Research On The Method Of Form-Finding And Complete Rigid Connection Of Steel Truss Stiffening Beams Of Large-Span Suspension Bridges In Mountainous Areas

During the construction of suspension bridges,the erection stage of stiffening beams is of great significance to the overall process,and the different connection methods of stiffening beams restrict the quality of the entire erection stage.The existing connection methods have their own shortcomings.For the poor construction environment of large-span suspension bridges in mountainous areas,research on more suitable connection methods will have positive significance in shortening the construction period,reducing costs,and increasing construction safety.Based on the Chi Shui River Bridge,this paper studies a new stiffening beam connection method—method of form-finding to complete rigid connection.The method is discussed and explained in terms of theory and actual construction.The main work and results are as follows:(1)The characteristics and the specific application of the calculation theory of single-cable structure are reviewed,and the influencing factors of the suspension bridge nonlinear analysis and the simulation calculation method of the construction process are introduced.(2)The principle of the method is explained.According to the construction experience,the theoretical argumentation thinking is changed,and the cable shape formula at cable finished stage and finished state of the bridge is calculated.According to the shape of the cable curve,it is similar to the bending moment diagram of a simply supported beam under the same load,the cable shape formula corresponding to the beam sections calculated,including: at the erection completion of one-third beam segments,at the erection completion of two-third beam segments,and at the best large-scale rigid connection stage.The theoretical feasibility of the method is demonstrated.(3)The full bridge model was established by using the nonlinear analysis software BNLAS of the bridge structure,and the concrete stiffening beam hoisting scheme was determined through the calculation of inverted disassembly,and according to the magnitude of the rigid relay force during the rigid connection of the beam segments and the force of the main components during the beam erection process The scheme was further verified.Through the analysis of the opening amount of the lower chord of the beam during the actual construction process and the results of the stress and strain test of the stiffening beam,the feasibility of the theoretical hoisting scheme is verified and the practical feasibility of the method is demonstrated.(4)The factors affecting the erection sequence of stiffening beams are introduced,and the feasibility of extending the method to steel box girder suspension bridges is theoretically analyzed.For the second-stage steel truss girder suspension bridge with a large ratio of dead load to total load,when using this method,should analyze the internal force state of each member after the stiffening beam is closed.