Research On Shear Lag Effect In Steel-Lightweight Concrete Composite Beam

The lightweight aggregate concrete(LWAC) and steel-concrete composite beam is becoming the hotspot of research of the colleges and the institutes,and the latter is the hotspot of the hotspots.The steel-concrete composite beam bridge is widely used abroad and more and more in China,especialyin intersection of cities.But,the steel-LWAC beam bridge is not reported being used in China.This shows that we don't have a deep understanding of the new form of structure and that this form of stucture is not accepted like steel-concrete beam bridge bypeople. In China,there are a lot of bridges which have various form of girders.These form of girders changed along with deeper engineering practice and research of human.Thecomposite beam is combined by the shear joint between the s-teel beam and the concrete board,so it can well develop the pull-resisting abily of steel and the press-resisting of concrete.In addition,it can reduce the weight of itself , have better deformabily and better ability of aseismatic and etc.So,wecan forecast the steel-LWAC beam bridge will become one of the important dir-ection of bridges.This paper is supported by the project of"experimental and theorial researh of the steel-LWAC beam"belonging to Communication Department ofJilin Province and this project is completed by transportation college of JiLin University This paper mainly researches the shear lag effect of the steel-LWAC beam and the author uses the energy variational principle method and finete elememt met-hod to analysis it.Also,the anthor do some research on effective width.Chpater two ,chaper three and chapter four is core of this paper.Chapter One is introduction of this paper.In this chapter,the anthor introduce the method and result of previous research,and the aim,meaning and main content of the paper.The LWAC is widely used abroad,but uesd less in China,especialy in bridge engeering.Now,the LWAC is mainly used for non-bearing part of bridge.Inthe approach bridge of Yongding River New Bridge in Tianjin,the LWAC is used for girders,but the span is just 35 metres.The research on shear lag effect of steel-LWAC beam has not beenreported.But,the research has important meaningChapter Two is the main content of the paper.The author use the nergy variational principle method to analysis the shear lag effect of the steel-LWAC beam,gained the formula of the portrait stress.Also,the author gain formula of the she-ar lag effect of the same section simple supported and cantilever bridge.Then,theauthor gain the method of caculating the shear lag effect of conti nuous bea m base d on coe ff i cient of she ar l ag e ffectChapter Three is also the important part of this paper.For every theory form-ula,it must be proved to show it is right,so in this chapter , I use the nonlinearFEM program Ansys to set up 10 models with variational parameters to prove the correctness of the formula of last chapter.The curve of stress-strain came fr-om the result of experimentation,the deformation coincide with the rusult of theFEM.This can prove the correctness of the fomula and the models.Then,author study the influence ofcoefficiet and collation of shear joint on the shear lag effect.And the anthor think that the collation of shear joints have more influence t-han the degree of shear jointon shear lag effect.Chapter Four is the core of this paper.All the research on shear lag effect ser-ver for the engeering practice.For shear lag effect , the most correl-ative question is the effective width.So,in this chapter the author analysis the criterion of so-me cuntries and study if they can be used to caculate t-he steel- LWAC beam bridge.Chapter Five is the last chapter,and it is the summarization of this paper.In this chapter,the author also point out the content and direction for fur-therstudy.