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Seismic Response Analysis of Long Span Continuous Rigid Frame Bridge with Thin-wall High Piers

Author: ZhangMingMing
Tutor: GaoDaFeng
School: Xi'an University of Architecture and Technology
Course: Structural Engineering
Keywords: thin-wall high piers long-span rigid frame bridge dynamic characteristics pile-soil effects seismic response analysis wave-passage effect
CLC: U441.3
Type: Master's thesis
Year: 2011
Downloads: 80
Quote: 0
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Abstract

In recent years, with the rapid development of traffic building in China, the continuous rigid frame bridge is used widely with growing towards long span and more flexibility. Our country is also in such an earthquake-prone area, if the major long-span bridges are damaged, it will bring serious consequences. Based on the above-mentioned situations, in this paper, taking a six-span continuous rigid frame bridge as the engineering analysis background, study its dynamic response in the earthquake, and these results will provide reference for seismic design, construction of building and testing reinforcement. The work and conclusions of the article are as follows:(1) The finite element model of the bridge is established by ANSYS considering the frequency and period of the bridge. After analyzing the dynamic characteristics of four different modes, so some conclusions are obtained: after considering the effect of pile-soil interaction, the overall stiffness of the structure is decreased and the natural period is prolonged; After considering the effect of the tie beam, the formation sequence of vertical deformation of the main beam is brought forward. The results show that it increases the flexibility of the thin-wall high pier, and makes the horizontal deformation of the whole bridge more evident because of not considering tie beam in the original design of the bridge.(2) The spectrum response method and the time-history analysis are adopted to calculate the dynamic response of bridge by using the original design model. The results are compared in detail and the influences of pile-soil interaction were discussed: considering the effect of pile-soil interaction in the two conditions, it is obvious that pile-soil effects of long-span continuous rigid frame bridge affects on the horizontal displacement and vertical internal forces. (3) El-Centro wave, Taft wave, Lanzhou wave are selected to carry on the coincident earthquake excitation to the bridge compared with the response of spectrum analysis. The results show that the influence of Taft wave and the El-Centro wave to the bridge are obvious compared with Lanzhou wave, and the vertical displacements and internal forces of the coincident earthquake excitation are smaller than those of spectrum response. On the contrary, the horizontal displacements and internal forces of the coincident earthquake excitation are larger, so the maximum of them should be selected in structural design.(4) The seismic response of bridge is numerically simulated considering vertical seismic input. The results show that the axial force of high piers and the vertical displacements and the vertical bending moment of become larger. On the whole, vertical seismic input can not be ignored.(5) The seismic response of bridge is numerically simulated considering wave-passage effect. Compared with coincident earthquake excitation, it is very significant for the bridge: the different results are produced by the different velocities.In general, the litter is the wave speed, the bigger effect is the internal force and displacement, and the time is decided the effects of in the different waves. On the contrary, when the velocities get bigger, theirs will be in line with the results of coincident earthquake excitation. The effects are very obvious and the effects of wave-passage effect benefits to the internal force of main thin- wall high piers, but it is bad for the main beam. It indicates that it should take into account wave-passage effect when carry on seismic design of long span continuous rigid frame bridge with high piers.

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