an experimental study of the seismic behavior of in lled rc...

Scientia Iranica A (2017) 24(5), 2271{2282

Sharif University of TechnologyScientia Iranica

Transactions A: Civil Engineeringwww.scientiairanica.com

An experimental study of the seismic behavior ofin�lled RC frames with opening

H. Tekeli� and A. Aydin

Department of Civil Engineering, Suleyman Demirel University, Isparta, Turkey.

Received 11 October 2015; received in revised form 21 April 2016; accepted 2 July 2016

KEYWORDSIn�ll wall;Opening;Reinforced concretebuildings;Cyclic lateral loading;Location and size ofthe openings.

Abstract. In�ll walls are not generally taken into account in structural analysis due totheir complex behavior at seismic actions. As it is known, they increase the sti�ness as wellas the lateral load capacity of the system. Sometimes, in�ll walls may have window anddoor openings in their planes. In the present study, behavior of Reinforced Concrete (RC)frames with in�ll walls, which have openings, is investigated under cyclic lateral loadings.Location and size of the openings in the in�ll wall are selected as investigation parameters.Test specimens are constructed and experimentally analyzed. The in�ll wall changes thebehavior of the frames under cyclic lateral loads signi�cantly. Location and size openingsin the in�ll wall are two main parameters that a�ect the behavior of the in�ll walls as wellas the frame. The test results clearly show that the contribution of the in�ll wall to thebehavior of RC frame diminishes signi�cantly when the opening ratio is larger than 9%.Therefore, the e�ect of the opening in the in�ll wall must be taken into account in thestructural modeling when the opening ratio is larger than 9%.© 2017 Sharif University of Technology. All rights reserved.

1. Introduction

Reinforced Concrete (RC) frames with masonry in�llwalls are widely used in structural systems in manyparts of the world. It is known that in uence of in�llwalls on the behavior of frames, which are subjected toearthquake loadings, is very important in some cases.If the in�ll walls are uniformly distributed throughoutthe structure, then they usually have a bene�cial e�ecton the seismic response of the structure. On theother hand, negative e�ects can appear due to irregularpositioning of the in�ll walls in plan, and especially inelevation [1]. Even with symmetric layout, irregularitycan be expected due to partial failure of these walls.

*. Corresponding author. Tel.: +90 246 2111190;Fax: +90 246 2370859E-mail addresses: [email protected] (H. Tekeli.);[email protected] (A. Aydin)

doi: 10.24200/sci.2017.4150

In�ll walls have attracted the attention of manyresearchers since the early 1950s. A large numberof researchers have studied the behavior of in�lledsteel and RC frames subjected to in-plane and out-of-plane lateral loads. These studies have involved bothexperimental and numerical analyses.

Uva et al. [2] have investigated the role of masonryin�ll in the seismic behavior of RC frames, pointing outsome relevant questions about the sensitivity to thematerial parameters and the choice of the modellingapproach. Chrysostomou and Asteris [3] have consid-ered the in-plane behavior and in-plane failure modesof in�lled frames and presented simpli�ed methods forpredicting these failure modes. Ricci et al. [4] haveanalyzed the e�ect on the elastic period of vibration ofin�ll contribution to lateral sti�ness of RC buildings.Shing and Mehrabi [5] have summarized some of therecent �ndings and developments of the behavior andmodelling of in�lled structures. Koutromanos et al. [6]have investigated the behavior of masonry-in�lled rein-forced concrete frames under cyclic lateral loading by

2272 H. Tekel_i and A. Aydin/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 2271{2282

using nonlinear �nite element models. Most of thesestudies have shown that use of masonry in�ll walls has asigni�cant impact not only on the strength and sti�nessbut also on the energy dissipation mechanism of theoverall structure. Celarec et al. [7] have investigatedthe sensitivity of the seismic response parameters tothe uncertain modeling variables of the in�ll walls andframe. Campione et al. [8] have improved an equivalentdiagonal pin-jointed strut model taking into accountthe sti�ening e�ect of vertical loads on the in�ll inthe initial state. Martinelli et al. [9] have proposed asimpli�ed procedure based on NonLinear Static (NLS)analysis for evaluating the seismic response of masonryin�lled RC frames.

Amanat and Hoque [10] and Kose [11] haveinvestigated the parameters a�ecting the fundamentalperiod of RC buildings with in�ll walls. Asteris etal. [12] have presented a detailed and in-depth ana-lytical investigation of the parameters that a�ect thefundamental period of reinforced concrete structure.From the analysis of the results, it has been found thatthe number of stories, the span length, the sti�ness ofthe in�ll wall panels, the location of the soft stories,and the soil type are crucial parameters that in uencethe fundamental period of RC buildings.

Pujol and Fick [13] have reported experimentson a full-scale building structure performed to addressquestions about the potentially positive or negativee�ects of masonry in�ll walls. The study has focusedon the assumption that measures are taken to preventout-of-plane failure of masonry panels. Tu et al. [14]have conducted shaking table tests on four full-scalesingle-story structures to investigate the out-of-planebehavior of unreinforced masonry (URM) panels inRC frames. They have presented an analytical modelfor the out-of-plane behavior of masonry panels inaccordance with the rocking mechanism. Arulselvanet al. [15] have tested a frame having �ve storiesand three spans with a central portion in�lled withbrick under cyclic loading simulating seismic action.Analytical studies have been carried out as well tostudy the sti�ness, strength, and behavior of thesetypes of frames.

In�ll walls may have window and door open-ings. Asteris [16] has analytically investigated thein uence of the masonry in�ll panel opening on thereduction in the sti�ness of the in�lled RC frames.A parametric study has been carried out by adoptinglocation and size of the masonry in�ll panel openingas investigation parameters. Altin et al. [17] andAnil and Altin [18] have investigated the behavior ofductile Reinforced Concrete (RC) frames strengthenedby addition of partial in�lls under cyclic lateral loading.Steel frames with masonry in�lls having openings havebeen tested by Tasnimi and Mohebkhah [19], and Liuand Manesh [20].

Experimental studies have been carried out byVoon and Ingham [21], Kakaletsis and Karayannis [22],Mansouri et al. [23] related to walls with openings.Voon and Ingham [21] have presented test results ofeight partially grout-�lled perforated concrete masonrywalls subjected to cyclic lateral loading. The eightwalls had variations in lintel reinforcement detailing.Test results obtained from this research indicatedthat the size of openings and the length of trim-ming reinforcement signi�cantly a�ected the lateralstrength of perforated masonry walls. Kakaletsis andKarayannis [22] have investigated the in uence ofmasonry openings on the seismic performance of in�lledreinforced concrete frames, designed according to thecurrent code provisions. The investigated parameterswere the shape and the size of the opening. In allthe examined cases, the shear strength of columnswas higher than the cracking shear strength of solidin�ll. The experimental results showed the signi�-cance of various forms of openings in the reductionof strength, sti�ness, and energy dissipation capabilityfor all the examined cases of in�lled frames. Mansouriet al. [23] have presented the in uence of openingson lateral behavior of low-shear-strength masonry in-�lled reinforced concrete frames. The design of thereinforced concrete frames aimed to re ect commonseismic design de�ciencies. Six half-scale single-story,single-bay frame specimens were tested under in-planelateral loading. The aspect ratio (h=l) of in�ll wall wasequal to 0.62. The investigated parameters were shape(window and door), size (regular and large windows),and location of the openings (eccentric and centralin horizontal direction). The results indicated thatpresence of openings altered the failure mode, increasedthe damage level, and reduced ductility, strength, andsti�ness of the in�lled frame.

The failure mechanism of an in�lled frame is quitecomplex and depends upon a large number of factorssuch as the relative strength and sti�ness properties ofthe in�ll wall and the frame. Although the subjectof in�lled frames has been studied for a long time,there are still questions to be investigated and answeredabout their behavior and interaction with the frame.Generally, window and door openings are formed inthe in�ll wall to satisfy architectural requirements ofthe buildings; however, they create various modellingdi�culties. In FEMA 306 [24], it is stated that \In spiteof the general success of modelling in�lled frames withsolid panels, major di�culties still remain unresolvedregarding the modeling approach for in�lled frameswith opening". Despite all these di�culties in themodeling of in�ll walls with and without openings,seismic behavior of in�ll walls is still a popular subjectfor experimental and numerical studies.

The seismic safety evaluation of masonry in�llwalled reinforced concrete buildings requires appro-

H. Tekel_i and A. Aydin/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 2271{2282 2273

priate macro-models for in�ll walls that have beencalibrated by experimental results. Because of lim-itation of experimental data, most of the existingmodels have been developed by �nite element analysesand have not been veri�ed by experimental results.Therefore, more experimental investigation is requiredfor predicting the sti�ness and strength of in�lledframes with openings.

The purpose of this study is to investigate thee�ects of in�ll walls with openings on the behavior ofthe RC frames, and improve experimental data in theliterature to deal with the in�ll wall having opening.Thus, the macro model of in�ll wall having openingcan be developed by using the experimental results.An experimental study has been carried out by usingvariables that are related to the location and sizeof window opening in the in�ll walls. In the fourspecimens, the opening is located in the middle ofthe in�ll wall whereas in the other four specimens,the opening is located on the upper left part of thediagonal. Openings of the in�ll walls are located onthe diagonal of all specimens.

The design of the reinforced concrete frames inthis study aims to re ect common seismic designde�ciencies, such as insu�cient transverse reinforce-ments at column and beam ends, lack of transversereinforcement at beam-column joints, and weak col-umn/strong beam connections that are encounteredfrequently in practice. The results of the studyincluding failure mode, lateral load capacity, energydissipation, and the lateral sti�ness of the framewith in�ll walls are investigated and given in �gurescomparatively.

2. Experimental work

2.1. Description of the test specimensTen test specimens are constructed with 1/3 scale andtested under cyclic lateral loading. Span length andheight of the frame in all specimens are kept constantat 1500 mm and 1200 mm, respectively.

Cross sectional dimensions of columns and beamsare given in Figure 1. Longitudinal reinforcements ofcolumns and beams consist of 10-mm bars. Stirrupsare provided for the columns and beams as 6-mmdiameter bars with 135� hooks. Spacing betweenthe stirrups is 80 mm. The design of the reinforcedconcrete frames in this study aims to re ect com-mon seismic design de�ciencies, such as insu�cienttransverse reinforcements at column and beam ends,lack of transverse reinforcement at beam-column joints,and weak column/strong beam connections that areencountered frequently in practice. A typical layoutof the beam and the column along with reinforcingdetails is presented in Figure 1. Properties of thereinforcement used in the study are listed in Table 1.

Tests for evaluation of concrete compressivestrength (fc) are carried out on 150 mm � 300 mmconcrete cylinders, and average strength values (fc) on28 days for each frame are given in Table 2. Three types

Table 1. Average values of the yield stress of thereinforcing bars.

Bar diameter (mm) fsy (MPa) fsu (MPa)

6 374 47610 449 52416 452 536

Figure 1. Dimensions and reinforcement details of the specimens (mm).


Table 2. Location and ratio of the opening on in�ll wall.

SpecimenID

fc(MPa)frame

Openingpercentage%

Openingposition

SpecimenID

fc(MPa)frame

Openingpercentage%

Openingposition

Specimen 1 21 100 Specimen 2 20 0





of frames are constructed for the experimental tests.The �rst type does not have any in�ll wall (bare frame),the second has a solid in�ll wall (without opening), andthe third includes partial openings at di�erent locationsof the in�ll wall. Table 2 summarizes the properties ofeach specimen.

The in�ll walls in the frames are constructedby using 1/3 scale hollow clay tiles with dimensionsof 55 mm � 100 mm � 100 mm after �nishing theconstruction of the frame. The aspect ratio (h=l) ofin�ll wall is equal to 0.83. A rough plaster is appliedon both sides of the in�ll walls where regular masonryunits are connected to each other by a regular mortar.The thickness of the plaster used at the two faces of thebrick walls is 10 mm, and total thickness of in�ll wallis 120 mm. The in�ll walls are not constructed on thesymmetric axis of the frame to simulate the exteriorwalls of the building. The mortar and plaster mixturecontains one part cement, one part lime, and four partssand according to the common construction practice.The sand used has a maximum aggregate size of 3 mm.The average compressive strengths of the mortar andplaster used in the construction of the masonry wallsof the specimens are found to be around 3.5 MPa.

Openings of the in�ll walls are located on thediagonal of all specimens, where strut is expectedto appear when the frame is subjected to a lateralload. In the four specimens, the opening is locatedin the middle of the in�ll wall whereas in the otherfour specimens, the opening is located on the upperleft part of the diagonal (Figure 2). Ratios of theopening area to the in�ll wall area are selected tobe 4%, 9%, 16%, and 25% where the rectangular

openings are chosen to be 240 mm�200 mm; 360 mm�300 mm; 480 mm � 400 mm; and 600 mm � 500 mm,respectively, where dimensions represent the lengthand height of the opening in the x and y directions,respectively (Figure 2).

The compressive strength of the in�ll wall is foundto be 5.0 MPa. All samples are painted with limewhitewash in order that cracking in the RC frame andin the in�ll wall can be observed clearly during thetest.

2.2. Test setupTest setup is shown in Figure 3. After the specimenshave been bolted to the rigid oor by the foundationbeam at the bottom, tests are carried out by applyingreversed cyclic lateral loading. Each load cycle consistsof push and pull loading steps. The lateral load isapplied at the beam level and increases by 5 kN at eachloading step. Loading in the tests is continued until thein�lled frame reaches its lateral load capacity in loadcontrol manner. Then, the test is continued in displace-ment control in order to obtain the load-displacementcurve until a decrease of 15% in the maximum load isreached. Furthermore, in order to provide a right angle(90�) between the load cell and the frame during theloading, a hinge is used as shown in Figure 3. Thelateral displacements are measured by using LVDTs(Linear Variable Di�erential Transformers). The lo-cations of LVDTs are also shown in Figure 3. Aftereach loading cycle, cracks and damage mechanisms inthe specimens are observed and recorded. A bracingsystem is employed to prevent out-of-plane movementof the specimens, as shown in Figure 4.


Figure 2. Location of the openings on the in�ll wall (mm).

Figure 3. Test setup.

Figure 4. Bracing system against out-of-plane movementof the specimens.

3. Experimental results

3.1. Observed damage in the specimensDistributions of the damage in the specimens areobserved and recorded throughout the experiment.Figure 5 shows damage variations in Specimen 1 andSpecimen 2. Specimen 1 represents the bare frame thathas failed due to the column mechanism, i.e. due to

plastic hinges developed at both ends of the columns,as it is expected due to strong beam/weak columncon�guration. In Specimen 2, the separation cracks are�rstly observed at the interface between the frame andthe in�ll wall due to deformation dissimilarity. Whilevertical cracks are formed at the bottom and top of thein�ll wall, horizontal cracks are formed in the middle ofthe in�ll wall. Propagation of the horizontal cracking inthe middle of the in�ll wall develops a diagonal crackunder increasing lateral load. After the formation ofa great number of hairline cracks on the in�ll wall,an increase in their widths is observed as well. Thediagonal cracks in the in�ll wall are followed by shearfailure at the bottom and top of the columns. This isdue to the shear force applied by the strut developedin the in�ll wall. This fact indicates an increase inthe design shear force at the columns as the horizontalcomponent of the strut, to avoid brittle shear failure atthe columns.

Crack con�gurations observed in all specimenswith the in�ll walls having openings are given inFigure 6. As seen, the �rst cracks occur obliquely onthe corner of the openings, where a stress concentration

Figure 5. Damage observed in Specimen 1 andSpecimen 2.


Figure 6. Damage observed in all specimens with the in�ll wall having opening.

is expected. Failure mechanisms of Specimens 3 and 4are quite similar to that seen in Specimen 2. Probablereason for this is that the size of the opening in thein�ll wall is quite small.

In Specimen 5, a crack is formed from the bottomcorner of the opening up to the upper corner of theframe. Later, the crack is widened under the increasinglateral load. The crack in the in�ll wall is extendedto the column at the frame corner and causes a shear

failure at the top and bottom of the column, asobserved in Specimen 2.

Cracking in the in�ll walls takes place outside thediagonal strip of the frame in Specimens 7 and 9, whilecracking takes place along the diagonal of the framein Specimens 6 and 8. Detailed inspection shows thatcracking in Specimen 7 takes place in the area of thewall beside the opening obliquely whereas a diagonalcrack is formed in the area of the in�ll wall under the


window opening in Specimen 9. As a result of theincrease in the crack width in these specimens, thein�ll walls fail by losing their load carrying capacity. InSpecimen 10, the starting point of the crack is at thewindow's corner and the crack continues horizontallytowards the column. From the experiments, it isobserved that the opening in in�ll walls changes thebasic behavior of the frame and creates a new failuremechanism when the opening ratio is larger than 9%.

Generally, it is observed that the failure mech-anism of frames that include the in�ll walls withopening depends mostly on the location and ratio ofthe openings.

3.2. Lateral load capacity of the specimensLateral load-displacement hysteretic curves that areobtained during the testing are illustrated in Figure 7.The tests clearly show that strength and sti�ness ofthe frames signi�cantly increase by the presence ofin�ll walls. The largest lateral load capacity has beenobtained 115 kN from Specimen 2, whereas the lowestlateral load capacity has been obtained 50 kN fromSpecimen 1. Lateral load capacity of the specimen withthe solid in�ll wall has increased by almost 130% ascompared to the specimen without in�ll wall. Envelopecurves obtained from the lateral load-displacementhysteretic curves are shown in Figure 8. Lateral loadcapacities obtained from the tests are given in Figure 9comparatively.

Lateral load capacity values in the pull and pushdirections are quite close to each other in the specimens(Specimens 4, 6, 8, and 10) having opening in themiddle of the in�ll wall. In contrast, in the specimens(Specimens 3, 5, 7, and 9) having opening on the upperleft part of the in�ll wall, the lateral load capacities inthe push direction are generally larger than the lateralload capacities in the pull direction. A comparison ofthe two tests, which have the same ratios of openingin the middle and on the upper left part of the in�llwall, yields that the lateral load capacity of the formeris generally larger than that of the latter.

The lateral load capacities of Specimens 3 and 4are almost equal to that of Specimen 2. As expected,the test results yield that as the opening ratio increases,the lateral load capacity of the specimen decreases,i.e. openings of 4, 9, 16, and 25%, lead to a decreasein the lateral load capacity of 1%, 10%, 20%, and30%, respectively. It is worth noting that these valuesrepresent averages in di�erent opening locations anddi�erent loading directions. The results obtained fromtests show that the contribution of the in�ll walls to thelateral load capacity of the frame decreases signi�cantlywhen the opening ratio is larger than 9%.

3.3. Story drift ratiosStory drift ratios are obtained for the all specimens in

two di�erent ways. First, story drift ratios are calcu-lated for all specimens corresponding to a lateral loadcapacity (50 kN) of the bare framed specimen. Thehighest and the lowest story drift ratios are observed inthe bare frame and solid in�ll walled specimen by 1.1%(0.86%) and 0.1% (0.13%), respectively, under pull(push) lateral loadings. The obtained results show thatthe story drift ratios increase as the openings on the in-�ll walls increase. Second, story drift ratios correspond-ing to the ultimate load capacity of each specimen areobtained. Except the specimens with the opening of25%, the highest value for the story drift ratio hasbeen observed in bare frame while the lowest valuehas been observed in solid in�ll walled frame. Thesecorresponding drift values are at the order of 0.9-1.1%(0.7-0.9%) under pull (push) lateral loadings, except forthe specimens with the opening of 25%. In the speci-mens with the opening of 25%, the story drift ratio ishigher than that in the bare frame under both push andpull loadings. For example, Specimen 10 (with openingof 25%) has experienced 1.4% story drift ratio andlateral sti�ness of 5.05 kN/mm with 80 kN of total loadcapacity, whereas these values for bare frame are 1.1%,4.16 kN/mm, and 50 kN, respectively. This observationis due the fact that maximum story drift ratios areproportional to the corresponding ultimate lateral loadcapacities of the Specimens 10 and 1. In�ll walls withopenings contribute to the lateral sti�ness and lateralload capacity of the frames. However, if the opening inthe in�ll wall is higher than 16%, the story drift ratiocorresponding to the lateral load capacity of specimenis observed to increase with respect to the bare frame.The obtained results clearly show that the e�ect ofopenings on story drift ratios is noteworthy. Incrementin the story drift ratio becomes signi�cant when theopening ratio is larger than 16% for both push and pullloadings. The opening becomes more e�ective whenthey are located in the middle part of the in�ll wall.

3.4. Sti�ness and energy dissipationLateral sti�ness of the specimens is calculated as theratio of the lateral load to the lateral displacement ateach cycle and presented in Figure 10. Specimen 2exhibits the highest sti�ness among all specimens whileSpecimen 1 has the lowest sti�ness. The specimenswhich have openings in the middle of in�ll wall exhibitapproximately equal sti�ness values for lateral loads inthe pull and push directions. The results show that thesti�ness of the specimens decreases as the opening ratioincreases. The lateral sti�ness for the push loading inall specimens having openings on the upper left part ofthe in�ll wall is generally larger than the sti�ness forthe pull loading.

Energy dissipation is determined by calculatingthe areas inside the hysteretic load-displacement loopsfor each cycle, whereas the cumulative dissipated en-


Figure 7. Lateral load-displacement hysteretic curves of all specimens.

ergy is evaluated as the sum of the areas of all previoushysteresis loops; cumulative energy dissipations aredepicted in Figure 11.

It is apparent from Figure 11 that the lowestenergy dissipation is observed in Specimen 1 amongall specimens. Among all the in�ll walled specimens,Specimen 2 displays the largest amount of energy.

When the opening ratio is less than 9%, the amountof the energy dissipation is almost equal to that of thesolid in�ll walled specimen.

4. Conclusions

In this study, the behavior of RC frames with in�ll


Figure 8. Envelope curves for all specimens.

walls having opening is investigated experimentallyunder cyclic lateral loadings. Location and ratio of theopening in the in�ll wall are selected as test parameters.RC frames with in�ll wall having opening are testedunder reversed cyclic loading. Failure mode, lateral

load capacity, energy dissipation, and sti�ness of eachspecimen are obtained from the experimental results.The following conclusions can be derived from thisstudy:

1. Presence of in�ll walls having openings changes thebehavior of the frame signi�cantly. It also modi�esthe failure mechanism, as opening ratio increases,especially when it is larger than 9%;

2. The obtained results have shown that in�ll wallslead to signi�cant increases in strength and sti�nessof bare RC frames. Lateral load capacity of thesolid in�ll walled specimen increases by about 130%as compared to the specimen without in�ll wall.The test results show that as the opening ratioincreases, the lateral load capacity of the specimendecreases. When the opening ratio of the in�llwall is 4, 9, 16, and 25%, the lateral load capacityapproximately decreases by 1, 10, 20, and 30%,respectively. Furthermore, the test results yieldthat the contribution of the in�ll wall to the lateralload capacity of the frame decreases signi�cantlywhen the opening ratio is larger than 9%;

3. Story drift ratios are obtained for all the specimensin two di�erent ways. First, story drift ratiosare calculated for all specimens corresponding to alateral load capacity of the bare framed specimen.The highest and the lowest story drift ratios areobserved in the bare frame and solid in�ll walledspecimen. The obtained results show that the storydrift ratios increase as the openings on the in�llwalls increase;

4. Second, story drift ratios corresponding to the ulti-mate load capacity of each specimen are obtained.In the specimens with the opening of 25%, thestory drift ratio is higher than that in the bareframe under both push and pull loadings. Thisobservation is due to the fact that maximum story

Figure 9. Lateral load capacities of all specimens.


Figure 10. Variation of sti�ness depending on displacement for all specimens.

Figure 11. Energy dissipation depending on displacement for all specimens.

drift ratios are proportional to the correspondingultimate lateral load capacities of the Specimens 10and 1;

5. In�ll walls with openings contribute to the lateralsti�ness and lateral load capacity of the frames.However, if the opening in the in�ll wall is higherthan 16%, the story drift ratio corresponding tothe lateral load capacity of specimen is observedto increase with respect to the bare frame. Theobtained results clearly show that the e�ect of open-ings on story drift ratios is noteworthy. Incrementin the story drift ratio becomes signi�cant when theopening ratio is larger than 16% for both push andpull loadings. The opening becomes more e�ectivewhen they are located in the middle part of the in�llwall;

6. Energy dissipation and sti�ness of the specimen aresigni�cantly reduced with the increase in the ratioof the opening on the in�ll wall. Furthermore, theamount of energy dissipation is almost equal to that

of the solid in�ll walled specimen when the openingratio is more than 9%;

7. Behaviors of the specimens under pull and pushloadings are quite close to each other when theopening is located in the middle of the in�ll wall.However, the pull loading is generally more criticalthan the push loading, when the behavior of thespecimen is considered, especially when the openingis located on the upper left part of the in�ll;

8. The test results clearly show that the contributionof the in�ll wall to the behavior of RC frame isgreatly reduced when the opening ratio is largerthan 9%. Therefore, the e�ect of the opening inthe in�ll wall must be taken into account in thestructural modeling when the opening ratio is largerthan 9%;

9. In order to avoid brittle shear failure at the top andbottom of the columns of the frames with in�ll, thedesign shear force should increase by the horizontalcomponent of the strut developed in the in�ll wall;


10. Experimental tests have shown that presence ofopenings signi�cantly changes the behavior of in-�lled frames. The macro model of in�ll wall withopening can be developed by using the experimentalresults. Empirical equations can be proposed forestimating changes in lateral load capacity, energydissipation, and the lateral sti�ness of in�ll walledframes because of the presence of openings.

Acknowledgements

The study presented in this article was sponsored bythe Research Project Coordination Unit of SuleymanDemirel University (SDU) under Project No. 3418-YL1-13 and Kelesoglu Construction Company. Theexperimental work of this study was conducted in theStructural and Earthquake Engineering Laboratory atSDU. The authors would like to thank Mr. OsmanAkyurek, Mr. Metin Deniz, Mr. Necmi Kara, Mr.Emircan Hersat, Mr. U�gur Tosun, and Mr. Fatih Kayafor their assistance in conducting the experiments.

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Biographies

Hamide Tekeli is an Assistant Professor in theCivil Engineering Department at Suleyman Demirel

University in Isparta, Turkey. She received her PhDdegree from Suleyman Demirel University in 2006. Shespecializes in the areas of behavior and modeling ofreinforced concrete buildings. Her research focuses onexperimental and theoretical studies.

Asim Aydin is an MSc student in the Civil Engi-neering Department at Suleyman Demirel University inIsparta, Turkey, and works as a Civil Engineer in theKelesoglu Construction Company in Ankara, Turkey.His research interests include modeling of reinforcedconcrete structures, and repair and strengthening ofearthquake-damaged structures.

an experimental study of the seismic behavior of in lled rc...

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