为制定预防性维护方案提供支撑，探究了悬索桥极限承载力随时间长期退化规律。以我国某公路耐候钢砼组合加劲梁悬索桥为工程背景，建立了考虑钢梁、主缆和吊索三类主要钢构件截面特性与力学性能随时间退化模型；利用梁格法，采用 Mises 屈服准则，考虑几何非线性和材料非线性，基于 U.L. 列式编制杆系有限元计算程序， 计算分析了 3 种最不利荷载工况下的悬索桥的弹塑性极限承载力。结果表明：耐候钢梁的截面积损失 4.5%~ 11.7%，吊索截面积损失 6.8%，主缆截面积损失 1.1%，钢梁退化较快，随着荷载的增大，钢梁塑性区不断扩大使得主缆应力还未达到屈服应力，悬索桥就不能继续承载；荷载‐位移曲线随着桥龄增加表现形式不同，在 20 年以前有明显的拐点；极限承载力呈现缓慢下降的趋势，100 年下降 27.2%~32.4%。
In order to provide support for the formulation of preventive maintenance programs， the long-term degradation of the ultimate bearing capacity of suspension Bridges with time is explored. Based on the engineering background of a composite stiffened beam suspension bridge in China， which incorporates weathering steel andconcrete， a degradation model was established for the section characteristics and mechanical properties of its three main components： steel beam， main cable and sling. Mises yield criterion was adopted by grillage method， and geometric nonlinearity and material nonlinearity were considered. The finite element calculation program for the bar system was developed based on U.L. formula. The elastic-plastic ultimate bearing capacity of suspension bridges was calculated and analyzed under the three most unfavorable load conditions. The results show that theweather resistant steel beam experiences a cross-sectional area loss ranging from is 4.5% ~ 11.7%， sling experiences a cross-sectional area loss of 6.8%， and the main cable experiences a cross-sectional area loss of 1.1%. The degradation of steel beam exhibits relatively rapid degradation. With the increase of load， the plastic zone of steel beam continues to expand， causing the stress in the main cable to remain below the yield point. As a result， the suspension bridge cannot continue to carry. The load displacement curve takes different forms with the increase of bridge age， and there was an obvious inflection point 20 years ago； The ultimate bearing capacity shows a slow downward trend， decreasing by 27.2% ~ 32.4% in 100 years.