Optimized Analysis Of Irregular Structure In City Multi-level Crossing Bridges

Mostly the grade intersection belongs to the flyover structures. To meet the road linear and landscaping request, the grade intersection is always designed to a curvilinear and irregular broadened bridge shape, while its built-up span can't be arranged as per logical span of bridge structure, thus, force state of bridge becomes really complex. Under all kinds of actions, such as bidirectional moment and torsion, temperature changes, pre-stressing, shrinkage and creep of the concrete, it is very difficulty to master the shape of structure under loads and service life of the structure and traffic safety have been badly threatened by the diseases which is caused by structure distortion. If span dividing, supporting system, bifurcate node and bifurcate length are taken into optimized design, the diseases of the structure would be reduced to a great extent and structure safety would be insured. Therefore, optimizing analysis on irregular and curvilinear structure of city grade intersection has great significance.In this thesis, lots of research has been made on computing theory of irregular and curvilinear structure of city grade intersection and the beam-grid theory was wildly used in computing analysis. On the basis of the theory mentioned above, the Zaoyuan grade intersection K circular route being taken as the project example, different computing models being established, the structure's reasonable bifurcate node and bifurcate length of the three cross-continual grade separation irregular type have been optimized and reasonable bifurcate node and bifurcate length have been ensured. Simultaneously, linking to the project reality, the cause mechanism of the disease has been analyzed. Through the mechanical analysis and the load experiment of Weiyang multi-level crossing bridge, the theoretical calculation data and the tentative data have been effectively compared. It is proved that the beam-grid theory's computing results is of the high computing precision. Computing internal force and displacement changes of structure have the coincidence tendency with bridge tentative data changes, which confirms rationality of conclusion in this thesis. They can serve as a reliable method for the analysis of irregular bridge.