大跨组合斜拉桥梁腹板及加劲肋合理设计

Proper Design of Web and Its Stiffeners for Long Span Composite Girder Cable-Stayed Bridge

为合理设置大跨组合斜拉桥钢板梁的腹板及其加劲肋,结合实例,在考虑后屈曲性能的影响下,对钢主梁受压区格长高比和加劲肋与腹板刚度比的合理选取进行研究。采用有限元软件EBPLATE计算腹板正应力屈曲系数、剪切屈曲系数及抗剪承载力,分析屈曲系数与钢主梁受压区格长高比和加劲肋与腹板刚度比的关系。结果表明：统筹考虑受压区纵肋布置及横肋的间距,受压区格长高比建议设计值区间为2.0~2.5,在这个区间纵肋的有效宽度大,局部正应力屈曲系数较大且剪切屈曲系数处于中值;在受压区,加劲肋与腹板刚度比建议设计值区间取13.0~15.0,在腹板厚度适中的情况下,使腹板成为中度加劲板。

To properly arrange the web and its stiffeners for the steel plate girder of long span composite girder cable stayed bridge, the proper selection of the length-to-height ratio and the stiffener and web stiffening ratio of the compressive zone grid of the steel main girder was studied with reference to the practical example and in consideration of the influence of post-buckling performance. The finite element software EBPLATE was used to calculate the normal stress buckling coefficient, shear buckling coefficient and the shear capacity of the web. The relationship between the buckling coefficients and the length-to-height ratio and the stiffener and web stiffening ratio of the compressive zone grid was analyzed. The results of the study indicate that in overall consideration of the arrangement of the longitudinal stiffeners and the spacings of the transverse stiffeners in the compressive zone, the design value interval of the length-to-height ratio of the compressive zone grid is proposed to be 2.0～2.5. In such interval, the effective width of a longi- tudinal stiffener is great, the value of the local normal stress buckling coefficient is rather great and the value of the shear buckling coefficient is medium. For the stiffener and web stiffening ra- tio of the compressive zone grid, the design value interval is proposed to be 13.0～15.0. Under the condition that the thickness of the web is proper, the web should be made to be a medium thick stiffening plate.