钢拱桥极限承载力的综合三因素检算方法

通过钢拱桥非线性计算及结果的分析,得出结论,钢拱桥极限承载力的实质是拱肋截面的材料屈服,随着塑性区的扩展,截面刚度降低,从而导致整体非线性位移的急剧增加。运用统计回归,逐一分析横向初始缺陷与横向位移因素指标R1l、拱圈整体横向刚度因素指标R2l和拱桥非保向力因素指标R3l,提出考虑上述三因素的综合因素指标Rl。依此建立钢拱桥极限承载力的综合三因素检算方法。经试验数据的初步验证以及用此方法对4座大跨钢拱桥进行检算的结果表明,该方法综合考虑了横向初始缺陷、横向位移、拱圈整体横向刚度和非保向力等影响钢拱桥极限承载力的主要因素,可简便且准确地检算钢拱桥的极限承载力。

Research on Synthetical 3 Factors Checking Method for the Ultimate Load Carrying Capacity of Steel Arch Bridges

On the ground of nonlinear calculation of arch bridges, essence of ultimate load carrying capacity of steel arch is systematically summarized. Due to the yielding of profiles and the diffusion of plastic zones at arch ribs, the stiffness of profiles is reduced. As the result, the nonlinear displacement will become relatively considerable. The effects of design parameters can be reflected by the variations of the internal forces at key profiles. So the factor index of lateral initial crookedness and lateral displacement R_(1l), the factor index of total lateral stiffness of ribs R_(2l) ,and the factor index of non-directional loads R_(3l) are analyzed respectively by statistics and regression. On the basis of these 3 indexes, a synthetical index Rl is finally put forwarded and a synthetical 3 factors method is established for checking ultimate load carrying capacity of steel arch bridges. Through comparison with the results of model tests and 4 steel arch bridges, it is pointed out that lateral initial crookedness, lateral displacement, total lateral stiffness of ribs and non-directional loads have been reflected in this method. It can calculate the ultimate load carrying capacity of steel arch bridge conveniently and correctly.