Research On Main Cable Control And Poisson Effect Involved In Suspension Bridge

Main cable was one of the most crucial steps in the process of long-span suspension bridge’s construction, whose configuration and tension was easily influenced by temperature, elastic modulus of main cable and deviation of tower, etc. So the process of construction should be guaranteed by accurate calculation. The control and the Poisson effect of suspension bridge main cable system was mainly studied,the main contents were as follows:Firstly, different theories were introduced, including parabola theory, virtual beam method, segmental catenary method and finite element method. Then the advantages and disadvantages of different theories were summarized, which pointed out that the calculation of the unstressed length and the shape of main cable under the final state should use segmental catenary method, and finite element method should be used in the structure of the stress state in the construction process.Secondly, the erection method of basic cable and general cable was introduced, and the suggestion of general strand elevating was given combined with engineering experience. Then analyzed two methods of the tension of anchor span adjustment, pointing out that the tension of anchor span should be adjusted after the completion of each strand. After that, the minimum adjustment quantity of anchor span tension of steel anchorage system was calculated, pointing out that the cable force produced by minimum adjusting deviation should be conducted in the subsequent strand.And then, the impact on main cable of elastic modulus, temperature, span and sag-span ratio was analyzed, gave the relationship between them respectively; according to the situation that unstressed length of main cable was insufficient, the impact of changing sag-span ratio on main cable was analyzed, pointing out that the impact on structure of small amplitude adjustment of sag-span ratio was very small.Finally, The influence of Poisson effect on the pretension force of the wrapping wires and pre-tightening force of cable band was analyzed, pointing out that the calculation should consider section temperature difference, vehicle load and temperature difference in operation. The 2nd phase dead load needs to be considered when the wrapping was advanced. The calculation formula of it was proposed. At last, this paper pointed out that pre-tightening force of cable band also should consider the 2nd phase dead load and gave the calculation formula of it.