工字形CFRP-钢管-混凝土组合构件的抗侧向冲击性能及设计方法

Buildings or bridges are often subjected to lateral impact loads during their lifecycles, which may cause local or overall collapse of the structures. The CFRP has the characteristics of light weight, high tensile and compressive strength. If the I-shaped CFRP is put into the concrete filled steel tube, it can increase the bearing capacity, reduce the weight of the structure itself, promote the ductility of the structure, and improve the ability to resist the impact. At present, the research on the behavior of concrete filled steel tubular (CFST) composite members with inner I-shaped CFRP profile under lateral impact has not yet been done. Therefore, the experiment, numerical modeling and theoretical analysis will be used to investigate in the performance and design method of concrete filled steel tubular (CFST) composite members with inner I-shaped CFRP under lateral impact. The dynamic constitutive relation of the steel tube, concrete and I-shaped CFRP profiles under the impact load will be proposed. The whole working process, energy dissipation mechanism, damage mode, and critical energy of composite components and the cooperative working mechanism of I shape CFRP, steel tube and concrete under lateral impact load are going to be studied. The influence of some important parameters, slenderness ratio, impact point and the like on the performance of members under the impact will be analyzed. The calculation formula of bearing capacity, design method and construction measure of two types of composite components under the lateral impact load are going to be put forwards. The design method of the new composite members is of great significance to improve the capabilities of buildings and bridges to resist the lateral impact on both practice and theory.

建筑物或桥梁在服役期间会遭受侧向冲击荷载的作用，并导致结构的局部或整体倒塌。工字形CFRP具有轻质、抗拉及抗压强度高等优点，将其内置于普通钢管混凝土构件中，可提高承载力、降低自重、改善延性、提高抗冲击性能。但目前对工字形CFRP-钢管-混凝土组合构件的抗侧向冲击性能的研究尚未开展。本项目采用试验研究、数值模拟及理论分析相结合的方法，在建立冲击荷载作用下的钢材、混凝土、CFRP的本构关系及混凝土和工字形CFRP的强度失效准则、刚度退化模型的基础上，研究圆形和方形截面的工字形CFRP-钢管-混凝土组合构件在侧向冲击荷载作用下的受力全过程、耗能机制、损伤破坏模态、临界能量及组合材料的协同工作机制；研究长细比、冲击位置等对构件抗侧向冲击性能的影响，提出两种截面形式的新型组合构件在侧向冲击荷载作用下的承载力公式、设计方法及合理构造措施。为提高建筑物及桥梁的抗撞击能力建立新方法，科学和现实意义显著。

建筑物或桥梁在服役期间可能遭受侧向撞击，导致构件的局部破坏，甚至引起整个结构体系的连续性倒塌。工字形CFRP型材具有质量轻、抗拉、抗压强度高等优点，将其内置于普通钢管混凝土构件中，具有承载力高、自重轻、延性好，抗冲击性能好等优势。.本项目通过试验研究、数值模拟及理论分析相结合的方法对工字形CFRP-钢管-混凝土组合构件抗侧向冲击性能进行了研究。建立了方、圆两种截面形式组合构件中钢管、混凝土和工字形CFRP型材的动态本构关系，强度准则。分析研究表明工字形CFRP-钢管-混凝土组合构件较普通钢管混凝土构件的变形、耗能能力、整体延性有所改善，抗冲击能力更强。. 在此基础上，分析了圆、方两种截面形式的构件在冲击荷载作用下工字形CFRP型材、钢管及混凝土三种材料的相互作用与协同工作机理，深入研究构件受冲击全过程中的能量转换、各组成部分的耗能能力、破坏机制及应力、应变的变化规律等。通过对组合构件在侧向冲击荷载作用下的详细受力全过程分析，构建了侧向冲击荷载下三种材料耗能的神经网络动态分配模型。. 采用有限元方法分析了含钢率、钢材屈服强度、混凝土强度、冲击质量、冲击速度、剪跨比等参数对工字形CFRP-钢管-混凝土组合构件在侧向冲击荷载作用下力学性能的影响。研究结果表明，提高含钢率、钢材屈服强度可有效增加构件抗冲击性能，混凝土强度对构件冲击性能影响不大；冲击质量对峰值位移和冲击持时的影响比较明显；冲击速度对冲击力峰值及冲击处挠度影响较大；剪跨比对冲击力平台值的影响比较显著。.在参数分析的基础上给出设计建议与相应构造措施，即型材抵抗侧向冲击荷载的最佳尺寸为H×W×T =72×82×10mm；对组合构件端部加肋板后，构件的抗变形和抗冲击能力显著提高。. 最终通过试验及有限元分析的大量数据分别给出两种截面形式构件在侧向冲击作用下的极限承载力计算公式与抗冲击设计公式，为实际工程设计提供依据。.该构件具有承载力高、延性好、抗冲击性能好等优势，在国防及各类基础设施中也有广泛的应用前景。