单向及双轴向压缩载荷下的圆竹径向力学性能  

Mechanical properties of bamboo with diametric uniaxial and biaxial compression tests

作　　者：陈复明[1] 江泽慧[1] 王戈[1] 程海涛[1] 

机构地区：[1]国际竹藤中心,国家林业局竹藤科学与技术重点实验室,北京100102

出　　处：《深圳大学学报（理工版）》2012年第6期527-533,共7页Journal of Shenzhen University(Science and Engineering)

基　　金：国家林业公益性行业专项资助项目(201204701)~~

摘　　要：研究圆竹在单向(x)和双轴向(x,y)压缩载荷下的径向力学行为.利用斜率法,估算双轴向载荷下竹间的长度尺寸效应;采用数字散斑方法,对应变场信息及长径比对环向应变的影响进行表征.结果表明:双轴向压缩强度是单向的2.4～2.5倍,压缩时间比单向减少30%～45%;双轴向载荷下竹节处强度是竹间的2.38倍,从结构方面看,竹节对竹筒是增强体而非缺陷.利用二参数Weibull分布函数,估算出双轴向压缩下的长度尺寸效应系数为0.056(x方向)和0.069(y方向),双轴向载荷下破坏首先发生在与x/y轴大约成45°位置处.应变场分析表明:x方向应变分布较均匀,应变值变化区间为-0.138～0.096,均值为-0.006;y方向应变呈现较大波动,应变值变化区间为-0.372～0.437,均值为0.002;在45°位置处,竹环内侧靠近竹黄部位受压应力,竹环外侧靠近竹青部位受拉伸作用.在双轴向载荷0～300 N下,随着长细比增加,应变的25%～75%分位值和均值的绝对值总体上呈减小趋势.Mechanical behaviours of bamboo at uniaxial （x） and biaxial （x, y） directions were investigated by diametric compression tests, and the long-size effects of bamboo under biaxial compression loadings were esti- mated by using the slope method. Meanwhile, the information of strain-filed and the effects of ration length/radius on strain were characterized by the digital speckle correlation method. The strength with biaxial texts was 2. 4 - 2.5 times as hard as that of the uniaxial while compression time was 30% ~ 45% less than that of the uniaxial. The strength of bamboo joint under biaxial compression loadings was 2.38 times as hard as its near parts at inter- modal region, so, it acts as reinforcement for the bamboo and not a defect in its structure. The size effects of length under biaxial compression loading were 0.056 （x-direction） and 0.069 （y-direction） with the help of 2P- Weibull distribution functions. Failure occurs at an about 45 ° position with x/y axial firstly when conducting biaxial compression. The x-strain distribution was uniform. The range of variation was -0. 138 -0.096, and the mean value was - 0.006. However, variation of y-strain field presented a more fluctuation compared with x-strainfiled, as the range of variation was -0. 138 -0. 096, the mean was -0. 006. The location at 45~ near the inner circle of bamboo ring suffered compression stress, conversely, the position close to the outside of the ring was given stretched effect. As the increase of length-diameter ratio, 25th - 75th percentiles of strain value and absolute value of mean, as a whole, presented a decreasing trend under biaxial loads 0 - 300 N.

关 键 词：竹质工程材料 竹质构件 圆竹 双轴向压缩 尺寸效应 数字散斑相关方法 应变场 力学性能 

分 类 号：TU502.6[建筑科学—建筑技术科学]