高性能混凝土框架火灾后抗震性能试验研究

对3榀火灾后和1榀未受火的高性能混凝土单层单跨框架进行了低周反复加载下的抗震性能试验研究,分析了高温火灾、混凝土强度等级对高性能混凝土框架结构破坏机制、承载力、滞回特性、延性、刚度以及耗能的影响规律,建立了相应的恢复力模型,并探讨了聚丙烯纤维(PPF)对这些性能的影响。研究表明,火灾后高性能混凝土框架结构易出现“强梁弱柱”,承载力、刚度及耗能均明显下降,仅延性有所提高,总体上抗震性能下降。混凝土强度等级低者火灾后框架结构抗震性能更低,而聚丙烯纤维对火灾后高性能混凝土框架结构抗震性能的影响需结合多种有利因素和不利因素综合考虑。

AN EXPERIMENTAL STUDY ON THE SEISMIC BEHAVIOR OF HPC FRAMES AFTER FIRE

Based on an experimental study on the seismic behavior of three single-span and single-storey HPC frames after fire and one such frame at ambient temperature,the effects of fire and HPC strength grade on the failure mechanism,bearing capacity,hysteresis property,ductililty,stiffness and energy dissipation of HPC frames are discussed,the recovery-force models are established,and the effects of the polypropylene fiber (PPF)on these characteristics are also investigated.The results show that a HPC frame structure after fire is easily changed into a strong-beam and weak-column structure,and the bearing capacity,stiffness and energy dissipation decrease greatly except for ductility.The seismic behavior of frame made of HPC with lower strength is even worse.The addition of polypropylene fiber brings both virtues and weaknesses to the seismic behavior of HPC frames after fire.