NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES: MODEL CALIBRATION AND PARAMETRIC STUDY

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1 9 th Intenational Masony Confeence 2014 in Guimaães NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES: MODEL CALIBRATION AND PARAMETRIC STUDY Fahad Akhoundi 1, Paulo B. Louenço 2, G. Vasconcelos 3 ABSTRACT: Geneally two methods ae poposed fo analyzing the infilled fames; Mico modelling appoach which finite element method is used to take into account local effects in detail and Maco modelling appoach which is a vey simplified method that takes into account the global behavio of the stuctue by eplacing the infill with diagonal stut. In the pesent study a numeical analysis is caied out on a one bay one stoey einfoced concete fame with masony infill unde in-plane loading by using finite element modelling though the DIANA softwae. The numeical model was calibated based on expeimental esults and then a paametic study was caied out, taking into account vaiation of mateial popeties of infill and its height to length atio. It is concluded that compessive stength and height to length atio of the masony infill has dominant ole on the in-plane behavio of these types of masony infilled fames. Inceasing the compessive stength of the masony enhances the lateal stength of the infilled fames while inceasing the height to length atio of the infill panel esults in decease of thei lateal stength and initial stiffness. Keywods: masony-infilled einfoced concete fame, in-plane loading, mico modelling appoach, DIANA softwae 1. INTRODUCTION Last seismic events in Southen Euope have highlighted the vulneability in the most usual constuctive typology in contempoay achitectue: famed stuctues with masony infills [1]. Contempoay stuctues have a good capacity to withstand these actions, given that they wee consideed fo thei design accoding to moden codes. Nonetheless, nonstuctual elements as masony infills show a high degee of damage even fo medium magnitude eathquakes, causing casualties and high economic losses [2, 3]. Fo decades, these elements have been consideed as nonstuctual and theefoe they wee not equested to have esisting conditions. Seveal expeimental studies have been caied out to investigate the effect of masony infills on the in-plane behavio of masony infilled fames. Some of them wee concentated on einfoced concete fames [2, 4-6] and some on steel fames [7, 8]. Although masony infills ae assumed as non-stuctual elements, thei pesence can affect the global behavio of the infilled fames by inceasing its stiffness, lateal stength and enegy dissipation capacity [4, 7] o causing the failue of 1 Ph.D candidate, ISISE, Civil Engineeing depatment, Minho Univesity, fahad.akhoundi@civil.uminho.pt 2 Pofesso, ISISE, Civil Engineeing depatment, Minho Univesity, pbl@civil.uminho.pt 3 Pofesso, ISISE, Civil Engineeing depatment, Minho Univesity, gaca@civil.uminho.pt 9 th Intenational Masony Confeence, Guimaães

2 Fahad Akhoundi, Paulo B. Louenço, Gaça Vasconcelos the system by foming shot column effect o soft stoy phenomenon [9]. Mehabi et al [4] concluded that the lateal stength of the einfoced concete fame with masony infill is 175% highe than that of a bae fame. In the anothe study caied out by Yuksel et al [10], it was concluded that the pesence of infills inceases the lateal stength of the bae fame about 100%. These conclusions highlight the impotance of the infills within fames to be consideed in the design pocess of the buildings. Expeimental esults confim that thee ae impotant paametes which could affect the in-plane behavio of infilled fames [11, 12]. Those paametes could be classified in thee diffeent categoies; (a) geomety and mechanical popeties of the infill; (b) geomety and mechanical popeties of the suounding fame; (c) condition of the infill-fame inteface. In the study caied out by Kakaletsis et al [12] it was concluded that the specimens with stong infills demonstate bette pefomance than those with weak infills in tems of lateal stength, stiffness, ductility and enegy dissipation capacity. Seveal studies wee concentated on the effect of opening and its position on the in-plane behavio of the infilled fames [8, 12] and a detailed state-of-the-at was conducted by Suendan et al [13]. The chaacteistics of the inteface between masony infill and its suounding fame can also affect the infilled fame s behavio [11, 14]. The unintentional gap between the infill and suounding fame, which is geneally the esult of masony shinkage is one of those paametes and unless this gap is not closed, the masony infill will not contibute to the lateal in-plane behavio of the stuctue. Using shea connectos along the whole peimete of the inteface enhances the behavio of the stuctue by inceasing its lateal stength and stiffness [14]. Numeical analysis povides bette insight into undestanding the exact behavio of the infilled fames. This needs a validated numeical model which is calibated by expeimental esults. In this pape it is intended to numeically investigate how the vaiation in mechanical popeties of masony infill and also its geomety affect the in-plane behavio of infilled fames. Geneally thee ae two methods fo numeically analyzing the infilled fames, namely maco and mico modelling appoaches. In the Maco modelling appoach, infill is eplaced by equivalent diagonal stut [15]. Expeimental esults evealed that the equivalent stut must have a width to accuately epesent the infill. Diffeent studies wee caied out to detemine the width of the diagonal stut [16, 17]. The single diagonal stut method is a simple and capable of epesenting the global behavio of the infill but it cannot pedict local effects in the infill esulting fom inteaction between infill and fame. To ovecome this, diffeent stut models such as double-stut, tiple-stut with diffeent configuations have been poposed [18, 19]. In the mico modelling appoach finite element method is used to model the infill panel which contibutes to bette undestanding of the local behavio of the infilled fames. As it is shown in Eo! A oigem da efeência não foi encontada.figue 1 thee ae thee diffeent appoaches to model the infill in mico modelling appoach, namely detailed mico model, simplified mico model and maco model by consideing a masony as homogenous and isotopic mateial (which is totally diffeent with maco model that infill is eplaced by diagonal stut) [20]. In the detailed mico modelling appoach infill panel is modelled as a set of thee diffeent components: bick, mota and inteface between mota and bick. In the simplified mico model, infill is modelled as a set of two diffeent elements: expanded bick and inteface elements. Inteface elements epesent the behavio of the mota and also the inteface between mota and bick. 2 9 th Intenational Masony Confeence, Guimaães 2014

3 NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES Figue 1 Vaious techniques in mico modelling appoach: (a) pat of a masony wall; (b) detailed mico-model; (c) simplified mico-model; (d) maco-model 2. NUMERICAL MODELLING To fulfil the objectives of this study and cay out a paametic study by evaluating some facto in the in-plane behaviou of bick masony infilled RC fames, a calibation of a finite element model was peviously caied out. The calibation of the numeical model in DIANA softwae was made based on the expeimental esults obtained by Peeia [5] on the in-plane static cyclic tests on masony infilled RC fames. In the expeimental pogam thee diffeent test specimens wee consideed and its desciption in tems of mateials and geomety is pesented in Table 1Table 1. The mechanical popeties ae epesented in Table 2Table 2 and a geneal oveview of the einfocing scheme and geomety of the RC fame ae epesented in Figue 2Figue 2. Figue 2 Geomety and einfocement scheme of the specimens Table 1 Popeties of test specimens Specimen Type of Panel Components Chaacteistics Wall-Ref-01 Simple Bick With dimensions of 30*20*15 cm (without endeing) Mota Mota M5 with 1 cm thickness Wall-Ref-02 With dimensions of 30*20*15 cm Simple Bick Mota M5 with 1 cm thickness (with endeing at both Mota Mota M5 with 1 cm thickness at sides) Rendeing each sides Wall-JAR Reinfoced panel Bick Mota Exteio endeing Inteio endeing Reinfocement With dimensions of 30*20*15 cm Mota M5 with 1 cm thickness Mota M5 with1 cm thickness Pojected Gypsum 2ɸ4 at bed joints Table 2 Mechanical popeties of the infilled fame s components Mechanical Popeties Concete Masony Reinfocement Elastic Modulus pependicula to the bed joints (GPa) Poisson s atio Tensile Stength (MPa) Mode-I Tensile Factue Enegy (N/mm) Compessive Stength (MPa) Compessive Factue Enegy (N/mm) th Intenational Masony Confeence Guimaães

4 Fahad Akhoundi, Paulo B. Louenço, Gaça Vasconcelos Yield Stess (MPa) The numeical model of the specimens was defined by using mico modelling appoach but consideing the infill panel as a homogenous mateial as descibed befoe. Masony infill and concete fame was modelled by using fou-noded shell elements. Reinfocement was added to the concete fame by embedding them to the concete elements. Inteface elements of (2+2) noded wee used to model the behavio of the inteface between masony infill and einfoced concete fame. The mesh of the finite element model of the test specimen is shown in Figue 3Figue 3. Figue 3 Finite element model of the test specimen A constitutive model of total stain fixed cack based on total stain which can descibe the tensile and compessive behavio of the mateial with one stess-stain elationship was used fo modelling masony and concete mateials. Futhemoe multi suface inteface model of combined cackingsheaing-cushing as shown in Figue 4Figue 4 is used to simulate factue, fictional slip as well as cushing along the inteface. Figue 4 Thee-dimensional inteface yield function Vetical load of 50KN was applied to the columns in the numeical model in accodance to what was consideed in the expeimental pogam to simulate the weight of the uppe stoeys. Thee tanslations and thee otations of bottom beam and also out-of-plane tanslations of the uppe beam wee fixed to simulate the constaints of the RC fame in a simila manne to what made in the expeimental tests. Mechanical popeties of the inteface between masony infill and its suounding fame epesented in Table 3Table 3 wee obtained by validating the numeical foce-displacement diagam of Wall-Ref-01 in compaison to the expeimental diagam obtained in the static cyclic tests along with its cack pattens with test esults. Fomat Table 3 Mechanical popeties of the inteface elements Elastic Popeties Nonlinea Popeties Nomal stiffness (N/mm 3 ) Shea Stiffness (N/mm 3 ) Tensile Stength (MPa) Mode I factue Enegy (N/mm) Cohesion (MPa) Nonlinea Popeties 4 9 th Intenational Masony Confeence, Guimaães 2014

5 NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES Tangent of Mode II factue Compessive Compessive factue Dilatancy Fiction Angle enegy (N/mm) Stength (MPa) enegy (N/mm) As it is shown in (a) (b) Figue 5Figue 5a the foce-displacement diagam of the validated numeical model of Wall-Ref-01 is almost an aveage of the test esults. This confims that numeical model is close to test esults. Because the tests wee pefomed cyclically, Test+ epesents the monotonic envelop diagam of the specimen in x diection and Test- epesents the monotonic envelop diagam in +x diection. At low lateal load levels applied to the infilled fame, masony infill and its suounding fame act as monolithic load esisting system but by inceasing the lateal load masony infill sepaates fom its bounding fame and foms diagonal stut as shown in Figue 5Figue 5b to withstand the applied load. Right afte sepaating the masony fom RC fame in left uppe cone at lateal load of 55KN, it sepaates in ight bottom cone at lateal foce of 65KN which is simila to what happened in test specimens. F F (a) (b) Figue 5 a) compaison of the numeical foce-displacement diagams with the monotonic expeimental envelop obtained in both loading diections b) distibution of pincipal minimum stess within infilled fame Defomed mesh of the infill panel in the numeical model which is shown in Figue 6Figue 6a indicates that the masony infill cushes in both cones at the diagonal compession stut. This cushing of the both ends is also obseved in expeimental esults as is shown in Figue 6Figue 6b. Aiming at evaluating the pefomance of the validated model based on the specimen Wall-Ref-01, it was impotant to assess the ability of the validated model fo pedicting the expeimental behavio of the test specimens of Wall-Ref-02 and Wall-JAR. To do this, Numeical models of Wall-Ref-02 and Wall-JAR wee made by using thei infill s mechanical popeties as epesented in Table 4Table 4 and modifying the inteface mechanical popeties of Wall-Ref-01 since pesence of endeing will change its popeties. Fo instance the tensile stength of the inteface fo Wall-Ref-02 and wall-jar was calculated by taking into account the tensile stength of layes of endeing as; f ti t w f t t f tin Eq. 1 t all 9 th Intenational Masony Confeence Guimaães

6 Fahad Akhoundi, Paulo B. Louenço, Gaça Vasconcelos (a) (b) Figue 6 Details of the calibation of the numeical model; (a) Defomed mesh of the infill in numeical model; (b) cushing the loaded cone in the test specimen In which f tin is the tensile stength of the inteface in new condition (afte adding endeing), f ti is the tensile stength of the inteface befoe adding the endeing, f t is the tensile stength of the added mateials, t is the thickness of the infill wall befoe adding the endeing (15 cm), w t is the thickness of the added mateials (1 cm) and t all is the all thickness of the wall afte endeing. Mechanical popeties of the inteface in shea such as cohesion, Mode I and Mode II factue enegies wee calculated in the same way by eplacing the tensile stength with cohesion, ModeI and Mode II factue enegies in Eq. 1Eq. 1 espectively as epesented in Eq. 2Eq. 2 to Eq. 4Eq. 4. Calculated mechanical popeties of Inteface fo Wall-Ref-02 and Wall-JAR ae epesented in Table 5. Because the compessive mechanical popeties of the inteface fo Wall-Ref-01 ae high enough, they did not ecalculated fo intefaces with endeing. In which C, in I M in and inteface in new condition espectively, C M M in I in II in C t C t i w t all I I M t M t i w t all II II M t M t i w t all Eq. 2 Eq. 3 Eq. 4 II M in ae the cohesion, Mode I factue enegy and Mode II factue enegy of the C i, I M i and II M i ae the chesion, Mode I factue enegy and Mode II factue enegy of the inteface befoe adding the endeing espectively and finally C, M II and M ae the cohesion, Mode I factue enegy and Mode II factue enegy of the endeing mateials espectively. I Fomat Inglês ( Fomat Inglês ( Fomat Inglês ( Table 4 Mechanical popeties of infill used fo modelling Wall-Ref-01 and Wall-JAR Mechanical Popeties Infill Wall-JAR Infill Wall-Ref-02 Young Modulus (GPa) Poisson s atio Tensile Stength (MPa) Mode-I Tensile Factue Enegy (N/mm) Compessive Stength (MPa) Compessive Factue Enegy (N/mm) th Intenational Masony Confeence, Guimaães 2014

7 NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES Table 5 Mechanical popeties of inteface afte endeing Inteface mechanical Popeties Wall-Ref-02 Wall-JAR Tensile stength (MPa) Mode I factue enegy (N/mm) Cohesion (MPa) Mode II factue enegy (N/mm) Accoding to what is seen fom Figue 7Figue 7, static nonlinea analysis of the numeical focedisplacement diagams of Wall-Ref-02 and Wall-Ja shows that they satisfactoily can epesent the expeimental esults of these wall specimens. F N (a) (b) Figue 7 Compaison between numeical and expeimental foce-displacement diagams; (a) Wall- Ref-02; (b) Wall-JAR 3. PARAMETRIC ANALYSIS Afte the calibation of the numeical model, it was decided to make a paametic analysis to evaluate the influence of the mechanical popeties of the masony infill such as compessive stength, compessive factue enegy, tensile stength and elastic modulus on the global esponse of the infilled fames unde in-plane loads. Besides the mateial popeties of the bick masony, also the geometic popeties, namely the height to length aspect atio was also taken into account Effect of Infill s compessive stength In a fist numeical analysis, the compessive stength of bick masony was taken as 2MPa and 5MPa to investigate the effect of its vaiation on the in-plane behavio of infilled fames. As it is shown in Figue 8Figue 8 inceasing the infill s compessive stength leads to incease in the lateal stength of the infilled fame. By inceasing infill s compessive stength fom 1MPa (used in the calibation of the numeical model) to 2MPa, infilled fame s lateal stength inceased about 15% while by inceasing its compessive stength fom 2MPa to 5MPa, the incease in its lateal stength is 64%. The impovement of the lateal stength of the masony infilled RC fame by inceasing the compessive stength of masony is much associated to the cack pattens and damage developed in the composite stuctue. In fact, the damage patten is much elated to the cushing of masony at the ends of the compession stut at the contact between the masony infill and the fame. This means that by inceasing the compessive stength of masony, the damage due to masony cushing is delayed and occus fo highe values of stesses developed in the walls, coesponding to highe values of the lateal load applied. 9 th Intenational Masony Confeence Guimaães

8 Fahad Akhoundi, Paulo B. Louenço, Gaça Vasconcelos Figue 8 Pushove diagams of the numeical models Usually the masony mateials with highe compessive stengths have highe factue enegies. To simulate this condition, infill s compessive stength and also its compessive factue enegy in Wall- Ref-01 was inceased fo two times to have the compessive stength of 2MPa and compessive factue enegy of 2N/mm. The esults of static nonlinea analysis in tem of foce-displacement diagams ae shown in Figue 9Figue 9. Figue 9 Pushove diagams of the numeical models It can be concluded that inceasing the infill s compessive stength fom 1MPa to 2MPa and also its compessive factue enegy fom 1N/mm to 2N/mm togethe cause incease of the maximum lateal stength about 23%. Compaing the foce-displacement diagams of the MCS(2) and MCS(2)- MCFE(2) demonstates also that by inceasing the compessive factue enegy highe non-linea displacement capacity of the composite stuctue is achieved leading also to the smoothing of the post peak behavio of the stuctue, see the post peak banch of wall specimen of MCS(2)-MCFE(2) Effect of Infill s tensile stength The effect of the tensile stength of bick masony infill wall on its in-plane behavio and lateal esistance is evaluated by vaying the tensile stength of masony fom 0.25MPa in the peviously calibated numeical model (Wall-Ref-01) to 0.5MPa. The tensile factue enegies ae kept constant to investigate only the effect of tensile stength on the in-plane behavio. Fom the esults obtained, it is obseved that foce-displacement diagam of the model with inceased tensile stength do not show any change in tems of maximum lateal stength, see Figue 10Figue 9. Load-displacement diagams of both models ae the same until the peak load, which means that infill s tensile stength does not have significant effect on the load-displacement diagams of these types of infilled-fames until the peak loads. Beyond the peak load, not significant mino changes wee also ecoded. 8 9 th Intenational Masony Confeence, Guimaães 2014

9 NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES Figue 10 Compaison of the foce-displacement diagams fo models with vaying tensile stength of masony 3.3. Effect of Infill s elastic modulus The effect of the elastic stiffness of the masony infill in the in-plane behavio of the masony infilled RC fames is analyzed by inceasing its elastic modulus about 100%. As it is shown in Figue 11Figue 11, 100% inceasing the elastic modulus of the infill panel inceases the initial stiffness of the infilled fame about 80% and its lateal stength about 5%, which appeas to be negligible. The fist cack in efeence infill panel develops at a displacement of 9.6mm, wheeas in the wall with inceased elastic modulus the fist cack develops at lateal displacement of 2.8mm. This means that in the panel with inceased elastic modulus the cacking develops ealie with espect to efeence wall. The geat diffeence in the esponse of the composite stuctue to in-plane lateal loading is the defomation coesponding to maximum lateal load and also the maximum lateal displacement of the infilled RC fame. This appeas to indicate that the use of less stiff infill masony leads to consideably moe ductile behavio of RC infilled fames. Figue 11 Foce-displacement diagams fo RC fame models with distinct stiffness of the bick masony infill 3.4. Effect of height to length atio of the panel In this section it is intended to investigate the effect of height to length atio of the infill panel on the in-plane behavio of infilled fames. To do this, thee walls with diffeent lengths of 100, 200 and 500cm with height to length atios of 1.7, 0.85 and 0.34 wee assumed to be analyzed and compaed with the analysis esults of efeence wall of Wall-Ref-01 that has a length of 350cm and height to length atio of The geomety of the specimens is epesented in Figue 12Figue 12. The main eason to have diffeent height to length ations by changing the infill s length is that in one specific stoey within building that has a constant height, walls with diffeent lengths can often be found. 9 th Intenational Masony Confeence Guimaães

10 Fahad Akhoundi, Paulo B. Louenço, Gaça Vasconcelos (a) (b) (c) Figue 12 Geometical configuations of the masony infilled fames; a) h/l(1.7) b) h/l(0.85) c) h/l(0.34) Static nonlinea analysis was caied out on the distinct walls to investigate thei behavio unde lateal in-plane loading. Foce-displacement diagam of the all numeical models ae epesented in Figue 13Figue 13. By compaing the foce-displacement diagams of the numeical models it can be obseved that by inceasing the length of the efeence model of Wall-Ref-01 fom 350cm to 500cm which leads to a decease of the h/l atio fom 0.47 to 0.34, model epesents highe lateal stength and also highe initial stiffness. Initial stiffness is defined as tangent of line connecting the fist point in gaphs to the point coesponding to 30% of maximum lateal foce. Fom the values of the lateal stength and initial stiffness of the numeical models pesented in Table 6Table 6 it can be seen that the incease of the h/l atio fom 1.7 to 0.34 esult in a eduction on lateal stength of about 46% and a eduction on the lateal stiffness of about 75%. Deceasing the length of the efeence numeical model fom 350cm to 200cm leads to decease in the initial stiffness and lateal stength about 38% and 7% espectively. Figue 13 Focee-displacement diagams of the numeical models with diffeent height to length atios In numeical models with h/l atios less than 0.85, the foce-displacement diagam pesents a sudden dop. Fo highe values of the h/l atio the behavio is consideably moe ductile, such in case of the numeical model with h/l of 1.7. In the othe wods, numeical models with h/l atios of less than 0.85 show bittle behavio while the numeical model with highe h/l atio (1.7) shows vey ductile behavio. Table 6 Initial stiffness and lateal stength of the numeical models Numeical Model h/l Initial Stiffness (N/mm) Lateal Stength (N) h/l(0.34) Wall-Ref h/l(0.85) h/l(1.7) th Intenational Masony Confeence, Guimaães 2014

11 NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES The distibution of the minimum pincipal stesses fo distinct masony walls along with thei geneal defomations fo a lateal load of 40KN is epesented in Figue 14Figue 14. As concluded befoe, highe h/l atios leads to lowe initial stiffness and thus to highe defomations. The same lateal load causes moe defomations in the model h/l(1.7). In this model the infill panel is totally sepaated fom its bounding fame and diagonal stut is completely fomed unde the lateal foce of 40KN. In both ends of diagonal stut the compessive stesses supasses the compessive stength of masony. By inceasing the length of the infill, h/l(0.85), a small amount of sepaation happens unde the same lateal load. The diagonal stut has fomed but the compessive stesses in its both ends ae lowe than the compessive stength and thus can withstand moe lateal loads. In the numeical model h/l(0.34), the sepaation has not been occued unde lateal load of 40KN and it must be inceased to even sepaate its infill fom the RC fame. In this condition the infill and its suounding fame monolithically esist the lateal load. It is clea that this numeical model withstand moe lateal load as epesented in Table 6Table 6. Cack pattens of the numeical models of h/l(1.7), h/l(0.85) and Wall-Ref-01 along with thei defomations unde lateal load ae epesented in Figue 15Figue 15. Because the cack patten of both models of Wall-Ref-01 and h/l(0.34) is simila, the cack patten of Wall-Ref-01 is epesented. The magnification facto fo all the numeical models in Figue 15Figue 15 ae the same. In the cack patten developed in the Wall-Ref-01, the masony cushes in both ends of the diagonal stut and cacks in vicinity of the ight column by fomation of some mino tensile cacks. (a) (b) (c) Figue 14 Distibution of the minimum pinciple stesses within the fame unde lateal foce of 40KN: a) h/l(1.7) b) h/l(0.85) c) h/l(0.34) By moving fom numeical model of Wall-Ref-01 to h/l(0.85), it can be obseved that although the masony cushes in both ends of the stut but some tensile cacks fom which connects the cushed cone to the opposite cones in a hoizontal diection. Fomation of hoizontal cacks in bottom pat of the infill could be intepeted as the effect of inceasing height to length atio esulting in highe inplane flexual stesses. In the numeical model of h/l(1.7), the sepaation of the infill fom its bounding fame is lage enough with espect to the othe numeical models which is due to highe h/l atio. This could be assumed as the main eason fo fomation of extensive hoizontal cacks in bottom pat of the infill. (a) (b) (c) 9 th Intenational Masony Confeence Guimaães

12 Fahad Akhoundi, Paulo B. Louenço, Gaça Vasconcelos Figue 15 Cack pattens of the infilled fames of a) h/l(1.7) b) h/l(0.85) c)wall-ref Conclusions A paametic analysis is pesented in this pape in ode to investigate the influence of vaiation in mechanical popeties of the infill and also its geomety on the in-plane behavio of masony infilled fames. The following conclusions can be dawn fom the pesent study: 1. Compessive stength of the masony infill has dominant ole in the in-plane behavio of masony infilled fames. Pesence of stong masony in tems of compessive stength enhances the lateal stength of the infilled fame. 2. Inceasing tensile stength of the infill panel does not appea to enhance the lateal stength of the infilled fame. 3. Inceasing the elastic modulus of masony infill inceases the initial stiffness of the infilled fame but no changes on the lateal stength wee achieved. The geat influence of the elastic modulus of the masony infill is in the in the inceasing the bittleness of the composite stuctue. The defomation at peak load educes significantly and almost post peak esponse is ecoded. 4. Inceasing h/l atio of the infill deceases the initial stiffness and lateal stength of the infilled fame. Fo instance inceasing the h/l of the infill fom 0.34 to 1.7 deceases the initial stiffness and lateal stength of the infilled fame about 75% and 45% espectively. 5. Inceasing the h/l atio of the infill changes the cack patten of the infilled fames. ACKNOWLEDGEMENTS The authos would like to acknowledge to the Potuguese Foundation fo Science and Technology (FCT) fo the funding of the eseach poject RetoInf Developing innovative solutions fo seismic etofitting of masony infill walls (PTDC/ECM/122347/2010). REFERENCES [1] Louenço PB, Vasconcelos G, Medeios P, Gouveia J. Vetically pefoated clay bick masony fo loadbeaing and non-loadbeaing masony walls. Constuction and Building Mateials. 2010;24: [2] Beteo V, Bokken S. Infills in seismic esistant building. Jounal of Stuctual Engineeing (ASCE ). 1983;109: [3] Al-Chaa G, Issa M, Sweeney S. Behavio of Masony-Infilled Nonductile Reinfoced Concete Fames. Jounal of Stuctual Engineeing. 2002;128: [4] Mehabi AB, Shing PB. Pefomance of Masony-Infilled R/C Fames unde In-Plane Lateal Loads: Analytical Modelling. Poceedings fom the NCEER Wokshop on Seismic Response of Masony. San Fancisco, Califonia1994. p [5] Peeia MFP. Avaliação do desempenho das envolventes dos edifícios face à acção dos sismos: Univesidade do Minho; [6] Kyiakides MA. Seismec Retofit of Uneinfoced Masony Infills in Non-ductile Reinfoced Concete Fames Using Engineeed Cementitious Composites Stanfod Univesity; [7] Altin S, Anil Ö, Kaa ME. Stengthening of RC nonductile fames with RC infills: An expeimental study. Cement and Concete Composites. 2008;30: [8] Mosalam K, White R, Gegely P. Static Response of Infilled Fames Using Quasi-Static Expeimentation. Jounal of Stuctual Engineeing. 1997;123: [9] DolŠEk M, Fajfa P. Soft Stoey Effects in Unifomly Infilled Reinfoced Concete Fames. Jounal of Eathquake Engineeing. 2001;5:1-12. [10] Yuksel E, Ozkaynak H, Buyukoztuk O, Yalcin C, Dinda AA, Sumeli M, et al. Pefomance of altenative CFRP etofitting schemes used in infilled RC fames. Constuction and Building Mateials. 2010;24: th Intenational Masony Confeence, Guimaães 2014

13 NUMERICAL MODELLING OF MASONRY-INFILLED REINFORCED CONCRETE FRAMES [11] Cisafulli F. Seismic Behavio of Reinfoced Concete Stuctues with Masony Infills. New Zealand: Univesity of Cantebuy; [12] Kakaletsis DJ, Kaayannis CG. Influence of Masony Stength and Openings on Infilled R/C Fames Unde Cycling Loading. Jounal of Eathquake Engineeing. 2008;12: [13] Suendan S, Kaushik HB. Masony infill RC fames with openings: eview of in-plane lateal load behaviou and modeling appoaches. The Open Constuction and Building Technology Jounal. 2012;6: [14] Liauw TC, Kwan KH. Static and cyclic behavious of multistoey infilled fames with diffeent inteface conditions. Jounal of Sound and Vibation. 1985;99: [15] Mallick DV, Seven RT. The Behaviou of Infilled Fames Unde Static Loading. ICE Poceedings1967. p [16] Cavalei L, Papia M. A new dynamic identification technique: application to the evaluation of the equivalent stut fo infilled fames. Engineeing Stuctues. 2003;25: [17] Holmes M. Steel Fames with Bickwok and Concete Infilling. ICE Poceedings1961. p [18] Cisafulli FJ, Ca AJ. Poposed maco-model fo the analysis of infilled fame stuctues. Bulletin of the New Zealand society fo eathquake engineeing. 2007;40. [19] Smyou E, Blandon C, Antoniou S, Pinho R, Cisafulli F. Implementation and veification of a masony panel model fo nonlinea dynamic analysis of infilled RC fames. Bull Eathquake Eng. 2011;9: [20] Louenço PB. Computational stategies fo masony stuctues [Diss, Technische Univesiteit Delft, 1996]. Delft: Delft Univesity Pess; th Intenational Masony Confeence Guimaães