Shaking table test and simulation of 12-story buildings with metallic dampers located on soft soil

Abstract

In this study, shaking table tests are carried out on 12-story reinforced concrete frames with metallic dampers located on soft site, and the corresponding fixed-base structures with metallic dampers are also proposed for comparison. The superstructure is connected with the 3-by-3 pile foundation by the pile cap in a designed shear laminar container, which exhibits a good ability of reducing the boundary effect. Three earthquake inputs, which include one artificial earthquake (Shanghai bedrock wave) and two recorded Kobe and Chi-Chi earthquakes with various peak ground accelerations (PGAs) are used in the shaking table test. A series of investigation are carried out on the test phenomenal, which consist of dynamic characteristics of the models, seismic analysis of the soil, and also the working mechanism of pile-soil-structure interaction (PSSI). Then, the hysteretic behavior and aseismic performance of metallic dampers in the PSSI system and fixed-base condition are compared. Finally, a nonlinear three-dimensional finite element model is built to establish a proper numerical method for the PSSI system with metallic dampers. The experimental and simulation results indicate that the PSSI system has longer periods, larger damping ratio and less decreasing degree of frequency after tests than the fixed-base condition. Meanwhile, under these earthquakes, PSSI tends to reduce the structural peak acceleration, story shear force and the elastic displacement. However, the total deformation of the superstructure is amplified significantly due to the rocking and translational deformation in PSSI system. Moreover, the hysteretic performance of the metallic dampers are degraded greatly by PSSI effect. Therefore, the PSSI effect should be considered in the design of tall buildings with metallic dampers, because the seismic analysis of the structure may be unrealistic and the performance of the metallic dampers may be overrated when it is ignored.