火灾下钢筋混凝土梁非线性有限元分析

为分析钢筋混凝土梁在火灾过程中的温度分布、结构变形非线性变化过程,在三组不同条件下对火灾后钢筋混凝土梁构件内部传热及变形过程进行全过程仿真。基于钢筋混凝土热工特性、温度-应变-应力本构特性,分析钢筋混凝土梁在受火时的温度分布演化过程,以及配筋率、初始载荷和受火时间等参数对钢筋混凝土梁防火承载力的影响。结果表明:火灾中材料强度的降低,自重和初始载荷以及不均匀升温引起的内部应力共同作用引起了构件的整体失稳。初始载荷对梁剩余承载力的影响不大,提高混凝土中钢筋数量能有效地提高钢筋混凝土梁的防火承载力。

NONLINEAR FINITE ELEMENT ANALYSIS OF REINFORCED CONCRETE BEAMS IN FIRE

Through numerical simulation of the whole process of heat transfer and deformation on three different conditions groups of reinfored concrete beams,it is analysed the non-linear changing process of the temperature distribution and structural deformation of reinfored concrete beams in fire.Based on thermal characteristics and the temperature-strain-stress constitutive characteristics of reinforced concrete beams it is analysied the influences of the evolutionary processes of the reinfored concrete beams temperature distribution in fire,as well as reinforcement ratio,initial load and heating time on the fire resistance capacity of reinfored concrete beams.Results show that the overall instability of the beams is caused by the reduction of material strength,weight and the initial load,as well as the internal stress because of the uneven heating in fire.The influences of initial load on the residual bearing capacity is little,but increase the number of rebars can effectively improve the fire resistance capacity of reinforced concrete beams.