摘要
为利用无损检测评估木框架受火后剩余承载力,进行了两榀梁柱式木框架受火试验、阻抗仪无损检测试验以及火灾后剩余承载力试验研究,了解不同受火时间下木框架炭化速度、破坏形态和剩余承载力的变化规律,并采用ABAQUS软件对受火后木框架进行数值模拟分析,验证其极限承载力及破坏规律。研究结果表明:受火后木框架构件梁柱炭化速度相差不大,其炭化速度随受火时间的增大而减小;受火后木材材性参数与阻抗值存在一定的线性回归关系;考虑小试件强度转化为构件强度的影响因素后,受火后木框架构件材性参数亦可通过阻抗值获得;受火后木框架极限承载力明显降低,最终为梁跨中底部拉裂破坏;结合无损检测手段获得的受火后木框架构件材性参数,进行有限元模拟的结果与试验吻合,因此采用无损检测对受火后木框架剩余承载力评估是可行的。
In order to evaluate the residual bearing capacity of post-beam timber frame after exposure to fire by using non-destructive tests( NDT),the fire resistance tests,the multi-point resistograph tests and residual bearing capacity tests of two post-beam timber frames were carried out to study the variation rules of charring rate,failure modes,and the residual bearing capacity under different time of fire exposure. The finite element software,ABAQUS,is used to analyze the bearing capacity and failure modes of post-and-beam frame,based on the wood properties by NDT. The results show that the charring rates of the wood beam is similar to that of the wood column and the charring rate decreases with the increase of exposure time to fire. There is a certain linear regression relationship between the drill resistance values and the wood properties after exposure to fire. Considering the differences between small timber specimens and realistic wood members,the performance parameter of the wood members after fire can be obtained by the drill resistance value. The ultimate bearing capacity of the post-beam timber frame after fire is obviously reduced and finally the results of the finite element simulation are in good agreement with the experimental results. So it is feasible to use the non-destructive testing to evaluate the residual bearing capacity of post-beam timber frame after fire.
引文
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