The Study Of Structural Analysis Of City Steel Box Girder Footbridge

In this thesis, we calculate the pedestrian bridge at Lidu road beside second-ring road by the following three methods such as simple beam element method (referred as SBEM), multiple systems superposition method (referred as MSSM), and shell finite element method (referred as SFEM). In the first method, we analysis the forces by FEM software named MIDAS. on the base of characteristics of steel box beam’s section. In this thesis, the concepts of shear lag effect and panel girder are introduced. We consider the effect of shear lag by calculating the effective width and using multiple system superposition algorithms. In the third method, base plate, web plates, diaphragm plates and stiffeners are modeled. It is analyzed by MIDAS software. A shell element model of the whole bridge is established for analyzing and calculating. Furthermore, the thesis compares the calculation results of the above three methods. The stress is similar in SFEM and MSSM, and it is less in simple beam element method, because the effect of the second system and shear lag cannot be calculated by SBEM. By the calculation, the deflection, static and dynamic performance is checked in this thesis. According to calculation, the deflection and the vibration frequency shall reach requirements, so the beam is safety. In the end, steel box beam pedestrian bridge with larger span is calculated and analyzed. In this thesis we discuss the feasibility of increasing beam height and changing the conditions of support. The calculation results show the self-vibration frequency can rise effectively by the change of end beam constraint method. It is checked by two pedestrian bridges of steel box girder of the span with40m and50m.