预应力混凝土箱梁桥腹板疲劳寿命评估方法研究

发布时间：2018-12-07 14:52

【摘要】：基于疲劳损伤累积理论,提出一种预应力混凝土箱梁桥腹板疲劳寿命评估方法。首先,分析预应力混凝土箱梁桥腹板受力特性,建立腹板与顶板早期开裂及腹板疲劳破坏准则;然后,通过箱梁桥局部平面有限元模型计算横向效应下混凝土及箍筋应力,基于混凝土S-N曲线分析混凝土疲劳开裂,引入裂缝影响系数对箍筋应力进行修正,基于全桥杆系有限元模型及变角度桁架模型计算仅考虑面内剪力作用下箍筋应力,两者叠加得到空间效应下箍筋应力历程,以雨流计数法获取箍筋应力谱,并基于疲劳损伤累积理论对箍筋进行疲劳寿命评估;最后,对一实例分析,同时分析箱梁横向效应、裂缝深度等对箍筋应力及疲劳寿命的影响。结果表明:当裂缝深度达到腹板保护层厚度时,箱梁横向效应对桥梁腹板寿命影响较大,可使其发生疲劳破坏。
[Abstract]:Based on the fatigue damage accumulation theory, a fatigue life assessment method for prestressed concrete box girder bridge web is proposed. Firstly, the stress characteristics of web plate of prestressed concrete box girder bridge are analyzed, and the early cracking and fatigue failure criteria of web and roof are established. Then, the local plane finite element model of box girder bridge is used to calculate the stress of concrete and stirrups under transverse effect. Based on the S-N curve of concrete, the fatigue cracking of concrete is analyzed, and the influence coefficient of cracks is introduced to modify the stress of stirrups. Based on the finite element model and the variable angle truss model of the whole bridge, the stress history of stirrups under spatial effect is obtained by considering only the in-plane shear force, and the stress spectrum of stirrups is obtained by the method of rain flow counting. The fatigue life of stirrups is evaluated based on fatigue damage accumulation theory. Finally, the effects of transverse effect of box girder and crack depth on stirrups stress and fatigue life are analyzed. The results show that when the crack depth reaches the thickness of the web cover, the transverse effect of the box girder has a great influence on the life of the bridge web, which can lead to fatigue failure.
【作者单位】：天津大学建筑工程学院;滨海土木工程结构与安全教育部重点实验室(天津大学);
【基金】：国家自然科学基金项目(51178305)
【分类号】：U446

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