Numerical Analysis Of Pre-stressed Trussed Combination Arch Bridge

In recent years, the construction project of domestic highroad, especially the highway, has been developed rapidly. As an important part of the highroad, the construction of the bridge has also been developed along with many types of bridge structure emerging. The trussed combination arch bridge originated by our country in the 1980's is such a distinct type. Compared with traditional truss bridge, it is simple and cost less, and it can be erected in cantilever assembling and system transform by Derrick mast. But many problems about this kind of bridge have arisen in recent years. For example, many cracks have been found at the intersections of the main trusses almost in all of these bridges, and some bridges even had been demolished, so it is necessary and exigent to investigate the damage reason of this kind of bridge.Firstly, the author calculated and analyzed the stress and deformation of the bridge under the action of dead loads and prestressing, based on the soild model of Qingshui Bridge in Guizhou Province and by the software of ANSYS. The numerical results show that the damage is coincident with the investigation report. By comparing the results of different loads, it is deduced that the irrational design of initial pre-stress may be a key factor in the damage of this bridge.Because the construction process has final effect on the mechanics performance of the whole bridge, the birth and death elements have been adopted for making numerical simulation of the construction process of the trussed combination arch bridge. And then, the deformation and stress state in the corresponding construction process can be obtained. It can be concluded that the structural system transform may be a key factor that influenced stress distribution of this bridge, especially the new arch springing. So it is necessary to make optimum design of the construction process.Then, the pre-stress parameters have been optimized by using orthogonal experimental design method. The maximal first principal stress in new arch springing is regarded as the object, the influence degree of pre-stress parameters on maximalfirst principal stress, which have great value and important in pre-stress design of the kind of bridge, can be obtainedLastly, the shell model was adopted to calculate and analyze the stress and deformation of the bridge under the action of dead loads and pre-stress force. Compared with the result of the soild model, it is found that the two results have great coherence. So it is feasible to take the shell model for numerical analysis of trussed combination arch bridge.