Experimental Study And Theoretic Research On Seismic Performance Of The Superimposed Slab Shear Wall

The superimposed slab shear wall system was a new apartment structural system. This structural system possessed several advantages compared to normal shear wall system, such as good quality control, speedy construction, low-cost of constructions, the high level industrialization of production and reduction of the form work during the process of construction. As a result, the superimposed slab shear wall system could replace the normal shear wall system and be utilized widely. Before the practical engineer application, the standards for superimposed slab concrete shear wall structure must be revised. The new standards would include a similar content as those for the normal shear wall system. As a total new system, systematically analytical study to the superimposed slab shear walls was necessary.Under this background, the study to the superimposed slab shear walls had vital practical significance. Supported by National Science Foundation(No:90715016) and MOHURD Science and Technology Project Plan(No:2008-K3-2), this paper studied seismic design by simulation and experiments.(1)Based on comparative experimental studies on superimposed slab shear walls and two general shear walls under low cyclic loading, the effects of vertical loads, horizontal reinforcement, vertical reinforcement and edge restricted measure were taken in to account. Such as the structural failure feature, deformation capacity, bearing capacity, ductility, stiffness, hysteresis property, energy dissipation were analyzed systematically. The theory of crack in the wall was analyzed and the control criterion of wall cracks width was brought forward based on the results of wall experiments. Additionally the control criterion of displacement was brought forward based on the results of wall experimental study.(2)Based on the above mentioned experimental analysis results, the analysis and design methods of the superimposed slab shear walls were presented. The reasonable constitution measures were given to guide construction. The cracking bearing capacity, ultimate bearing capacity and stiffness resistance to side load were inferred to instruct the practical engineer application. Based on the theoretic formulas and testing data, the three trilinear restoring models under low cyclic load were established. The models showed good agreement with the testing results. Based on wavelet transform, a calculating method about character parameter of the restoring force model was also advanced.(3)In order to appraise and judge the damage of the structure or component after earthquake, the seismic damage model based on stiffness and the seismic damage model based on displacement and energy for these shear walls were analyzed and compared. The calculating results of the two different seismic damage indexes and the experimental phenomenon were in good agreement. The seismic damage model based on stiffness computed more easily and could be used first. Based on wavelet transform, a damage model for these shear walls was advanced. This seismic damage model for four superimposed slab shear walls with edge restricted measures of two different forms and two general shear walls were analyzed. The calculating results of this seismic damage indexes and the experimental phenomenon were in good agreement. This damage index could not only represent the damage extent at every load stage, but also be referred to judge when the structure was yielded. On the basis of the above, the shear wall element model with damage is presented. By use of the model, the calculated results were closed to the test results.(4)At last, based on the test, nonlinear finite element analysis of the shear walls under unidirectional load was carried out by ANSYS program in order to study the crack, deformation and failure feature in theory computing. The finite element computing results agreed with the test well. Then the simulation of low cyclic loading test using CANNY program was carried out to validate the selected element analytical models and analytical parameters. The result showed that the analytical models and parameters were accurate and powerful in simulating the deformation response of the walls. The result also provided base for elasto-plastic time history analysis on the superimposed slab shear walls.Based on the above mentioned analysis results, this paper provided the reliable scientific basis for the local standards Technical specification for superimposed slab concrete shear wall structure. In addition, this paper also provided instruction for the practical engineer application.