木质工字梁翼缘和腹板梯形槽接口的垂向承载能力

Vertical Bearing Capacity of the Trapezoidal Flange-Web Joint of Wood I-Beam

对不同槽深的木质工字梁（IJ）翼缘、腹板梯形槽接口的垂向承载能力作检测分析，结果表明：接口抗压破坏可分为先期破坏和终极破坏，先期破坏以翼缘与腹板胶合层的剪切破坏或翼缘槽底的横纹拉伸破坏为主，终极破坏包括了胶合层剪切、翼缘木材横纹拉伸和压缩破坏的最终综合性全面破坏，终极破坏荷载大于先期破坏；接口槽深的设计应避免发生先期破坏；接口破坏形式反映了翼缘材料的性能、接13的胶合性能和垂向承压能力。研究指出：以国标（GB／T20241-2006）90E型LVL为翼缘、以林业行标（LY／T1580-2000）OSB／3型大片定向刨花板为腹板，槽深为9～15mm的IJ可以满足我国和美国标准对接口垂向承压能力的要求，其中以12mm糟深为最佳。

The vertical bearing capacity of the flange-web joint of wood I-joist （IJ）with different groove depths was tested. Tile results showed that there were two types of failure to the joint, i.e. , the pre-failure and the final failure. The pre-failure included either shear failure of the glue line between the flange and web or tensile failure perpendicular to the grain of the flange wood at the groove bottom, whereas the final failure was a complete failure including not only the shearing and tensile failure but also the compression failure perpendicular to the grain of the flange wood ; and the bearing capacity against the final failure was stronger than that of the pre-failure. The results also indicated that the groove depth of the trapezoidal flange-web joint should be designed to avoid pre-failure, the failure appearances reflected the mechanical properties of the flange and the glue line and the vertical bearing ca- pacity of the joint. As a conclusion, this paper pointed out that the vertical bearing capacity of the IJ made of the 90 E LVL as a flange and web grade 30SB as a web, whose mechanical properties were complied with the 90E LVL of Chinese Standard GB/T 20241--2006 and the OSB/3 of Chinese Forestry Standard LY/T 1580--2000 re- spectively, could meet the requirement by USA Standard PRI 400, with the groove depth 9 -15 mm even though 12 mm was the best.