Force Analysis And Experimental Study On Web Of Prestressed Concrete Composite Box Girder Bridge With Corrugated Steel Webs

The composite box girder with corrugated steel web s is a more reasonable structure in which concrete webs are replaced by corrugated steel plate s.Due to that the accordion effect in corrugated steel webs reducethe longitudinal stiffness of webs,so that the longitudinal stress of the web is small.In this paper,the longitudinal equivalent stiffness of webs and the longitudinal force in webs and concrete slabs are systematically analyzed using the method of combining theory,finite element method withmodel test.The main work and research results are as follows:(1)Firstly,the calculating formulaof longitudinal equivalent stiffness are deduced based the unit force method.Then the longitudinal equivalent stiffness ratios of this type bridge at home and abroad are analyzed.The results show that the longitudinal stiffness of corrugated steel webs is much less than that of straight steel webs,which can help reduce the layout of the externally prestressed tendons and improve the efficiency of the prestress effect.(2)The force of the corrugated steel webs are calculated using equivalent stiffness method and on the basis of ignoring the relative slip of concrete slab s structure and steel webs.According to decomposing the corrugated steel webs into vertical webs section and the inclined webs giving the appropriate boundary conditions,the longitudinal force formula are obtained based on the Saint Venant’s principle and trigonometric series method.(3)From the longitudinal stress of webs obtained by the formula and the comparison with results from ANSYS finite element models.The following conclusions are obtained:firstly,the longitudinal stress of webs achieves the maximum when under the same point force alone at both ends and the maximum soon to reduce and tend to zero.Secondly,in the middle of the web width direction(x=0).When the webs are under uniformly distributed moment at both sides,the bending stress on vertical web surface increase first and then decrease along the height direction and tend to be stable in the 1/4 height.Due to the central moment of inclined webs in the middle span tends to be zero,which imply indicate the longitudinal stress concentration at both ends of the web.Becausethe finite element calculation results and theoretical derivation are in good agreement,Which shows that using the finite element to analyzethe effect that variable parameters to longitudinal bending stress of vertical webs is reliable.It was found that the maximum bending stress of straight central webs increased linearly with the thickness of the web plate,and curved decreased with the width and height of the vertical webincreasing.(4)By contrast to the comparative analysis results from finite element models,theoretical calculation and measured data of the test beam,the accuracy and practicality of the theoretical derivation of corrugated steel webs areverified.First,calculate the equivalent stiffness webs of the test beam whoselongitudinal equivalent stiffness is larger than that ingeneral examples.Secondly,through the comparative analysis of the longitudinal stress of the web,the results show that the three are in good agreement.The maximum bending stress in the half height is close to the lower edge of the longitudinal stress of concrete values,and longitudinal stress on the web surface is not small enough to be ignored.The above findings may provide a theoretical basis for the web design.