Elastic-Plastic Analysis Method For Seismic Response Of Steel Frame-Concrete Tube Hybrid Structures

At present, the external steel frame-internal concrete tube hybrid structures have been applied to the tall buildings and super-tall buildings more and more widely in our country. But the poor study on the structures is behind of the project practice at a certain extent, and there are many different viewpoints on seismic behavior and mechanics analysis of the structures at home and abroad. So this paper gives mainly the elastic-plastic seismic response analysis model and the analysis method of steel frame-concrete tube hybrid structures. The method lays a foundation to research further the seismic behavior and seismic design method of the hybrid structures. To analyze the elastic-plastic seismic response of the structures when adopting the model of bar system, two key problems should be solved. The one is how to simplify the spatial structures to a reasonably planar model and the other one is how to simulate well the elastic-plastic character of each element. At first, the two-dimensional elastic-plastic seismic response analysis model is determined as the analysis model of the steel frame-concrete tube hybrid structures based on the cooperating model of the frame-shear wall structures, because the character of the steel frame-concrete tube hybrid structures is similar to the frame-shear wall structures. In the presented model, the concrete is farther simplified to a planar wall using the principle of stiffness equivalency. By analyzing the mechanics and deformation behavior of the steel frame, concrete tube and longitudinal beam between them composed of the hybrid structures, the reasonable nonlinear analysis models of each element are given on the basis of the model in the large nonlinear analysis program DRAIN-2D and the new model of the concrete tube. Secondly, the spatial restrain effects of the transverse beam between steel frame and concrete tube are applied to the two-dimension model to give the pseudo-three-dimension elastic-plastic seismic response analysis model of the hybrid structures. In the model, one end of the transverse beam is hinged with the concrete tube, the other end is rigid with the frame. Thus, the spatial restrain effects problem of the steel frame-concrete tube hybrid structures is solved in a simple and feasible way. At last, the two-dimensional and pseudo-three-dimension elastic-plastic seismic response analysis method of the hybrid structures is given by using the determined analysis model, and the corresponding analysis program is complied on the basis of the large special computer program DRAIN-2D and added to DRAIN-2D as the...