Seismic Response Analysis Of Irregular High Rise Pier Long Span Continuous Rigid Frame Bridge

In west China, a lot of highway and railway lines across valleys, ravines and rivers are built and planed, which are mostly related to the high piers and long-span bridges. In order to adapt to the terrains as well as to consider the economy, more and more irregular high rise pier long span continuous rigid frame bridges are applied in west China. However, the dynamic characteristics of this bridge type are complex, and there aren’t any seismic design criteria for this kind of irregular bridges both home and abroad, which restrict its further development. Thus, seismic research on the irregular high rise pier long span continuous rigid frame bridges has both theoretical value and practical significance.In order to obtain the seismic response of an irregular high rise pier long span continuous rigid frame bridge in southwest China, the motion equations under the condition of uniform excitation are established. The dynamic analysis models are set up by using the Midas Civil software, and the seismic responses are calculated and analyzed by time-history method. The main work is as follows.1) The two finite element models (model A:considering the pile-soil interaction; model B:not considering the pile-soil interaction) are established. The method for determining the soil spring rigidity of the pile-soil interaction is discussed, and the vibration characteristics of the two models are compared and analyzed according to the dynamic equations of the structure.2) Reasonable seismic wave time history data is input the dynamic analysis model, and the damping of the structure is rationally simulated referencing to the specifications and literatures both home and abroad. The motion equations under the condition of uniform excitation are established, and the linear seismic time-history response is analyzed. The impact of the vertical seismic effect on the seismic response of structure is comparatively analyzed.3) Nonlinear factors of structure are discussed in this paper. Based on nonlinear fiber model theory and nonlinear dynamic equations, the dynamic analysis models input reasonable constitutive model of reinforced concrete are calculated and analyzed by the kinematic hardening hysteretic model theory and the elastic-plastic theory. The impact of the pile-soil interaction on the elastic-plastic seismic response of structures is investigated, and the distribution and development of plastic hinges of both the high pier and the low pier are analyzed. Comparing to the existing seismic codes of bridges, the plastic hinge arrangement of the irregular high rise pier long span continuous rigid frame bridges is discussed, and the suggestions for seismic design of this kind of bridge are put forward as engineering practice reference.