胶合木植筋黏结锚固性能试验研究

对25个胶合木植筋（带肋钢筋）试件进行对拉试验，研究植筋长细比(λ=la/d)及胶层厚度对胶合木植筋的连接承载力及界面黏结性能的影响，并对试件的破坏形态和破坏机理进行分析。为获得胶层界面黏结应力的分布，设计钢筋内贴片试件进行试验。结果表明，试件的破坏形态主要有钢筋拔出、木材环向剪切、木材劈裂、钢筋屈服；植筋连接的拉拔承载力随锚固长度及胶层厚度的增加而增大，当植筋长细比λ达到12.5时，试件发生钢筋屈服破坏，属延性破坏模式；锚固长度与胶层厚度对植筋 木材的黏结性能影响显著，不同锚固长度和胶层厚度的试件，其胶层界面黏结应力分布符合Volkersen(1938)理论，总体上沿锚固长度方向呈两端附近大而中部小趋势；在胶层厚度2~6mm范围内，随着胶层厚度的增加，钢筋-胶层界面与木材-胶层界面平均黏结应力呈不同的变化规律，前者随胶层厚度的增加而增大，而后者随胶层厚度的增加而减小，且胶层厚度的适当增加有利于加载端部的黏结应力峰值的降低。

Experimental study on bond and anchorage behavior of glued-in rebar in glulam

This paper describes an experimental program of 25 glulam specimens with glued-in rebar which aim to investigate the influence of slenderness ratio (λ= la/d)of rebar and glue-line thickness on the pull out load, and bond behavior of glued-in rebar axially loaded parallel to the grain. The failure modes and mechanics of specimens were analyzed. Moreover, in order to obtain the bond stress distribution along the anchorage length of rebar, specimens with strain gauges attached to steel rebar internally were designed. The experimental results show that failure occurs mainly due to pull-out of rebar, shear failure of timber around the glue-line, splitting of timber and yielding of rebar. The pull out load of glued-in rebar increases with the increasing of both the anchorage length and glue-line thickness. The ductile failure of yielding rebar occurs with the slenderness ratio of rebar up to 12.5. Anchorage length and glue-line thickness have obvious influence on the bond behavior of glued-in rebar. The distribution of bond stress at rebar/adhesive interface is not uniform, but rather accentuated near both the loading end and the anchorage end, which confirms the theory of Volkersen(1938). The variation of bond stress at rebar/adhesive interface is different from adhesive/timber interface with the increasing of glue-line thickness. With glue-line thickness increased from 2 mm to 6 mm, bond stress at rebar/adhesive interface increases, while decreases at adhesive/ timber interface. Appropriate increasing of glue-line thickness is beneficial to the decreasing of peak value of bond stress.