Optimization Design For Multiple Pre-Stressed Steel Structure

Pre-stressed steel structure, a new kind of structure in which combined pre-stress with steel structure, can take full advantage of the elastic strength of steel, and multiple pre-stressed steel structure can repetitively make full use of the elastic strength of steel, thus it can enhance the structural capacity and further improve the rigidity of structure, proving that it is more economic than single pre-stress. Therefore, it is both theoretically and practically important to conduct in-depth research on multiple pre-stressed steel structure.The main work of this paper was as fellows: (1) generalized the development of pre-stressed steel structure in our nation and abroad, and pointed out the main problem in practice; (2) presented the mechanism of pre-stressed steel structure and revealed its applicable range; (3)established the optimization design model for pre-stressed steel structure, which accounts for constraints on stresses and displacements of structure; (4)brought forward the optimization design method, which combined linear programming and the principle of full restriction, through which we can obtain the magnitude of each time pre-stress and the optimized sections of each members of structure; (5)analyzed the best times of pre-stress and pointed out that 2~3 times is preferable; (6)conducted optimization design on large-space steel roof, horizontal parallel steel truss with local cables, horizontal parallel steel truss with global cable, and ultra-static steel truss, the result of which indicated that the multiple pre-stress structure is very economic; (7)compared different schemes of cable placement for horizontal parallel steel truss, and the results showed that the local cable only unloaded the second girders, but had no response on the first girders and stomach poles, while global cable could unload the second girders and the stomach poles outside of turning point of cable, thus proving that global cable is more economic than local- cable.The optimization design model and solution made designing of multiple pre-stress steel structure be based on theoretical research, which overcame the shortcomings of establishing the value of pre-stress through trial and error and experience. It has instructive importance on optimization theory and important value in practice, and prepared for the optimization design theory of pre-stress steel structure based on reliability.