大纵肋正交异性组合桥面板疲劳性能研究

Styudy on Fatigue Performance of Orthotropic Composite Bridge Deck with Large Longitudinal Ribs

在大纵肋正交异性钢桥面板结构中引入混凝土结构层,通过栓钉将钢桥面板与混凝土结构层组成新型大纵肋正交异性组合桥面板,是从结构体系层面提高大纵肋正交异性钢桥面板疲劳性能的有效途径。基于有限元数值分析,明确了大纵肋正交异性组合桥面体系对于钢桥面板典型疲劳易损细节的应力幅改善效果;采用足尺节段模型试验对结构的关键疲劳易损细节进行了疲劳试验研究,验证了关键疲劳易损细节在设计寿命期内的抗疲劳安全性和混凝土结构层在疲劳荷载作用下的耐久性,在此基础上对关键疲劳易损细节的疲劳损伤演化及结构体系的疲劳破坏模式进行了试验与理论研究。研究结果表明:大纵肋正交异性组合桥面板结构体系能够显著降低U肋与顶板以及U肋与横隔板连接细节的应力幅,横隔板开孔部位是控制钢桥面板疲劳性能的关键构造细节;设计寿命期内钢桥面板疲劳性能与混凝土结构层的疲劳耐久性均满足要求,且具有一定的安全储备;混凝土结构层负弯矩区疲劳开裂对钢桥面板各疲劳易损细节疲劳性能的影响不显著;大纵肋正交异性组合桥面板的疲劳破坏模式表现出典型的两阶段特征,栓钉发生疲劳断裂并导致组合效应局部劣化,进而加速钢桥面板关键疲劳易损细节的疲劳损伤累积速度并最终发生疲劳开裂。

A new type of composite bridge deck with large longitudinal rib was composed of steel bridge deck and concrete structure layer connected by headed shear studs,which was an effective way for improving the fatigue performances at the structure system level.The improvements of composite bridge deck with large longitudinal rib on the stress range of typical fatigue prone details of steel deck were explicated based on finite element numerical analysis.The full-scale girder segment model was designed to investigate the fatigue prone details,and the anti-fatigue security of fatigue prone details during design lifetime and fatigue durability of concrete structure layer under the loading condition were verified.So the damage evaluation of typical fatigue prone details and the failure mode of composite structure system under cyclic loading were investigated experimentally and theoretically.The results indicate that the stress range of rib-to-deck platejoints and longitudinal-to-diaphragm welding joints can be significantly reduced by the structure system of composite bridge decks with large longitudinal ribs.The opening of diaphragm is important structural detail to control the fatigue performance of steel bridge deck.The fatigue performances of steel bridge decks and the fatigue durability of concrete structure layer meet the requirements of design with a certain safety margin,and meanwhile the crack of concrete structure layer in the negative region has little influence on fatigue performances of the fatigue prone details of steel bridge decks.The fatigue failure mode features of composite bridge decks with large longitudinal ribs can be divided into two stages.With shear studs rupturing,the local failure of the composite action intensifies the damage cumulative of typical fatigue prone details in the steel bridge deck,eventually leading to crack propagation.