The Method Of Optimization For Design Of Simply Supported Steel Truss Bridge Based On Reliability Theory

Bridge optimization has became the newest subject of bridge technology. Although optimized design in the fields of mechanical been widely applied, but because of the restrictions of bridge engineering make bridge optimization design developed slowly and applied less in practice.At present the bridge are designed to meet regulatory requirements, which can not describe and handle the existence of various uncertain factors, expecialy not coordination of the contradictions between those factors scientific, making they achieve a reasonable balance. So it is necessary to pay more attention in the bridge optimization.In the process of writing this paper Author collected a large amount of design optimization and reliability analysis literatures,then Calculated truss bridge with ANSYS software based on reliability theory.The main work as following.First. Establishment of steel truss bridge finite element model. Then on the steel truss bridge for loading simulation .Analysis of the characteristics of the bridge and the stress distribution, so as to lay the foundation for the design optimization..Second. Using the optimization function of ANSYS software optimizes the bridge on the basis of the maximal stress and deflection taken as the constrained condition, the sectional dimension of tress taken as designed variables and the volume of steel taken as the objective function. Furthermore checking the Optimization results for the local stability and overall stability,then Adjustments section size which are not satisfied the requirements, and ultimately determines them.Third. Calculat the results after optimized, Analysis of the system reliability of bridge under the vehicle load.The results show that this bridge has a sufficiently high reliability.Then Calculat the system reliability sensitivity to determine the degree of influence on the reliability Of the size of each section .Forth. Optimal design of the bridge based on the reliability of sensitivity analysis,achieve optimization based on the reliability. Fifth. In view of the current truss bridge damage characteristics,By using composite material Replacement the weak bar, so as to achieve the purpose of enhancing carrying capacity bridges, And calculat and analysis the specific numerical of improvement.