制作了4组带有不同深度纵向干缩裂缝的木梁进行三分点加载试验，观察试验现象并记录极限承载力。根据试验现象，结合有限元应力分析和木材双折线顺纹本构模型，推导出木梁由受弯破坏变为顺纹剪切破坏的裂缝临界指标，以及相应的极限承载力计算公式，并将推导所得承载力公式归纳简化成承载力下降系数曲线。将试验数据代入后，发现试验现象符合临界指标的判定，且根据承载力下降系数曲线得到的极限承载力理论值与试验值相符。

Firstly, four groups of timber beams with shrinkage cracks in diversified depth were made and one-third loading method to observe the experimental data and record the ultimate bearing capacity was carried out. Then, according to the experimental data, combining finite element stress analysis, and the model of bilinear constitutive model of wood, the critical indicators which indicated that bending failure become shear failure and the corresponding ultimate bearing capacity formula were deduced. After that, the bearing capacity formula was simplified as the bearing capacity reduction coefficient curve. Finally, by comparing theoretical analysis with experiment, the results show that the theoretical values of ultimate bearing capacity coincide well with the test values, and the test phenomenon is consistent with the judgement of the critical indicator.

TU266.2

“十二五”国家科技支撑计划（2012BAJ14B02）