燕尾榫约束古建木梁环境温度效应试验研究  

Experimental Analysis of Ancient Timber Beam with DovetailJoint Restraint under Environmental Temperature Effect

作　　者：白晓彬[1,2] 杨娜 常鹏[1] BAI Xiaobin;YANG Na;Chang Peng(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;Central Research Institute of Building and Construction Co,Ltd,Beijing 100088,China)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]中冶建筑研究总院有限公司,北京100088

出　　处：《湖南大学学报（自然科学版）》2020年第3期63-72,共10页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(51778045);北京市自然科学基金重点项目(8151003);国家自然科学基金重点项目(51338001)。

摘　　要：为了研究古建木梁在环境温度效应下顺纹方向的应变特征,在拉萨室内布置了一根无约束木梁和一根燕尾榫约束木梁,分别在室温变化下对其进行了空载和分级加载试验.根据试验数据,分别对木材的顺纹方向弹性模量及燕尾榫的拉压刚度、转动刚度进行识别,将各参数识别成随环境温度变化的变量.根据燕尾榫的构造特点,将升温段和降温段识别为不同的拉压刚度.分析了上部荷载、约束条件等因素对梁底顺纹方向应变的影响,试验结果表明:无约束梁在环境温度作用下的应变增量和上部荷载无关,约束梁在环境温度作用下的应变增量随上部荷载的增大而增大.梁端反力对梁底部的二阶弯矩作用引起了附加应变,附加应变随温度和荷载的增大而增大.最后,根据附加应变的理论计算公式,将计算值与实测值对比,二者吻合较好,说明附加应变的理论公式是合理的.An unrestrained timber beam and a dovetail joint timber beam are placed in Lasa,and non-load test and step loading test are carried out,respectively,to study the strain parallel to grain of the timber beam under envi-ronmental temperature effect.According to the test data,the elasticity modulus parallel to grain of the wood,the ten-sion and compression stiffness and rotation stiffness of the dovetail joints are identified.Considering the environmental temperature effect,the parameters are determined as variables related to the temperature variations.According to the construction features of the dovetail joint,the tension and compression stiffness in the temperature increasing stage and temperature decreasing stage are different.The influences of upper load and boundary conditions on the strain parallel to grain are analyzed.The results show that the strain variations of unrestrained beam under environmental temperature effect is unconcerned with the top load,and the strain variations of restrained beam increase along with the environmental temperature.The extra strain is induced by the second order moment of the counterforce at the beamend,which increases along with the temperature and the upper load.Finally,according to the theoretical formula of extra strain,the measured value and calculated value matched well,which indicates that the theoretical formula of the extra strain is rational.

关 键 词：古建木梁 环境温度作用 燕尾榫 顺纹应变 拉压刚度 附加应变 

分 类 号：TU366.2[建筑科学—结构工程]