Seismic Behavior Investigation Of The Superimposed Wall With Strong Connection At The Horizontal Joint

The superimposed wall panel which can be treated as a new kind of green buildingsystem studied in this paper was first introduced from Germany. The precast part of thewall panel is composed of two precast panels and the connecting truss bars. Coreconcrete was cast and composite member was formed after precast part installed. Itbelongs to the structure of semi-precast shear wall. Compared with the structure oftraditional precast shear wall (large panel structure), the superimposed wall panel showsbetter integrity, and has a lower accuracy requirement for field installation. So this kindof residential building structure system is more suitable for our country’s currentsituation.Through the early seismic performance test of superimposed wall in our researchgroup, it can be found that the horizontal joint between precast panel and the foundationbeam is the weak position of this kind of structure. The connecting joint was openingunder cyclic load and then it run through the whole member and the main crack wasformed. The plastic deformation of rebar and concrete was focus around the joint. Thetension rebar would be fractured under large deformation. The specimens show poorperformance in deformability and ductility. In order to improve the performance of thehorizontal joint, the joint of the wall panel specimen in this paper was formed by“strong connection”.Based on the philosophy of capacity design, two superimposed walls formed by“strong connection” were tested under quasi-static reversed cyclic loading. Thegeometry, material strength and the area of rebar in the precast panel was identical. Thearea of lap rebar was different. The test result indicated that the design objective of“strong connection” can be achieved on specimen W-2which has sufficient area oflap rebar. The plastic area transferred from horizontal joint to the inside wall panel. Sothe mechanical behavior can be closer to the cast-in-place shear wall. In spite of the factthat the area of lap rebar in specimen W-1was slightly less, the plastic deformation wasfirst emerged in the inside wall panel. The plasticity developing on the top of thefoundation beam was smaller, so the mechanical behavior was also close to thecast-in-place shear wall. The hysteretic curves of the two test specimens were bothplump, which was in spindle shape in the early stage of the test and in reversed S shapein the later stage.Based on the experimental investigation, numerical analysis by using finite element software ANASYS, was conducted to simulate the monotonic loading and thequasi-static reversed cyclic loading. The result indicated that hysteretic loops andenvelop curves obtained by the numerical analysis agree well with the test results,including the load and displacement of the key point, and the mechanical process andthe failure mode was almost the same with the test result. Indicating that the finiteelement model has high accuracy and it is capable of simulating the behavior of thiskind of structures.