Investigation Of Effect Of Infill Walls With Brick In Buildings

Infill walls are widely used as partitions worldwide. Field evidence has shown that continuous infill walls can help reduce the vulnerability of a reinforced concrete structure. Often, engineers do not consider infill walls in the design process because the final distribution of these elements may be unknown to them, or because walls are regarded as non-structural elements. It is known that infill walls considerably change the behaviour of frames under lateral loads. Contribution of infill walls in the strength and stiffness of reinforced concrete (RC) frames is neglected in the design of RC frame buildings. This leads to incorrect idealization of the structurePrevious experimental research on the response of RC frames with masonry infill walls subject to static and dynamic lateral cyclic loads (1-2 etc. ) have shown that infill walls lead to significant increases in strength and stiffness in relation to bare RC frames.. Separation between masonry walls and frames is often not provided and, as a consequence, walls and frames interact during strong ground motion. This leads to structural response deviating radically from what is expected in the design.This study focuses on, several story building was designed with bricks which has different modulus of elasticity were selected for its infill walls. The infill wall was considered as weight and equivalent diagonal compression strut model. It is found that infill walls have significant effect on stiffness, period, lateral displacement, base shear force and structural behavior. The performance and rigidity of structure having infilling walls increased and these were exhibited positive behavior under seismic loads compared to structure having bare frame

Finite Element Modeling of Masonry Infill Walls Equipped with Structural Fuse

Masonry infill walls in multi-story buildings are intended to function as envelope and partition walls, and without sufficient gaps between the infill and the frame, the infill tends to contribute to lateral seismic load resistance, which can lead to damage. By isolating the infill walls from the frame, vulnerability to damage will be reduced; however, the potential benefit from the strength and stiffness of the infill walls will be lost too. The compromise solution seems to be a controlled engagement of the masonry infill walls by employing a structural fuse concept. In this chapter, initially, a review of the literature on seismic performance of masonry infill walls is presented. This is then followed by explanation of the concept of the masonry infill structural fuse. Then a discussion on experimental tests carried out on different types of fuse elements as well as ¼ scale specimen of frame and infill walls with fuse elements is presented. Finally, the results of finite element computer modeling studies are discussed. The study has found that the concept of using structural fuse elements as sacrificial components in masonry construction is practical and can be given consideration for more refined design and detailing toward practical application

Seismic vulnerability analysis of reinforced concrete frame with infill wall considering in-plane and out-of-plane interactions

The seismic performance of a building hinges on the seismic capacity and damage features of the reinforced concrete (RC) frame with masonry infill walls. To reasonably evaluate the seismic performance and seismic economic loss of masonry infill walls, it is necessary to consider the in-plane (IP) and out-of-plane (OOP) interactions of these walls under seismic actions, and to model the vulnerability of the infill walls and the frame. Based on the test data on masonry infill walls, this paper designs a performance indicator for infill wall in the light of IP-OOP interactions, and determines the response threshold of each damage state. With the aid of OpenSees, the authors developed and verified a reasonable modeling method for RC frames with infill walls. As per the current code in China, a 5-storey RC frame with infill walls was designed, and two three-dimensional (3D) space models were established for the structure by the proposed modeling method. One of them considers IP-OOP interactions, and the other does not. Then, the structure was subjected to incremental dynamic analyses (IDA), and different damage indicators were determined to examine the damage of the infill walls and the overall structure, producing a set of vulnerability curves. The results show that the consideration of IP-OOP interactions significantly increases the probability of seismic damages on the infill walls and the overall structure. The most prominent increase was observed in the medium to serious damage stages

Investigating the effect of infill walls on steel frame structures

Infill walls consisting of materials such as hollow concrete, hollow clay and autoclaved aerated concrete bricks are not only preferred in reinforced concrete buildings but also in steel frame structures. It is a well-known fact that infill walls limit the displacement of frames under horizontal loads. However, they may also bring about certain problems due to being placed randomly in horizontal and discontinuously in vertical directions for some architectural reasons. Moreover, cracks in frame-wall joints are observed in steel frame structures in which ductile behaving steel and brittle behaving infill walls are used together. In this study, the effect of infill walls on steel frames has been investigated. In the steel frame structure chosen for the study, four different situations consisting of different combinations of infill walls have been modeled by using ETABS Software. Later, the pushover analyses have been performed for all the models and their results have been compared. As a result of the analyses done by using the equivalent diagonal strut model, it has been found out that infill walls limit the displacement of steel frames and increase the performance of a structure. However, it has been also determined that in the steel frame structure in which the infill walls have been placed discontinuously in vertical and asymmetrically in horizontal, infill walls may lead to torsional and soft story irregularities. As a result, it is possible to observe cracks in the joints of infill walls and steel frame, the deformation properties of which differ, unless necessary precautions are taken

Damage-imperfection indicators for the assessment of multi-leaf masonry walls under different conditions

The complexity of multi-leaf masonry walls suggests further researches on the dy- namic behaviour mainly characterized by incoherent response between the different layers. The intrinsic discontinuity and the manufacturing imperfections are amplified by the incre- mental damage that triggers different failure mechanisms that affect the dynamic parameters, such as modal shapes, frequencies and damping ratios. The dynamic identification with out- put only methodology has been proposed in this work on different multi-leaf masonry walls subjected to uniaxial compressive load. The responses of full infill, damaged infill and strengthened infill masonry panels with different widespread damage have been recorded. The evolution of the damage scenario changes the modal shapes, the related frequencies and the damping ratios that through the comparison with the data of the initial conditions can de- tect the anomalies and then the intrinsic vulnerabilities. Through the curvature modal shape methods and the structural irregularity indices applied to different phases, it was possible evaluate the imperfection and the induced damage entity

Effect of the openings on the seismic response of an infilled reinforced concrete structure

The seismic behavior of the infill masonry infill walls has a significant impact on the global response of reinforced concrete frame structures. One factor influencing its behavior is the existence of openings in the walls, such as doors and windows, which are crucial for the infill seismic performance. Although the numerical simulation of the seismic behavior of RC buildings with infill walls has evolved significantly in recent years in terms of micro- and macro-modelling, most of the existing studies are only related to infill walls without openings. Based on this motivation, four main objectives were defined for this research work: (i) present a simplified modeling approach and its calibration to simulate the seismic behavior of infill walls with central openings such as windows; (ii) evaluate the impact of the openings on the global seismic response of an RC building; (iii) study the impact of the irregular distribution of the infill walls (vertical and in-plane) on the global seismic response of an RC building; and (iv) study the impact of the central openings ratio (i.e., relative percentage between opening and infill wall area) on the global seismic response of an RC building structure. A four-story infilled RC building was used as a case study to perform parametric analyses investigating the impact of the masonry infill walls’ irregular distribution (vertical and in-plan) and their openings ratio. The results are discussed in terms of natural frequencies and vibration modes, initial lateral stiffness, and maximum lateral resistance. This study found that the openings caused a reduction in the natural frequencies of about 20% compared with the full infill (without openings). The openings did not modify the vibration modes. In addition, the openings reduced the initial stiffness by about 20% compared with the model without openings. The maximum strength increased about 50% with the infill walls, but this was reduced by the openings by 20%.publishe

Effect of infill wall stiffness variations on the behavior of reinforced concrete frames under earthquake demands

Thesis (Master)--Izmir Institute of Technology, Civil Engineering, Izmir, 2013Includes bibliographical references (leaves: 79-81)Text in English; Abstract: Turkish and Englishxi, 83 leavesReinforced concrete (RC) structures with infill walls are the most common building types in earthquake-prone regions of Turkey. Due to the complications in modeling the infill wall - frame interaction, they are generally neglected in structural design. However, presence of the infill walls has been proved to affect stiffness, strength and behavior of the structures significantly. Effects of infill walls may be either beneficial or detrimental under seismic demands. Infill walls typically increase the stiffness and strength of the structures. This situation may be advantageous for nonductile buildings up to a certain limit. However, brittle nature and variety of failure modes of infill walls may cause unforeseen and irreversible damages. Particularly, softstory mechanisms may occur due to drift concentrations at lower stories. An organized stiffness distribution along the height of the structure may help mitigating these negative effects. The main purpose of the study is to investigate the effects of stiffness variations in infill walls to the behavior of the frames. In order to achieve the purpose, an analytical software that supports an infill model, was selected. The software is calibrated and verified by simulating a series of experiments. Afterwards, a planar, fivestory, five-bay reinforced concrete frame was designed with common deficiencies observed in residential buildings in Turkey. The performance of the bare frame (BF) was determined using pushover analysis. Then, two types of infilled frames were obtained by introducing infill walls into two bays. The infill walls of the first infilled frame (IF-1) had a uniform stiffness and strength distribution along the height of the frame. In the second infilled frame (IF-2), the stiffness and strength of the infill walls had a decreasing profile from the bottom to the top story. By this distribution, drift concentration at the lower stories was aimed to be mitigated. Nonlinear dynamic and pushover analyses were performed on the frames. The results indicated that the organized stiffness distribution of IF-2 mitigated the drift concentrations and improved he seismic performance of the frame

Betonarme Binalarda Dolgu Duvarların Deprem Etkisi Altındaki Davranışının İncelenmesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada, betonarme binalarda dolgu duvarların deprem etkisi altındaki yapısal davranışının incelenmesi amaçlanmıştır. Dolgu duvarların yapının taşıyıcı sistemi üzerindeki etkileri ve dolgu duvar modelleri ayrıntılı olarak incelenmiştir. Çalışmada, altı katlı ve on iki katlı iki betonarme bina kullanılmıştır. Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik 2007 ve TS 500 Betonarme Yapıların Tasarım ve Yapım Kuralları’ na uygun olarak her iki bina için taşıyıcı sistemler tasarlanmıştır. Binalar dolgu duvarsız, tuğla dolgu duvarlı ve gazbeton dolgu duvarlı olarak oluşturulmuştur. Dolgu duvarsız, tuğla dolgu duvarlı ve gazbeton dolgu duvarlı binaların taşıyıcı sistemlerinin üç boyutlu modelleri SAP2000 yapı analiz programında oluşturulmuş ve Eşdeğer Deprem Yükü Yöntemi kullanılarak çözüm yapılmıştır. Dolgu duvarlar deneysel ve analitik çalışmaların ışığında eşdeğer diyagonal basınç çubukları olarak modellenmiştir. Çözümleme sonrasında tüm modellerin doğal titreşim periyotları, taban kesme kuvvetleri, yer değiştirme değerleri, kat rijitlik değerleri, burulma düzensizliği katsayıları ve etkin göreli kat ötelemesi değerleri elde edilmiştir. Modellerin analiz sonuçları karşılaştırılmış ve yorumlanmıştır. Anahtar Kelimeler: Dolgu duvar etkisi, Dolgu duvarlı çerçeveler, Dolgu duvarlı perde çerçeveler, Eşdeğer diyagonal basınç çubuğuIn this study, investigating structural behavior of infill walls in reinforced concrete buildings under earthquake effect is aimed. Effects of infill walls on the bearing system of structure and the modeling of infill walls are investigated in detail. In the study, two reinforced concrete buildings, six-story and twelve-story, are examined. The bearing frame systems for each building are designed in accordance with Turkish Earthquake Code 2007 and Turkish Standards 500. The buildings are constituted without infill walls, with brick infill walls and with aerated concrete infill walls. Three dimensional models of the bearing frame systems of the buildings with and without infill walls are constituted in SAP2000 structural analysis program and analyzed by using Equivalent Seismic Load Method. Infill walls are modeled as equivalent diagonal pressure bars in the light of experimental and analytical works. After the analyses the values of free vibration periods, base shear forces, displacements, rigidities of tories, torsional irregularity factors and effective relative story drifts of all models are obtained. The analysis results of the models are compared and commented. Keywords: Effect of infill wall, Frames with infill walls, Shear wall-frames with infill walls, Equivalent diagonal pressure ba

Seismic performance of Portuguese masonry infill walls: From traditional systems to new solutions

The use of masonry infill walls in reinforced concrete structures are a common solution in Portugal and other European countries for more than 50 years. These walls are used as exterior enclosures to build the envelope of the buildings, or as interior partitions to divide the different spaces of the houses. In the building construction practice these walls are built only after the hardening of the reinforced concrete elements. For that reason, they are assumed as non-structural elements, and not considered in the structural design of the building. However, when buildings are subjected to seismic action, these walls assume a structural behavior. This leads in many cases to the existence of an unsatisfactory behavior of infill walls, resulting in damage of the walls, which put human lives in dangerous and cause extensive economic losses. This seismic vulnerability of masonry infill walls is well recognized by the scientific community and has been observed in many works carried out in the last decades, as well as the recent earthquakes in southern Europe. In the case of a seismic event of high intensity in Portugal, it is expected that similar problems will occur in the Portuguese masonry infill walls, given the similarity of the construction typologies, in southern Europe. It is therefore important to study the masonry infill walls used in Portugal over the years, to fully understand their seismic behavior, and thus be able to propose and study reinforcement systems for existing walls and new masonry infill systems for new construction. Thus, in this paper is made a characterization of masonry infill walls typologies used in Portugal over the years. A review of the mechanical behavior of masonry infill walls is carried out using several In-Plane and Out-of-Plane tests performed at the University of Minho and other studies carried out in Portugal. Several strengthening techniques possible to be used in this type of walls are presented, as well as some mechanical characterization tests of these strengthening solutions applied on Portuguese infills walls. Finally, are presented two proposals for new systems of masonry infill walls to be used in new construction, with the objective of present a better seismic behavior in this type of elementsEuropean Union’s Seventh Framework Program for research, technological development and demonstration under grant agreement No 606229, which support this work. This work was also supported by FCT (Portuguese Foundation for Science and Technology, within ISISE, project UID/ECI/04029/2013, and through a doctoral scholarship reference SFRH/BD/125094/201

Out-of-plane behavior of masonry infill walls

In order to investigate the out-of-plane behaviour of masonry infill walls, quasi-static testing was performed on a masonry infill walls built inside a reinforced concrete frame by means of an airbag system to apply the uniform out-of-plane load to each component of the infill. The main advantage of this testing setup is that the out-of-plane loading can be applied more uniformly in the walls, contrarily to point load configuration. The test was performed under displacement control by selecting the mid-point of the infill as control point. Input and output air in the airbag was controlled by using a software to apply a specific displacement in the control point of the infill wall. The effect of the distance between the reaction frame of the airbag and the masonry infill on the effective contact area was previously analysed. Four load cells were attached to the reaction frame to measure the out-of-plane force. The effective contact area of the airbag was calculated by dividing the load measured in load cells by the pressure inside the airbag. When the distance between the reaction walls and the masonry infill wall is smaller, the effective area is closer to the nominal area of the airbag. Deformation and crack patterns of the infill confirm the formation of arching mechanism and two-way bending of the masonry infill. Until collapse of the horizontal interface between infill and upper beam in RC frame, the infill bends in two directions but the failure of that interface which is known as weakest interface due to difficulties in filling the mortar between bricks of last row and upper beam results in the crack opening trough a well-defined path and the consequent collapse of the infill