Static And Dynamic Analysis Of Steel Box Continuous Girder Bridge

This thesis is based on the static and dynamic performance of the design of an overpass bridge over metro station in Chengdu. Three dimensional finite element model of the entire bridge, which has a continuous steel box girder superstructure, is developed using general commercial sofware MIDAS/CIVIL 2006.Firstly, an introductory review of the development and structural characterics of continuous steel box girder bridges are summaried. Methods of finite element analysis of the bridge structures are also presented. Then, stresses and deformations of the bridge were analyzed incrementally following multi construction stages. So is the structure behaviors under the live load and temperature load. Static load cases for analysis include live loads, wind loads, temperature variations, and various combinations of these loads. Further, the structure dynamic characteristics are studied. The free vibration modes and frequencies of the bridge are computed using the subspace iteration method. Subsequently, spectrum analysis and time history dynamic analysis are carried out and the results are compared. Further, static stability or engienvalue of the bridge subjected to both dead loads and live loads are computed. Results of both static and dynamic analysis with or without pile-structure interaction are compared. Finally, a combined finite element model, which involves plate element and solid element, of the entire bridge is developed using the general finte element software AGLOR. The member forces and stress distribution of the main plates of steel box girder, such as top slab, bottom slab and vertical diaphragm are analyzed sufficiently.Overall analysis results are summarized and therefore the static, dynamic characteristics as well as eigenvalue stability of the structure are evaluated. Comprehensive structural performances of the bridge are well understood and some design optimizations are identified.