A Research On Wide Single Box Double Room Girder Bridge Space Effect

With the in increasing traffic pressure,main road box girder in normal width can’t meet the traffic needs any more.For the development of transportation,single box wide section with double rooms or more have been used in high frequency.Features of wide section girder,like the large space of web,the thin walled box,the wide frange plate,cause the significant shear lag and other spatial effect.Thus leads to the obvious crack in the process of construction and engineering accident.In this paper,wide space effect of box girder cross section are analyzed by using the finite element software MIDAS FEA with Youganghe grand bridge as the engineering backgroundThe main content of this thesis:(1)The wide box girder of the development,characteristics and research situation of shear lag effect is introduced,and then at home and abroad in the design of wide box girder of research at home and abroad in the specification for the consideration of shear lag is discussed.(2)To establish 40 m wide span single box finite element model of a simply supported beam with double room,wide box girder are analyzed in dead weight,weight plus space under concentrated load and dead weight plus symmetrical load effect.The results show that the concentrated load on the load location of horizontal stress and vertical stress and the vertical displacement obvious mutation effects;The farther the cross section,the smaller the impact of load;Symmetrical loading does not change the original wide box girder of horizontal stress and vertical stress and the vertical displacement change trend,will only change in the position of the load stress and the displacement of each value.(3)Establish a 39m+65m+39m wide span continuous beam finite element model of single box double room,analyzes the self-respect,self-respect plus transverse prestressing respectively under the action of shear lag coefficient on the critical section and their distribution.Results show that the shear lag effect of each section of roof and floor are very obvious,most of the cross section of shear lag effect;Under the weight of the shear lag effect than gravity and transverse prestressing shear lag effect under the action of obvious,this shows that the transverse prestress can improve the stress distribution of box girder.(4)Use a variety of traditional partial load coefficient solution for this project under the background of wide single box double room the partial load coefficient of continuous beam are calculated and compared.Using the established finite element model,has carried on the analysis of partial load coefficient.The results show that the experience coefficient method for wide single box double chamber continuous beam is unsafe.