Analysis Of Cable Forming And Mechanical Behavior Of Suspension Bridge

With the rapid development of social economy and technology,the development of suspension bridges in our country is also like this.Long-span suspension bridges emerge endlessly in China.In order to ensure suspension bridges accomplished successfully,and satisfy the construction quality with design-requirement,to monitor all the steps in construction process is necessary.The main research work of this thesis is as follows:1.Two calculation theories of main cable finding of suspension bridges are studied: the segmented catenary theory and the force density method theory.According to these two calculation theories,the computer software is used for programming.The parameters of the main cable of the Sunxi River Extra Large Suspension Bridge are taken as an example.The results of self-balanced are calibrated by Midas Civil software.It is proved that the force density method can be applied to shape-finding of the main cables of suspension bridges.2.Based on the program compiled by two form-finding theories of suspension bridge main cables,the calculation method of stress-free length of suspension cables is studied.The parameters of the main cable and sling of the Sunxi River Extra Large Suspension Bridge are taken as examples to calculate and analyze.And the results are compared and validated.The correctness of the calculation method of sling is proved.Meanwhile,it is studied that the influence of whether the self-weight is considered.It is concluded that the influence of the self-weight of the sling on the elongation of the sling is more less.And the difference of tower height has little effect on the linearity of main cable.3.Based on the Sunxi River Extra Large Suspension Bridge,the effects of the elastic modulus,statistical load error,temperature and pylon height difference of the main cable on the main cable shape were studied by using the catenary shape finding theory.The effects of elastic modulus on the unstressed length of the main cable,the elongation of the main cable and the horizontal component of the main cable are studied.The effects of statistical load error on the unstressed length of the main cable,the elongation of the main cable,the internal force of the main cable and the sling,the unstressed length and the shape of the bridge line are studied.The effects of temperature on the mid-span main cable midspan elevation are studied with the computational comparison based on the parabola method,Midas finite element software and catenary method.Finally,the effects of the tower height difference on the unstressed length of the main cable and the midspan elevation are studied.It is concluded that the elastic modulus,statistical load error,temperature and tower height difference of the main cable have great influence on the main cable.4.Two methods of hoisting the stiffening beam during the construction of the suspension bridge,three methods of connecting the stiffening beam sections,and the setting of the pre-bias of the main cable saddle and the significance of the main cable saddle pushing are summarized.Taking the Sunxi River Extra Large Suspension Bridge as an example,the influence of the setting error of the main-cable saddle pre-bias on the mid-span midspan elevation is calculated and analyzed.Based on the simulation of two lifting methods of stiffening beams with Midas,the effects of these two lifting methods on the horizontal displacement of the main cable saddle and the vertical displacement of the mid-span midspan are studied.It is concluded that the method of hoisting stiffening beam from mid-span to cross-strait is better.The regulation of stiffening beams elevation in construction process is obtained by simulating the hoisting process with Midas.Finally,the effects of random weight of stiffening beams on the construction stage and the line shape of completed bridge are studied.The influence range of the weight change of stiffening girder on the alignment of the completed bridge is obtained.