正交异性钢桥面疲劳开裂研究

STUDY OF FATIGUE CRACKING FOR ORTHOTROPIC STEEL BRIDGE DECK

正交异性钢桥面板的钢结构桥梁在车辆荷载作用下易出现疲劳开裂，为了解决这一问题，该文采用在正交异性钢桥面板上设置薄层RPC（Reactive．Powder-Concrete）超高性能混凝土层，将钢桥面转变成组合桥面，从而提高了桥面刚度，能有效改善结构受力状态，且不会增加桥梁上恒载重量。通过对某大桥的计算分析表明：采用组合桥面后，车辆荷载作用下的钢桥面应力大幅度下降。钢桥面疲劳敏感点处的拉应力降幅达到71．32％-72．39％，大幅度的提高了钢桥面的抗疲劳寿命；薄层RPC面板的高强度和高韧性，完全能满足组合桥面的最大拉应力10．08MPa的强度要求，成为钢桥面上的永久结构层，可以大幅度降低钢桥面板的开裂风险。

The orthotropic steel bridge decks are easy to suffer from fatigue cracking under the traffic load. In this paper, a new-type composite bridge deck system, which is composed of an orthotropic steel deck and thin RPC （Reactive-Powder- Concrete） ultra-high-performance concrete layer, is proposed to solve this problem. With the adoption of the composite bridge deck system, the rigidity of orthotropic deck is enhanced, while the main structural mechanic performance is improved without increasing the dead load weight of the bridge deck. Analyses of a certain bridge with such composite bridge deck show that the stresses in steel bridge deck deduce greatly under the traffic load. Tensile stresses at the fatigue sensitive points of the steel bridge deck are decreased by 71.32% to 72.39%, leading to an elongated bridge＇s fatigue life. Due to its high strength and high toughness, the thin RPC layer can completely satisfy the limited requirement of tensile stress of 10.08 MPa. The thin RPC layer can be used as a permanent structural overlay in steel bridge deck, and the risk of causing fatigue cracks of the steel bridge deck can be greatly reduced.