考虑爆裂影响的轴向约束高强混凝土柱耐火性能研究

应用有限元软件ABAQUS,基于一次爆裂模式,建立了轴向约束高强混凝土（HSC）柱的抗火分析模型.采用试验数据验证了模型的合理性.采用验证后的模型,分析了不同轴向约束刚度比下高强混凝土柱轴力及位移变化的规律,重点考虑了爆裂深度、爆裂长度、爆裂开始时间等爆裂参数对高强混凝土柱轴向位移、截面温度场和耐火极限的影响规律.研究表明：相同爆裂时间前提下,HSC柱轴向位移随爆裂深度、爆裂长度的增大而增大,耐火极限随之减小.爆裂深度、爆裂长度相同前提下,爆裂开始时间对HSC柱的耐火性能影响很小.当荷载比不变时,轴向约束刚度比对HSC柱膨胀阶段的最大轴向位移影响甚小,但是在越过初始平衡位置的收缩阶段对轴向位移影响很大.轴向约束刚度比对轴向约束HSC柱的耐火极限影响不大.

Fire performance of axially restrained HSC columns including spalling effect

Tbe finite element software ABAQUS was used to study the fire performance of axially restrained High Strength Concrete （HSC） columns including a concentrated spalling. Test results were used to verify the model. The validated model was then used to analyze the change of the axial force and axial deformation of HSC columns with a different axial restraint stiffness ratio. The concentrated spalling time, the length and the depth of spalling were greatly considered as the influence roles on the temperature field, axial deformation and fire resistance of the HSC columns. It is found that, on the condition of keeping spalling time invariable, the fire resistance of HSC columns reduces significantly with the increase of depth and the length of spalling. At the same time, the increase of the length and the depth of spalling leads to a rise of axial deformation. The concentrated spalling time seems to have little effect on fire performance of HSC columns. For a given load ratio, axial restraint stiffness ratios have little effect on the maximum deformations during expansion. Once the displacement goes back to initial state, the axial deformations during the contraction phase are mostly influenced by axial restraint stiffness ratios. The fire resistance keeps invariable with an increase of axial restraint stiffness ratio for HSC columns under the same load ratio.