轻型钢-UHPC组合桥面板的疲劳可靠性评估

Fatigue reliability assessment of light-weighted steel-UHPC composite bridge deck

为了研究轻型钢-超高性能混凝土(UHPC)组合桥面板的疲劳可靠性,以广东虎门大桥为实例,建立局部梁段有限元模型,基于可靠度理论和疲劳累积损伤模型,计算并对比钢-UHPC组合桥面板和沥青混凝土铺装桥面板易疲劳开裂细节的疲劳可靠度,并研究UHPC层厚度等参数对轻型组合桥面板疲劳使用寿命的影响。研究结果表明:与沥青混凝土铺装桥面板相比,轻型组合桥面板可有效提高桥面板各疲劳细节的疲劳可靠度,延长其疲劳使用寿命;UHPC层厚度、交通量增长率以及车辆超载对轻型组合桥面板疲劳细节的疲劳使用寿命均有显著影响:当UHPC层厚度在一定范围(35~55 mm)时,厚度每增加10 mm,疲劳使用寿命至少延长37%;当年交通量增长率为5%时,疲劳使用寿命缩短超过45%;当车辆超载率为50%时,疲劳使用寿命缩短约70%。

In order to investigate the fatigue reliability of a light-weighted composite bridge deck consisting of a steel deck and an ultra-high performance concrete(UHPC)structural layer,a finite element model for a girder segment of the Humen Bridge in Guangdong Province was established.The fatigue reliability indexes of typical fatigue-prone details of the steel-UHPC composite bridge deck and the asphalt concrete pavement bridge deck were calculated and compared,and the influence of a few parameters including the UHPC layer thickness on the fatigue life of light-weighted composite bridge deck was investigated based on the reliability theory and fatigue cumulative damage model.The results show that compared to the asphalt concrete pavement bridge deck,the light-weighted composite bridge deck can effectively increase the fatigue reliability of fatigue-prone details and extend the fatigue life of the light-weighted composite bridge deck.UHPC layer thickness,traffic volume growth and vehicle overloading rate have a significant impact on the fatigue life of the fatigue details of the light-weighted composite bridge deck.A 10 mm increment of UHPC layer thickness(within range of 35-55 mm)can extend the fatigue life by at least 37%;5%annual traffic volume growth rate can reduce the fatigue life by more than 45%,and 50%vehicle overloading rate can reduce the fatigue life by about 70%.