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Partially infilled reinforced concrete (RC) frames have experienced significant damage during past earthquakes. Due to the partial confinement of columns in these structures, the shear force demand increases significantly, resulting in a brittle failure. This study investigated the efficiency of the strong frame-weak infill wall design concept to avoid the brittle failure mode of captive columns. For this purpose, two large-scale partially infilled RC frames with similar material properties and geometry but with different seismic detailing were constructed and subjected to a quasi-static cyclic loading. The obtained results from the conducted experiment were compared with two bare frames with similar detailing and geometry. It was observed that the partially infilled frames had up to 49.6% larger ultimate load than bare frames. Besides, at a 3% drift ratio, the cumulative energy dissipation of partially infilled frames was up to 180% more than bare frames. However, the stiffness degradation rate of the partially infilled frames was higher than the bare frames, particularly at drift ratios less than 1%. Besides, at larger drift ratios (i.e., around 3%), the infill walls contributed to partially infilled frames' lateral strength and increased it up to 60% compared with the bare frames.

In the present study, assessment of contribution of masonry infill wall in the linear range as well as exploration of post peak behaviour of RC buildings with open ground storey is targeted. Three different scaled RC building models having open ground storey and with different sizes of opening on infill walls have been tested on a shake table with low intensity of input excitations. Using acceleration response from these models, structural parameters have been identified adopting a system identification technique. The storey lateral stiffness in the linear range has been estimated using the above-mentioned identified modal parameters and an expression for stiffness representing the contribution of the masonry infill wall in the form of a diagonal strut has been proposed. Numerical models of all the specimens tested on shake table have been simulated. These numerically simulated models with different configurations have been used for assessment of post elastic behaviour of RC building models. While the lateral stiffness in the elastic range as well as peak load carrying capacities have been observed to increase in all the models due to the presence of infill wall, some interesting observations have been noted for shear force distribution across floors and possible reasons of failure of building with soft storey. Further, it has been observed that for a particular area of opening in the infill wall, the location does not considerably influence the load-displacement response of the building system.

The presence of masonry walls has a significant effect on the seismic response of structures. The infill panels can increase the overall lateral stiffness and strength of structures. This increase in strength and stiffness is normally beneficial to the overall seismic resistance unless the presence of masonry walls creates an irregularity in the structure or the infill-frame interaction induces excessive forces in the frame, leading to local failure. This study evaluated a proposed design method to prevent local shear failure of RC columns due to infill-frame interactions. 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 deformation states . Simplified equations based on the equivalent strut concept together with finite element analysis (FEA) are used to determine the demand of the surrounding frame due to infill-frame interaction and to assess key response parameters for the design. An RC frame with a concrete block masonry wall was designed with the proposed method and tested under cyclic loading. The test showed that local failure of the surrounding frame could be prevented, resulting in a ductile behavior. Only horizontal cracks were observed at the ends of the frame members, indicating only the flexural yielding. Finally, since a large variation in the infill wall strength may exist, the implementation and limitations of the method are also discussed.

Calculus complexity, time-consuming and high computational effort of the nonlinear dynamic analysis coupled with the complexity of simulating the interaction between masonry infill walls and reinforced concrete frames cause this fact that infill panels are usually considered as the non-structural elements to analyze and design the process of reinforced concrete frames infilled with masonry walls. In this study, to predict the influence of masonry infill panels on the imposed damage of moment-resisting reinforced concrete frames (MRRCFs) under earthquake excitation, incremental inelastic dynamic damage analyses are performed several MRRCFs under twenty seismic ground motions. The MRRCFs are simulated once without considering masonry infill wall effect (as bare frames) and another one considering masonry infill wall effect (as infilled frames). The diagonal compression strut model used to simulate the infill walls is compared with some other proposals in terms of the equivalent strut width, the bed-joint sliding shear strength, the diagonal tension cracking strength, the corner crushing strength, and the diagonal compression strength. Results show that the equivalent strut width, the diagonal tension cracking strength, and the corner crushing strength predicted by FEMA306 are in reasonable compliance with the model used in this study. The capacity and damage curves of bare, and partial, and full infilled frames using incremental dynamic analyses are achieved and compared. The consequences proved that masonry infill walls improve the lateral load-bearing capacity of MRRCFs and decrease the imposed damage of these frames in the seismic excitations. Furthermore, two relations are derived to predict the damage of bare and infilled frames under the earthquake excitations. To assess the accuracy of proposed relations, three new frames are designed. The values of their seismic damage are achieved through inelastic damage analyses and presented relations. Comparing the outcomes confirms the validity of proposed relations.

This paper presents a multi-platform simulation method for the modelling of reinforced concrete infilled frames . The method is developed for multi-scale modelling, where the frame is modelled in detail by two-dimensional elements while the infill wall is represented by equivalent struts. The proposed method not only significantly decreases the computational time compared to the conventional single platform simulation method but also allows the combination of multiple analysis tools with different capabilities. The method is also extended to model the dynamic effects induced by the sudden removal of a supporting column. A special element is developed for such purpose to account for the two analysis phases, i.e., before and after the column removal. The proposed multi-platform method is general and can be implemented in various problems related to the response of masonry infilled frames, e.g., reinforced concrete and steel frames, linear and nonlinear responses , static and dynamic analyses, lateral and vertical loads that represent earthquake and column failure scenarios.

In this experimental study, a method is presented for the seismic isolation of masonry infill walls from surrounding reinforced concrete frames using polyethylene foam at the interface of infill masonry walls and reinforced concrete frames. The main objective of this research work was to study the change in infill-frame interaction, by using polyethylene sheet for isolation of masonry infill wall from RC frame. For this purpose, two full scaled reinforced concrete frames having infill masonry walls and a window opening, were fabricated. One of the RC infilled frames was having no polyethylene foam at the infill-frame interface (RC Frame 1) while the other frame was having polyethylene foam at the infill-frame interface (RC Frame 2). Data of bare frame was obtained from PhD research work of Engr. Syed Azmat Ali Shah (UET Peshawar, Pakistan). Quasi static cyclic tests were conducted in displacement-controlled manner. Different graphs were plotted from the data obtained during test such as hysteresis curves , energy dissipation curves, envelope or backbone curves , bilinear idealization of backbone curves, stiffness degradation curves and performance levels were also determined for both the RC frames. It is concluded that by using polyethylene foam at the interface of masonry infill wall and RC frame, the infill frame interaction was reduced during early cycles of lateral displacements . At lower values of lateral displacements, response of RC Frame 2 (having PE foam) was similar to bare frame having less stiffness and strength. By further increasing the value of lateral displacement, the polyethylene foam was compressed and therefore infill masonry walls were activated, due to which stiffness and strength of RC Frame 2 were increased and its behavior was similar to infilled frame behavior. It is also concluded that damages produced in infill wall in RC Frame 2 (having PE foam) were less as compared to damages produced in RC Frame 1.

Masonry infill walls are the standard solution to build envelopes and partitions walls in reinforced concrete buildings in southern Europe. In Portugal, masonry infill walls appeared in the sixties, with the massive use of reinforced concrete frames for residential and commercial buildings. Since then and until our days the masonry infills walls (cavity walls) have not experienced significant changes, apart from some variations in thickness and introduction of thermal isolation between the masonry layers. The construction system remains based on cavity walls without any connection between layers and constructed with horizontal perforated bricks and poor mortars. Their vulnerability under seismic actions is recognized by the scientific community and proven whenever an earthquake occurs. Nevertheless, they continue to be used, because until now there was not much innovation in the development of attractive solutions to be implemented in new constructions, and particularly there are no clear design and detailing construction guidelines that can contribute to higher quality masonry infill walls with reduced seismic vulnerability. This paper aims to contribute for the advance on the innovation in brick masonry infills by presenting two proposals of new masonry infill walls systems to be enclosed by RC frames. An extensive experimental campaign is presented and results are discussed on mechanical properties of materials and masonry assemblages associated to the two innovative masonry infill wall systems. The data provided in this paper is important to understand further in-plane and out-of-plane experimental tests to be carried out on the masonry infill walls as well as further numerical simulations and analytical analysis of the masonry infill systems.

The paper presents an experimental investigation on the behavior of two identical large-scale masonry infill walls subjected to different shearing deformations resulting from lateral or vertical loading. The former produces a horizontal displacement field that simulates the behavior of the wall under earthquake excitation. The latter produces a vertical displacement field that simulates the case followed by loss of gravity support. Both scenarios were identified in past earthquakes. The experiments were conducted on similar infill walls with an aspect ratio of 1:1 made of hollow concrete blocks. The tests show fundamentally different behaviors in terms of the cracking patterns and load-bearing mechanisms. The orthotropic properties of the masonry infill wall significantly affect the load-displacement behavior, including the load resistance mechanism, the stiffness, and the unloading behavior. The major differences between the two cases call for caution in simulating the behaviour of infilled frame structures in the case of loss of a supporting column based on the accumulated knowledge on the behavior under lateral loading.

This study aims to propose a multi-strut macro-model, capable of simulating the overall force-displacement behaviour of infilled frames with various opening configurations. For this purpose, the results of finite element modelling calibrated against several experimental data are employed to determine the characteristics of a multiple-strut model for such infilled frames. The results indicate that the size of the opening along with its position, compared to the size of the infill wall, can significantly affect both the inclination and also the effective width of the struts and therefore, the overall behaviour of infilled frames with opening. The proposed model is evaluated parametrically against FEM numerical results, with varying characteristics such as opening size and position, opening height-to-length ratio, height-to-length ratio of the infilled frame and relative rigidity of frame to the infill wall. The comparison of the derived results with the analytical and experimental findings demonstrates the ability of the model to approximate the lateral response of infilled frames with openings in a reliable and robust manner. A simple reduction factor for the ultimate strength of the perforated infilled frames is proposed based on opening size relative to infill wall size as well as relative stiffness of the frame and infill wall.

In this paper, the structural performance of steel frames with novel lightweight composite infill walls is experimentally and numerically investigated under curvature ground deformation, which is a common consequence of ground mining activities that can cause significant effects on structures and buildings in these areas. A new structural form that combines steel frames and lightweight composite infill walls has recently been used; its performance under curvature ground deformation is of great interest but still not entirely clear. This study compares the mechanical behavior of the open-frame, the closed-frame with mudsill, and the closed-frame with infill walls, through experimental testing under positive and negative curvature ground deformations. Structural responses such as basement counterforce, additional strains at different key locations, and effects of mudsill and infill walls are evaluated. In addition, 3D finite element models are established to simulate the performance of the tested samples and are validated by comparing the results against those from experiments. After validation, the numerical model is applied to a few complex structures incorporating the composite infill walls to investigate their structural performance under both positive and negative curvature ground deformation. It has been found that steel frames with the new composite infill walls can considerably increase the stiffness of structures in resisting ground deformation and re-distribute the loads amongst the beam and column members in the frame. Failure modes for the structures can also be changed by shifting the most dangerous ones from the upper part of the frame to the lower part. Moreover, it has been found that the vertical force of the infill walls is more sensitive to curvature ground deformation than the horizontal force. Further, the influence of the infill wall on the column is more significant, in comparison to that on the beam of the frame.