火灾后方钢管混凝土侧向力-位移曲线的理论分析

Analysis of lateral resisting behavior of concrete filled square steel tube frame column after fire

给出了方钢管混凝土构件遭受火灾后的材料本构关系 ,及侧向力 -位移关系曲线的数值计算方法 .算例分析表明 ,钢管混凝土结构遭受火灾后 ,其承载力大大降低 ,随着火温的升高 ,混凝土的弹性刚度降低 ,抗压强度极限降低 ;钢材的屈服点降低 .但温度对弹性阶段的应力影响不大 ,随温度的升高 ,钢管对混凝土的约束性能越明显 .

Cinstitutive relationship of steel and concrete in concrete filled square steel tube, which is subjected to fire, is put forward in this paper. A kind of numerical method used to analyze the P-Δ curve is presented. From the analyses, we can draw conclusions as follows: Load bearing capacity of CFST after fire will decrease greatly. Elastic stiffness and ultimate compress strength of concrete will decrease with the fire temperature increas. Temperature has little effect on stress in the elastic stage. Constraint behavior of steel to concrete is more and more distinct with the temperature increase.