Construction Stress Monitoring And Zero Block Stress Analysis Of Continuous Beam Bridge

Prestressed concrete continuous beam bridge in practical engineering is a very common type of bridge,it has a sleek appearance,good overall performance,construction and convenient.The KeJia main bridge is a continuous beam bridge of(85+3×138+85)m,Construction method is cantilever laying method.In the whole construction stage,with the increasing length of the cantilever,the internal stress of the zero block is constantly changing and the distribution is complex.So the need for continuous beam bridge pier top zero block finite element simulation of stress field and spatial analysis to ensure safety during bridge construction and construction quality.This paper describes the method and content of stress monitoring in the construction stage of long span prestressed concrete continuous beam bridge,the finite element software is used to establish the model of the whole bridge model and the block model of the pier top zero block,do some analysis to the local stress field of zero block The main contents are as follows:(1)This paper briefly describes the development process and current situation of prestressed concrete continuous beam bridge at home and abroad,and introduces the basic theory of stress monitoring at home and abroad in the large span prestressed concrete continuous beam bridge.At the same time,the importance of spatial stress analysis of zero block is described.(2)In the construction process for the whole bridge of KeJia Bridge,I use the finite element analysis software Midas Civil to establish the full bridge model.In the modeling process,I have given full consideration to the weight of the structure,prestressed load,construction load,concrete shrinkage and creep,bridge live load,secondary dead load,structure system transformation in the process of construction and boundary condition change and so on.Based on the finite element model,the stress variation of the key section of the bridge in different construction stages is obtained.(3)This paper introduces the method of stress testing of continuous beam bridge and the principle of stress measuring point arrangement.In view of KeJia Bridge,the stress values of the key section of the post and tension of each segment were obtained by Midas Civil finite element model,comparing with the field measured value and summaring of the causes of error,verifing the correctness of the model.(4)The zero block of the prestressed concrete continuous beam bridge is a complicated stress structure with three-dimensional prestress.Using Midas Fea to establish the finite element model of the pier top zero block of KeJia Bridge to carry on the analysis of the maximum cantilever state and the finished state,In the process of building solid model,the model fully consider the load of vertical,horizontal and vertical three-dimensional prestressed bar and Pavilion,respectively,analysis the three-dimensional stress of the zero block roof plate,bottom plate,web plate,diaphragm and the position of the hole.(5)This paper define the convective boundary conditions,establish the hydration heat model and analysis of temperature and stress distribution and variation law of zero block.According to the result of stress analysis,it is possible to know the position of the crack in the construction phase of the zero block and the corresponding measures.