Research On The Key Technology Of The Construction Of The Prestressed Concrete Continuous Beam Bridge

With the development of China’s economy and transportation,new lines often need to cross existing railways,highways,canyons,etc.The turnstile construction method is used to cross the line without interrupting the traffic,which has less interference on the existing line and is safe and reliable.Therefore,it is gradually used in the bridge construction across the existing railway and highway due to its unique advantages.The turning of pier top and bottom is very common.The continuous beam bridge(52m + 88m+ 52m)of the third line of Longchuan River Bridge in Dashucun,which is relied on in this paper,is the turning technology of pier middle.If the turning of pier top is adopted,the construction space is limited.If the turning of pier bottom is adopted,the height of pier is high and the center of gravity is difficult to control.This paper studies and analyzes the setting height of the spherical hinge,the construction process,the influence of the change of the sensitive parameters on the main beam,the closure method of the mid span of the mid span and the construction technology of the roof。(1)From the theoretical point of view,the calculation formula of the stability of the swivel structure with the setting height of the spherical hinge is derived.The finite element model of the swivel structure is established by using ABAQUS.The influence of the weight of the swivel pier body and the swivel beam on the stress and deformation of the swivel pier body is analyzed.The reasonable setting height of the spherical hinge in the horizontal rotation construction is discussed from the theoretical and calculation aspects.(2)The Midas civil finite element software is used to establish the mechanical model and simulate the construction process of the Long Chuan River Third Line Bridge in Dashucun,analyze the change rule of the stress and deformation of the key section in the cantilever construction stage,side span closure and middle span closure,and obtain the characteristics of the key section in the key construction stage to provide the basis for the monitoring of the turning body in the pier.(3)Midas civil finite element software is used to change the elastic modulus,bulk density,friction coefficient and deviation coefficient of prestressed steel tendon pipe in the main beam of the bridge.(4)This paper puts forward the improved steel shell construction technology of the middle span closure section of the pier middle rotating continuous beam bridge,including the system composition of the improved steel shell method and the construction process of the improved steel shell method.The improved steel shell method solves the problems such as the influence of the stiffened rib plate on the construction,the stress on the steel shell,the influence on the substructure caused by the welding of the closure steel shell and the hoisting and closing of the closed steel shell Problems such as bad timing stability.In this paper,ABAQUS finite element software is used to analyze the concrete pouring stage of steel shell to verify the rationality of stress.(5)In this paper,the design principle,system structure and roof formwork construction technology of the universal roof formwork system of the continuous beam bridge with mid pier rotation are put forward.The advantages of the universal roof formwork structure with swivel in the pier are to reduce the loss of the roof formwork,save materials,reduce the modification time and save the construction period,and the structure has good universality,especially for the non serrated block beam section and the serrated block beam section.