CFRP加固火灾作用后圆钢管混凝土构件的侧向撞击性能研究

建立了火灾作用后和碳纤维增强复合材料(CFRP)加固受火后圆钢管混凝土构件的侧向撞击数值模型，通过不同试验分别验证了模型的准确性。分析了加固受火后构件的撞击全过程，对比了构件的撞击力、跨中挠度和截面弯矩。对构件的抗撞击承载力和抗弯承载力，塑性变形和吸能能力，以及内力分布与发展进行了分析，并给出构件在撞击荷载作用下跨中最大挠度简化计算公式，最后讨论了CFRP加固方式对受火后构件撞击性能的影响。结果表明:采用CFRP加固受火后构件的撞击力平台值和平均截面弯矩提高，跨中挠度和撞击持续时间明显减小，CFRP加固对构件的抗撞击性能和抗弯能力提升显著；构件的抗撞击承载力、抗弯承载力和吸能能力随着受火时间的增加逐渐降低；构件在跨中产生不同程度的塑性变形，其主要通过形成塑性铰吸收能量；在峰值阶段构件的弯矩和剪力分布形态与相应静态荷载作用时差异明显，但在平台阶段时其分布形态与静态荷载作用时一致；简化计算公式可以很好地计算构件撞击后的跨中最大挠度，CFRP加固方式对受火后构件的抗撞击性能影响明显。

LATERAL IMPACT BEHAVIOR OF CFRP-REINFORCED CIRCULAR CONCRETE-FILLED STEEL TUBULAR MEMBERS AFTER EXPOSURE TO FIRE

The numerical model for the lateral impact of circular concrete-filled steel tubular (CFST) members after exposure to fire with and without carbon fiber reinforced polymer (CFRP) is established. The accuracy of the model is verified by different experiments. The whole impact process of reinforced post-fire members is analyzed. The impact force, mid-span deflection and sectional moment of the specimens are compared. In addition, the impact resistance and flexural capacity, plastic deformation and energy absorption capacity, as well as the distribution and development of the internal force are investigated. A simplified calculation formula for the maximum mid-span deflection of the specimens under impact load is proposed. The influence of CFRP reinforcement methods on the impact performance of the post-fire specimens is discussed. The results show that the plateau value of the impact force and the average sectional moment of post-fire specimens were increased by the CFRP reinforcement. However, the mid-span deflection and impact duration were significantly reduced. The impact resistance and flexural capacity of the specimens were significantly improved by the CFRP reinforcement. The impact resistance, flexural capacity and energy absorption capacity gradually decrease with the increase of the fire duration. In addition, the specimens experienced different degrees of plastic deformation at the span, and the energy was mainly absorbed by the formation of plastic hinges. The bending moment and shear force distributions of the specimens under lateral impact at the peak stage were different from those of the specimens under static load, but the distributions at the plateau stage were consistent with those of the specimens under static load. The simplified formula can well predict the maximum deflection of the specimens after lateral impact. The CFRP reinforcement methods have a noticeable influence on the impact resistance of post-fire members.