大小跨高比落叶松胶合木梁抗弯性能对比研究

Comparative study on flexural behavior of larch glulam beams with large and small span⁃height ratio

为对比大小跨高比落叶松胶合木梁的抗弯性能,对2组6根落叶松胶合木梁进行了四点弯曲试验研究,其中两组试件跨高比分别为20和12。结果表明:大、小跨高比胶合木梁的破坏形式分别为顺纹受拉脆性破坏和顺纹受剪脆性破坏;与大跨高比胶合木梁相比,小跨高比胶合木梁受弯极限承载力相对较高;大跨高比胶合木梁受弯过程中,中性轴位置基本不变;小跨高比胶合木梁受弯过程中,中性轴略有下移。小跨高比胶合木梁抗弯刚度约为大跨高比胶合木梁的3.4倍;大跨高比胶合木梁延性系数约为小跨高比胶合木梁的3.9倍。最后,基于极限应变分析方法,提出了胶合木梁发生受拉和受剪破坏界限跨高比的计算公式,并求得落叶松胶合木梁的界限跨高比为12.62。

In order to compare the flexural behavior of larch glulam beams with large and small span-height ratio,four-point bending tests were carried out on six larch glulam beams in two groups.The span-height ratio of the two groups were 20 and 12,respectively.The results show that the failure modes of glulam beams with large and small span-height ratios are tensile brittle failure along the grain and shear brittle failure along the grain.Compared with the large span-height ratio glulam beam,the small span-height ratio glulam beams has a relatively high ultimate bearing capacity.During the bending process of the large span-height ratio glulam beams,the position of the neutral axis is basically unchanged.In the bending process of small span-height ratio glulam beams,the neutral axis slightly moves down.The bending stiffness of glulam beams with small span-height ratio is about 34 times that of glulam beams with large span-height ratio.The ductility coefficient of glulam beams with large span-height ratio is about 39 times that of glulam beams with small span-height ratio.Finally,based on the ultimate strain analysis method,the calculation formula of the limit span-height ratio of tensile and shear failure of glulam beams was proposed.The limit span-height ratio of larch glulam beam is 1262.