重组竹短期蠕变性能研究  

Study on short-term creep property of bamboo scrimber

作　　者：孙丽惟 卞玉玲[2] 周爱萍[1] 朱彦[1] SUN Liwei;BIAN Yuling;ZHOU Aiping;ZHU Yan(National-Provincial Joint Engineering Research Center of Biomaterials,Nanjing Forestry University,Nanjing 210037,China;Wuxi Vocational Institute of Commerce,Wuxi 214153,Jiangsu,China)

机构地区：[1]南京林业大学生物质材料国家地方联合工程研究中心,南京210037 [2]无锡商业职业技术学院,江苏无锡214153

出　　处：《林业工程学报》2020年第2期69-75,共7页Journal of Forestry Engineering

基　　金：国家自然科学基金(51778299);江苏省研究生科研与创新计划项目(KYCX17_0832)

摘　　要：在重组竹房屋的正常使用过程中,构件会因荷载及温湿度共同作用而产生蠕变。因此,明确蠕变性能是重组竹结构设计体系不可忽视的重要问题之一。在25℃和相对湿度60%条件下,通过不同应力水平下重组竹顺纹单轴受拉、受压、三点受弯24 h短期蠕变试验,获得了蠕变应变-时间曲线及蠕变量-时间曲线,并以Burgers模型为基础,对试验结果进行了拟合。结果表明:当温湿度一定时,在较低应力水平下,蠕变只包含瞬态及稳态蠕变2个阶段,初始蠕变应变及蠕变应变总量与应力水平呈线性正相关关系,达到稳态阶段后重组竹几乎不再发生变形及破坏,具有良好的抵抗蠕变变形的能力。在较高应力水平下,重组竹蠕变不稳定性增强,抵抗蠕变性能有所降低,设计时应控制构件尺寸,确保其处于较低工作应力水平下,以利于其发挥自身抗蠕变性较高的优势。对比顺纹受拉、顺纹受压、三点受弯3种受力情况可知:顺纹受拉破坏呈脆性,无明显的破坏征兆;顺纹受压、三点受弯均具有一定的破坏征兆。Burgers模型对于包含瞬态及稳态蠕变阶段的重组竹短期蠕变性能拟合程度较高,能够较好地反映其短期蠕变性能。Bamboo scrimber is a high strength bamboo-based composite material,which was fabricated by gluing a large number of bamboo strand elements together with adhesive along the longitudinal axis of the element member.The original properties of bamboo are greatly optimized,and the utilization rate of raw materials is high.The bamboo scrimber has superior mechanical properties as well as flame retardancy,and its emission performance can be up to the environmental standard E 1 according to the European emissions standards.With the development of its structural design system,it has been applied to the main body of building structure.Creep is the phenomenon that stress is constant and strain increases with the time duration.During the usual application of the bamboo scrimber house,the components will creep due to the combination of load and humiture.Defining creep performance is one of the important issues that cannot be ignored in the bamboo scrimber structure design system.Based on the Burgers model,the creep strain-time curve and its fitting results were obtained by the 24 h short-term creep tests of uniaxial tension,compression and three-point bending along the grain direction of the bamboo scrimber under 25℃and 60%relative humidity,and at different stress levels.The analysis showed that,when the humiture remained unchanged,under the low stress level,the creep only contained two stages of transient and steady creep.The initial creep strain and the total creep strain were positively linearly correlated with the stress level,reaching the steady state.After this stage,the bamboo scrimber was almost no longer deformed or destroyed,and had good resistance to creep deformation.At high stress levels,the creep instability of bamboo scrimber was enhanced and the creep resistance was reduced.The design should control the size of members to ensure that it is at a low working stress level,so as to facilitate its self-creep resistance.It can be seen from the comparison of three kinds of stress conditions:uniaxial tension,compress

关 键 词：重组竹 短期蠕变试验 应力水平 蠕变性能 BURGERS模型 

分 类 号：TU531.3[建筑科学—建筑技术科学]