移动荷载作用下正交异性桥面板应力响应分析

Stress Response Analysis of Orthotropic Steel Bridge Deck under Moving Load

研究目的:正交异性桥面板在钢结构桥梁中的应用愈发普遍,但在往复车辆荷载作用下容易引发疲劳开裂。准确评估桥面板在移动荷载下的应力响应是后续开展疲劳分析的基础,因此显得尤为必要。鉴于此,本文建立连续三跨正交异性桥面板实体-板壳多尺度有限元模型,采用Fortran语言编制Dload子程序实现移动荷载施加,全面分析桥面板在不同加载工况下的应力动态响应过程,以便明确典型构造细节的受力状况,为正交异性桥面板的疲劳性能评估与改善提供科学依据。研究结论:(1)加载中心线接近盖板-U肋连接焊缝或U肋开口正上方时是钢桥面板的最不利加载位置;(2)对于盖板-U肋节点,单轮加载分析即可较好地反映其应力响应状态,而对于U肋-横隔板连接处以及横隔板弧形切口区,双轮加载导致的应力影响不可忽略;(3)不同加载工况下,横隔板弧形开口区总是处于高应力态,属于钢桥面板的最不利受力部位,容易引发疲劳破坏;(4)本研究成果可用于钢桥面板结构在车辆移动荷载作用下的应力状态评估。

Research purposes:The orthotropic decks are increasingly used in steel bridges,but these structures are prone to fatigue cracking under cyclic vehicle loads.It is necessary to accurately evaluate the stress response of the bridge deck under moving load,which is the basis for the subsequent fatigue analysis.A multi-scale FE model of continuous three span orthotropic bridge deck is established,which combines the solid element with the shell element.Fortran language is used to compile the sub-program Dload to apply moving load,and the dynamic stress response process of bridge deck is comprehensively analyzed under different loading conditions.Therefore,the stress condition of typical structural details is clarified,which provides a scientific basis for the fatigue performance evaluation and improvement of orthotropic bridge decks.Research conclusions:(1)The most unfavorable loading position of steel bridge deck is when the loading center line is close to the U-rib-to-deck connection weld or just above the U-rib opening.(2)For U-rib-to-deck weld joints,the stress response state can be well reflected by single wheel loading analysis,while for U-rib-floor beam weld joints and arc opening of floor beam,the stress effect caused by double wheel loading cannot be ignored.(3)Under different loading conditions,the arc opening area is always in a high stress state,which is the most unfavorable stress bearing part of the steel bridge deck and easy to cause fatigue damage.(4)The research results can be used to evaluate the stress state of steel bridge deck structures under vehicle moving loads.