离心钢管混凝土短柱火灾下与火灾后的极限承载力

Analysis on resistance on and after exposure to standard fire of short centrifuge concrete-filled steel tubular colunms

针对离心钢管混凝土结构抗火设计、火灾中受损评价以及修复等有关问题,通过对钢材与混凝土高温下与高温后的应力-应变关系的分析,建立了离心钢管混凝土短柱四面均匀受火及其火灾后的有限元分析计算模型,进行了火灾下与火灾后荷载-变形关系曲线全过程分析,结合离心钢管混凝土结构的常温极限承载力表达式,提出了ISO-384标准升温曲线作用下和作用火灾后轴压构件的极限承载力简化计算公式.研究表明,短柱在火灾下与火灾后的极限承载力随升温时间的增加而剧减,承载力与温度场的分布基本上成线性关系.

To solve the problems such as fire resistance design, assessment and repair after fire for centrifuge concrete-filled steel tubular （CCFT） columns, based on analysis on stress-strain relationships of steel and concrete in fire environments and after high temperatures, a finite element model for calculating fire resistance and residual strength of CCFT columns was established. The behaviors of short CCFT columns during the whole period of fire were carried out by considering the fire damage on the strength and displacement of the steel and concrete at every time step. Combined with capacity formula under normal temperature, together with ISO-384 Standard, which contained the standard temperature rise curve, a simplified capacity formula of CCFT on and after fire was put forward. The study concluded that the capacity of CCFT decreased sharply with the increase of fire time and the capacity was almost directly proportional to the temperature distribution.