•Small-scale test were performed to investigate the hysteretic-shear performance of damping layer joint (DLJ) constructed by four materials and the optimized material was determined.•Quasi-static ...test was conducted to verify the feasibility of the damped masonry infill wall (DMIW) configuration and to investigate the seismic performance of DMIW.•DMIW is capable of significantly decreasing the intrinsic lateral stiffness and force of traditional masonry infill wall via the shear deformation of DLJs.•The fitted equation of the relationship between the shear deformation demand of DLJ and the lateral deformation of frame was developed to help control the shear strain limit of DLJ.
Aimed at improving the seismic performance of the traditional masonry infill wall (MIW), an innovative configuration called Damped Masonry Infill Wall (DMIW) is developed through subdividing the MIW horizontally and introducing damping layer joint (DLJ) into the wall. In order to verify the feasibility and the seismic performance of DMIW, the optimized material used as DLJ was determined among four types of materials via the shear-hysteretic test firstly. Then, a quasi-static test was performed to investigate the seismic performance of 1:2 scaled RC frame specimens with DMIW and traditional MIW, in terms of damage pattern, seismic parameters, shear deformation characteristics of DLJ. The results show that the modified asphalt waterproof (MAW) product, APF-500 (also labelled No.1 MAW in this study), is the optimized material used for DLJ among other three tested material. The expected working mechanism of DMIW that the shear deformation of the wall concentrates in the DLJs is able to be realized by using the optimized DLJ material. Also, it proves that DMIW is capable of presenting a prominent reduction of damage level and significant decrease of the lateral force and stiffness. It is anticipated that the detrimental effect of traditional MIW on the seismic performance of the frame structure can be avoided by adopting DMIW. Furthermore, a fitted equation of the relationship between the maximum shear deformation demand of DLJ and the lateral deformation of the RC frame is developed for determining the minimum thickness of DLJ in the case where DMIW has three masonry units.
Infill walls are a primary source of structural loss under service level and design basis earthquakes, so developing high-performance infill wall is an effective strategy to reduce seismic loss. ...While several high-performance infill walls have been proposed, most studies only reveal the damage characteristics of infill walls at the component level. However, the interaction between infill walls and structures can alter the seismic response of structures and consequently affect the loss of infill walls under earthquakes. Therefore, it is necessary to investigate the seismic responses and loss of high-performance infill wall at the structural level. In this paper, the working mechanism and damage characteristics of the slotted infill wall (SIW) are firstly introduced and verified through cyclic loading test. Then, an in-plane hysteresis model of SIW is developed, and the calculation method of key parameters is proposed. Finally, a numerical analysis model of a 10-story frame with slotted infill wall (SIW-F) is developed to study the seismic response and seismic losses. The results indicate that SIW-F’s displacement response is larger than that of the frame with ordinary infill wall (OIW-F) on most floors. However, the floor acceleration response is less. The seismic loss of SIW-F is less than that of OIW-F, particularly under design basis earthquakes. The repair cost ratio of infill wall decreases from 19% to 8%, the total repair cost of the SIW-F decreases by 41%, and the total repair time also reduces by 25%.
•The working mechanism and damage characteristics of the SIW is Introduced and verified.•A general in-plane hysteresis model of SIW is proposed, and calculation methods of key parameters are suggested.•The seismic responses of 10-story frames with SIW and OIW are comparatively evaluated.•The seismic loss including repair cost and time of 10-story frames with SIW and OIW are discussed.
•Study progressive collapse of frames with or without infill walls by experiment.•Infill walls enhance maximum resistance but reduce ductility of frames.•Infill walls change strains distributions in ...beams.•Infill walls change the cracks development and failure mode of the frames.•Failure mechanisms of the two frames were proposed.
The interaction between the infill walls and the reinforced concrete (RC) frame members in the progressive collapse process was examined experimentally in this study. Two 1/3 scaled, four-bay, two-story RC frame specimens, one of which was featured without infill walls while the other with infill walls, were tested. The frame specimens were designed in such a way that the center column of the first story was missing, in order to simulate the failure of the structural component due to abnormal loads or design flaws. The frame specimens were quasi-statically pushed downward at the top of center column under displacement control to investigate the progressive collapse mechanism of the RC frames, with a focus on the effects of infill walls. Specifically, the physical quantities and phenomena of great interest in this study include the collapse resistance force and mechanism, strain variation and crack development in structural components, and local and global failure modes of the frames. The test results showed that the infill walls can provide alternative load paths for transferring the loads originally only supported by the beams, and thus, improve the collapse resistance capacity of the RC frame. The infill walls, however, may reduce the ductility of the RC frame and may change the failure mode of the frame. It is concluded that the infill walls may affect (i.e., either improve or impair) the performance of RC frames against progressive collapse in different aspects.
•In-plane behavior of the frame with non-interacting infill was studied experimentally.•Behavior of the frame with non-interacting infill compared with bare and fully infilled frames.•The ...non-interacting wall got minor damage even in extreme displacements.•In-plane behavior was improved.•Numerical FE models were validated by the experimental behavior.
Infill walls, which are generally assumed as dead loads in building design, affect the lateral resistance, stiffness, and energy consumption of the frames. Investigations conducted after earthquakes show that the infill walls, whose effects are neglected in the design, can change the earthquake behavior of the structure and cause unforeseen damages in the buildings and even collapses in some cases. In order to match the behavior of designed and built frames, the technique of isolating the infill wall from the RC frame with non-interacting infill was adopted. In this study, in-plane behavior of bare, traditionally infilled frames and a frame with non-interacting infill wall were investigated experimentally under reversed cycling loads, then their numerical models were calibrated. As a result, in contrast to the traditionally infilled frame, it has been seen that the frame with non-interacting infill behaves close to the bare frame in the initial drifts and maintains its lateral resistance without a damage until further drifts. Therefore, it has been found that constructing the infill wall with non-interacting joint improves the in-plane behavior.
•Collapse mechanisms of self-centering infilled PC frame are revealed by test.•The concrete damage of self-centering bare frame is concentrated at the beam ends.•Infill walls with lower strength ...enhance resistance of frame.•Infill walls with lower stiffness have little effect on the failure mode of frame.•Reduction of beam span greatly enlarge the initial stiffness and resistance of frame.
The self-centering precast concrete (PC) frame has been proved to perform excellently under seismic load in many studies. However, its progressive collapse-resisting mechanism, especially in the presence of infill walls need to be investigated further. Three 1/2 scaled self-centering PC frame specimens, including one self-centering PC frame and two self-centering infilled PC frames were tested under quasi-static pushdown loading regime. The test results showed that the damage of self-centering bare frame was mainly concentrated at the beam ends under vertical load. The compressive arch action (CAA) and the tensile force in the prestressed strands undertook the vertical load together at the beginning of the test. The infill walls with lower strength could still obviously enhance the initial stiffness and progressive collapse resistance of self-centering frame, but did not change the failure location of the frame. The initial stiffness of self-centering infilled frame was 2.47 times of self-centering bare frame, and the peak load in the CAA stage was 1.33 times. The additional load path produced by the infill walls mitigated the concrete damage at the beam ends, thereby improving the ductility performance and repairability of the beams. As the beam span of self-centering infilled frame decreased by 1/4, the initial stiffness and peak load in the CAA stage increased by 1.65 times and 1.66 times respectively. Nevertheless, the concrete damage at the beam ends became severer and the ductility of the frame was reduced.
•Compressed air-driven large cross-section (3m×3 m) shock tube is developed.•Blast test on seven unreinforced and SPUA-retrofitted brick MIWs is conducted.•Applicability of theoretical calculation ...and numerical simulation methods is verified.•Improved evaluation criteria of unreinforced and SPUA-retrofitted MIWs are given.•W-R diagrams for the blast-resistant assessment of typical MIWs are proposed.
Unreinforced masonry infill walls (MIWs) are prone to crack, fragment, and even collapse under blast loads, threatening the safety of building structures, as well as the inside occupants and equipment. Spray polyurea (SPUA) has been proven to be an excellent retrofitted material for MIWs to improve their blast resistance. Aiming to study the dynamic behaviors of brick MIWs under far-field range blast loads, the successive blast tests on seven unreinforced and SPUA-retrofitted brick MIWs with different thicknesses and boundary constraints were first carried out based on the developed compressed air-driven large cross-section (3m×3 m) shock tube. It was indicated that the blast resistance of MIWs significantly improved by increasing wall thickness and strengthening boundary constraint; SPUA coating can improve the blast resistance of MIWs and effectively suppress the debris generation and splash. Then, the equivalent single degree of freedom model based theoretical calculation and the simplified micro-model based numerical simulation methods previously established by authors were briefly introduced. Additionally, the dynamic behaviors of seven examined MIWs were further predicted and compared with test results, which verified the applicability of theoretical calculation and numerical simulation methods. Finally, the improved damage and failure evaluation criteria of unreinforced and SPUA-retrofitted MIWs were given, and the charge weight and standoff distance diagrams of typical MIWs were proposed based on the validated theoretical and numerical methods as well as the improved criteria, which would provide a helpful reference for blast-resistant evaluation and retrofitted design of brick MIWs.
Brick infill walls are one of the most common types of nonstructural elements used for exterior enclosures as well as interior partitions in steel frame buildings. The recent earthquakes have shown ...that damage to masonry infill walls may cause danger for human lives and dramatically affects economic losses. The damage estimation of masonry infill walls and the effects within the corresponding consequences of the performance-based earthquake engineering need fragility functions. The procedure implemented in this study is based on incremental dynamic analyses of two models, i.e. with and without brick infill walls. The primary objective is to develop fragility curves that permit the estimation of damage in masonry infill walls. Comparative analyses were conducted among the models considering four damage levels. The increase in the height has reduced the probability of damage to infill walls, so there was slight damage in drifts less than 3%. Therefore, with increases in stiffness, the probability of damages to the infill walls will increase. The fragility curves obtained by HAZUS show that there is a negligible variation in the infill walls seismic fragility estimated by the number of bays.
Masonry infill walls (MIWs) are essential partition components that are often damaged during earthquakes because of their brittle nature. As a result, innovative solutions are attractive to improve ...performance of MIWs by reducing damage during in-plane drift or increasing damping. Examples of innovative solutions have been investigated experimentally, but mesoscale or microscale numerical modelling techniques could also be useful to evaluate performance and investigate the principal failure mechanisms of both ordinary and innovative MIWs, and subsequently optimize their design. This paper employs the Distinct Element Method (DEM) to predict the in-plane (IP) and out-of-plane (OOP) response of ordinary and innovative MIWs within RC frames. The DEM methodology used in this study account for the crushing of concrete and masonry, the shear-compression behavior of mortar and the shear behavior of a novel damping layer joint (DLJ) inserted in the MIW (named damped masonry infilled wall (DMIW)). DEM results are compared against experimental results for both MIWs and DMIWs. Two IP and four OOP experimental tests were simulated in total. The DEM simulation methodology is capable of predicting the IP and OOP load–displacement response as well as the damage patterns of the ordinary MIWs and DMIWs, although the local displacement mechanism at the DLJ locations of the DMIW varied for the OOP tests. Local stress distribution differences, as well as modeling modifications for simulating the damage pattern of DMIWs, are further discussed. Overall, the effectiveness of the DEM simulation provides confidence that it could be used to improve upon the DMIW design in the simulation environment.
The damped masonry infill wall (DMIW) has been experimentally validated to have the ability to ameliorate the seismic problem caused by the diagonal action of the traditional masonry infill wall ...(TMIW). To lay the foundation for further structural analysis, a macro-modelling method for predicting the in-plane behaviour of the DMIW is developed. In this paper, the in-plane working mechanism is illustrated first and then a macro model of two diagonal elements which represent the behaviour of the damping layer joints (DLJs) is developed. In addition, the modelling method of the DLJ is developed and the method of identifying the parameters is considered. At last, experimental results are used to verify the macro-modelling method of the DMIW, followed by a case study on the seismic performance evaluation of the frame infilled by the DMIWs. The results indicate that the macro-modelling method has a clear physical meaning and is capable of predicting the in-plane cyclic behaviour of DMIW. The storey drifts and shear response of the frame infilled by the DMIW under the earthquake are almost the same as that of the bare frame, indicating that the effect of the DMIW on the bare frame is much less than that of the TMIW and further confirming that the DMIW is able to ameliorate the seismic problems caused by the diagonal action of the TMIW. In addition, the inter-storey drift is evenly distributed without a significant increase in the case where the DMIWs are not placed only in a particular storey, suggesting that the risk of developing the soft-storey failure mechanism of the frame can be significantly reduced even in the case where the arrangement of the TMIWs is irregular along the height.
•A macro-modelling method for the in-plane behaviour of the damped masonry infill wall (DMIW) has been developed.•A macro modelling method for the shear hysteretic behaviour of the damping layer joint in the DMIW has been proposed.•Parameters of the damping layer joint model have been identified via the Particle Swarm Optimization (PSO).•The risk of soft-storey failure mechanism for the frame with DMIW has been discussed.
•The interaction between the URM infill wall and the surrounding RC frame members was investigated in the non-retrofitted specimen and the specimens retrofitted by the thick hybrid wing-walls.•The ...ability of the thick hybrid walls in increasing the lateral strength, stiffness, and ductility of URM-infilled non-ductile RC frames was assessed.•The steel-jacketed non-reinforced hybrid walls were used to retrofit the URM-infilled non-ductile RC frames.•The RC column with URM wing-wall was tested under cyclic horizontal loading and a constant axial force.
The present study aims at using the hybrid wall technique to prevent the occurrence of shear failure of the reinforced concrete (RC) columns in the unreinforced masonry walls (URMs) infilled in the RC frames and to increase their lateral strength, stiffness, and ductility. The hybrid wall integrates a boundary RC column with its adjacent URM infill with the help of jacketing steel plates, to make them perform as a unified member. Two series of experimental tests, including one element test (RC column with URM wing-wall) and five frame tests (one-bay one-story RC frames with URM infills), were conducted under reversed cyclic loading. The interaction between the masonry infill wall and the boundary RC columns before and after retrofitting by the hybrid wall technique is studied, and a corresponding design framework is suggested. The experimental results of the retrofitted frames demonstrated not only enhancing lateral strength, stiffness, and ductility of the URM-infilled RC frames but also the prevention of the shear failure of the boundary RC columns and postponement of the occurrence of the URM infills’ failure to larger drifts. The columns’ shear failure is a significant concern due to infill-column interaction in URM-infilled RC frames. However, one of the important impacts of the thick hybrid walls is that the boundary RC columns remained undamaged even in large lateral drifts due to flexural behavior. From the viewpoint of applicability, the thick hybrid walls technique does not require relocation of occupants and does not disturb RC buildings’ operations during construction. Moreover, it is not a labor-intensive technique.
