOlu~iclft lua1:891•• for StAticall, r.o..s.s _lin.aI' I_~ure••• by ,1••• 11_e and G. H.......11 """'1' 19112

llCB/I:I:IlC-IIZ/Z3 ·_lytic:aJ. 1104.1 of Dafonad lu Ilftc:hor.9U undel' GeUI'aJ.i&ed bc:itA~ioft•• • by V. Ci....i. _.SU9da_. v. v. lutero aIl4 E••• PopoY - .....aIIa&' 1982 ("'3 169 532)1lo06

tICIl/l:l:ac-82/Z4 .1\ IIatloa_"lcal """-1 fol' tIw leapcm_ of IIUonq ••U. W DyIIul.. EltClb"lon•• " by II. Suc:u0911l.Y. _.i .... S. D. HcIIi..... - ............. 1982 (..83 169 011)1101

0CIIEE1lC-82/26 ·Claepubu-aJ. Ml>4ala for Cyclio 'la.Uo1ty. lata IlIIpudwlce .... Cr_p.· by I. Iloaaddad and G•••~1l- .......... 1982

UC8/D:1lC-82/27 ·IMlu~10 llAa1yal. of Pipla9 and '!'Ubu1ar I~....... • by M. Ilabullftraoll.1 and G. H. '-all - 110..-..1982

1IO/lZ1IC-83/01 .'!ba t:conc.i......1bUity of lelaa1c ..baI>UltAtlOll of lui1din9. b:' Rue bol.ti.... • by J. It. bU, January 1983

uca/lZ1lC-83/03 ·sal.-1....." COMec1:1ona for ......."-...bt1D9 Staal lr_•• " by E. P. Popov - January 1983

uca/lZIlC-83/03 ·Dael9ft of L1IIII:. aIId .....to-Ool-. ~ioft. fol' 1 .._td...11, Inced St..1 'r_e." b, I. Po .".OYU>ll J. O....Uey - January 1913

OCII/UIIC-83/04 ·_1caJ. '1'ec:ba1.,... fol' UIa I:9a1_Uan of IloU-ltNCture tntenc:Uor -tfeeta in UIa TiM ~in.·

~ I. "yo and S. L. 1111_ - rebEuary 1983

tJa'/IEIlC-I3/05 ·A~r for .........in9 ~be Intea>a1 ~. in tIw Col_. of rr_-wall "intorced CDncnt40.~•• br' .. - ....s v. V. "rta~ - ..., IH3

OCII/EZW:-I,/OI .Dpaaio Jrourat*l...._~n_~ Ice ...a orr-bo..."""ctun••• by •• a<>taau - May 1913

OCII;'I!Z.o-13/0'7 .DJM-ic Mal"ab of MII1Upl, 'f\.-I U>ll ~lt:l:ad1J' ......... --..sary .,..-." br' ,.. 19uaaand A. ller tiureqhiloa - oJ'JIle IH3

OCII/IEIlC-I3!011 ·A LaIIocatMY Rudy of .......... IIII1U-bo4F .,._ in~••• by G. a. -n - ".. 1113

uc:a/DIC-a31O' -Sffec:b of t'naden" ro.edatian 17pU~ _ Iarthquab ".pan.. of ftnctan•• • br' C.-I. 'ria an4A. K. 0Iapn - ~ 1113

OCII/IZJIl-13/10 .q.t1aa1 o..1l" of hl..U ......nc:e4 h_. IIIldu ..1-.10 ~,. by II. A. Jlu8till and K, I, plateI' ~1.3

OCII/IZ1IIO-83/11 ·1bakboJ 'ftbl. Itud7 ot 'iatle-1tOZy --..,. 1Iouae., Drn-i" ftl'r- under '1'Ilne ~nt"1am.o 1Ilpu~ aD(, --..seUana,· br G. C.......... a. II. C10UgIa aIl4 It. L. Ma,.. - J ..... 19113

uc:a/DIIC...3/13 "IJlIl8rL.atal ...... llAalytice1~ of tIw 1Iodlanic:aJ. Cbazw:tarL.t1c. of • l/5-ac:ale Model of a7-atory ~~U ...uti". Itzuctuze.- br A. S. ~. v. V. "1'_, A. A. C2Ic>oolIhI&ry an4,.. 1I&9UlIia - ....t 1113

~31l4 .~~ 'lHu of ur.......l _R ~te IlallAUftt Iya"- Aaaeel>1ape,· br II. G. OILYe anda••• Cl.outh - JlDguR 1113

0CII/DIlC...3/1S •..1-.c .....Y1w of MUft ... LiIIJIa in lIccMu1ca11y InIMd ....... " .. It. D• .,.1..u4 ..... I. P.JIoIoC" - J\aly 1.3

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UCB/DllC-83/18 -Jnte~.et1". COIIIlUter Analyl1a IIKhoda for P~ctJ.1l9 the lReI••tic Cyclic .....vior of SectioN. - by8. Ilaba an4 S. NaMn - July 198)

UC8/DllC-83/19 -ZfrKte of IIClnd Ileterlo~.t.lOft on IlyatenUc .....¥1o~ of "lnforce4 Concrete ,J",lnh,- by F. C. Filippo1:. P. PopoY aM V. V. Berten> - A....t 1983

1JC:lIftZIC-8V20 -Analytical an4 ZJIIl8ri_tal Correl.tion of Lar<Je-.....1 Preca.t Build11l9 Syat_ 'erfo~..ce. - by fl. G.ou..... N. Clou9h. M. Ve1llov. P. Gavri10Yic and 3••etrovski - JIoy.....r 1983

UCII/DJC.8J/21 -Mecbllnic.l OauacterlaUca of t.M Materiala Used in t.M 1/5 SCale .nd rull Sc.le Modeh of tJo.. '-Stor"lnfolCe4 concftte 'I'IIat Structun.· by V. v ...rtelO. A. 1:. Aktan ..... A. A. ChoordhlU}' - SapU__r 1913

llCII/DJC.U/22 -lIPrl4 Modelllll9 of SoU-Structure Interactl_ in l.ayere4 1Ie4J.••• by !'.-3. Taoll9 end 3 .......'.n OCtaber 1983

UCB/EERC-83/23 "Local Bond Stress-Slip Relationships of Defomed Bars under ~neralized

Excitations," by R. E1 i gehausen, L P. Popov and V. V. Bertero - October 198

UCB/EERC-83124 "Design Considerations for Shear Links in Eccentrically Braced Frames,"by J. O. MR11ey and E. P. Popov - November 1983

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