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Open ground story (OGS) buildings, prevalent in urban areas of countries like India, are structurally unique due to the absence of infill walls in the ground floor. This characteristic increases their seismic vulnerability. Traditional design practices often neglect the stiffness contribution of upper-story infill walls, leading to inadequate ground floor column design, which cannot withstand the amplified bending moments and shear forces during an earthquake. This study identifies the most vulnerable story in OGS buildings through a comprehensive seismic fragility analysis. The findings from the probabilistic seismic demand model (PSDM) log-log graph reveal that the ground floor is the most vulnerable, exhibiting significantly higher inter-story drift (ID), compared to upper levels, due to its reduced lateral stiffness from the absence of infill walls. ID, used as the demand variable in a power law model, captures this vulnerability, providing critical insights into the ground floor's heightened risk during seismic events. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent seismic events have prompted research into innovative and sustainable materials for strengthening and repairing obsolete and vulnerable buildings. These earthquakes have exposed the high seismic vulnerability of existing reinforced concrete (RC) buildings, particularly in secondary structural elements like infill walls. In addition to structural issues, these buildings often face significant energy deficiencies, such as thermal bridges, due to inadequate insulation. Traditionally, structural and energy improvements for residential buildings are addressed separately with different methods and protocols. This preliminary study is part of a broader research initiative at the University of Reggio Calabria (Italy), aiming to design an innovative fiber-reinforced plaster using natural, sustainable, and locally produced materials to enhance the energy and structural performance of existing wall infills. The study investigates two plaster matrices made of natural hydraulic lime and silica sand, with 15% and 30% cork granules added. Mechanical and thermophysical tests on multiple specimens were conducted to evaluate their suitability for seismic and energy retrofitting of infill walls. Results indicate that adding cork reduces mechanical strength by approximately 42% at a 30% cork content without compromising its use in seismic retrofitting. Thermophysical tests show improved thermal performance with a higher cork content. These findings suggest that the lime–cork mixture at 30% is effective, offering excellent ductility and serving as a promising alternative to traditional cementitious plaster systems. The next experimental phase will test matrices with varying percentages of gorse fiber. [ABSTRACT FROM AUTHOR]

During earthquakes structures in active seismic areas are affected by different random ground motions that cause different forces in the structure such as displacement, acceleration, and stresses. These structures consist of a skeleton of reinforced concrete and masonry walls. The behavior of these composite structures is very complex and complicated to model. Furthermore, there is an observation lack in the regulation’s guidelines and seismic codes for the infill design process and behavior through the earthquakes. In practice, infill walls are considered a non-structure component, and so it is neglected in the design process. However, eliminating the infill leads to negative consequences. This paper investigates and evaluates the infill walls effect on the structure behavior during earthquakes. Four structural models consisting of basement with seven, nine, and eleven stories, without and with walls in different locations were idealised. The 3D analysis program PLAXIS was adopted in this study. A series of investigated models under the effect of lateral loads were conducted to discuss the infill walls effects on the model’s response. Results confirmed that infill walls take a place in increasing the structure's resistance to horizontal actions and improve the structure's lateral response. The infill walls reduced both the soil acceleration and strain by 56% and 16.7% respectively from their initial values. Also, walls’ presence reduced both the foundation displacement and acceleration by 49% and 28% respectively compared to bare structures. Finally, the wall existence has a vital role in the modification of the superstructure lateral performance against displacement and story drift. It may be considered as an alternative technique to construct foundation resistance structures.

Prefabricated panel-assembled wall systems, comprising a confining frame and infill lightweight panels of autoclaved aerated concrete (AAC), are widely employed in framed structures. Different from studies on a main frame with infill walls, this study aimed to explore the seismic performance of partition walls, which were fabricated with AAC panel-assembled walls and located outside of the main frames. Two full-scale specimens, one with a door opening and the other without, were constructed and cyclic loading tests were executed to examine the failure modes, hysteresis characteristics, envelope curves, ductility, strength and stiffness degradation, as well as energy dissipation capacity of the AAC panel-assembled walls. Additionally, a restoring-force model for the panel-assembled walls was developed and a method for predicting the lateral load-bearing capacity of the AAC panel-assembled walls was proposed. The findings indicated that the panels enhanced the system's lateral resistance, energy dissipation capacity, and deformation capability. The door frame increased the initial stiffness, peak lateral load and energy dissipation capacity of the AAC panel-assembled wall compared to the wall without a door frame. Compared to the specimen without a door frame, the peak lateral load of the specimen with a door frame increased by 19.7–30.1%. The deformation capacity of the panel-assembled walls aligned with the requirements for concrete framed structures. [ABSTRACT FROM AUTHOR]

Recent seismic events have prompted research into innovative and sustainable materials for strengthening and repairing obsolete and vulnerable buildings. These earthquakes have exposed the high seismic vulnerability of existing reinforced concrete (RC) buildings, particularly in secondary structural elements like infill walls. In addition to structural issues, these buildings often face significant energy deficiencies, such as thermal bridges, due to inadequate insulation. Traditionally, structural and energy improvements for residential buildings are addressed separately with different methods and protocols. This preliminary study is part of a broader research initiative at the University of Reggio Calabria (Italy), aiming to design an innovative fiber-reinforced plaster using natural, sustainable, and locally produced materials to enhance the energy and structural performance of existing wall infills. The study investigates two plaster matrices made of natural hydraulic lime and silica sand, with 15% and 30% cork granules added. Mechanical and thermophysical tests on multiple specimens were conducted to evaluate their suitability for seismic and energy retrofitting of infill walls. Results indicate that adding cork reduces mechanical strength by approximately 42% at a 30% cork content without compromising its use in seismic retrofitting. Thermophysical tests show improved thermal performance with a higher cork content. These findings suggest that the lime–cork mixture at 30% is effective, offering excellent ductility and serving as a promising alternative to traditional cementitious plaster systems. The next experimental phase will test matrices with varying percentages of gorse fiber.

The steel frame infilled with the autoclaved lightweight aerated concrete (AAC) masonry wall is widely applied in buildings. However, earthquake damage investigation has revealed that infill walls have a significant influence on the mechanical behaviors of the frame structure. In this paper, a new type of AAC masonry wall with circular-arc openings at the corners was proposed based on the principle that setting openings at the corners of the infill wall would weaken the tension (compression) band, so as to reduce the unfavorable interaction between the steel frame and the infill walls. Additionally, the seismic performance of steel frames infilled with AAC masonry walls with circular-arc openings at the corners under low cycle loading was investigated through finite element (FE) method simulations on 11 specimens. The results demonstrated that the circular-arc openings are effective in delaying the cracking of the AAC wall and weakening the additional stiffness of the AAC masonry wall for the steel frame.

Reinforced concrete is a construction that is vulnerable to damage during an earthquake if not done properly. This article focuses on the results of field observations after the earthquake disaster in Lombok and Palu in 2018, with the aim of identifying the type of damage that occurred in reinforced concrete buildings. This identification is important to understand the potential causes of damage and/or collapse in reinforced concrete buildings. The results of field observations show that low concrete quality and lack of standard reinforcement detailing processes are the main factors contributing to the large number of buildings experiencing damage and/or collapse during the earthquake. Poor quality concrete, such as a mismatch in the mix or a lack of strength, can make a structure brittle and unable to withstand excessive earthquake forces. Apart from that, lack of attention to the reinforcement detailing process is also a cause of significant damage. Non-standard reinforcement detailing includes a lack of the required amount of reinforcement in the structure, installation of shear reinforcement that does not meet the requirements, and a lack of shear reinforcement at beam and column connections. Lack of reinforcement in structural connections reduces the strength and stiffness of the structural system, thereby increasing the risk of collapse during an earthquake. The location and method of installing brick walls is also one of the factors causing building damage. Through analysis of the results of these observations, it can be concluded that good quality concrete and the process of detailing reinforcement and brick walls according to standards are very important to reduce damage and increase the resistance of reinforced concrete structures to earthquakes. Proper implementation of structural design specifications and careful monitoring during construction can help reduce the risk of damage caused by earthquakes.

Prefabricated panel-assembled wall systems, comprising a confining frame and infill lightweight panels of autoclaved aerated concrete (AAC), are widely employed in framed structures. Different from studies on a main frame with infill walls, this study aimed to explore the seismic performance of partition walls, which were fabricated with AAC panel-assembled walls and located outside of the main frames. Two full-scale specimens, one with a door opening and the other without, were constructed and cyclic loading tests were executed to examine the failure modes, hysteresis characteristics, envelope curves, ductility, strength and stiffness degradation, as well as energy dissipation capacity of the AAC panel-assembled walls. Additionally, a restoring-force model for the panel-assembled walls was developed and a method for predicting the lateral load-bearing capacity of the AAC panel-assembled walls was proposed. The findings indicated that the panels enhanced the system’s lateral resistance, energy dissipation capacity, and deformation capability. The door frame increased the initial stiffness, peak lateral load and energy dissipation capacity of the AAC panel-assembled wall compared to the wall without a door frame. Compared to the specimen without a door frame, the peak lateral load of the specimen with a door frame increased by 19.7–30.1%. The deformation capacity of the panel-assembled walls aligned with the requirements for concrete framed structures.

Experiences of past earthquakes show that the infill wall is one of the non-structural elements which has the highest collapse potential of the structure. Although architects are responsible for designing the form and arrangement of walls, little research has been done in this regard with the aim of architectural design. In this research, a method was developed to control the infill walls in the basic architectural design. In this method, architectural design features are preserved, and only by applying minor modifications to the specifications of walls, undesirable effects such as short column, soft story, and torsion are prevented and without using more materials, additional potential for seismic resistance of the building is provided. For this method, two accurate and approximate models were developed. In the accurate model which includes five algorithms, a structural model is required, so close collaboration between architect and structural engineer is necessary. In the approximate method which includes four algorithms, only geometric specifications of architectural design are required and architects can control the effects of infill walls on the structure. The results of the practical test of the approximate model indicated that this model can be used by various groups of architects. This model will not prevent the creativity of architects and the designer has a great degree of freedom in applying solutions. [ABSTRACT FROM AUTHOR]

Existing reinforced concrete structures designed according to previous generation seismic codes, often suffer from premature, abrupt and detrimental failures in cases of intense earthquakes. In this study the seismic response of an existing building is analytically investigated while taking into account the influence of different detailing of brick wall infills. The assessment is performed with 3D static inelastic (Pushover) or with incremental Dynamic time‐history analyses (IDA) with the SeismoStruct Software. Buildings with inadequate performance receive continuous transverse pre‐tensioned Basalt Fiber Ropes (BFR) as external shear and confining strengthening reinforcement. The inelastic analyses conclude that buildings with short columns suffer from early collapses at low top displacements due to detrimental local shear failure of the above‐mentioned members. Both shear and crush confined concrete related failures of the critical columns are eliminated and overall base shear strength is increased. BFR external wrapping increases the ultimate top building displacements as well. IDA are thoroughly elaborated to assess the collapse mechanism of the structures and conclude ultimate base shear and top displacement values for the critical cases of buildings under investigation. [ABSTRACT FROM AUTHOR]

Many RC(reinforced concrete) frame structures were severely damaged in the Wenchuan earthquake, but the collapse rate of RC frame structures in the extreme earthquake area zone far exceeded that of multi-storey brick and concrete structures. Since September 2022, frequent earthquakes have occurred in Sichuan. It is necessary to re-explore the collapse mechanism and seismic performance. The collapse mechanism and seismic response analysis of RC frame structures were studied by field earthquake damage and failure forms of multi-storey RC frame structures, combining numerical models and using the MIDAS Gen finite element method. The results show that the damage and yielding of the frame columns are the main factors for the RC frame collapsed, the simulation of additional infill walls,when the seismic intensity reaches 10 degrees, the inter-storey displacement angle is about 1 / 46, which reduces the axial compression ratio of columns, improves the damage ductility of columns, increase the limit lateral capacity of the structure, have the effect of seismic first line of defense, to avoid the overall yielding damage [ABSTRACT FROM AUTHOR]

During an earthquake, the detachment and local interaction between infill wall panels and surrounding frame can occur, potentially leading to significant local damage to both structural and non-structural elements, if not global collapse. Yet, a procedure to assess the relative deformation mechanism in terms of detachment shape and values, rather than, and in addition to, the diagonal compression strut mechanism and associated internal panel strain and stress path, is still missing in the literature. Therefore, in this paper the concept of shape functions is proposed and adopted to assess the seismic displacement incompatibility between infill walls and the surrounding frame structure. A parametric study on different typologies of infilled frames is developed to investigate the key parameters affecting the infill-frame detachment. The proposed concept of shape functions can support the design/retrofit of improved construction details, such as shear keys and/or steel dowels, in view of either decoupling or strengthening retrofit/repair strategies. Moreover, as infill-frame detachment can lead to damage to energy enhancement rehabilitation solutions, such as external thermal insulation systems, which are becoming more common nowadays in view of the international target towards a significant reduction of energy consumption and CO2 emission, it is suggested to implement the proposed displacement-compatible design check to assess and detail for adequate displacement capacity. [ABSTRACT FROM AUTHOR]

Evaluating the structural performance of low-rise RC buildings with infill walls is an essential issue in Thailand, as most infill walls were not designed for lateral load resistance. The purpose of this study was to predict the structural behavior and illustrate the effects of infill walls. Residential, commercial, and educational buildings were selected as representative buildings with different patterns of infill walls. Based on the results, infill walls contributed to considerable strength and stiffness. Most of the infill walls that affected the low-rise buildings were at the ground floor level. The behavior of the buildings that had a contribution of infill walls was found to be brittle until the infill walls collapsed, and then the buildings became ductile. Some patterns in which infill walls were placed improperly led to a torsional effect, resulting in columns in the affected areas reaching failure criteria more than those without this effect. Considering the NLRHA procedure, only infill walls on the ground floor contributed to the building being subjected to a ground motion. The fully infilled frame tended to reach the infill crack before the other patterns. For the UMRHA procedure, only the first vibration mode was adequate to predict seismic responses, such as roof displacement and top-story drift. [ABSTRACT FROM AUTHOR]

Considered nonstructural elements, infill walls and their participation in earthquake resistance are often neglected in structural design, which leads to deviations in the predictions of seismic responses. Generally, infill masonry walls are the most extensively used type, but they often exhibit out-of-plane vulnerability and insufficient reliability during earthquakes. To overcome the drawbacks and further improve the beneficial contributions of infill walls, a reinforced concrete (RC) infill wall isolated by polyvinyl chloride (PVC) tubes, abbreviated as PVCIW, was proposed to incorporate with coupled shear walls. Featuring flexible connections, the PVC tubes were adopted to eliminate the unfavorable constraints between infill walls and the main structure. RC panel was adopted for the infill because of its excellent compressive properties and out-of-plane resistance. Compression of the PVCIW was allowed during extreme quakes to contribute to anticollapsing of the coupled shear walls. Cyclic loading tests were applied to compare the hysteretic properties between coupled shear wall specimens equipped with RC infill walls, PVCIWs, and without infill walls, and the advantages of PVCIWs were validated. Finite-element analysis (FEA) was performed to simulate the test results, and parametric cases were investigated to optimize the design of PVCIWs. Finally, based on a modified coupling ratio CRM considering the influence of PVCIWs, a new seismic design approach was developed to obtain the optimized properties of this novel system. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the infilled frames through various important parameters (i.e., the openings' percentage in infill walls - several columns on the first floor are removed - partial infilled) in the RC structures, subject to progressive collapse scenarios. To this end, 3D finite element models were constructed by using the software ABAQUS. Numerical and experimental results were compared to substantiate the finite element models' capability of simulating the experimental models' behavior of Al-Chaar et al. (2002) in an accurate manner. The results showed that there was good agreement between experimental and numerical results. Moreover, the results indicated that there was a significant effect, which cannot be neglected, on the progressive collapse resistance; the reduction ratios in vertical displacement at the regions removed columns can reach up to 80%. [ABSTRACT FROM AUTHOR]

Observations obtained in the course of previous earthquakes and studies performed by different researchers indicate the influence of cladding (façade) on seismic performance of structure. there is a dearth of technical knowledge in this field and no proper understanding exists of the actual response of different facade systems to earthquakes, and few studies, especially in Iran, have conducted about how building facade is damaged and about the performance analysis. As a matter of fact, even considering the cladding as non-structural members, those will interact with the encompassing frame during strong earthquakes, and these interactions can alter seismic performance of the structure. This is even more important when it comes to concrete frames wherein material properties and cladding arrangement along the structure height impose significant impacts on the failure mode and failure mechanism of the encompassing frame. In the present paper, three-, five-, and nine-story frames with conventional moment-resisting systems were analyzed using OpenSees Software by considering two typical façades in Iran, namely brick-finished and granite-finished structures. Results of the analysis show that, materials and cladding arrangement impose significant impact on the wall stiffness, distribution of seismic forces by elements, and lateral displacement of the structure. Moreover, it is observed that, with increasing the number of stories, effects of cladding on the structure behavior and performance decrease gradually.

Evaluating the structural performance of low-rise RC buildings with infill walls is an essential issue in Thailand, as most infill walls were not designed for lateral load resistance. The purpose of this study was to predict the structural behavior and illustrate the effects of infill walls. Residential, commercial, and educational buildings were selected as representative buildings with different patterns of infill walls. Based on the results, infill walls contributed to considerable strength and stiffness. Most of the infill walls that affected the low-rise buildings were at the ground floor level. The behavior of the buildings that had a contribution of infill walls was found to be brittle until the infill walls collapsed, and then the buildings became ductile. Some patterns in which infill walls were placed improperly led to a torsional effect, resulting in columns in the affected areas reaching failure criteria more than those without this effect. Considering the NLRHA procedure, only infill walls on the ground floor contributed to the building being subjected to a ground motion. The fully infilled frame tended to reach the infill crack before the other patterns. For the UMRHA procedure, only the first vibration mode was adequate to predict seismic responses, such as roof displacement and top-story drift.

This paper presents a seismic response evaluation of self-centering prestressed concrete frames with infill walls (SCPC-IW frames). Three types of infill walls with different load capacity were selected to be installed in a bare self-centering prestressed concrete frame (SCPC-Bare frame). Beam web friction devices are included in the beam-column connections to provide energy dissipation capacity. Numerical models of the SCPC frame, and the three SCPC-IW frames were established and analyzed in a finite element software, OpenSees. Firstly, the nonlinear static analyses and nonlinear dynamic analyses under 44 ground motions were performed. Secondly, the incremental dynamic analyses (IDAs), seismic fragility analyses, and collapse resistance capacity evaluation were conducted. The results showed that the initial stiffness, energy dissipating capacity of SCPC-IW frames are increased in comparison to SCPC frames. After adding infill walls, the lateral displacement of the SCPC-IW frames decreases. However, the residual deformation and axial compression ratio of the SCPC-IW frame increases. As the infill walls strength increases, the increased amplitude of residual displacement becomes much larger than the decreased amplitude of the drift. It is concluded that when the load capacity of infill walls ranges from 37% to 79% of the web friction force, the SCPC-IW frames can achieve a good balance in terms of stiffness, energy dissipation, and self-centering capability as well as collapse resistance capability. [ABSTRACT FROM AUTHOR]

Recently, the contribution of infill walls on progressive collapse resistance of reinforced concrete (RC) structures attracts a great many research attentions, but the research interests are mainly concentrated on the static resistance and the macro-modeling approaches, which require predefined one-dimensional load paths through two-dimensional walls. However, the load transfer paths in dynamic loading regime are still not fully understood. To this end, high-fidelity finite element (FE) models of multi-story RC infilled frames are built and validated through quasi-static experimental results. Then the FE models are used to investigate the dynamic responses of infilled frames under different single and double CRS as well as the effect of the number of stories on the load transfer paths of full-height infill walls (FHIW) and infill walls having opening (IWHO). The results indicate that the load paths along the infill walls in static and dynamic loading regimes are similar prior to the peak resistance but different in post-peak resistance for single infilled story frames. Such difference results from the loading distribution pattern, in which the static loading is typically represented by a concentrated load whereas the dynamic loading involves the uniformly distributed load. Moreover, increasing the number of infilled stories with FHIW, trans-story load paths due to composite effect always exist to enhance resistance and such paths are scenario-dependent. In comparison, the load paths for multi-story frames with IWHO are relatively scenario-independent with minor composite effect. Therefore, to generalize the macro-modeling, it is conservative to ignore the trans-story load paths. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhengzhou University: Engineering Science is the property of Editorial Office of Journal of Zhengzhou University: Engineering Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Masonry infill walls are commonly used in the frames of reinforced concrete (RC) buildings around the world. The seismic performance of these buildings is strongly affected by the presence of the infill walls and partitions, as shown by the post-earthquake damage in many cases. The effect of these components is particularly important for RC frame constructions underdesigned for seismic actions that usually are characterized by deformable frames magnifying the contribution of the infill walls to the seismic response. Also the flexibility of the floors could be influenced by the collaboration of the infill walls to the transversal stiffness of the building. The paper addresses the seismic assessment of a typical infilled RC frame building designed only for gravity loads in the 1960s in the Southern of Italy that currently is a high-seismic zone. The structural identification of the building based on ambient vibration test has been already done pointing out the significant role of infill walls and partitions through the updating of the numerical model. Based on the results of the calibrated model, the effect of the floor flexibility on the dynamic behavior of the structure is discussed, and the seismic capacity at life safety limit state (LSLS) is assessed by means of the linear dynamic analyses. The effects of the infill walls on the seismic performance of the building are discussed in detail considering a strengthening solution that involves the infill panels as masonry walls cut from the RC columns to avoid the local interaction but strengthened by composite grids in mortar matrix (FRCM).

The aim of this study is develop an effective strengthening method to provide a fast, economical, lightweight, functional system which also ensures good heat and sound insulation. The experimental study includes a total of 4 reinforced concrete frames that were produced to reflect the defects in the existing structures. Two of the reinforced concrete frames were strengthened by using drywalls sheathed with steel sheet. Other two frames were the reference specimen to check the effectiveness of the strengthening strategy. The first reference specimen was a bare reinforced concrete frame. The second reference specimen was produced by filling the frame with autoclaved aerated concrete walls. The specimens are subjected to cyclic lateral load reversals while a constant axial load was applied. As a result of this study, it has been observed that single and double skeleton drywall systems improves the lateral load carrying capacity, energy dissipation capacity and initial stiffness of the reinforced concrete frame. [ABSTRACT FROM AUTHOR]

An innovative concept is proposed to isolate – at low and moderate story drifts – infill panels from the surrounding steel frame, using thin layers of cellular materials. The concept is verified experimentally through testing of fully infilled frames under in-plane cyclic loading. A simple analytical model is developed and implemented in OpenSees; the model is in good agreement with test results. It is concluded that the proposed technique has a high potential in reducing infill-frame interactions – hence damage of the infills – up to moderate drifts, whereas full interaction is still in place when drifts are large. [ABSTRACT FROM AUTHOR]

Concrete block infill walls, due to their high strength and stiffness, can significantly influence the seismic behavior of the frames. The infill walls can increase the overall lateral frame strength and can also induce local failures in the surrounding frames. In general, if local failure can be avoided, the presence of the infill walls can provide additional reserved strength that can be beneficial to the frames. For this reason, a new RC frame with infill walls could be designed as a bare frame without considering the increase in strength, but measures must be taken to prevent local failures due to the infill wall-frame interaction. However, this infill wall-frame interaction is very complex, and clear design strategies to prevent local failures are not normally given in design codes. For this reason, two full-scale intermediate RC moment-resisting frame specimens with infill concrete block walls were tested under a horizontal cyclic load to study the infill wall-frame interaction. Finite element analysis was carried out to evaluate the response particularly on the infill-frame interactions. Based on the results, a design strategy to eliminate local failure in the surrounding frame is suggested. The proposed method is based on local plastic mechanism analysis of the column considering the variation in the column shear demand and column shear capacity at different states of the response as the frame deforms. The shear demand depends on the magnitude and direction of the bearing force from the infill wall. The column is considered as a captive or slender column depending on the restraint from the infill wall, thereby affecting the shear capacity of the column. The proposed approach can be readily applied without radically changing common design practices and design codes. [ABSTRACT FROM AUTHOR]

Summary: Past earthquakes had shown vulnerability of infill walls especially under out of plane (OOP) loading. Although some new infill walls show a good OOP performance, generally, they do not have the right economic justification or have complexity in construction. Therefore, in this paper, an innovative economical infill wall is presented that is not complicated in construction. The proposed wall constructed by light expanded clay aggregate in especial shape that reinforced with side plates, top, and bottom rebars. Experimental and numerical studies were carried out to investigate its seismic performance. Experimental results showed a high continuity between blocks of wall due to its especial shape that is increased ultimate OOP strength and ultimate OOP displacement of the wall. Numerical results indicated, because the infill wall is isolated from boundary frame, no drift is imposed to infill wall from boundary frame. Therefore, the infill wall only suffered OOP seismic acceleration. Due to light weight of the infill wall, low OOP load that corresponds to seismic acceleration is applied to the infill wall. In the infill wall, no separation is made even up to drift frame of 2.5%. The relations to design of the proposed infill wall were also presented. [ABSTRACT FROM AUTHOR]

Reinforced concrete structure systems are usually designed as frame or shear wall-frame systems. It is possible to reduce the deformation and displacement in the system by increasing the structural stiffness. Besides, large displacements on the floors caused by horizontal load are damped by the cracks in these walls. The present paper aims to examine the effects of materials used in the wall construction as well as thickness of the plaster on the behavior of infill walls under cyclic loads. In order to investigate the above mentioned effects, three Infill walls that were produced from three different materials namely, horizontal hollow bricks, pumice blocks and aerated concrete blocks were tested in three setups (without plaster, with 1 cm plaster and 2.5 cm plaster on it). In order to determine pure wall contribution, the infill walls were placed in a steel frame test set-up which was hinged from all four corners and were then exposed to cyclic loads taking into account the displacement controlled loading protocol proposed in FEMA 461. Right after applying the plaster to the infill walls, load carrying and energy dissipation capacities of the walls were examined comparatively. Loaddisplacement, backbone curve and cumulative dissipated energy curves of each infill walls are generated using the data collected from the experiments and the infill walls behaviors are graphically explained. Test results showed that existence and thickness of plaster significantly affected cyclic behavior of the test walls by increasing energy dissipation capacities and load carrying capacities. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional, four-storied, reinforced concrete (RC) building is designed for seismic zone-IV and seismically evaluated for different infill configurations along with consideration of openings in infills to develop a realistic model. Four models are considered, i.e. model I (full RC-infilled frame without lintel beam), model II (bare frame without lintel beam), model III (full RC-infilled frame with lintel beam) and model IV (bare frame with lintel beam). In this study, we have evaluated the effect of lintel beams on response reduction factor of the frame structure. The nonlinear static adaptive pushover analysis has been done using Seismostruct program. In seismic design, the response reduction factor (R-factor) reduces from the elastic to inelastic strength. The R-factor is one of the design tools to show the level of inelasticity in a structure and so it has significant importance in the earthquake engineering field. The response reduction factor mainly consists of 'ductility reduction factor' and 'over strength factor', which are evaluated from static adaptive pushover analysis. Ultimately the response reduction factor is obtained for the building and compared with the value recommended by IS 1893 Part-1 (2016). The results depict that the R-factor values of full RC-infilled frames and bare frames with incorporation of lintel beams are higher than other frames without lintel beam. However, R-factor values of bare frames are lower than the corresponding values recommended in the BIS code. [ABSTRACT FROM AUTHOR]

Reinforced Concrete buildings with masonry infills are among the most common structural systems in many countries with regions of high seismicity. Masonry infill walls increase robustness of damaged RC structures. Although their mechanical contribution is usually neglected in structural analysis and design, they significantly affect the seismic response of RC frames. In this paper, we concentrate on the development of infill walls by using various structure design and brick types. An experimental investigation is carried out on two types of mortar mixes like conventional mortar and mortar used with hybrid fibers (polypropylene, sisal, kenaf, and aramid). Here, two types of masonry brick infills such as clay bricks and fly ash bricks are used. After construction of the specimens, each was marked properly according to their respective test of total 60 specimens, which have conventional and fiber‐mixed mortars. After 28 days curing, the masonry specimens attain their full strength and they became ready for the test. The material ratio followed to construct test specimens was according to the Indian standard. The shear test is conducted for masonry triplets and the flexural test is conducted for masonry wall panel structures. After that, the mechanical properties of this structure are validated with the help of the Restricted Boltzmann Machine (RBM)‐based Deep Neural Network (DNN). The performance of the proposed modeling is evaluated by comparing with those of the existing techniques. [ABSTRACT FROM AUTHOR]

• High fidelity solid-element based numerical models are built and validated. • Progressive collapse performance of infilled RC frames are studied. • Interaction between infill walls and framed members are illustrated. • Peak resistance of infilled frames is reduced as a function of opening ratio. • Composite action of multi-story infilled frame forms for full-height infill walls. In practice, infilled frame is a common structure but the contribution of infill walls is typically ignored in previous research on progressive collapse. To this end, numerical models based on solid-element are employed to investigate the behavior of reinforced concrete (RC) frames with concrete masonry infill walls under a middle column removal scenario (CRS). The numerical models of bare and infilled frames are initially validated through previous experimental results. Then the numerical models are used to illustrate the effects of infill walls on the load transfer mechanisms of the frames under a CRS and the interaction between infill walls and frame members. Thereafter, the size effect of the frame models is discussed and the numerical models are further extended to study the effects of pertinent geometric parameters on the progressive collapse behavior, including the height of partial-height infill walls, the opening position and area of wall panels as well as the number of stories. The results indicate that the load transfer mechanism of a two-story infilled frame in a middle CRS is the frame action provided by frame members and the truss mechanism provided by the interaction of infill walls and surrounding frame members, in which the latter remarkably enhances the initial structural stiffness and peak resistance. For the multi-story infilled frame with opening in which the geometric and mechanical properties are identical in each story, the load transfer mechanism is basically independent of the number of stories, whereas for the frame with full-height infill walls, the composite effect of multi-story walls is evident, increasing the peak structural resistance. Therefore, if each full-height infill wall is simplified into equivalent strut models in structural analysis, the results are underpredicted but on the safe side. [ABSTRACT FROM AUTHOR]