The Study Of Stress Properties And Finite Element Analysis For Spine-like Girder Cable-stayed Bridge With Large Cantilever

Spine-like girder with large cantilever appeared at the end of the 20^th century.Since then,it developed rapidly both at home and aboard.However,there is no design specification for the spine-like girder in China,and the systematical analysis of the the long cantilever spine-like girder is very few.This paper is based on two design schemes of Kongcheng River bridge-ribbed spine-like girder and strutted spine-like girder.Utilizing finite element method,some engineering application problems were studied in view of the girder’s mechanics characteristics.The main work included following aspects:（1）The historical background of the change in girder’s section shapes,and the development process and the research status quo of the ribbed spine-like girder and the strutted spine-like girder were introduced.Additionally,several methods about how to calculate the load distribution factors were stated.Through it all,there were still many problem about this kind of girder needed to be studied,and existing method cannot precisely measure the load distribution of ribbed spine-like girder.（2）In order to explore the stress characteristics,the two full-bridge models were fabricated according to two design cases of Kongcheng River Bridge,on which the finished bridge state,vehicle load and temperature effect were calculated.The force characteristics of the ribbed spine-like girder and the strutted spine-like girder were compared.（3）Subsequently,a more detailed study was carried out on the two kinds of spine-like girders.For ribbed girder,according to the parameter analysis about the rib spacing and the deck thickness,the fitting equation of the load distribution was obtained.Based on the fitting equation,a simplified method for single segment finite element calculation was put forward.（4）For strutted girder,in view of characteristics of the external struts under the cantilever,the construction procedure between the struts and prestressed bars and the parameter analysis of the struts angles were studied.The results shows that constructing the struts first makes sense,and with the increase of the struts angle,the deck tensile stresses and the strut axial force increase,the vertical deformation decreases.