The Impact Of Arch Degree Of Stiffening Gir-Der Upon The Static And Dynamic Functions Of Suspension Bridges

Self-anchored suspension bridge is different from the earth-anchored suspension bridges, the prime difference is that the main cables of earth-anchored suspension bridges will be anchored directly on both ends of the stiffening girder. This transforms the flexible structure of a stiffening girder into the hydraulic structure, though increasing the intensity and cross-sectional area of a stiffening girder, it saves the cost by avoiding the setting of huge ends anchorage. According to the calculating theory for current self-anchored suspension bridge, this paper utilizes the finite element analysis software"MIDAS/Civil"for large-scale bridge to establish three-dimensional space finite element analysis model for stiffening girders with the arch degrees of 0.438m, 0.875m, 1.313 m, 1.750 m, 2.188 m, and 2.625 m for a self-anchored suspension bridge with the span arrangement of (75.0 + 200.0+ 75.0) m, analyzing the static function and dynamic function of the force system of the final bridge in phase of constant load.(1) Under this background, this paper firstly reviews the development course and present research of self-anchored suspension bridge at home and abroad.(2) Then says some basic calculating theories of suspension bridge such as: elasticity theory, deflection theory and finite element theory, and expounds the nonlinear finite element analysis method for the self-anchored suspension bridge, as well as the nonlinear impct from the self-anchored type.(3) Then based on the hydraulic forces upon stiffening girders of the self-anchored suspension bridge, this paper specifically studies the impacts arch degrees exerts upon of a self-anchored suspension bridge when setting the arch degree of a stiffening girder.(4) Through the analysis, it is proved that the setting of arch degrees can partially effectively decrease axial force of main cable, midspan deflection and the axial force of stiffening girder, i.e. it has obviously beneficial effects on the static function of a suspension bridge. And the improvement is in propotion to the increase of the arch degree, therefore, when gratifying the condition of longitudinal slope, we can try to increase the midspan arch degree of stiffening girder.(5) For the dynamic function, setting the arch degree of stiffening girder further strengthens the mechanical properties of hydraulic components in stiffening girder of the self-anchored suspension bridge, transforming the planar structures of stiffening girder into space structure which is equivalent to adding longitudinal arch ribs to the stiffening girder, improving the flexural stiffness, the stability and the resistance to overturn force effectively, and upgrading the free vibration characteristics of bridges. Moreover, arch degrees of stiffening girder can obviously improve the dynamic response of bridges in dynamic loading over time.By means of such analysis, we can conclude that setting the arch degree of stiffening girder improves the static and dynamic functions of suspension bridges, and achieves preferable technical, economic and social benefits.