日本落叶松正交胶合木抗弯性能研究

Bending properties of cross-laminated timber fabricated with Larix kaempferi

【目的】探究日本落叶松正交胶合木(cross-laminated timber,CLT)抗弯性能的影响因素,为CLT在木结构建筑中的应用提供基础数据。【方法】以产自辽宁清原的日本落叶松锯材为供试材料,依据层板弹性模量(>8～<12GPa(低)、≥12～≤16GPa(中)、>16GPa(高))、层数(3层和5层)、层板厚度(15和25mm)、组坯方向(正交和斜45°)的不同共设置6种组坯方式,基于美国标准ANSI/APA PRG320-2012测试6组CLT的抗弯弹性模量和抗弯强度,以考察CLT抗弯性能的影响因素;根据机械连接理论、复合层板理论、剪力类比理论和简单设计法推算CLT的等效抗弯刚度和抗弯弯矩,通过实测值验证理论预测值的精确性,筛选适宜的预测方法。【结果】层板模量和层数对日本落叶松CLT的抗弯弹性模量、抗弯强度影响显著,但锯材厚度和组坯方向对CLT的抗弯弹性模量、抗弯强度影响不显著;采用剪力类比理论、简单设计法分别计算的等效抗弯刚度值和抗弯弯矩值更加接近实测值,相对误差分别在5.0%和6.5%内。【结论】采用日本落叶松锯材制备的CLT具有较好的抗弯性能,利用理论模型能够很好地预测CLT的等效抗弯刚度和抗弯弯矩。

【Objective】The influence factors of bending properties of cross-laminated timber(CLT)fabricated with Larix kaempferi were studied to provide data for application of CLT in wood structure construction.【Method】L.kaempferi were collected from Qingyuan,Liaoning and six layup methods were setup based on plate modulus(>8-<12 GPa(low),≥12-≤16 GPa(middle),and>16 GPa(high)),number of layers(three and five layers),thickness of timber(15 and 25 mm),and layup direction(orthogonal and inclined 45 degrees).According to ANSI/APA PRG320-2012,the bending modulus and strength of six different types of CLT were tested.The effective bending stiffness and moment bending resistance of CLT were calculated based on the mechanically jointed beams theory,composite theory,shear analogy theory,and simplified design method.The accuracy of the theoretical model was verified by the experimental values to select suitable perdition methods.【Result】The modulus of outer layer and number of layers had significant influence on the bending modulus and strength of CLT,but the thickness of timber and direction of layup had no significant influence.The effective bending stiffness and the moment bending resistance values calculated by the shear analogy method and the simple design method were closer to the tested values with relative errors of 5.0%and 6.5%,respectively.【Conclusion】CLT fabricated with L.kaempferi had better bending properties.The effective bending stiffness and moment bending resistance of CLT could be well predicted by theoretical models.