An Analysis Of The Forming Method And Construction Process Of The Frigid Zone Of The Hollow Rigid Bridge

The hollow continuous rigid frame bridge is a highly competitive new bridge type,which not only solves the problems of cracking and scratching in the early continuous rigid frame bridge,but also has a lighter weight of the upper structure and a smaller influence of the main beam section due to the pier body.So the ability to span is also more prominent than the ordinary continuous rigid frame bridge.The formation of the hollow triangle area has always been the key and difficult point of the construction of the hollow continuous rigid frame bridge,which has a great influence on the stress of the structure during the construction process.This article uses the Lijia Jialing River Bridge with a main span of 245 m as its engineering background.In this paper,the construction of the Lijia Jialingjiang Bridge with the main span of 245 m is taken as the engineering background.The influence of the three triangular formation modes on the structural parameters is analyzed by comparing the double buckle construction,the joint construction of the buckle and bracket,and the construction with the upper and lower chord beam temporary auxiliary rod cantilever,and put forward the application conditions of the three formation methods.At the same time,the formation of three fasting triangle regions was simulated and the structural forces were analyzed.(1)Three types of fasting triangle formation and their mechanical properties are studied.In the construction phase,the axial force of the main girder under the formation of the three fasting triangulation zones has little difference,and the maximum shearing force and positive bending moment values near the zero segment during double buckle construction are smaller than those of the other two types.And in the construction process,the lower shear beam shear force and shear force change amplitude is also the smallest.As for the deflection of the main beam during construction,the vertical displacement at the zero segment under the double buckle construction is the minimum.No matter whether it is the junction of the upper and lower string beams or the joint of the lower string girder,the vertical displacement of the lower string beam in the construction phase is the largest for the temporary auxiliary bar suspended construction of the upper and lower string beams.For the suspension construction of the temporary auxiliary rods of the upper and lower string beams,the temporary auxiliary rods are in the process of erection,and the lower string beams have large tensile stress due to no temporary cable.When the triangles are suspended by the temporary auxiliary rods of the upper and lower stringers,the compressive stress of the main beam during the demolition of the temporary auxiliary structural members increases,and the compressive stress of the main beams under the other two types of construction decreases.Regardless of the joint construction of the buckle bracket or the suspension construction of the temporary auxiliary rods on the upper and lower strings,stress concentration will occur on some brackets and temporary auxiliary rods.This is unfavorable for construction,and double buckle construction will not happen.Therefore,for the Lijia Jialingjiang Bridge,the use of double buckle construction of the empty triangle area is more favorable for the stress of the main beam structure during the construction process,and is more suitable as a recommended scheme.However,the three forms of fasting triangles have their own advantages and their application conditions are also different.(2)Construction process analysis of double triangle construction forming triangle area.Several parameters for double buckle construction were analyzed for perform parameter optimization analysis such as the number of string fasteners,the height of the auxiliary tower,and the process of dismantling the lower string.During the formation of the triangular zone,the increase in the number of cable buckles will lead to a decrease in both the bottom plate compressive stress and the top plate tensile stress of the upper beam,so the upper string must not be excessive.The higher the auxiliary tower,the higher the compressive stress of the upper string in the construction process,and the lower string will not be affected,and the largest change in the stress is the zero segment section.In the three types of lower string closures listed in this article,the peak compressive stress and the amplitude of change at the top of the pier roof and the top beam floor during the process of removing up and down the lower strings are the smallest.At the stage of dismantling the temporary auxiliary components,the peak bending moment peak of the zero segment and the change of the negative bending moment of the top beam in the triangle area in the unified removal of temporary buckle program is the largest.In addition,the positive bending moment at the junction of the bottom chord beam and the negative bending moment at the bottom beam are the largest during the construction of the solid belly.Regardless of whether the solution of removing up and down the lower strings or the solution of removing the buckle from bottom to top,the stress distribution of the lower string beams is more even.Finally,it concludes that these three parameters are optimal when the four pairs of buckles for the upper strings,the auxiliary towers are 20 meters high,and the lower string buckles are used to remove up and down the lower strings,which is more suitable for the conclusion of the double buckle construction.