钢管混凝土叠合构件抗撞击工作机理及设计方法研究

Civil structures such as bridge piers might be crashed by moving masses during their lifecycles and it is a challenging issue to consider this problem in structural design. Due to the lack of systematic research on the impact resistances of steel-concrete composite structures, there are no robust design methods for such structures under impact loading in the design codes of China and other countries now. As a result, it is important to carry out research on the impact behaviour of the composite structures, which will benefit both the theoretical backgrounds and engineering applications. As Concrete Filled Steel Tube Reinforced Concrete (CFSTRC, also named as concrete-encased CFST) members are widely used in bridges and high-rise buildings in the recent years, the mechanical behaviour and design method of such structures under lateral impact loading are investigated in the present study. A finite element analysis (FEA) model is established to simulate the full-range behaviour of CFSTRC member under lateral impact. Then impact tests are carried out on CFSTRC specimens with different parameters, in which the failure modes and impact resistances of the specimens are analysed. With the FEA model, the mechanical behaviour of the member under lateral impact is studied, including the composite actions of different materials in the member. Parametric study is also conducted to study the influences of main parameters, such as axial load ratio, steel ratio and impact energy on the impact behaviour of the composite member. Finally, design methods and construction measures on the impact design of CFSTRC members are drawn based on the parametric study.

结构耐撞性是工程结构设计中的难点问题之一。结构服役期间，特别是桥墩，经常会遭遇撞击荷载作用。目前，由于缺乏对钢-混凝土组合结构动态极限承载能力的系统研究，我国及世界各国的有关设计规范中尚缺乏组合结构构件防撞设计方面的规定。因此，深入开展组合结构耐撞性研究具有重要的理论意义和实用价值。本项目以近年来开始在桥梁和高层建筑中大量使用的钢管混凝土叠合构件为对象，开展其在侧向撞击荷载作用下工作机理和设计原理的研究。建立钢管混凝土叠合构件在侧向撞击荷载作用下动力响应全过程分析的有限元模型，进行叠合构件在不同参数下的耐撞性试验，研究其残余破坏形态和动态极限承载能力的变化规律。深入研究叠合构件在侧向撞击荷载下的工作机理，明晰受力全过程中各组成材料间的相互工作特点。在系统分析轴压荷载比、含钢率、冲击能等主要参数对叠合构件动态工作性能影响规律的基础上，提出钢管混凝土叠合构件的耐撞性设计方法和构造措施。

结构耐撞性是工程结构设计中的难点问题之一。结构服役期间，特别是桥墩，经常会遭遇撞击荷载作用。目前，由于缺乏对钢-混凝土组合结构动态极限承载能力的系统研究，我国及其他国家和地区的有关设计规范中尚缺乏组合结构构件防撞设计方面的规定。因此，深入开展组合结构耐撞性研究具有重要的理论意义和实用价值。本项目以近年来开始在桥梁和高层建筑中大量使用的钢管混凝土叠合构件为研究对象，深入开展其在侧向撞击荷载作用下工作机理和设计原理的研究工作。本项目首先系统研究了静力荷载作用下实心和箱型钢管混凝土叠合构件在轴压、弯曲和压弯荷载作用下的工作机理，细致分析了结构受力全过程中组成钢管混凝土叠合构件各材料间的组合作用，研究了结构全过程性能以及重要参数的影响规律。在此基础上，建立钢管混凝土叠合构件在侧向撞击荷载作用下动力响应全过程分析的有限元模型；进行叠合构件的系列耐撞性试验，研究其残余破坏形态和动态极限承载能力的变化规律；深入研究叠合构件在侧向撞击荷载下的工作机理，明晰受力全过程中各组成材料间的相互作用特点；分析了轴压荷载比、和冲击能等主要参数对叠合构件动态工作性能的影响规律。基于上述试验研究和理论分析工作，提出了钢管混凝土叠合构件在压弯荷载作用下的承载力实用设计方法及其耐撞性设计构造措施。