Mechanical Characteristics Analysis Of Unequal Span Cable-stayed Bridge With Arch Single Tower

Cable-stayed bridge is a special kind of structure which the main girder and pylon are connected by many staye cables.The pylon is mainly used to bear the pressure transmitted by the cables,the cables are mainly used to bear the tension transmitted from the main girder,and the main girder is mainly used to bear the bending moment which is generated by the constant loads and moving loads.It can be regard as a kind of multi-span continuous girder bridge supported by cables instead of pires.This arrangement can reduce the bending moment of the girder,the building height,the weight of the structure and what is more,it can save materials.It has larger span ability than girder bridge as a kind of cable-stayed system.But this could result in more complicated mechanics performance.Based on a prestressed concrete unequal span cable-stayed bridge with arch single-tower,this paper carried out experimental research and analysis on the mechanical properties of it.The main research contents and results are as follows:1.For the cables without shock absorbers,when the external conditions are the same,the formula of cable force calculated by frequency method is deviated,and the deviation varies with the length of the cable.By adding the correction coefficient to the effective length of cable in the calculation formula and fitting the curve of "correction coefficient cable length",the equation of correction coefficient varying with effective length of cable is finally approximated.It is found that the accuracy of the frequency method can be improved obviously with the modified cable lengths by comparing the cable force of the bridge.2.Finite element application software was employed to analyze the parametric sensitivity of the unequal cable-stayed bridge with single tower.Including the influence of the structural parameters of cross diaphragm on its stress distribution,and the influence of beam weight on the cable force,the internal force and deflection of main beam.Then establishing the relationship curve of the main girder stress changing with the beam weight,and comparing with the stress which is collected in each construction stage.Finally,calculating the bulk density of the reinforced concrete main grider.The result was fed back into calculation model,so as to make the calculation results more accurate.And ensure the safety of structure.3.Based on the finite element software Midas civil 2017,the forward-iteration method was carried out to analyze construction stage of the unequal cable stayed bridge with single tower.Cable tension sequence was changed under the conditions that control parameters meet the design and construction requirements,and comparing the cable force,the stress and deflection of main girder and the deviation of tower,so as to obtain a more reasonable cable tension method,and avoid the complicated process of secondary cable adjustment.4.Finite element softwares were used to analyze the temperature effect on girder.And monitoring the temperature change of the roof of the main beam.Calculation results show that: Temperature effect on main beam could not be ignored,especially in the pier-tower-girder fixed region,the stress distribution was complicated.The influence of temperature field on grider should be considered carefully at design state.The China's new code(JTG d60-2015)was close to actual situation and safe.According to the measured temperature of main beam,the reasonable casting temperature was put forward.