既有RC拱肋不利车载效应随刚度损伤的变化

Unfavorable Vehicle Load Effect Varying with Stiffness Damage of Existing RC Arch Ribs

为合理评估既有RC拱桥的承载能力,对损伤后拱肋最不利车载效应的变化问题进行了研究。采用机动法分析了拱肋区段刚度损伤后各典型截面弯矩和轴压力影响线的变化情况。在此基础上,按照现行公路桥涵设计通用规范中的车道荷载布置方式,并结合正交试验设计方法,研究了具有不同拱轴系数、矢跨比和跨度参数的无铰拱肋各典型截面的不利弯矩和轴压力值随损伤程度的变化规律。结果表明在无铰拱肋中各截面不利轴压力值随损伤程度的变化不大,而不利弯矩值则有较大变化;当损伤程度相同时,拱顶截面不利负弯矩对应的变化系数值最大,而拱脚截面不利正、负弯矩对应的变化系数值相当,且数值也较大。

In order to obtain a reasonable result in evaluation of load bearing bridges, the change of unfavorable vehicle load effect on the damaged arch ribs capacity was inves of existing RC arch tigated. The change of influence lines of moment and axial compressive force at each representative section when stiffness damages occurred in some zones of arch ribs were analyzed with the kinematical method. On this basis, according to the lane load model in the current general code for design of highway bridges and culverts and the orthogonal experimental design method, the variation regularity of unfavorable moment and axial compressive force with damage for each representative section of hingeless arch ribs with different arch-axis coefficients, rise-span ratios and spans was studied. The result indicates that （ 1 ） the unfavorable axial compressive force varies with damage in a small range, and the unfavorable moment varies in a large range; （2） the varying coefficient of unfavorable negative moment at top section is the maximum, and the varying coefficients of unfavorable negative moment and positive moment at foot section are close and larger when arch ribs have the same damage degree.