摘要
分析新型竹材结构建筑热湿应力的产生机理和计算方法,利用电阻应变法测试了新型建筑竹材的湿膨胀系数和新型竹材结构墙体的热湿膨胀变化,进一步分析了墙体内的热湿自由膨胀以及热湿应变。结果表明,试验工况下新型竹材的湿膨胀系数横向为55.28μm/(m·%),纵向为11.64μm/(m·%),横向湿膨胀系数为纵向的4.7倍。竹材的热胀冷缩和湿干缩可导致墙体内产生热湿应变,热湿应变量为自由热湿膨胀量与测量值之差。虽然热湿膨胀测量值相同,但墙体竹材纵向与横向热湿应变实际值相差很大,是竹材结构热湿失效的重要原因。
This paper is oriented to present our analysis of the failure mechanism of a new-type bamboo-made building due to heat and moisture attack. Our analysis has been based on the principle of the thermal stress, the regularity of the heat and moisture stress of the new-type bamboo structure. To make our analysis as reliable as pos- sible, we have accomplished our test of the moisture expansion coeffi- cient of the said bamboo structure through testing its resistance strain. In addition, our test has also been done to test the variation of the heat and moisture expansion of the said bamboo wall under the natural environment. Moreover, we have also tested the free expansion of the heat and moisture plus the strain of the heat and moisture of the bam- boo wall. The results of our analysis show that tl~ obvious influence of the moisture on the expansion of the bamboo building under the in- fluence of natural high-temperature and humid environment. Statisti- cally speaking, the transverse moisture expansion coefficients of the new-type bamboo under experimental conditions are 55.28 ktrn/（m＇%） with the longitudinal one being 11.64 /lm/（m＂ %）, whereas the transverse moisture expansion coefficient is 4.7 times of that of the longitudinal one. I4. is of equal importance to take infi~ ^- count the changes of new-type bamboo structure in both moisture ex- pansion and thermal expansion. Due to the constraints of the wall it- self and the boundary of the bamboo wall, both the thermal expansion and moisture expansion can all lead to the heat and moisture strain in the bamboo wall, which is equal to the difference between the free thermal and moisture expansion volume and the measured data. Though the measured heat and moisture expansion data both at the transverse and longitudinal levels of the bamboo building is of the same nature, their strains on the bamboo vary greatly due to the dif- ference of the expansion coefficients. That is to say, since they are the key factors accounting for the failure of the bamboo structure, the difference between the transverse and the longitudinal thermal and moisture expansion tend to canoe the change of the bamboo in natural thermal and moisture environment, resulting in the strain variation to a great extent because of the greatest temperature and humidity varia- tion on the outer surface of the bamboo. The surface of the bamboo wall has thus been turning to be most susceptible to the failure caused by the thermal and moisture strain.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2013年第5期155-159,共5页
Journal of Safety and Environment
基金
国家自然科学基金项目(50878078)
关键词
建筑环境与能源应用工程
竹材结构
热湿传递
湿膨胀系数
热湿应变
热湿失效
building environment and energy engineering
bamboostructure
heat and moisture transfer
wet coefficient ofexpansion
heat and moisture strain
heat and moisturefailure
