木屋架选材,一般说来,以树干长、纹理直、木节少、扭纹少、能耐腐蚀虫蛀、易干燥、少开裂、力学性能好和便于加工为最好。其标准就是应符合国家对木材缺陷的允许程度和等级范围的各项规定,严格遵守木材的质量标准。但是,树木是天然生长的,不可避免地会有大小头、顺纹横纹和木节等弊病,这些弊病都对木材的力学性能有影响,因此,根据屋架的受力特点,扬优避劣,木尽其用,显得非常重要。 Generally speaking, the selection of timber truss roofs is best with long trunks, straight texture, few knots, less twist lines, corrosion resistance, easy drying, less cracking, better mechanical properties, and easier processing. Its standard is to comply with various provisions of the state’s allowable degree and range of wood defects, and strictly abide by the quality standards of wood. However, trees are naturally grown. Inevitably, there are shortcomings such as size heads, horizontal stripes, and knots. These drawbacks all affect the mechanical properties of wood. Therefore, according to the characteristics of the roof trusses, the advantages of the roof are avoided. It is very important for wood to make the best use of it.