Mechanical Performance Analysis And Cable Force Optimization Of Extra-dosed Cable-stayed Bridge With Three Cable Planes

As a transitional type bridge,the extra-dosed cable-stayed bridge has been developed rapidly and used widely in the world due to its superior performance and attractive appearance and economy.The mechanism characteristic of extra-dosed cable-stayed bridge lies between continuous rigid frame bridges and cable-stayed bridges,that is,compared with the traditional cable-stayed bridge,the girder is more rigid and tower is much lower.Based on an extra-dosed cable-stayed bridge with three cable planes,the mechanism performance of this bridge has been studied.Details of this study are summarized as follows:(1)According to the design details of the extra-dosed cable-stayed bridge with three cable planes,a two dimensional finite element model has been built using Midas/Civil.The structure behavior under four different load combinations,via the current design codes,has been checked and verified.The results shows that the mechanical behaviors of girder,cable and tower of the extra-dosed cable-stayed bridge can meet the requirements of the design codes.The whole structure is safety.(2)A three dimensional finite element model has been rebuilt by using Ansys.Based on the characteristics of the extra-dosed cable-stayed bridge with three cable planes and single tower,three main factors,the length of no-cable area,the angle of the cable and the stiffness of the tower,on the structure performance has been proposed.And then,the parameters analysis has been carried out to determine the rational value of those design parameters.(3)The principle of the reasonable completed bridge state of the extra-dosed cable-stayed bridge has been summarized.Based on the requirements of the reasonable completed bridge state,the cable force has been optimized by using the method of cable/girder weight matrix.The optimal results shows that the optimization structure performance a good behavior.(4)The transverse mechanical behavior of extra-dosed cable-stayed bridge with three cable planes of the can be simplified as a two span continuous beams with flexibly supported.And then,the principle of minimum total potential energy,the ratio of the cable force between different cable planes has been derived.And then,the influence of the transverse stiffness of girder and the stiffness of cable on this ratio has been studied.The result shows that,when the transverse stiffness of girder is approaching to zero,or the stiffness of cable is infinite,the ratio of the cable force is 3/10;while the stiffness of cable is approaching to zero,or the transverse stiffness of girder is infinite,the rigid motion will occur,that is,the cable force is equal.