重型货车撞击作用下预制节段RC桥墩的动力行为

DYNAMIC BEHAVIOR OF PRECAST SEGMENTAL REINFORCED CONCRETE BRIDGE PIER UNDER HEAVY TRUCK IMPACT

  • 摘要: 针对预制节段RC(PSRC)桥墩面临重型货车撞击的威胁,采用LS-DYNA软件开展了重型货车撞击下PSRC桥墩动力行为的数值仿真分析。分别建立了原型PSRC桥墩和重型货车精细化有限元模型,通过复现已有撞击试验,验证了数值仿真分析方法的可靠性,对比了重型货车撞击下PSRC桥墩和现浇整体式RC(CMRC)桥墩的动态响应和损伤破坏,揭示了撞击偏心距、撞击角度、节段数量、初始预应力和剪力键对PSRC桥墩抗车撞性能的影响规律。结果表明:重型货车撞击过程中,PSRC桥墩发生剪切破坏;与CMRC桥墩相比,由于节段接缝处的不连续性、相对滑移和摩擦耗能,以及预应力钢绞线与剪力键的共同作用,PSRC桥墩承担的撞击力峰值和侧向变形较小,遭受的损伤程度较低,呈现较好的抗车撞性能;随着撞击偏心距、初始预应力的增加和节段数量的减少,PSRC桥墩抗车撞性能逐渐增强,而撞击角度和剪力键对其影响相对较小。

     

    Abstract: In response to the threat of heavy truck impacts on precast segmental reinforced concrete (PSRC) bridge piers, numerical simulation and analysis were carried out on the dynamic behavior of PSRC bridge piers under heavy truck impacts using finite element (FE) program LS-DYNA. Refined FE models of the prototype PSRC bridge pier and heavy truck were established and validated by reproducing existing impact tests. Moreover, the dynamic response and damage of the PSRC bridge pier and the cast-in-place monolithic reinforced concrete (CMRC) bridge pier under heavy truck impact were compared. The study reveals the factors that influence the truck impact resistance of PSRC bridge piers, e.g., impact eccentricity, impact angle, number of segments, initial prestress, and shear key. The results show that the PSRC bridge pier experiences a shear failure under heavy truck impact. Compared with the CMRC bridge pier, the PSRC bridge pier presents better truck impact resistance with smaller peak impact force, lateral deformation and reduced damage due to the discontinuity, relative sliding, and friction energy dissipation between segment joints, as well as the interaction of the tendons and shear key. The impact resistance of the PSRC bridge pier increases with the increase of impact eccentricity, initial prestress, and the reduction of segment number, while the impact angle and shear key have a relatively less effect on the impact resistance of PSRC bridge pier.

     

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