Fire resistance and thermal stability are among the most important criteria for engineered wood product applications in mass-timber buildings. This project investigated the shear strength of mass timber adhesively bonded joints at high temperatures. Shear tests were conduct on specimens made of Douglas-Fir Glued-laminated Timber and a steel plate glued in with a one component polyurethane adhesive.

The results indicate that the shear strength of the adhesive was affected by temperature. Between 20 °C and 75 °C, the shear strength of the joints decreased with increasing temperature. Above 75 °C, the strength of the adhesive became constant at less than half that at 20 °C. Therefore, it is recommended that if the polyurethane adhesive is used for glulam-steel plate structures above 75 °C, the design strength should be only about 40% of the design strength at room temperature.

耐火性和热稳定性是大型木结构建筑中工程木产品应用的最重要标准之一。该项目研究了大块木材粘合接头在高温下的剪切强度。对由道格拉斯冷杉胶合层压木材和用单组分聚氨酯粘合剂粘合的钢板制成的试样进行剪切试验。

结果表明，粘合剂的剪切强度受温度的影响。在 20°C 和 75°C 之间，接头的剪切强度随着温度的升高而降低。高于 75 °C 时，粘合剂的强度变得恒定，低于 20 °C 时的一半。因此，建议75℃以上胶合钢板结构使用聚氨酯胶粘剂时，其设计强度应仅为室温下设计强度的40%左右。