受火后型钢混凝土框架结构抗震性能研究

Post-fire seismic performance of steel reinforced concrete frame structures

为了给受火后型钢混凝土框架结构的性能评估及修复加固提供方法,进行了火灾后型钢混凝土框架结构的抗震性能研究。在ABAQUS平台上,采用梁单元,同时通过编制材料子程序和场变量子程序,建立了可进行型钢混凝土框架结构火灾升降温作用下的力学性能及受火后抗震性能分析的计算模型。利用该计算模型对火灾升降温作用下型钢混凝土框架结构的变形及内力进行了分析。同时,考虑起火层位置、受火时间等参数的影响,采用考虑升降温的火灾后静力非线性分析方法和动力弹塑性时程分析方法,对火灾后型钢混凝土框架结构的破坏形态、地震作用后结构承载能力、变形特征等抗震性能进行了参数分析。分析表明,火灾升降温过程中,由于结构升温的滞后性,构件的变形增长及恢复也滞后于火灾空气升降温过程,受火后构件有残余变形;针对火灾发生在某一层的火灾工况,受火后框架承受水平地震(静力)作用时,框架破坏机构出现在底部3~5层;当受火层位于底层时,受火后框架的水平地震作用后结构承载能力降低幅度最大,受火时间为180、300 min时降幅分别为8%、9%;受火层位置越低,框架顶部位移越大;随受火时间增加,框架顶部位移增大。

In order to provide the method for the evaluation and retrofitting of steel reinforced concrete（SRC） frame structures which have undergone fire,the post-fire seismic performance of steel reinforced concrete frame structures was studied. A finite element（FE） model for the fire performance and the post-fire seismic performance of the SRC frame structures was proposed by using beam elements,a user material subroutine and a user field subroutine based on ABAQUS. The deformation and internal force of the SRC frame structure during fire was first analyzed by using the FE model. Then,a systematically parametric analysis of the post-fire seismic performance including the collapse mode,earthquake load carrying capacity,and displacement of the SRC frame,was carried out by using a post-fire static nonlinear analysis and a post-fire dynamically elasto-plastic time history analysis. The analysis considered the effects of temperature increase and decrease with the FE model,and the parameters include the fire location floor and the fire duration. The analysis results show that the deformation changes later than the temperature changes because the temperature in the member changes slower than the fire temperature,and a residual deformation occurs after fire. A collapse mechanism will appear in the first 3-5 floors of the SRC frame. When the fire occurs in the first floor instead of other floors,the post-fire horizontal earthquake load carrying capacity of the SRC frame is the smallest. When the fire duration is 180 min and 300 min,the load carrying capacity of the frame is reduced 8% and 9%,respectively. The frame top displacement increases when the fire location floor decreases and the heating time increases.