Research On Some Theoretical Problems In Combined Box-Girder With Corrugated Steel Webs

Based on the theory of the box girder, this article, considering the mechanical behavior of the corrugated steel web box girder and based on the approximate plane sections hypothesis, researched the shear-lag effects temperature effect and the creep effect of the corrugated steel web box girder.(1)Based on "the approximate plane sections hypothesis", this article analysed and derived the formula of the shear lag coefficient by the three match rod method, and verified the correctness of the formula by the comparison of the results of the experiment and the finite-element. This article gets the following conclusions through the analysis:1) The three match rod method is a very good one in analyzing the creep effect of the corrugated steel web box girder, this formula is simpler and more practical in the engineering than the energy method;2) The basic assumptions presented based on its own characteristics are right in the calculation of the creep effect of the corrugated steel web box girder.3) This article further proofed that the creep effect cannot be ignored in the analysis of the corrugated steel web box girder.(2) Based on the force method and the age-adjusted effective modulus method, this article proposed the creep effect analysis method of the statically indeterminate structure. And combined with the deformation coordination principle, derived redistribution of internal force calculation formula of the statically indeterminate structure considering the creep effect, and analysed the creep effect by this method. This article gets the following conclusions through the analysis:1) In the calculation of the creep stress of the corrugated steel web box girder, the basic assumptions presented based on its own characteristics are right.2) Under the same condition, the creep time internal force of the corrugated steel web box girder is smaller than the ordinary concrete box girder, and the deformation caused by creep is also smaller than the ordinary concrete box girder, this is mainly because that the stiffness of the corrugated steel web is smaller and the weight of the corrugated steel web girder is also smaller than the ordinary concrete girders.(3) Based on "the approximate plane sections hypothesis", the article analysed and deduced the temperature stress calculation formula of the corrugated steel web box girder under the sunshine temperature load using the force method, and analysed the temperature effect of the corrugated steel web box girder by this method. This article got the following conclusions through the analysis:1) In the calculation of the temperature stress of the corrugated steel web box girder, the basic assumptions presented based on its own characteristics are right;2) Under the same temperature load, the temperature time internal force of the corrugated steel web box girder is smaller than the ordinary concrete box girder, but the deformation causesed by the change of temperature is larger than the ordinary concrete box girder.