Evaluation of the seismic performance of masonry-infilled reinforced concrete (RC) frames is challenging because a number of damage patterns can be induced by the interaction between the infill and the frame. In this paper, the extended finite-element method (XFEM) is adopted to model the cracking behavior and the compressive failure of concrete in frame members as well as masonry units in infill panels, and the discrete interface element is employed to simulate the behavior of the masonry mortar joints and the joints at the frame-to-infill interface. With the XFEM, the crack can propagate in an arbitrary manner during the analysis. In addition, multiple continuous cracks are allowed in this model. The nonlinear finite-element model is validated by the available experimental data. It can be concluded that the proposed model is capable of predicting the load-displacement response of a masonry-infilled RC frame structure. The damage patterns regarding cracking and crushing of frame members and masonry panels, tensile fracture and compressive compaction in mortar joints, and shear sliding of masonry units along mortar joints are also reproduced very well.

This study presents a finite element (FE) model, the accuracy of which is verified by the comparison between the numerical and test results. The calibrated model is used to investigate the influence of vertical arrangement and masonry material of infill walls on the seismic performance of reinforced concrete (RC) frames through pushover analysis and time–history analysis. The lateral capacity, interstorey drift ratio, and plastic hinge distribution of structures is discussed. It was found that the damage of frames with irregular vertical infill arrangement is more serious than that of bare frames, which should be limited in the seismic design process. Moreover, the disadvantages induced by the elastic modulus of masonry material should be considered in the seismic design and assessment of the frames with vertical irregularly arranged infill.

Masonry infilled RC frames are one of the most common structural forms, the damage of which, in earthquake events, usually cause serious losses. The determination of the seismic performance target is the key foundation of performance-based seismic evaluation and design for masonry infilled RC frames. In this paper, an extensive database of experimental tests on infilled RC frames loaded in an in-plane direction is collated. According to the crack propagation and elastic-plastic characteristics of infilled RC frames, the damage process is divided into four stages, and then the criteria of the damage states (DS) are proposed. In addition, the seismic performance targets expressed as inter-story drift ratio (IDR) for the four stages are suggested, which would support the performance-based in-plane seismic analysis of infilled RC frames. Finally, the proposed in-plane seismic performance target is utilized to analyze the fragility of two masonry infilled RC frame structures.

Pile groups are designed to sustain complex loads in various engineering. During the design of a pile group, the obvious pile group effect should be considered for closely spaced pile groups. However, the group effect considered by different scholars varies, which makes it hard for engineers to consider the pile group effect for the design of a pile group. In this study, the finite element (FE) method is proposed to advance our understanding of the variations of pile group effects developed by different researchers, based on the concept of soil–pile relative stiffness. The relationship between soil–pile relative stiffness and normalized lateral load–displacement curves and bending moment profile response of the pile group is investigated. The results show that the pile group effect increases with the increase in soil–pile relative stiffness; the pile group effect increases with the decrease in pile spacing, increases with the increase in of number of piles in the group, and is significantly affected by pile group arrangement as well.

This study presents a finite element model to investigate the bidirectional seismic behavior of masonry infill walls. The test data are utilized to verify the numerical model. The comparison between the analytical and the experimental results indicates that the finite element model can successfully predict the failure mode, stiffness, and strength of the masonry infill wall. Based on the model, the effects of aspect ratio (height to length), slenderness ratio (height to thickness), and masonry strength on the out‐of‐plane (OOP) response of infill wall with in‐plane (IP) damage are explored. Considering the aspect ratio, slenderness ratio, and masonry strength of infill wall, the OOP behavior of infill wall with and without IP damage is studied. Finally the reduction of the stiffness and strength in the OOP direction, due to the IP damage, is discussed.