Research On Effect Of Cross Diaphragm On Mechanical Behavior Of Continuous Box Girder Bridge

Long-span prestressed concrete continuous box-girder bridge play a vital role inbridge construction in our country. Moreover, cross diaphragm is of essential in it. Toimprove the mechanical behavior of continuous box girder bridge, cross diaphragm is aperfect solution for problems such as the oversize distortion stress and deformation inthe box sections. If the design of cross diaphragm is unreasonable and inappropriate, itwon’t play a positive effect. Besides, with the self-gravity effect of cross diaphragm, itwill increase the burden of a bridge and play a negative effect. This dissertationperformed the following work in order to optimize the design of cross diaphragm andgive full play to engineering significance.(1)This dissertation analyzes the advantages of load decomposition method incomparison to generalized coordinate method. Through this method, it does a researchon stress conditions under eccentric loading of box girders and discusses longitudinalbending theory, torsion theory, distortion theory and transverse bending theory in detail.(2)According to the code, the structure stress analysis of long-span prestressedconcrete continuous box-girder bridge has been done. With load decomposition method,the eccentric vehicle living load is decomposed into symmetrical longitudinal bendingload, interdependent torsion load and distortion load, which constitute theantisymmetric load, transverse bending load which is analyzed by plan frame method.With the functioning of these4loads, it analyzes4basic force distributions ofcontinuous box girder bridge.(3)This dissertation makes a finite element model of continuous box girder bridgevia ANSYS and makes a analyses on4basic force forms of box girders with andwithout cross diaphragm functioned by concentrated load and uniform load, for thepurpose of further research on effect of cross diaphragm on mechanical behavior ofcontinuous box girder bridge.(4)This dissertation does a further research on impacts of the number and the localstructure form of cross diaphragm in continuous box girder bridge from the point ofmaximum distortion angle which produced by distortion effect on continuous box girderbridge of cross diaphragm and in the basis of effect on the mechanical behavior offull-bridge. (5)Considering the negative effects of self-gravity of the cross diaphragm, thisdissertation makes suggestions about numbers and thickness of cross diaphragm so as togive full play to the theoretical significance and engineering significance.