车撞节段桥墩破坏机理及性能提升方法研究

Failure mechanism and performance improvement method of segmental piers under vehicle impact load

随着车撞桥墩的事故不断增加,预制节段桥墩的抗冲击性能引起了广泛关注。为了有效控制预制节段之间的相对滑移从而改善其抗冲击性能,该文建立车辆撞击桥墩的三维有限元模型,分析了局部破坏机制,并且提出采用剪力键和内嵌形状记忆合金(shape memory alloy,SMA)钢筋的方法。研究结果表明:预制节段桥墩在汽车冲击荷载作用下发生了局部剪切破坏,并基于理论推导提出了动态抗剪强度计算方法,得出其值小于现浇桥墩;采用剪力键有效地控制了节段之间的相对位移,使得预制节段桥墩在汽车冲击荷载下的整体变形由剪切型转向弯曲型;对于预制节段桥墩内嵌SMA钢筋也具有较好地改善相对位移的效果,提高预制节段桥墩整体抗变形能力。

With increase in accidents involving vehicles hitting bridge piers,anti-impact performance of prefabricated segmental bridge piers attracts widespread attention.Here,to effectively control relative slip between prefabricated segments and improve their anti-impact performance,a 3D finite element model for vehicle to impact bridge pier was established to analyze local failure mechanism,and the method to use shear keys and embedded shape memory alloy(SMA)steel bars was proposed.The study results showed that prefabricated segmental bridge piers have local shear failure under impact load of vehicles,and a dynamic shear strength calculation method based on theoretical derivation is proposed,its calculation value is smaller than that of cast-in-place pier;using shear keys can effectively control relative displacement between segments to make the overall deformation of prefabricated segment piers shift from shear type to bending type under vehicle impact load;SMA steel bars embedded in prefabricated segmental piers also have a better effect on controlling relative displacement and improving the overall anti-deformation ability of prefabricated segmental bridge piers.