Update Of Segmental Construction Calculation Model Of Cable-Stayed Bridge Without Back Cable Based On Response Surface Method

The cable on one side of the cable-stayed bridge without back cable is cancelled.After the tower column is tilted,the gravity of the tower column is used to balance the dead load of the main beam transmitted through the cable.The consolidation of tower beam pier will be affected by the joint action of main beam,main tower and stay cable.The stress is complex,the construction is difficult,and the requirements of construction monitoring,analysis,measurement and control are high.There are two main problems in the construction monitoring of cable-stayed bridge without back cable:(1)when revising the model,the Unified overall parameters are taken as the parameters to be corrected,which is inconsistent with the actual situation;(2)How to obtain the estimated value of cable parameters which is consistent with the actual cable when measuring cable force by indirect method.In view of these two problems,combined with the construction monitoring of YingCheng bridge,the research on dynamic updating of segment parameters and identification of cable force parameters of monitoring calculation model based on response surface method is carried out.The main contents are as follows:(1)This paper introduces the development and theory of response surface method model updating,including experimental design,parameter screening,response surface fitting accuracy test and parameter optimization,and focuses on the principle of parameter updating and analysis of variance(ANOVA)in parameter significance test,which lays an important theoretical foundation for subsequent model updating and cable force identification.(2)Combined with the characteristics of real bridge and related research,the parameters to be screened and their value range are given.Based on the response surface method,this paper proposes a model dynamic updating method that takes the segment parameters as the parameters to be updated and uses more construction monitoring data as the objective function,which can dynamically update the model when there is a big difference between the theoretical model and the construction practice.The analysis results show that the parameter correction values obtained by this method meet the requirements of parameter variability,and have clear physical significance;The dynamic update of the construction monitoring model ensures that the analysis results of the calculation model are highly consistent with the measured structural response.The maximum deviation between the final completed bridge alignment and the design alignment is 1.1%,which meets the requirements of the completed bridge design,which proves that this method has high application value.(3)The influence of bending stiffness,calculation length and unit weight on cable force calculation is analyzed,and the existing cable force calculation formulas are summarized,and the parameter updating method of the cable finite element model based on the response surface method is proposed.In this method,the explicit function relationship between the parameters to be updated and the objective function is obtained through the central composite design(CCD),and then the parameters of the stay cable are updated according to the measured data of the stay cable.The analysis results show that using this method,the updated values of the parameters of the cable can be obtained according to the measured data,and the updated values of the parameters are consistent with the reality;The deviation between the calculated value of cable force and the actual cable tension obtained according to the parameter updating decreases significantly,and most of the deviation is reduced from 33.46%before updating to less than 5%.The update effect is obvious.The calculation accuracy of cable force obtained by this method meets the engineering requirements and has high application value.