轻型组合桥面板球扁钢纵肋-横隔板连接细节局部应力分析

为降低正交异性钢桥面板疲劳开裂的风险，提出带球扁钢纵肋的轻型组合桥面板方案。以洞庭湖二桥轻型组合桥面板为工程背景，建立钢桁梁局部有限元模型和球扁纵肋-横隔板连接细节的子模型，并基于热点应力法，对横隔板上开孔孔型和厚度进行了参数分析。研究表明：球扁纵肋-横隔板连接处3个典型疲劳细节的疲劳性能受横隔板厚度影响显著|综合比较，苹果型开孔的疲劳性能最优。为进一步验证轻型组合桥面板的球扁钢纵肋-横隔板连接处3个细节的疲劳性能，开展了足尺模型疲劳试验，试验模型采用16mm厚带苹果型开孔的横隔板设计。疲劳试验中,控制细节（横隔板切口自由边缘）的应力幅为90.6MPa，历经250万次循环加载后，试验模型中典型疲劳细节均未出现疲劳裂纹。这表明，带球扁钢纵肋的轻型组合桥面板关键细节的疲劳性能良好，能满足洞庭湖二桥的工程要求。

Analysis on local stress at bulb flat rib-diaphragm connections in a lightweight composite bridge deck

In order to decrease the risk of fatigue cracking in orthotropic steel decks, a lightweight composite bridge deck with bulb flat ribs was proposed. As a typical bridge with lightweight composite bridge deck, the Sencond Dongting Lake Bridge is taken as an example, in which the local finite element models of steel truss girder and the sub-models of bulb flat rib-diaphragm connections were established. Then the shape of cutouts and thickness of diaphragms were investigated based on the hot spot stress method. The results show that the fatigue properties of 3 typical details at bulb flat rib-diaphragm connections were affected significantly by the thickness of diaphragms. On the basis of comprehensive comparison, it is concluded that the fatigue properties of apple-shaped cutout are the best. Additionally, fatigue test was performed on a full-scale model to verify the fatigue strength of 3 details at bulb flat rib-diaphragm connections in a lightweight composite bridge deck with 16mm diaphragms and apple-shaped cutouts. In the test, the fatigue stress range for the most unfavorable detail, i.e. the free edge of the cutout, was 90.6MPa and no fatigue cracks developed after 2.5 million loading cycles. The research results show that the key details in the lightweight composite bridge deck with bulb flat ribs have good fatigue performance and can satisfy the design requirements of Sencond Dongting Lake Bridge.