Analysis Of Influence Surface And Loading For Suspension Bridges

Modern times, forms of the upper structure of bridges is more and more multiplicative and the structure is more and more complex. The vehicle load is one of important loads which the structure of bridges need to take on. Generally, the living load of bridges mostly adopts the method of lateral distribution coefficients which from 3-D are translated into 2-D. But along with the complication of bridge structure, the error of the method is growing. The calculation of influence surface is an analysis method based upon space structural model which can reflect the bridge's practical force state better. For the suspension bridge such a complex structure, through influence surface and loading analysis to determine the most disadvantageous position and response maximum of a complex load is a necessary and effective way. Suspension bridges are a kind of complex system which consist of a variety of materials and different components and have a unique and complex nature in influence surface and loading analysis. Thus analysis of influence surface and loading for suspension bridges has major significance and practical value.Based upon related theory, this paper researches and analysises on calculation and loading on influence surface of a suspension bridge structure. The principal tasks are as follows:(1) Based on the finite element theory and the characteristics of suspension bridges, a suspension bridge model is set up in ANSYS. Through the static unit force calculation method of imposed mobile unit force, the paper analyzes the static response such as the internal forces and displacement of the key section of the suspension bridge.(2) Basis on the finite element analysis, according to static response such as the internal forces and displacement of the key section which are extracted, the paper draws the internal forces and displacement of influence surface in MATLAB, and the graphics are compared and analyzed. And the graphics of influence surface are encrypted and the encryption makes the graphics of influence surface more smooth, so as to improve the analysis of loading on influence surface accuracy. (3) According to the principle of dynamic programming, the paper analyzes the loading on the encrypted graphics of influence surface. A loading program, by which both the most disadvantageous loading position and the maximum value can be obtained, is developed.(4) In order to study the influence that the nonlinear effects of suspension bridges impact on influence surface and loading, according to the most disadvantaged position of loading, the most disadvantaged value obtained by loading in ANSYS analysis are compared with the value of dynamic programming, and the reasons for error are briefly analyzed.