Abstract This paper identified a reliable testing method for determining the shear strength of bond lines between concrete and engineered wood. The identification was carried out based on analytical derivations and experimental tests on concrete (compressive strength of 24.8 MPa) and engineered wood composite connections glued by two types of epoxy. Forty specimens were tested under two commonly used test setups, i.e. 20 double-shear tests on timber-concrete composite specimens with a bond length of 50 mm and another 20 compression-shear tests on specimens with a bond length of 300 mm. The result analysis showed that there was no significant statistical difference between the shear strength of the bond lines (around 2.3 MPa) as well as between the failure modes obtained (dominated by concrete failure), regardless of the considered bond lengths and adhesive types investigated. The analysis used a quasi-non-linear fracture mechanics model, considering the boundary conditions of the tests. The analytical model revealed that the ultimate shear stress is approximately uniformly distributed both in the double-shear and in the compression-shear tests, so the spatially averaged shear stress value can approximate the critical shear stress of the bond line with sufficient accuracy. However, if the failure occurred in the wood or the strength of the concrete was higher, the shear stress distribution at ultimate load in the compression-shear tests with a bond length of 300 mm would not be uniform. The maximum shear stress value, which is significantly larger than the average one, occurred at the fixed (or supporting) end of the bond line. Even so, in the shear tests with a bond length of 50 mm, the average ultimate shear stress value was still close to the shear strength with a difference smaller than 5%. Hence, a bond length of 50 mm is recommended for determining the shear strength of a bond line between normal strength concrete and engineered wood when using a push-out shear test setup.

中文翻译：

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混凝土与不同类型工程木材之间粘结层剪切强度的试验方法

摘要 本文确定了一种可靠的测试方法，用于确定混凝土和工程木材之间的粘合层的剪切强度。该鉴定是基于对混凝土（抗压强度为 24.8 MPa）和由两种环氧树脂胶合的工程木复合连接件的分析推导和实验测试进行的。40 个试样在两种常用的测试设置下进行了测试，即对粘结长度为 50 毫米的木材-混凝土复合试样进行 20 次双剪切试验，对粘结长度为 300 毫米的试样进行另外 20 次压缩剪切试验。结果分析表明，结合层的剪切强度（约2.3 MPa）以及获得的破坏模式（以混凝土破坏为主）之间没有显着的统计差异，无论所考虑的粘合长度和粘合剂类型如何。考虑到测试的边界条件，分析使用了准非线性断裂力学模型。分析模型表明，在双剪和压剪试验中，极限剪应力近似均匀分布，因此空间平均剪应力值可以足够准确地近似胶层的临界剪应力。但是，如果破坏发生在木材或混凝土的强度较高，则在粘合长度为300 mm的压剪试验中，极限载荷下的剪应力分布将不均匀。最大剪切应力值明显大于平均剪切应力值，出现在粘合线的固定（或支撑）端。尽管如此，在粘结长度为50 mm的剪切试验中，平均极限剪切应力值仍与剪切强度接近，相差小于5%。因此，当使用推出剪切测试装置时，建议使用 50 毫米的粘合长度来确定普通强度混凝土和工程木材之间粘合线的剪切强度。