明珠湾大桥钢桥面板易损焊接节点疲劳寿命预测

Fatigue Life Prediction of Vulnerable Welded Joints in Steel Deck of Mingzhuwan Bridge

准确预测正交异性钢桥面板疲劳易损部位在往复车辆荷载下的疲劳寿命,能够为桥面板的日常维护提供依据,进而避免疲劳破坏的发生。首先,建立了明珠湾大桥正交异性钢桥面板节段有限元模型,使用Dload子程序实现了移动车辆荷载模型的施加,确定了3个易损部位的应力历程;然后,通过编写雨流计数法程序得到了易损部位的疲劳应力频值谱;最后,基于热点应力法与临界距离理论对易损部位进行了疲劳寿命预测。结果表明,在车辆荷载作用下,钢桥面板U肋-横隔板连接处受力最为不利,疲劳寿命预测值仅23 a,为明珠湾大桥钢桥面板中最易产生疲劳开裂的位置,日常巡检时需尤为注意;U肋-盖板连接处和横隔板弧形开口部位在设计基准期内不会出现疲劳开裂。

Determining the fatigue life of fatigue vulnerable parts of orthotropic steel bridge decks under reciprocating vehicle loads can provide a reference for routine maintenance and avoid the occurrence of fatigue damage.Firstly,a finite element model of the orthotropic steel deck section of the Mingzhuwan Bridge was established,and the application of a moving vehicle load model was achieved using the Dload subroutine.The stress histories of three vulnerable parts were determined.Then,the fatigue stress frequency spectrum of vulnerable parts was obtained by writing a rain flow counting method program.Finally,based on the hot spot stress method and the critical distance theory,the fatigue life of vulnerable parts was predicted.The results show that under vehicle load,the stress at the U-rib to floor beam connection in the steel bridge deck is the most unfavorable,and the predicted fatigue life is only 23 years.It is the most prone location for fatigue cracking in the steel bridge deck of the Mingzhuwan Bridge,and special attentions should be paid during daily inspections,while the U-rib to deck connection and the arc opening of the floor beam will not undergo fatigue cracking during the design reference period.