Research On Construction Control Method Of Hybrid Beam Cable-stayed Bridge Based On Dual Objective Control

With the rapid development of long-span mixed beam cable-stayed Bridges,construction control plays an increasingly important role.The task of bridge construction control is to ensure that the stress and deformation of cable-stayed Bridges are always within the safety range during construction,and the stress line of the main girder after completion of the bridge conforms to the expectation in advance.This paper analyzes and studies the construction control method of the long-span cable-stayed bridge with mixed beam with the background of the Yangtze river highway bridge in jianyu,hubei province.① The basic ideas and principles of cable-elevation control method and geometric control method,as well as their implementation process,are briefly described.The advantages and disadvantages of the two methods are analyzed,and the feasibility of the two methods is analyzed in combination with the specific situation of the jiayu Yangtze river highway bridge.②Combining with the characteristics of long span hybrid girder cable-stayed bridge,a reasonable choice of unstressed configuration based on adaptive control method as the research of the theoretical basis to double objective control method as the research train of thought,concrete beams with stress as the main control target,steel girders with elevation line as the main control objectives,to control the long-span cable-stayed bridge.③ In the middle of construction,the large cantilever end will be encountered in the mixed-beam cable-stayed bridge.Because the steel main beam material is steel,the stiffness is small,the deformation is big,and is affected by the temperature obviously.Under the influence of cable force,temperature,temporary load and many other factors,it is difficult to control the main beam line.Based on the jianyu Yangtze river highway bridge,the influence parameter fitting equation is established through the influence of cable force on elevation and the influence of temperature on elevation.In this process,the temporary load is strictly controlled so as not to affect the elevation of the main beam.The specific gravity of cable force and temperature during construction is obtained.In this way,the cable force value to be adjusted can be accurately obtained through the known elevation difference and temperature.④ As for the influence of the order of removal of supports on the stress of concrete beams,four kinds of removal order of supports are simulated and calculated in this paper.Mainly by monitoring the stress of the upper and lower sections of the concrete beam and the axial force of the auxiliary pier,it is required that the stress of the upper and lower sections of the concrete beam should be under uniform compression,even if the tensile stress should be less than the limit value,and the force of the auxiliary pier should not be tensile.⑤This paper introduces the traditional closure method,analyzes the advantages and disadvantages of the closure method,and selects the single closure closure method based on the actual situation of the jiayu Yangtze river highway bridge.The specific implementation process of closure is introduced in detail.And according to the idea of two-objective control,the key steps of its closure control are simulated and calculated.