重组竹力学性能及设计强度取值研究

竹材为快速可再生材料，性能优越，用于建筑领域可提高长期固碳能力、增加经济附加值，且建筑业迫切需要寻找再生资源降低对环境的影响。通过试验研究浙江省4～5年生毛竹枝下材制成的重组竹顺纹抗拉、顺纹抗剪、抗弯强度、抗弯弹性模量及其破坏模式，参照《木结构设计手册》分析其设计值，并将其与常见建筑材料进行对比。结果表明，顺纹抗拉强度设计值为16.3 MPa，抗拉破坏属于脆性破坏，破坏模式有3种:受拉纤维拉断、锯齿状界面剪切破坏、纤维拉断和界面剪切破坏同时发生；顺纹抗剪强度设计值为3.69 MPa，抗剪破坏属于脆性破坏，破坏模式为纤维界面的剪切破坏；抗弯强度设计值和抗弯弹性模量分别为33.8 MPa和8.3 GPa，抗弯破坏属于塑性破坏，破坏模式为受拉纤维先拉断、受压纤维后压溃破坏。重组竹可作为建筑结构主体受力材料使用，但须适当提高抗压和抗剪安全系数，用作受弯构件时以挠度控制较为准确。

Mechanical Properties and Strength Design Value of Bamboo Scrimber

Bamboo timber is a fast growing and renewable material with superior performance.It can improve long-term carbon sequestration capacity and increase economic added value when it is used in the construction field.The construction industry urgently needs to find out renewable resources to reduce the negative impact on the environment.This paper experimentally studied the tensile strength,shear strength,flexural strength,flexural elastic modulus and failure mode of the bamboo scrimber made from 4-to 5-year-old bamboo timber from Zhejiang Province.The design values were analyzed with the reference of "Wood Structure Design Manual" and compared with common building materials.The design value of the tensile strength along the grain was 16.3 MPa,and the tensile failure was brittle failure.There were three failure modes:tensile fiber breakage,zigzag interface shear failure,fiber breakage and interface shear failure.The design value of the shear strength along the grain was 3.69 MPa,the shear failure was brittle failure,and the failure mode was the shear failure of the fiber interface.The design values of the flexural strength along the grain and the elastic modulus of the flexural strength along the grain were 33.8 MPa and 8.3 GPa,respectively.The flexural failure was plastic failure,and the failure mode was that the tensile fiber was broken first,and the compressive fiber was then crushed.It was suggested that the bamboo scrimber could be used as the main stress-bearing material of the building structure,but the safety factor of compression and shear must be appropriately increased.When it is used as a bending member,the deflection control is more accurate.