Study On Mechanical Performance Of Extradosed Cable-stayed Curved Bridge With Corrugated Steel Webs

With the development of bridge construction,the extradosed cable-stayed bridge(E-D bridge)with corrugated steel webs has been more and more widely applied because of its extensive applicability and good aesthetics.Sometimes limited by terrain conditions,the scheme of building curved bridge is common.Curved bridge shows the mechanical characteristics of bending-torsion coupling,whose spatial effect is prominent,while there are few studies on the mechanical properties of the E-D curved bridge with corrugated steel webs recently.Based on the existing research results and the engineering background of an E-D curved bridge with corrugated steel webs in Tianjin,numerical simulation method was used to study some mechanical properties of the E-D curved bridge with corrugated steel webs.The main contents and conclusions are as follows:(1)The spatial finite element model of the whole bridge was established,and the static and dynamic characteristics of the structure were analyzed.The results show that the reasonable arrangement of diaphragm can effectively limit the warping deformation of section.In terms of support layout,the middle supports of the E-D curved bridge can be offset to the inside of the curve to balance the inside and outside support reaction under the dead load,meanwhile the anchor points of the cable and tower can be offset to the outside of the curve to improve the stress state of the tower and the middle support to a certain extent.(2)According to the mechanical characteristics of the E-D curved bridge,aimed at the objective of structural energy minimization and based on the principle of influence matrix,an optimization program of cable forces was compiled,and the genetic algorithm was used to optimize the completed cable forces.The results show that the constrained optimization method of cable forces based on the principle of influence matrix is suitable for the optimization of cable forces of the E-D curved bridge with corrugated steel webs.The genetic algorithm has good optimization efficiency and global convergence to the optimization of cable forces of the E-D curved bridge with corrugated steel webs.(3)According to the design parameters of the original bridge,the finite element models of the bridges with different curvature radius were established,and the influences of curvature variation on the mechanical properties of the E-D curved bridges with corrugated steel webs were studied.The results show that the change of curvature is a significant factor causing the mechanical performance of the E-D curved bridge.On the one hand,for the static performance of the structure,with the decrease of the radius of curvature,the structural deformation increases,and the proportion of positive symmetric stress decreases,and the proportion of antisymmetric stress increases,while the distribution law of section shear lag is basically not affected by curvature.On the other hand,for the dynamic performance of the structure,the variation of curvature mainly affects the modes related to the main beam.(4)The finite element model of the whole bridge construction stage was established,and the influences of the variation of cable force and prestress were studied.The results show that the influences of the change of cable force and prestress on the structural effect are linear,and the cable force can be considered as a special external prestress to some extent.Compared with adjusting the prestress,the adjustment of cable force is more effective for controlling the section stress of the main beam.