The Research On Error Characteristics And Control In Construction Parameters Control Of Long-span Suspended-cast Arch Bridge

Error control theory and method is the core issue of long-span bridge construction control,and it is also an important guarantee for bridge construction safety,quality and structural durability.In recent years,the cantilever pouring of reinforced concrete arch bridge has developed rapidly.During the construction of this type of bridge,the structural system is complicated and the number of statically indeterminates is high.Due to the existence of component size deviation,material parameter variation,temporary load and many other uncertain factors,it often leads to the occurrence of structural state errors.The errors will continue to change and spread with the progress of the construction stage,showing dynamics and coupling,which will pose the dual challenges of quality assurance and risk suppression for construction control.The limitations of traditional construction control related research in the application of cantilever pouring of reinforced concrete arch bridge are becoming more and more significant.Based on the Jiashi bridge under construction,this paper studies the uncertainty of structural parameters,error propagation characteristics and error control in the construction process of cantilever pouring of reinforced concrete arch bridge.The main research content and results are as follows:(1)Based on the random response surface method of Hermite polynomial chaotic expansion,the approximate explicit relationship between random input parameters and structural response is constructed.Then the structural random multi parameter sensitivity analysis is carried out for the uncertain factors caused by errors in the construction process of the cantilever pouring of reinforced concrete arch bridge.The sensitivity index is obtained by partial derivative method,and the sensitivity grading is completed.The results show that the initial tension of buckle cable and the weight of arch ring are the main sensitive parameters that affect the structural state,such as,arch ring alignment,section stress,buckle cable force,buckle tower deflection and construction stability.Buckle cable elastic modulus and arch ring elastic modulus are the secondary sensitive parameters,while buckle tower elastic modulus,hanging basket load and temporary construction load are not significant sensitive parameters.(2)Qualitative analysis and example analysis of the formation and variation characteristics of the arch ring alignment error during the construction process are carried out.The variation propagation characteristics of the error and its influence on the key construction state of the bridge are studied.Studies have shown that the effect of the the arch ring weight and the error of the initial buckle cable tension changes and propagates forward along with the construction of the subsequent sections.The linear error at the beginning of the construction of the new section gradually increases.The longer the cantilever length of the arch ring,the stronger the error propagation ability,showing typical divergence.Error propagation has a significant impact on the maximum cantilever,bare arch,and the structural state of the bridge.(3)This paper analyzes the errors in the construction process of cantilever pouring of reinforced concrete arch bridge,and puts forward corresponding error control measures.Aiming at the parameter error,based on the least square method,the mixed estimation of error identification is carried out for the main sensitive parameters,such as the dead weight of arch ring and the initial tension force of buckle cable,which affect the arch ring alignment and stress.Then the identification results are used to modify the theoretical calculation model.Aiming at the construction error,on the premise of ensuring the safety of arch ring section stress,based on the influence matrix theory,taking the minimum square sum of arch ring linear residual error as the objective function,the quadratic programming model of error adjustment is constructed by using MATLAB,and the optimal cable force adjustment is obtained.By comparing the results before and after error control,the feasibility of error control measures is verified.