Study On Construction Control Of 500-meter Scale Concrete Filled Steel Tubular Arch Bridge

The research on construction control of concrete filled steel tubular(CFST)arch bridge has an important influence on the safety of the construction process,the comfort of the driving and the durability of the structure.At present the method for construction control of CFST arch bridge with open-loop control and closed-loop control and feedback control,however,with the increase of the span of CFST arch bridge,the nonlinear problems caused by super large span arch ribs can not be ignored.Structure is affected more obvious by the construction error,and the debonding phenomenon of concrete filled steel tube is more remarkable.The existing construction control method is difficult to achieve good results.Supported by the research project of the core technology of 500 m grade concrete filled steel arch bridge of Guangxi Provincial Communications Department,an adaptive construction control system based on adjustable domain method is established for super long span CFST arch bridge.In combination with the scientific problems found in the construction control process,the related research work was completed and the theoretical foundation and construction control technology was further improved.The main work of this paper is as follows:(1)The significance of construction control of concrete filled steel tube arch bridge is expounded,and the development of CFST arch bridge is reviewed.The construction control technology of concrete filled steel tubular arch bridge is summarized.The difficulties of construction control of 500 m grade concrete filled steel tubular arch bridge are studied,and the research contents of construction control of 500 m grade concrete filled steel tubular arch bridge are analyzed.(2)The theoretical basis of construction control of CFST arch bridge is expounded,and the influence of nonlinear factors during construction of Super Long Span CFST arch bridge is analyzed.The constitutive relation and calculation method of concrete filled steel tube are studied.The construction process,structural stress characteristics and control requirements of 500 m super long span CFST arch bridge are summarized,on the basis of the above research and analysis,an adaptive construction control system based on adjustable domain method is established.(3)The error formation mechanism and transfer law of concrete filled steel tubular arch bridge during construction are studied.Based on the study of the error of CFST arch bridge,the method of variable domain construction control for concrete filled steel tubular arch bridge is put forward,and the division principle of the control section and the calculation method of the adjustable domain are studied.The simplified mechanical model of the hoisting process of arch rib is established,and the reliability of the construction control of the adjustable domain method is verified theoretically.Based on the characteristics of adjustable field construction control,the calculation and control method of arch rib alignment in every construction stage are analyzed,and the construction accuracy and time limit of 500 m super long span concrete filled steel tube arch bridge are solved.(4)The method of bridge state adjustment is analyzed,and the advantages and disadvantages of the state adjustment method of existing bridges are summarized.Based on the stress free state method,the principle of error adjustment during construction is analyzed,and the method of state adjustment compensation is put forward,at the same time,the application of the state adjustment compensation method in the arch rib hoisting stage and the core concrete pouring stage is studied.The problem of the structural adjustment accuracy of the CFST arch bridge is solved.Based on entropyweight method,the sensitivity of design parameters is analyzed.D-value method is used to eliminate the influence of error factors.The accurate construction response data are obtained and the structural design parameters are corrected.According to the revised calculation model,the calculation method of structural state deviation and adjustment quantity is studied,and the accuracy of bridge structural state adjustment calculation is improved.(5)Based on the static analysis of concrete filled steel tubular structures,a formula for debonding of concrete filled steel tube is proposed.By using the Hamilton variational principle,this phenomenon is analyzed from the dynamic point of view.Combined with the monitoring data in the engineering,the cause of the vibration of the arch rib during the pouring process of the core concrete is revealed.Based on the calculation and analysis of the theoretical model of concrete filled steel tube debonding,the effect of debonding on the structural rigidity and bearing capacity of concrete filled steel tube is studied by loading test with a scale model of concrete filled steel tube.The measures for debonding control of common concrete filled steel tubes are introduced,the core concrete pouring process is simulated by the scale model of CFST arch rib,the vacuum assisted suction grouting technology was studied,and the vacuum assisted grouting technology was used to control the debonding and void of concrete filled steel tube.