锯材/单板层积材混合正交胶合木力学性能研究

Mechanical performances of hybrid cross laminated timber fabricated by lumber/laminated veneer lumber

为改善正交胶合木(Cross laminated lumber,CLT)的力学性能,将加拿大云杉-松-冷杉规格材和单板层积材按照不同结构进行混合组坯,形成3种不同结构的混合结构CLT,并对CLT试件进行弯曲和剪切力学性能测试,观察试件破坏形式。试验结果表明,芯层(横向层)剪切破坏是CLT梁试件弯曲破坏的主要、关键形式,单板层积材(Laminated Veneer Lumber,LVL)显示了较低的横纹剪切性能;将LVL置于表层,能较大地改善CLT材料的力学性能,其顺纹抗弯弹性模量比普通结构CLT值提高17.6%,将LVL置于芯层(横向层),SPF作为表层形成的混合CLT材料力学性能低于普通结构CLT性能。

Hybrid cross laminated timber （HCLT） was fabricated using lumber（Spruce-pine-fir, SPF） and/or laminated veneer lumber （LVL）, the mechanical performances of which were evaluated. Three types of CLT panels, one generic CLT （used as control） and two types HCLT were fabricated. The failure modes of each kind of specimens were visually examined and recorded. The properties measured included the bending properties （in the major direction） and planar shear properties （in both major and minor directions）. It was found that the planar shear failure of cross layer was the key and primary failure mode of CLT and HCLT in bending test. Lumber and LVL had different direction of crack propagation in planar shear, and LVL had lower planar shear properties than SPF lumber. The HCLT having LVL as the outer layer has the highest bending and shear properties, The modulus of elasticity （MOE） of the HCLT having LVL as the outer layer and lumber as the cross layer was 17.6% higher than that of generic CLT. However, the HCLT having lumber as the outer layer and LVL as the cross layer had the lowest mechanical properties.