Analysis Of The Seismic Response Of Long-Span Bridges By State Space Method

As an important part of the traffic key projects and the lifeline engineering, how to improve the seismic safety of long-span bridges is always the focus problem to be paid more attention in the engineering field, in which seismic response analysis method is a main aspect. State space method from the modern cybernetics, as the symbol of the modern cybernetics, recurs to the development of the electronic computer, and studies complicated dynamic system. State space method analyzed the seismic response of long-span bridges in nature is the time history method, and in this method, the motion equations are transformed to state space equations discretely solved by the state vectors.In this thesis, the finite element method and state space theory were used to solve the seismic response of long-span bridges. This paper is mainly concerned with the following studies:1. The displacement of the structure response was decomposed to the quasi-static and dynamic displacement, and the equations of motion of long-span bridges, subjected to seismic multi-support excitation, are deduced, which are transformed to the state space equations by the state vectors.2. The basis theory of state space method, the dynamic iterative method and state transform matrix solution were presented. On the base of the finite element method, 3 dimension seismic response analysis model of the long-space cable-stayed bridge was programmed in MATLAB and was verified by using the numerical example.3. Using ANSYS, the properly simplified model of the long-space cable-stayed bridge was analyzed and its dynamic properties were calculated.4. the seismic response analysis of the long-span bridges was calculated under the traveling wave effect and consistent excitation respectively by the MATLAB program and ANSYS. At the same time, the 1-D, 2-D, 3-D seismic response analysis in MATLAB and ANSYS was compared.