正交异性钢桥面板疲劳易损区应力分析

盖板-U肋-横隔板三向连接节点是正交异性钢桥面板中最容易发生疲劳开裂的部位。采用ABAQUS软件建立了四跨连续正交异性钢桥面板结构的实体与板壳混合有限元模型。利用AASHTO标准疲劳车开展静力响应分析。发现最外侧U肋处的连接节点应力集中最为明显。在此基础上开展在单轮和横向双轮作用下各关键位置正应力的纵、横向影响线分析,并最终得到了后轴四轮同时作用的最不利荷载位置。进一步基于外推法对各疲劳易损区焊趾处的热点应力进行计算和分析,得到了相应的应力集中系数。结果表明:U肋外推区的应力分布比较符合线性外推准则,但横隔板外推区的应力呈现明显的非线性变化,建议采用二次外推方法。

Stress Analysis of Fatigue Vulnerable Zones in Orthotropic Steel Bridge Decks

The deck to rib to diaphragm connections have been considered as the locations most prone to fatigue cracking in orthotropic steel bridge decks. A combined shell-solid element model of four-span orthotropic steel deck was firstly established by using ABAQUS software, and the standard fatigue loading vehicle as provided in AASHTO specification was employed for the analysis. The longitudinal and transversal influence lines for the stresses at critical spots near the most outside rib, where stress concentrations appear to be the most significant, are obtained, respectively for the cases of single tire print and double tire prints. The most unfavorable position of all four back-axle tire prints is also determined. Furthermore, the hot spot stresses as well as stress concentration factors (SCFs) at weld toes were calculated by using the extrapolation method. Results show that linear distribution of stresses are real in the extrapolation zones of ribs, while quadratic extrapolation method is suggested for the diaphragm due to signification non-linear stress variations in the extrapolation zones.