Construction Simulation And Dynamic Characteristics Analysis Of Concrete Bridges

From beginning to finishing constructing a bridge, there are so many complex construction processes and structure system conversions that result in complicated changes on internal force and displacement. Therefore, it is a necessity to simulate the process of bridge construction to determine the ideal state in every condition of loads and distortions. As the basic variables of controlling structural damage is related to maximum distortion and cumulated damages, the effect of the internal forces formed in the course of construction to should be considered when studying the influence of earthquakes to bridges.Firstly, this paper has analyzed various internal forces and their changes during the cantilever construction of concrete bridges. It could be concluded that internal force of bridge under completion stage were closely related to the sequence of construction. With FEM software ANSYS, the user subprogram has been finished which accords with domestic concrete bridge creep calculation criterion. And simulation of concrete bridge construction has been fulfilled by controlling computing process with APDL language. Then, this paper has analyzed a bridge to validate the feasibility of the proposed method. Moreover, dynamical characteristic of bridges has discussed. After analyzing a bridge example, it has been found that the portrait and landscape modals account for a great part in components of low order frequency, when analyzing response spectrum CQC modal combination method should be chosen if natural vibration frequency is dense, and internal force of bridge under completion stage may reduce the natural vibration frequency of bridges in some sort. Finally, according to relevant criterion this paper has argued the theory of earthquake response spectrum. And several conclusions have been gained as follows: portrait and landscape orientation liberation would not couple with each other, the middle of between the pier and main span should be paid more attention to for the stresses caused by earthquake are relatively great, internal force of bridge under completion stage may increase the effect of earthquake a little.