Three Dimensional Stress State Analysis Of Prestressed Concrete Box Girder Bridge Constructed By Cantilever Method

In this paper,the problem of cracking of large span prestressed concrete continuous rigid frame bridge in the course of use in recent years is studied in this paper:(1)The present research status of stress state of box girder anchorage local pressure zone and transverse internal force distribution of box girder under prestressed action is expounded,and summarized and evaluated.(2)In view of the stress characteristics of the prestressed anchorage zone of the box girder,we use the Ansys finite element analysis software to establish the solid finite element model of the section box girder,calculate the local stress distribution under the roof beam anchorage of the box beam,and analyze the characteristics and laws of the local stress distribution.(3)The numerical analysis shows that under the preloading of the roof beam,the local stress under the roof of the box beam and the anchor on the web can be decomposed into 2 local pressure problems of the plate.The equivalent calculation formula of the decomposed load and stress is given in the paper,and the numerical calculation is carried out.At the same time,the influence of the thickness ratio of the roof and the web on the equivalent ratio coefficient is also analyzed.(4)The stress calculation of the plate local pressure is considered as a plane stress problem.By using the elastic mechanics method,the local stress series solution of the plate local pressure is obtained by drawing up the stress function of the trigonometric series.(5)By establishing a finite element calculation model with a prestressed beam pipe,we analyze the stress distribution of the web under the prestress bending,and study the influence of the change of the thickness of the web and the bending radius of the bending beam on the local stress of the web,Finally,we compare the influence of straight beam and downward bending beam on the stress distribution in the anchorage zone of web.(6)In this paper,the frame analysis method is used to calculate the lateral internal force of the box beam produced by the radial force,and the effect of this effect on the stress of the web plate of the box girder is analyzed.The research results in this paper have practical reference value for the design of continuous rigid frame bridge.