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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 concept of damage field, the influence of damage on material elasticity and plasticity is considered. The temperature distribution of the section is calculated, the relative isotherms are calculated, and the actual width of each section is reduced according to the damage variable (temperature function) , The corresponding equivalent cross-section is obtained, and then the ultimate load of the component can be calculated according to the equivalent cross-section of the strength at room temperature.A large number of experiments have proved that the destruction of frame structure under high temperature (fire) is the same as that at room temperature, And their adjacent sections form plastic hinges successively to form a flexible system of degrees of freedom and destroy. Therefore, the ultimate load is obtained by the mechanism superposition method in traditional structural mechanics. The feasibility of this method is verified by single-layer and two-span model tests.