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Seismic performance of high-strength steel eccentrically braced frames

with low-strength removable links

D. Dubina1; A. Stratan; F. Dinu

Department of Steel Structures and Structural Mechanics, Faculty of Civil Engineering, Politehnica

University of Timisoara, str. oan Curea nr. !, "##$$% Timisoara, &omania

Abstract

Structural damage in buildings designed according to the dissipative philosophy can be

significant, even under moderate earthquakes. epair of damaged members is an

e!pensive operation and may affect building use, "hich in turn increases the overall

economic loss. #f damage can be isolated to certain dissipative members realised to be

easily replaced follo"ing an earthquake, the repair costs and time of interruption of

building use can be reduced. $ccentrically braced frames "ith removable links

connected to the beams using flush%end plate bolted connections are investigated. &igh

strength steel is used for members outside links in order to enhance global seismic

performance of the structure, by constraining plastic deformations to removable links

and reducing permanent drifts of the structure.

Keywords

high strength steel, eccentrically braced frames, removable bolted links, seismic

performance

1

' (orresponding author. )el.* +- /0 - 2-$%mail address* dan.dubina3ct.upt.ro4Dan Dubina5

1
mailto:[email protected]:[email protected]


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1. Introduction

According to modern seismic design codes 4e.g. $6 1227 819, A#S( --/ 895, design

of buildings is carried out for t"o limit states* :ltimate imit State 4:S5 and

Serviceability imit State 4SS5. )"o earthquake ha-.%-./ "ith respect to the :S event5.

For ordinary occupancy buildings, the fundamental requirement at the :S is to assure

life safety of people by avoiding local or global collapse of the structure 819. #n the

design of dissipative structures the behaviour factor q is used to reduce the elastic

response spectrum to the design one. )he components that contribute to the value of the

behaviour factor q are related to structural ductility, redundancy and overstrength. arge

values of 'factor are specified in codes for ductile structures like moment resisting

frames or eccentrically braced frames. Structures designed using large values of

behaviour factor 'are e!pected to e!perience considerable damage under the design

seismic event, making repair of such structures unfeasible technically and economically.

)he primary requirement at the SS is prevention of damage that may result in

limitation of use. Acceptance of SS requirements is accomplished in codes by

imposing limits on interstorey drifts, related to type of non%structural elements 4brittle or

ductile5. (onsidering that drift limits are not related to the structural typology, SS

criteria do not prevent damage 4plastic deformations5 of structural elements. ?hen

considerable structural damage is e!perienced under a moderate earthquake event,


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repair of damaged elements is necessary, "hich may result in high economic losses due

to interruption of use, costs of repair, etc.

A bolted connection bet"een dissipative


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eccentrically braced frame "ith ! spans and five storeys 4seeFigure 15. Span

dimensions "ere / m, "hile storey height "as ./ m, e!cept the first one, equal to m.

)he eccentrically braced frame "as designed according to $6 122 8/9and $6 1227

41225 819. Dead load on the floors amounted to .=/ k6m, e!terior cladding "as

considered of 1.=- k6m, "hile live load "as .- k6m. Seismic design parameters

"ere* -./g peak ground acceleration, stiff soil conditions 4class A5, a behaviour factor

'> /./, and interstorey drift limitation of -.--0 of the storey height. A short link

4e> -- mm5 "hose behaviour is governed by shear only "as considered. (apacity

design according to $6 1227 governed dimensioning of non%dissipative members.

&$B0- S// columns, #C$- S// beams in the outer bays, #C$- S/ links and

beams in the middle bay, and &S 1-!1-!4=.1%1./5 S/ "ere obtained.

#n the e!perimental model, the removable link "as fabricated from #C$- profile of

S/ grade steel, "hile the rest of elements from S// grade steel. Four link lengths

"ere considered 4e > --, --, /-- and 0-- mm5, to study the influence of moment to

shear force ratio. All links "ere classified as short ones according to A#S( --/ 89.

Another parameter considered "as the spacing of "eb stiffeners, provided to prevent

"eb buckling and to improve rotation capacity of the link. )"o limit values of stiffener

spacing "ere considered according A#S( --/ 89* EcloseE spacing % -t(%h/, specified

for a rotation capacity -.-7 rad, and ErareE spacing % /t(%h/, specified for -.- rad

rotation capacity. For each combination of link length and stiffener spacing, three

specimens "ere tested* one monotonically and t"o cyclically, follo"ing the complete

$((S 127/ 809procedure. Bolts "ere preloaded to 1-- of the full preload value for

friction%grip bolts in the case of the monotonically loaded 4m5 and the first of the


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cyclically loaded 4c15 specimens, and /- for the second cyclically loaded specimen

4c5. A total of specimens "ere thus obtained, see )able 1.

)he yield force )yand displacementDy, "ere determined from the force%displacement

curve of the monotonic specimen "ith rare stiffeners, according to 809,as the

intersection of the initial stiffness line and the tangent to the shear force % link

displacement curve having 1- of the initial stiffness. Gield displacement "as used to

apply cyclic loading to the specimens of the same length. )he cyclic tests consisted of

four cycles in the elastic range 4-./Dy, -./Dy, -.=/Dyand 1.-Dy5, follo"ed by

groups of three cycles at amplitudes multiple of Dy4!Dy, !Dy, !0Dy, etc.5

)he loading "as applied quasi%statically, in displacement control.

Crevious e!perimental research by Dubina et al. 8=9 on e!tended end%plate beam%column

@oints in moment resisting frames sho"ed a series of problems that undermined their

cyclic performance* 415 fillet "elds are inappropriate in the case of cyclic loading; 45

full%penetration 1H "eld "ith the root at the e!terior part of the beam cross%section

promotes fragile ruptures, due to cracks initiated at "eld root; 45 "eld%access hole acts

as a stress concentrator, causing brittle ruptures of the beam flange. ?elding details

used for the link to end plate connection "ere chosen so as to prevent the causes of poor

performance mentioned above. )hus, link flange "as "elded to the end plate "ith a

full%penetration 1H "eld, realised from the e!terior part of the cross%section 4"eld

root at the interior5; the "eld access hole "as eliminated completely, and reinforcing

fillet "eld "as applied at the interior part of the flanges and on the "eb.

/


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2.2. Design of connections

Bolted connection bet"een the link element and the beam is located in a


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provide a mode 4bolts in tension5 failure mode of the equivalent )%stub. A linear

distribution of bolt forces "as then assumed, and the bolts checked for tension, shear,

combined tension and shear resistance. Demand to capacity ratio for combined tension

and shear ranged from -.= for the & and specimens to -.27 for the &= and =

specimens. Additionally, connection slip resistance "as checked.

2.3. Behaviour of specimens

)he instrumentation consisted of the actuator load cell, and a series of displacement

transducers used to measure both absolute and relative displacements. esponse of

removable link elements "as characterised by shear force )% shear distortion angle .

For classical links, the distortion is determined as the difference of end displacements

DTdivided to the link length 829.?ith the notations from Figure , is e!pressed as*

TD e =

Assuming that the edges of the panel bounding the link remain straight after

deformation, the same angle may be determined from the deformations of the

diagonals 4DD!andDD$5 4see Figure 5*

( ). . 1

a e DD DD

a e

+

=

Halues of angle determined according to relationships and have close values in the

case of classical links. &o"ever, in the case of removable bolted links, the behaviour of

the link is more comple!, and angle determined from relationships and "ill be

different. )otal link deformation is given by the sum of* 415 shear distortion of the link

=


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panel % , 45 rotation in the t"o connections M>S+*, and 45 slip in the connections,

characterised by an equivalent rotation +>4D+S+D+-5e, and can be e!pressed as*

T M +, = + +

#t can be directly obtained from the total displacementDT*

T TD e =

#nstrumentation permitted both direct determination of characteristic deformations

according to , and indirect one according , using the component deformations. A

satisfactory correlation "as observed bet"een the t"o methods.

Strength characteristics obtained from nominal and measured geometry and strength are

presented in )able . Account "as taken of the different flange and "eb yield strength

in determining the link plastic moment* , , ,'y pl ( y ( pl y fM f f= + .

Jeasured mechanical characteristics of steel sho"ed higher increase of plastic shear

force in comparison "ith plastic moment, "hich caused a decrease of the 1.0My/)ylimit.

$ven so, the links are classified as short. At the same time, ma!imum shear force and

moment used for connection design are considerably higher than the initial estimates

based on nominal characteristics. (onnection strength "as checked using estimates of

ma!imum forces determined from measured geometrical and mechanical

characteristics, considering a partial safety factor M0>1.- for the connection. esults

indicated that the connection should have responded in the elastic range, though "ith

little reserve for the longer = and &= specimens. &o"ever, at large displacements,

both bolt failures and end%plate deformations "ere observed during the tests. )"o types

of bolt failures "ere observed* 415 by thread stripping, "hich results in a ductile

7


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response 4dominant in this e!perimental program5, and 45 by fracture in bolt shank,

"hich results in a brittle response.

Bolted connections had important contributions to the overall link response and in

general did not sho"ed an elastic response. (onnection suffered important degradations

at the = and &= specimens, and caused a pronounced pinching effect "ith a reduced

energy dissipation capacity 4see Figure /5. $lement degradation started by bending of

the end plate and bolt thread stripping, follo"ed by local buckling of link flanges and

"eb. (loser stiffener spacing had as main effect isolation of local flange and "eb

buckling in outer "eb panels. Failure "as attained by complete degradation of bolt

threads.

Smaller length of 0 and &0 specimens reduced the damage to connections and the

pinching behaviour. Failure "as attained by complete damage to bolts 4see Figure =a5,

but also by "eb cracking after repeated plastic "eb buckling in the case of 0%c

specimen, "ith rare stiffeners.

Starting "ith / and &/ specimens, connections "ere characterised by a more stable

response, plastic "eb buckling being more important and preceding the one of the

flanges. Failure of /%c1 and /%c specimens, "ith rare stiffeners, "as attained by

tearing of the "eb on three edges, at the cracks initiated in the base metal at the "eb%

stiffener and "eb%end plate "elds. (loser stiffener spacing in the case of &/%c1 and

&/%c specimens reduced "eb tearing due to severe and repeated buckling 4but did not

eliminate it completely5 and failure "as attained by damage of the connection.

2


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esponse of specimens from the and & series "as dominated by "eb shear.

(onnection had a quasi%elastic response. Flange buckling "as observed only after

important "eb buckling. &ysteretic response "as characteri


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rigid connection behaviour, or consideration of equivalent link stiffness is necessary for

global analysis of frames "ith bolted links.

(onnection slip "as defined "hen relative displacement bet"een the end plates of a

connection e!ceeded -.1/ mm, according to (17 81-9. According to this criterion,

"ith the e!ception of the first tested =%m, all other specimens e!perienced slip during

the test. (onnection slip "as larger in the case of cyclic loading and partial preload of

bolts.

Gield force determined from )2DTrelationship "as not influenced by the test

parameters and "as controlled by shear response of the "eb. o"er e!perimental values

4see )able 5 are partially e!plained by the procedure used to determine yield force,

according to 809, "hich underestimates it for high initial stiffness. Kn the other hand,

e!perimental ma!imum force presents an increase from the longer to the shorter links

4effect of connection strength5 and is higher for closer stiffeners 4prevention of "eb

plastic buckling5.

)he ma!imum moment determined from equation "as lo"er than the theoretical one

used to design the connections. Coor performance of connections could be e!plained by

the fact that vertical displacement in the e!perimental set%up "as constrained, "hich

generated supplementary tension in the connections at large displacements. Follo"ing

the e!perimental observations in this study, in order to reduce damage in bolted

connections, it is recommended to limit the length of bolted links to y ye -.7 J H ,

"hich corresponds to links and &.

11


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:ltimate link displacementDTu, representing the stable hysteretic response is presented

in)able . (yclic loading reduced by - to =- plastic deformation capacity, "ith

the ma!imum reduction for short links. :ltimate displacements "ere slightly lo"er in

the case of short links in comparison "ith longer ones. &o"ever, in terms of

deformations 4Tu5, rotation capacity is larger in the case of shorter links, "ith the

e!ception of and & specimens. ?ith the e!ception of longer links "ith rare

stiffeners 4=5, specimens sho"ed a stable deformation capacity of at least -.1 rad,

"ith a number of 10 to cycles in the plastic range. Bolt preloading did not affect

rotation capacity, "hile closer spacing of stiffeners improved link deformation capacity.

Behaviour of long specimens "as much influenced by the response of the bolted

connection, characteri


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characteristic of intermediate length specimens 0%/ and &0%&/. &o"ever, it

may be difficult to control this response in practice, due to variability of mechanical

steel characteristics.

$!perimental tests demonstrated e!cellent plastic deformation capacities under cyclic

loading and ductile failure modes 4ultimate shear deformation of -.11%-.1 rad5. #n

order to limit damage to the connections, shorter links are recommended. )here are

several sources of link deformation* shear deformation, bending deformation, end plate

rotation and progressive slip in bolted connection. )he most convenient "ay to account

for these effects is by considering equivalent link stiffness. )he average stiffness of

bolted links "as of the order of / of the theoretical shear deformation of a

conventional continuous link.

". valuation of performance of #$s with removable links

3.1. Design and modelling

#n order to assess seismic performance of eccentrically braced frames "ith removable

links, a medium rise structure "as investigated as a case study. )he building has !

bays of 0 m each, and 7 storeys 4see Figure 75. All storeys are ./ m, e!cept the first

one, "hich equals ./ m. )he design "as carried out according to $6 1228/9,

$6 1227 4--5 819and C1--%1--0 81194omanian seismic design code, aligned to

$6 12275. A k6mdead load on the typical floor and ./ k6mfor the roof "ere

considered, "hile the live load amounted .- k6m. )he building location "as

considered as Bucharest, characterised by -.g design peak ground acceleration and

soft soil conditions "ith control period TC>1.0 s. A behaviour factor '>0, and

interstorey drift limitation of -.--7 of the storey height "ere considered in design.

1


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#n assessing the potential benefits of using &igh Strength Steel 4&SS5, different steel

grades "ere used for members. )he reference structure, denoted as B, used mild carbon

steel 4grade S/5 for all members, e!cept the central columns of the first t"o storeys,

"hich are &SS steel 4grade S0-5, see Figure 7b. A conventional link 4i.e. part of the

beam5 "as used in the B structure. #n order to assess the influence of reduced stiffness

of bolted links, a ne" structure 4denoted by 5 "as considered. Based on e!perimental

tests, an equivalent stiffness of -./ of the theoretical shear stiffness of continuous links

"as considered for bolted links. #n order to reduce inelastic deformations in members

outside links, higher steel grade "as used in these members. )his structure "as denoted

by 0, and used S0- steel grade in beams and columns of the moment%resisting bays,

seeFigure 7c. )he period of the fundamental mode of vibration of the B structure

amounted to 1.-/ seconds, "hile for the and 0 structures it "as 1.1 seconds.

Beams, columns and braces "ere modelled "ith fibre hinge beam%column elements,

"ith plastic hinges located at the element ends. 6ominal steel characteristics "ere used.

$lastic%perfectly plastic behaviour "as assumed, "ithout strength and stiffness

degradation. )he inelastic shear link element model "as based on the one proposed by

icles and Copov 819. As the original model consisted in four linear branches, it "as

adapted to the trilinear envelope curve available in Drain%d!.

3.2. Ground motion records

A set of seven ground motions "ere used. Spectral characteristics of the ground motions

"ere modified by scaling Fourier amplitudes to match the target elastic spectrum from

C1--%1--0 8119, seeFigure 2. )his results in a group of semiartificial records

1


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representative to the seismic source affecting the building site and soft soil conditions in

Bucharest. )he procedure "as based on the S#JLI$%1 program 819.

3.3. nalysis procedure and results

#n order to assess structural performance, nonlinear static and dynamic analyses "ere

performed. )hree performance levels "ere considered* serviceability limit state 4SS5,

ultimate limit state 4:S5, and collapse prevention 4(CS5 limit state. #ntensity of

earthquake action at the :S "as equal to the design one 4intensity factor > 1.-5.

Mround motion intensity at the SS "as reduced to > -./ 4according to > -./ in

$6 1227 8/95, "hile for the (CS limit state "as increased to > 1./ 4according to

F$JA /0 8195. Based on e!perimental results and F$JA /0 provisions, ultimate

link deformations at :S and (CS "ere u>-.11 rad and u>-.1 rad, respectively.

Cushover curves for the B, and 0 structures are sho"n in Figure 1-. #n comparison

"ith the conventional structure B, the ones using removable links 4 and 05 are

characterised by slightly reduced initial stiffness. &o"ever, base shear force at the first

yield in links is similar for the three structures, implying similar design strength under

seismic action. Mlobal capacity of the structure 4"ith removable links5 is reduced in

comparison "ith the B structure, but the 0 structure, that uses removable links and

&SS in moment%resisting bays, is characterised by a larger global strength. Another

advantage of &SS 40 structure5 is that elements outside links yield under larger

lateral deformations than the B and structure. :S criteria are the deformation

capacity uof member. #n all cases, the critical elements "ere links.

1/


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esults of the #ncremental Dynamic Analysis 4#DA5 are synthetically presented in

Figure 11, in terms of ma!imum transient #nterstorey Drift atio 4#D5 and ma!imum

permanent #D. )he conventional structure 4B5 performs slightly better than the

structures "ith removable links 4 and 05. &o"ever, it can be observed that all three

structures 4B, and 05 have adequate performance at the SS 4>-./5, :S 4>1.-5

and (CS 4>1./5 limit states. )here are no substantial differences bet"een the t"o

structures "ith removable links 4 and 05 in terms of ma!imum #D 4at SS5 and

ma!imum plastic deformation demands 4at :S and (CS5, see Figure 11a. )he benefit

of &SS for the structure "ith removable links 405 is clearly identified in Figure 11b,

giving the lo"est values of permanent drifts up to intensity factors of > 1.-%1.. o"

permanent drifts allo" easier replacement of damaged removable links.

As it "as presented earlier, structures designed using the dissipative approach, may

e!perience structural damage even under moderate 4SS5 earthquake. )his can be seen

inFigure 1, "here plastic deformation demands in members are represented. Clastic

deformations in links 4ranging bet"een -.-0 rad and -.- rad5 indicate a moderate

damage to the structures at SS. Clastic deformations in elements outside links 4beams,

columns, and braces5 are negligible for the B and structures, and are completely

avoided for the &%4 structure. Ja!imum plastic deformation demands in members at

SS, :S and (CS are presented in )able /. )he behaviour of the structures "ith

removable links is improved "hen &SS is used in the moment%resisting bays, this

structure sho"ing lo"er plastic deformation demands in elements outside links. Smaller

plastic deformations are directly related to smaller permanent drifts.

10


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%. &onclusions

Seismic performance of removable links "ith flush%end plate connections "ere

investigated e!perimentally, proving the technological feasibility of the solution.

Cerformance of short removable links and possibility to be easily replaced makes them

attractive for dual eccentrically braced frames. Hery short links, "hich assure an elastic

behaviour of the connection are preferred, due to their easier replacement.

(oncentration of damage in the removable link 4performing like passive energy

dissipation devices5 may be accomplished by the capacity design principles, including

fabrication of the link from a steel "ith lo"er yield strength in comparison "ith rest of

the structure.

$!perimental investigation indicated a significant reduction of stiffness of bolted links

in comparison "ith conventional links. Structures "ith removable links sho"ed larger

interstorey drift and inelastic deformation demands than structures "ith conventional

links. &o"ever, seismic performance "as adequate under serviceability, ultimate and

collapse prevention limit states. Dual steel structures in "hich high strength steel is used

in moment%resisting bays of eccentrically braced frames "ith removable links are

characterised by reduced inelastic deformation demands in members outside links and

lo"er permanent interstorey drifts. #n these conditions, the dissipative behaviour of

structures can be better controlled by design. Joreover, interventions for repair of the

structure affected by a moderate to strong earthquake are limited to replacing the bolted

links.

1=


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'. Acknowledgements

Support of the omanian Jinistry of esearch and $ducation through the ($$N%

JA)6A6)$(& grant 2--/ EStructural Systems and Advanced )echnologies for

Structures from &igh%Cerformance Steels for Buildings ocated in &igh Seismicity

Areas % S)KC#S(E and ($$N%$) grant 1--/ EDual steel structures "ith

removable dissipative elements for buildings located in seismic areasE is gratefully

ackno"ledged.

(. )eferences

819 $6 1227 4122, --5. E$urocode 7* Design of structures for earthquake

resistance. Cart 1* Meneral rules, seismic actions and rules for buildingsE. ($6 %

$uropean (ommittee for Standardi


19/32

Bi@laard, A.J. Mresnigt, M.Q. van der Hegte. Delft :niversity of )echnology, )he

6etherlands, pp. %

8/9 $6 122 4--5. E$urocode . Design of steel structures % Cart 1%1* Meneral rules

and rules for buildingsE. ($6 % $uropean (ommittee for Standardi


20/32

819 icles Q.J., Copov $.C. 41225. E#nelastic link element for $BF seismic analysisE.

AS($, Qournal of Structural $ngineering, 122, Hol. 1-, 6o. * 1%0.

819 Masparini, D.A., and Hanmarcke, $.&. 412=05. ESimulated $arthquake Jotions

(ompatible "ith Crescribed esponse SpectraE, Department of (ivil $ngineering,

esearch eport =0%, Jassachusetts #nstitute of )echnology, (ambridge,

Jassachusetts.

819 F$JA /0 4---5. ECrestandard and commentary for the seismic rehabilitation of

buildingsE, ?ashington 4D(5* Federal $mergency Janagement Agency.

-


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*. +otation

link shear distortion angle

% multiplier factor for earthquake intensity

% reduction factor "hich takes into account the lo"er return period of the seismic

action associated "ith the damage limitation requirement

+ equivalent link rotation angle due to connection slip

M, S, * average, bottom, and top connection rotation

M0 partial safety factor for bolt resistance

T total link distortion angle

+s% link shear area ( )s ( f+ t h t=

D+-,D+S measurements of link slip displacement transducers

DD!,DD$ measurements of link diagonal displacement transducers

DT total link displacement

DTu, Tu ultimate displacement, ultimate deformation

Dy, )y yield displacement, yield shear force

ebolted link length

e, b link panel dimensions

fy,fu yield stress, tensile strength

fy,(, fy,f "eb and flange yield stress

3% shear modulus

1T,1,1-and1S total, "eb shear, and connection initial stiffness

'% behaviour factor

1


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tf, t(, h flange thickness, "eb thickness, and cross%section height respectively

)ma5,Mma5 ma!imum shear force, ma!imum moment

)y,My plastic shear resistance, plastic moment

pl,(, 6pl plastic modulus of the "eb and flanges, respectively 46pl>pl 2 pl,(, pl5


23/32


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L

L

DALJ

DALS

DT

4a5 4b5

Figure . Deformation of a bolted link 4a5 and its ideali


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4a5 4b5

Figure =. Failure by connection degradation at the &0%c specimen 4a5; plastic "eb

buckling at the %c1 specimen 4b5

IPE400 IPE400IPE400

HEB00

HEB00

HEB00

HEB00

HEA240

HEA220 IPE400 IPE400IPE400

HEB00

HEB00

HEB00

HEB00

HEA240

HEA220

4a5 4b5 4c5

Figure 7. Structural layout* 4a5 plan vie"; 4b5 elevation of B and structures;

4c5 elevation of 0 structure

/


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$igure ,. lastic response spectra of semiartificial records and 1-1/2( elastic

spectrum.

Figure 1-. Cushover curves 4normalised base shear vs. normalised top displacement5 for

the B, and 0 structures

0


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4a5 4b5

Figure 11. #DA curves* ma!imum 4a5 and permanent 4b5 drift vs. acceleration multiplier,

average of all records

Figure 1. Clastic deformation demands in members at SS 4> -./5

for the B, and 0 structures, average of all records

=


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)able 1. Kvervie" of e!perimental program on removable links

link length e > 0-- mm e > /-- mm e > -- mm e > -- mm

stiffeners rare close rare close rare close rare close

monotonic loading

41-- bolt preload5=%m &=%m 0%m &0%m /%m &/%m %m &%m

cyclic loading 41--

bolt preload5=%c1 &=%c1 0%c1 &0%c1 /%c1 &/%c1 %c1 &%c1

cyclic loading 4/-

bolt preload5=%c &=%c 0%c &0%c /%c &/%c %c &%c

7


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)able . Gield and ma!imum forces evaluated from nominal and measured

characteristics

specimen pl,

cm

pl(,

cm

pl6,

cm

)y,

k6

My,

k6m

1.0My/)y,

mm

)ma5,

k6

Mma5,

k6m

nominal &=,

=

00.0 =/.2 21.1 17/. 70. = =7.1 7.

&0,

0

00.0 =/.2 21.1 17/. 70. = =7.1 02./

&/,

/

00.0 =/.2 21.1 17/. 70. = =7.1 //.0

&,

00.0 =/.2 21.1 17/. 70. = =7.1 1.=

measure

d

&=,

=

00.0 =/. 21. 00.= 1-./ 01 --.1 1-.-

&0,

0

00.0 =/. 21. 00.= 1-./ 01 --.1 1--.-

&/,

/

00.0 =/. 21. 00.= 1-./ 01 --.1 7-.-

&,

00.0 =/. 21. 00.= 1-./ 01 --.1 0-.-

note*Mma5determined according to equation

2


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)able . Gield )yand ma!imum )ma5shear forces

parameter specimen = 0 / &= &0 &/ &

)yth, k6 00.='

)y, k6 m 7.- -2.- 172./ 121.- -1.0 1=.7 127. -1./

c1 .7 17. /.- 1=. =. 1.2 2.0 0.0

c 10./ 10.2 1=/. .= 11.1 . 1./ 2.-

)ma5th, k6 --.1''

)ma5, k6 m -.2 . 7.1 77. =-.1 -=./ /./ -.0

c1 20.2 -7. . 0-.2 -/. 17./ 0.1 --.0

c 72.0 1.2 //.= 0./ -1.0 . 0.- -.2note* average of positive and negative values presented for specimens c1 and c

' plastic shear resistance based on measured geometry and yield strength

'' )ma5th>1./)y

th

-


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)able . :ltimate displacementDTuand corresponding deformationTu

specimen = 0 / &= &0 &/ &

DTu,

mm

m 2.- 10.0 1. 117. 1-.7 17.7 1=.2 1/.2

c1 /7.1 0. . -. 07. =1.= /7.0 =.7

c //. 00. 0./ ./ 0/./ 07. =.7 =.0

Tu m -.1// -.= -.0- -.2/ -./ -.=7 -./ -.-

c1 -.-2= -.12 -.1-0 -.1-1 -.11 -.1 -.1= -.10

c -.-2 -.1 -.1/0 -.11 -.1-2 -.10 -.17 -.1/

note* minimum of positive and negative values presented for c1 and c specimens

1


32/32

)able /. Clastic deformation demands in members at SS 4> -./5, :S 4> 1.-5 and

(CS 4> 1./5 for the B, and 0 structures, average of all records

links beams columns

B 0 B 0 B 0

SS -.-= -.-0 -.-0 -.-- -.-- % % -.--1 %

:S -.-07 -.-2 -.-2 -.-1- -.-1 -.-- -.--/ -.--= -.--

(CS -.1-/ -.12 -.1/ -.-1= -.- -.-1 -.-11 -.-1 -.--7

dubina_ebf

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