局部屈曲FRP增强薄壁钢管混凝土抗震性能

为了研究FRP(Fiber Reinforced Polymer)增强薄壁钢管混凝土的抗震机理,提出FRP约束钢管局部屈曲应力-应变关系并建立FRP约束钢管恢复力模型,在此基础上建立FRP增强薄壁钢管混凝土柱滞回模型,开展FRP增强薄壁钢管混凝土柱拟静力试验以验证滞回模型的合理性,同时考查FRP布置方式对柱体抗震性能的影响,利用滞回模型对FRP增强薄壁钢管混凝土的耗能机理进行分析。研究表明,薄壁钢管局部屈曲所导致的强度退化是柱体抗震性能劣化的主要原因,基于纤维力学特性合理设计FRP的增强方式可有效提升柱体的抗震性能。CFRP宜采用环向约束方式抑制薄壁钢管的局部屈曲;GFRP宜采用纵向抗弯方式提高柱体大变形下的承载能力。FRP增强薄壁钢管混凝土的耗能主要由钢管承担,在本文研究参数范围内,薄壁钢管耗能占比超过80%,混凝土耗能介于10%～20%,纵向FRP耗能小于8%,对薄壁钢管实施有效约束后,其耗能可提高40%以上。

Seismic performance of locally buckled FRP reinforced concrete filled thin-walled steel tube

For investigating the seismic mechanism of FRP(Fiber Reinforced Polymer)reinforced concrete filled thin-walled steel tube,a stress-strain relationship and a restoring force models of FRP confining steel tube with local buckling were proposed.A hysteretic model for FRP reinforced concrete filled thin-walled steel tube was developed eventually.A quasi-static test was carried out to verify the reasonability of the proposed hysteretic model and study the influence of FRP reinforced scheme on the seismic performance of FRP reinforcing concrete filled thin-walled steel tube column.The studies revealed that the strength degradation caused by local buckling of thin-walled steel tube is the main reason for the deterioration of seismic performance of the column.Rational design of FRP layouts according to the mechanical property of the fiber can effectively improve the seismic performance of the composite column.The CFRP is fit for restraining the local buckling of the thin-walled steel tube,while the GFRP is fit for improving the loading capacity of the column.The imported energy of the column is mainly dissipated by the thin-walled steel tube.In the parameter range of this research,the energy dissipation proportion of the steel tube,the concrete core and the longitudinal FRP are larger than 80%,ranged from 10% to 20% and less than 8%,respectively.The energy dissipation of the steel tube can be improved by more than 40% after being constrained effectively.