船车撞击作用下桥梁破坏机理与性能控制

This project is designed to investigate the response and failure mechanism of bridge structures subjected to vessel and vehicle collisions, and to develop measures to reduce structural damage: (1) by impact experiments, to understand the failure mechanism of reinforced concrete beams and columns, and to modify the dynamic constitutive model of concrete for low-velocity impacts, and furthermore to establish the methods, indecies and parameters to quantify the damages of reinforced concrete beams and columns at cross-section scale under vessel and vehicle collisions. (2) to establish the equivalent vessels and vehicles based on the statistical features of impact actions of vessels and vehicles; to establish the simplified time-history load functions, simplified relationship of impact force-deformation, and to propose model’s parameters; to develop the modeling method for strong nonlinear dynamic coupled system of vessel (vehicle) – bridge – protection structure – soil – water, numerical analysis methods and software; (3) Based on the experimental test of concrete members (beams and collumns) and model bridges, and numerical simulations of typical bridges, to investigate the main factors influencing the impact responses of coupled system of vessel (vehicle) – bridge – protection structure – soil – water, and further to understand the failure mechanics of the coupled system. (4) to develop damage indecies and parameters for bridges, protection structures, and furthermore for the coupled system; to establish the anti-impact performance control methods based the design of configuration of bridge, the connecting components between the superstructure and substructure, and protection structures. (5)Based on the research findings, guidelines will be proposed for bridge design against potential collisions from vessels and vehicles, and will be applied to the design of 2-3 bridges against the impact of vessels or vehicles.

开展船车撞击下桥梁破坏机理和抗冲击性能控制方法的研究：（1）通过材料冲击试验、构件冲击试验和数值模拟分析，研究钢筋混凝土构件的冲击破坏机理，修正中低应变速率范围内的混凝土冲击本构模型和参数，并建立广义力-变形关系和构件层面的冲击破坏描述指标和参数；（2）研究等代船车模型；建立简化时间荷载函数模型、简化撞击力-撞深关系模型，及其参数确定方法；研究船车-桥-防撞装置-土壤-水耦合系统动力学建模和数值分析方法，开发分析软件；（3）通过构件和模型桥梁的冲击试验和数值模拟分析，研究该耦合系统在船车撞击作用下的破坏、倒塌过程及其主要影响因素；（4）建立桥梁、防撞装置及其耦合系统撞击破坏性能等级的定量划分方法、确定关键参数；从桥梁体系、构型与尺度、防撞装置等方面，研究桥梁在船车撞击作用下结构体系性能控制方法；（5）提出桥梁抗船车撞击性能控制与设计的技术条文，并应用于2-3座桥梁的抗撞击设计。

近年来由于船车等碰撞冲击导致的桥梁破坏事件频繁发生，造成了大量的人员伤亡和重大的财产损失，因而桥梁在冲击作用下的破坏机理及其安全防护已成为全球研究的热点问题。在本项目的资助下，针对船车冲击作用下桥梁的安全问题，开展了以下研究内容：.（1）开展了混凝土材料动态性能试验，基于试验结果标定了混凝土动力本构模型参数，改造和完善了水平冲击试验系统，并利用该平台开展了构件水平冲击试验，建立了构件层面的广义力-广义变形关系模型；（2）开展了桥墩结构体系水平冲击试验，探究了桥墩结构体系的冲击破坏机理，进行了等效车辆模型撞击大比尺桥墩试验；（3）建立了不同吨位、类型的船车等代精细化有限元模型，通过开展数值仿真，获得了船车撞击力过程样本，建立了简化的船车荷载模型，建立了桥梁在船车冲击作用下破坏过程的数值模拟方法，包括质点碰撞法、强迫振动法、冲击谱方法等，探讨了船舶-防撞结构-桥梁系统考虑浮力影响的简化建模方法，设计和研发了面向对象MIPS有限元程序；（4）对桥梁构件冲击破坏过程的数值模型的关键参数进行了标定，并基于试验构件，对数值模型的可靠性进行了验证，以国道325原九江大桥与某城市桥梁为例，基于数值模拟研究了桥梁在船车撞击作用下的倒塌机理，探讨了影响桥梁结构破坏机理的主要因素；（5）基于试验与数值仿真，建立了船车冲击作用下的桥梁性能指标模型，给出了桥梁性能等级的定量划分，提出了基于性能的桥梁抗撞设计理论；（6）在此基础上，以某长江大桥为例，基于建立的基于性能的桥梁抗撞设计方法开展了工程实例应用。