Study On Wind Resistance And Construction Control Of High Pier And Long Span Continuous Rigid Frame Bridge In Mountainous Area

Based on the previous construction and monitoring experience of high-pier and longspan continuous rigid frame Bridges,the two main factors controlling bridge stability are random wind load and the load caused by sunshine and ambient temperature change.Therefore,combined with the actual project,the finite element model of the industrial and agricultural bridge was established to analyze the influence of static wind effect and temperature effect on the stability of the bridge at different construction stages,and the linear and stress monitoring was carried out based on the adaptive construction control method.The main research of the text is as follows:(1)The wind load value at each position of the main bridge under different construction conditions was calculated according to "Code for Wind Resistance Design of Highway Bridge" and "Code for Load of Building Structure".For Bridges located in valleys,the transverse wind load of piers can be calculated according to the simple algorithm of the two codes,that is,the wind load of piers at a height of 10 m to 70 m is determined according to the calculated value of the "Wind Resistance Code",and the wind load below 10 m and above 70 m is determined by 1.04 times of the calculated value of the "Wind Resistance Code".(2)The finite element software Midas Civil was used to establish the simulation model of the main bridge.Based on the analysis of its natural vibration characteristics based on the multiple Ritz vector method,it was found that the transverse stiffness of the main bridge was poor.Therefore,the transverse deformation of the main bridge was focused on in the wind resistance analysis.The static wind load effect of the highest bare pier stage,the maximum cantilever stage and the bridge completion stage was analyzed by loading the transverse bridge wind load corresponding to five different basic wind speeds.The results show that the wind resistance of the main girder in the bridge formation stage is better than that in the maximum cantilever stage,and the transverse deformation of the main pier is the most unfavorable in the highest bare pier stage.The maximum combined stress of the main girder appears at the position of 1/4 of the side span in the maximum cantilever stage,and sudden changes occur at the end of the beam,the closing position of the middle span and the main pier.The overall compressive stress of the main pier in the bridge forming stage and the maximum cantilever stage is significantly higher than that in the highest bare pier stage.(3)The uniform temperature effect and nonlinear gradient temperature effect on the linear shape and stress of the main beam in operation stage were studied.The results show that the maximum longitudinal displacement occurs at the midpoint of the side span,the longitudinal displacement at the constraint is smaller than the longitudinal displacement away from the constraint position,and the maximum vertical displacement occurs at the midpoint of the middle span.The maximum stress appeared at the end of the main beam,but in the effect of seasonal uniform temperature,the stress at the lower edge reached the maximum stress at 1/3 of the side span and the stress at the middle point of the middle span reached the maximum stress of the main beam.(4)According to the problem of time lag in construction site,the construction optimization scheme is put forward.The control section was determined by the position of the most unfavorable section in the stress analysis of static wind and temperature load effect.The linear and stress monitoring of each control section was carried out based on the adaptive construction control method.The results show that the linear control precision and stress of the bridge meet the design requirements,and the structure is safe and stable.