Study On Shear Lag Effect Of Big Span Box-section Beam Structure And Nonlinear Seismic Response Analysis

In this dissertation, the shear lag effect for large span box-section beam structure and the structural nonlinear anti-seismic capability have been theoretically and experimentally investigated.When the box-section beam structure is under both the axial and bending load, the distribution of the box-section normal stress becomes more complicated and the shear lag effect becomes more serious. Therefore it is necessary to perform detail analysis of the structure under actual load to guarantee the safety of the bridge structure. This is also an imperative requirement for design institute. Meanwhile, when the large span bridge under strong earthquake, most bridge structures are under nonlinear status, for example, the yield of the pier, beam fallout due to the large displacement of bridge support. So it is imperative to understand the damage mechanism of the bridge structure under strong earthquake in order to develop the nonlinear analysis method for large span bridge structure anti-seismic analysis. The main contributions of this dissertation are:(1) Using 3D FEA to perform the simulation analysis about the shear lag effect of the box-section beam of cable-stayed bridge under static and seismic load, respectively. In this research, when performing the shear lag effect analysis of the box-section beam structure, it is not only analyzed under static load, but also it is analyzed under seismic load firstly. By comparing the simulation results, the different distribution laws of shear lag effect corresponding to static and seismic load have been gained. This is a new way of investigating shear lag effect. Meanwhile to verify the correctness and feasibility of the FEA theory calculation model, organic glass scaled model is adopted to have an experiment for analyzing the shear lag effect of the box-section beam. The experiment result is the basically same as the theory calculation which proves the FEA method can well calculate shear lag effect.(2) Based on the seismic nonlinear time-history response analysis theory, a comparison research has been performed to investigate seismic isolation effect for the nonlinear dynamic response of the bridge structure when using different seismic isolation device. The new research results provide an important reference for improving the seismic isolation support design method and standard.(3) Based on elasto-plastic anti-seismic analysis theory, an structural elastic-plastic anti-seismic analysis software which using Wu-tian hystersis loops of the curvature and moment has been...