船舶撞击双柱式桥墩破坏模式分析
Analysis of failure patterns of double？？column bridge？？piers subjected to vessel collision

为了研究双柱式桥墩在船舶碰撞作用下的损伤破坏机理，对冲击作用下钢筋混凝土结构的材料本构、黏结模拟方法进行了分析。采用可以考虑开裂的混凝土连续光滑本构模型模拟墩柱混凝土材料，采用考虑应变速率的随动塑性强化模型模拟墩柱纵筋及箍筋；基于显式动力有限元软件LS？？DYNA，在考虑双柱式桥墩纵筋配筋率变化及是否存在桩土相互作用的情况下，对驳船撞击双柱式桥墩进行动力仿真分析。研究结果表明：在船舶撞击作用下，混凝土双柱式桥墩的破坏过程可分为4个阶段：初始接触碰撞阶段、撞击墩破坏阶段、非撞击墩破坏阶段、系梁与墩柱连接破坏阶段；结构在碰撞接触区域发生了局部剥落损伤，同时在碰撞侧桥墩、非碰撞侧桥墩以及系梁连接处均发生开裂破坏，船艏经历了2次加载？残对乩？程，船舶动能的76%转化为船艏及结构的内能；双柱式桥墩纵筋配筋率对结构的破坏模式影响明显，随着配筋率提高，桥墩墩柱逐渐由弯曲破坏转变为只出现少量横向裂缝；在配筋率为2%时，墩柱基本不发生弯曲破坏，而碰撞侧墩柱与系梁连接处属于双柱式桥墩薄弱构造环节，在不同配筋率情况下均发生破坏；桩土相互作用对桥墩的破坏模式影响显著，在计算分析时应予以考虑，在墩底固结情况下，桥墩主要发生剪切破坏。
To investigate the damage and failure mechanisms of bridge double？？column piers subjected to vessel collision, the material constitutive models of the reinforced concrete (RC) structure and the modeling approach of bond effects were discussed. The concrete material in RC piers was simulated with a concrete continuous？？smooth？？cap？？model (CSCM), and the longitudinal reinforcement and stirrup were modeled with a kinematic hardening plastic model, including the strain？？rate effect. The explicit dynamic finite element software LS？？DYNA was employed to conduct the numerical simulation of barge double？？column pier collision, considering the influences of longitudinal reinforcement ratio and soil？？pile interaction. The results show that the failure process of the double？？column could be classified into 4 stages， initial contact and collision, collided column failure, non？？collided column failure, and joint between tie beam and column failure stage，under the vessel impact loading . The contacted area of the pier suffered the first local damage. Then, both the collided and non？？collided pier columns, as well as the tie beam joints is damaged by a rupture？？failure pattern. The barge bow endured the loading？？unloading process twice. Around 76% of the vessel kinetic energy is transformed into the internal energy of the barge bow and structure during the collision process. The ratio of longitudinal reinforcement affects the failure patterns of the bridge pier significantly. The damage pattern of the bridge pier transferred from the flexural failure to a few transverse cracks as the reinforcement ratio increases. No flexural failure occurred as the reinforcement ratio is reach to 2%, whereas the joint between the contacted column and tie beam suffered severe rupture failure under various reinforcement ratios. The soil？？pile interaction has a significant influence on the failure pattern of bridge pier, which should be considered in the structural design. Shear failure occurs as the pier bottom is fixed rigidly. 2 tabs, 11 figs, 25 refs