基于 ABAQUS 的震损后型钢混凝土空间节点耐火性能有限元分析

震后火灾下引起的建筑结构响应与普通火灾并不相同, 其力学性能变得更加复杂, 破坏的时间、模态也会有所改变, 为研究型钢混凝土(steel reinforced concrete, SRC)空间节点在震损后的耐火性能变化, 文章基于ABAQUS有限软件, 对节点进行往复加载模拟地震作用, 选取合理损伤指数建立不同损伤程度的SRC空间节点在2种火灾工况下的耐火极限模型并进行分析。结果表明: 损伤程度大小对节点破坏模态影响较小, 不同损伤程度下2种火灾工况的SRC空间梁柱节点均有柱破坏达到耐火极限破坏, 节点耐火极限整体变化趋势与损伤程度呈负相关, 损伤程度越大, 耐火极限下降越多, 当加载幅值接近极限位移时, 工况1、工况2耐火极限下降到34.90%、57.00%, 此时工况2损伤节点的耐火极限衰减为未损伤节点的1/2; 在接近节点破坏时, 工况2节点的耐火极限下降幅值接近工况1的2倍。

The structural response of buildings under post-earthquake fires(PEF) differs from that under ordinary fire, with the mechanical properties becoming more complex, and the timing and modes of failure being changed. In order to study the changes of fire resistance of steel reinforced concrete(SRC) spatial nodes after earthquake damage, the ABAQUS finite software is employed to simulate the seismic action through the reciprocal loading of the nodes. A reasonable damage index is selected, and the fire resistance limit model of SRC spatial nodes with varying degrees of damage under two fire scenarios is established and analyzed. The results show that the degree of the damage has a small impact on the failure modes of the nodes, and under the two fire scenarios, the SRC spatial beam-column nodes with varying degrees of damage exhibit column failure reaching the fire resistance limit, and the overall change trend of the fire resistance limit of the nodes is negatively correlated with the degree of damage, the greater the degree of damage, the more the fire resistance limit decreases. When the loading amplitude is close to the ultimate displacement, the fire resistance limits of Scenario 1 and Scenario 2 decrease to 34.90% and 57.00%, respectively. At this point, the fire resistance limit of the damaged nodes of Scenario 2 decays to half of the undamaged nodes. When approaching the node failure, the fire resistance limit of the nodes of Scenario 2 decreases by nearly two times that of Scenario 1.