钢结构构件高温极限承载力实用计算方法

Practical calculation methods for ultimate bearing capacity of members of steel structures under high temperature

利用损伤场概念,考虑损伤对材料弹性、塑性的影响,通过对已确定的截面温度分布,计算相关等温线位置,将各温度区段的截面实有宽度按损伤变量(温度函数)加以折减,得到相应等效截面,此后对构件的极限荷载就可按常温下强度的等效截面进行计算.大量实验已证明框架结构在高温(火灾)下的破坏和常温下一样,是由于若干临界截面及其附近区段相继形成塑性铰,构成一个自由度的可变体系而破坏,因此利用传统结构力学中机构叠加法求得极限荷载,并通过单层两跨模型试验验证该方法的可行性.

Based on the damage field and its impact on the material mechanical features,and the calculated isotherms of a definite section,the effective area can be acquired after the reduction of the actual width of the area in every temperature zone according to the damage parameter（function of temperature）;then the ultimate bearing capacity can be calculated based on effective area as the structure under room temperature.A lot of experiments have shown that steel frame structures under high temperature will collapse as under room temperature for that several critical sections and their neighbor critical zone will gradually form plastic hinges.The superposition method is used for the calculation of ultimate bearing capacity.Finally,the method is certified by a one layer two spans model.