Research On Key Technology Of Pre-tensioned U Shape Beam Used In Rail Transit

In recent years,with the national economic development,rail transit is in the ascendant in numbers of cities.Subway or viaduct as well as other forms is often used in construction of rail transit.Compared to the traditional box girder,U-beam used in the construction of viaducts shows obvious advantages.U-beam can significantly lower the track height and wheel-rail noise,and can reduce the amount of engineering work,decrease the total investment of whole project.During the construction,the use of pre-tensioning prestressing process,can bring down the difficulty of construction and lower the requirement to construction site.But the academic knowledge of the mechanical behavior of the pre-tensioning prestressing U beam is far from thorough,there is quite a lot of further work need to be done to lucubrate present works.This paper introduces the development of U-beam and its application at home and abroad,and introduces the concrete application of U-beam rail transit project based on Qingdao Rail Transit R3 line.Based on the design data,the spatial finite element analysis model of U-beam is established by using the eight-node hexahedral element.The principal mechanical data of the U-beam are obtained by calculation and analysis the U-bean finite element model.According to the model,the stress distribution,Effects stress,concrete yield and failure criteria are discussed.In addition,the U-beam is subjected to field loading test to obtain the strain and deflection data of the U-beam under load.The behavior of deformation and cracking of the U-shaped beam under actual load is evaluated on the data of field loading test.The results of spatial finite element calculation and field loading test show that the mechanical behavior of the U-beam is consistent with the requirement.And the U-beam can work as an instruction to the design and construction of other forms of U-beam.