残损木柱受力性能退化试验研究与有限元分析

梁、柱等构件存在腐朽等局部残损是现存古建筑木结构的普遍状况，其显著地降低了木结构受力性能。为研究残损木柱受力性能退化规律，采用局部去除腐朽木材的方法模拟木柱上的局部残损，对4根不同残损程度的矩形木柱进行了轴心受压试验，得到了残损木柱的荷载-侧移、荷载-应变关系曲线，分析了残损木柱的破坏模式、承载力及刚度退化规律。试验结果表明，随着残损程度增加，残损木柱逐渐由轴压破坏变为偏压破坏，受压承载力显著降低。采用ABAQUS有限元软件对4种不同残损程度的木柱受压性能进行了模拟分析，模拟结果与试验结果吻合较好。在此基础上，分析了残损区域深度、长度等因素对木柱受力性能退化的影响规律。分析结果表明：随着损伤区域深度的增大，承载力降低幅值随之增大；随着损伤区域长度的增大，承载力降低趋于缓和。

Experimental study and finite element analysis on degradation of mechanical properties of damaged timber columns

Local damage of decayed beams and columns is a common condition of existing ancient timber buildings, which significantly reduces the mechanical properties of timber structures. In order to study the degradation law on the mechanical properties of damaged timber columns, the local damage on the timber column was simulated by local removal of the rotten timber. The axial compression test on four rectangular timber columns with different damage degrees were carried out. The behaviors of the damaged timber columns, such as the load-lateral displacement and load-strain curves, were obtained. The failure mode, degradation laws of the bearing capacity and stiffness of the damaged timber columns were analyzed. The experimental results show that the compressive bearing capacity decreases significantly with the increase of the damage degree, and the failure mode is gradually converted from axial compression failure to eccentric compression failure. Three-dimensional finite element models were developed by the commercial software ABAQUS to simulate and analyze the compressive properties of the four timber columns. The results from the numerical simulation are in good agreement with the test results. Based on the above analysis, the influences of the depth and length of the damaged area on the mechanical degradation properties of the timber column were analyzed. The results show that as the depth of the damaged area increases, the magnitude of the reduction in bearing capacity increases. As the length of the damaged area increases, the reduction in bearing capacity tends to be less significant. The research results can provide important guidance for damage assessment and protection of existing historic timber structures.