Research On Optimization Of Cable Saddle Pushing Scheme And Adjustment Of Completed Bridge Alignment Of Ground-anchored Suspension Bridge

Due to the complexity of the suspension bridge structure and the complex construction process,it is necessary to monitor the bridge construction process in order to ensure the safety of the structure and the final state of the structure as close as possible to the design state.In the erection stage of stiffening girder,in order to ensure the safety of the bridge tower structure,the.saddles should be preoffset and timely pushed step by step.The rationality of pushing value and timing of each pushing is a very important factor related to structural safety.However,at present,the research content is mostly the principle of pushing scheme formulation,and there is little research on the accurate pushing value analysis of each pushing.In addition,as the main determinant of the final state of suspension bridge is its completed bridge alignment,in order to make the final state of the structure as close as possible to the design state,the key influencing parameters of the completed bridge alignment are analyzed,so that it can be strictly controlled and adjusted in the construction process.With Changshou Second Yangtze River Bridge as the engineering background,this paper researchs the formulation and optimization of the pushing scheme and the control strategy of the completed bridge alignment during the construction of suspension bridge.The main work and achievements are as follows:1.Taking the reference cable as an example,the stress-free length is calculated and compared by analytical method and finite element method respectively;According to the geometric relationship between the saddles and the anchor span cable in the completed state,the calculation formula of the tangent point between the anchor span cable and the saddles in the completed state is derived.According to the principle of mechanical balance,the formula for calculating the tension of anchor span cable is obtained from the consistent tension.2.According to the equilibrium condition of the main cable at the saddle,the preoffsets of the saddles are calculated by analytical method and finite element method respectively;According to the principle that tensile stress and compressive stress do not exceed the limit value of the control section of the bridge tower,the limit value of the deflection of the bridge tower top in each construction process is obtained.Based on this,four pushing construction schemes are formulated,and the structural states of different schemes are compared and analyzed,and the advantages,disadvantages and application of different schemes are obtained.3.Based on the segmented catenary theory,the mechanical equilibrium equations of the saddles of suspension bridge are established through formula derivation,and the pushing value used to reach the specified place of the top deflection of the bridge tower can be obtained by solving them,and the pushing scheme is optimized accordingly;The results show that the pushing value obtained by this method can accurately make the deflection of the top of the bridge tower reach the specified place.In actual construction,according to this pushing value,it can be pushed into place at one time,thus reducing the number of pushing times in each pushing construction.4.Some structural material characteristic parameters and construction parameters are selected,and the sensitivity analysis of the influencing parameters of the completed bridge alignment of suspension bridge is carried out.The influence of each parameter on the completed bridge alignment of suspension bridge is obtained,which is taken as the basis for adjustment.Assuming that there are errors of the cable shape in the free cable state,the adjustment strategy in the construction process of the completed bridge alignment of suspension bridge is explored and formulated.