Full-scale experimental study on masonry infilled RC moment-resisting frames under cyclic loads

Abstract

The reinforced concrete (RC) moment-resisting frames with masonry infill walls are widely used in buildings. It has been well recognized that the arrangement and constructional detail of infill walls have significant effects on the seismic performance of RC frames. During 2008 Wenchuan Earthquake, a lot of masonry infilled RC frame structures suffered serious damages due to detrimental effects brought about by infill walls rigidly connected to the main structure. In the updated Chinese seismic design code, the flexible connection between infill walls and RC frames is recommended in order to reduce the unfavorable interaction between them. In this study, seven full-scale, single-bay and single-storey RC frame specimens, five with masonry infill wall and flexible connection, one with masonry infill wall and rigid connection, and one without infill wall, were tested under low-cycle reversed loads. For the specimens with flexible connection, the variable parameters are the type and amount of constructional column, the amount of tie steel bar, and the amount of vertical slit set in the infill wall. Based on the test results, the damage behavior, lateral strength, displacement ductility ratio, stiffness degradation, and energy dissipation of the specimen are compared. The influence of constructional details of infill walls on the seismic behavior of RC frames is analyzed. It is found that with the addition of masonry infill wall rigidly connected to the frame, the lateral strength, the stiffness and the energy-dissipation capacity of the bare RC frame increase significantly while the displacement ductility ratio decreases significantly. Compared with the infill wall with rigid connection, the strength, the stiffness and the energy-dissipation capacity contributed by the infill wall with flexible connection drop significantly, but the displacement ductility ratio of the frame rises up.