EXPERIMENTAL STUDIES ON MULTI-STORY MULTI-BAY HPC FRAMES UNDER LOW REVERSED CYCLIC LOADING

摘要

High performance concrete (HPC) can be defined as concrete made with appropriate materials to give excellent performance in some properties. The use of HPC has become widespread in many projects in civil engineering. A piece of four-story tow-bay HPC frame is tested under low reversed cyclic loading. The failure pattern, failure mechanism, hysteretic model, deformation restoring capacity, displacement ductility, stiffness degradation and energy dissipation capacity of the HPC frame are systematically investigted. Studies show that the HPC frame undergos the three stages of elastic, yield and ultimate. At the ultimate stage the concrete at bottom of middle column crushed. The frame specimen fails in a partial beam sideway mechanism which is a better way to provide a ductile response. The global and inter-story P-Δ hysteresis curves of the frame are full and fat, which show that the HPC frame has good capacity of energy absorption and dissipation under earthquake. According to the analysis of the hysteresis curves, four-linear restoring-force model is proposed as well. The displacement restoring capacity of the frame decreases with increase of displacement, which reflects that damage accumulates in the specimen. The frame specimen behaves in good ductility with the global and inter-story displacement ductility coefficients ranging from 4.5 to 8.0. The frame specimen exhibits obvious stiffness degradation, with the stiffness in the yield stage largely decreasing comparing with that in the elastic stage. In addition, the P-Δ effect is obtained by using the Multifunctional Structure Test-machine Systems of 10000kN whose vertical actuator can be drived frictionlessly in horizontal direction based on closed-loop control.