循环荷载作用下木材横纹力学特性与本构模型  

Perpendicular-to-grain mechanical properties and constitutive model of wood under cyclic loading

作　　者：张利朋 谢启芳[1,2] 韩永刚 王莹锦 吴亚杰 ZHANG Lipeng;XIE Qifang;HAN Yonggang;WANG Yingjin;WU Yajie(College of Civil Engineering,Xi’an University of Architecture&Technology,Xi’an 710055,China;Key Lab of Structural Engineering and Earthquake Resistance,Ministry of Education(XAUAT),Xi’an 710055,China)

机构地区：[1]西安建筑科技大学土木工程学院,陕西西安710055 [2]西安建筑科技大学结构工程与抗震教育部重点实验室,陕西西安710055

出　　处：《建筑结构学报》2024年第5期230-242,共13页Journal of Building Structures

基　　金：国家自然科学基金项目(52178303);陕西省杰出青年科学基金项目(2021JC-44);陕西省教育厅重点科学研究计划(21YJ022、21YJ026)。

摘　　要：木材循环受力特性与本构模型是木结构在地震、振动等反复荷载作用下受力分析的基础。试验中设计并加工了一种适用于木材横纹循环加载的狗骨状试件及其配套夹具,基于木材径向、弦向、偏轴60°三类共44个横纹试件的单调拉伸、单调压缩、循环受压、循环拉压试验,分析木材在不同循环加载条件下的变形特征、破坏模式、应力-应变全曲线性质与加卸载刚度变化规律。在此基础上,建立木材横纹循环应力-应变曲线中受压卸载残余应变、受拉卸载开始点应变、受拉卸载残余应变与受压卸载开始点应变的相关关系。研究结果表明:木材横纹循环受力过程中受压侧变形特征、破坏模式、骨架曲线与单调受压时相似,径向与偏轴60°试件的循环受压骨架曲线屈服点后的应变硬化特征明显,而弦向试件则表现出明显的应变软化特征;各类试件的卸载刚度、卸载后的反向加载刚度显著退化。进一步建立了木材横纹循环受力本构模型,并通过试验验证了其正确性,可用于木结构受循环荷载作用时的受力分析。The cyclic mechanical behavior and constitutive model of wood are the basis for the mechanical analysis of timber structures under earthquake and fatigue loads.A dog bone shaped specimen and its supporting fixture were designed and manufactured for transverse cyclic loading.A total of 44specimens were tested under cyclic compression and cyclic tension compression based on the three types of transverse samples with radial,off-axis 60°and tangential directions,respectively.The deformation characteristics,failure modes,full stress-strain curve features and unloading stiffness changes under different loading conditions were analyzed.The relationship between the compression unloading residual strain,the strain of tension unloading started points,tension unloading residual strain and the strain of compression unloading control points was quantitatively characterized.The results show that the strain hardening characteristics of the monotonic compression stress-strain curves of the wood specimens with transverse grain and off-axis at 60°are obvious after the yield point,while the tangential compression specimens show an obvious strain softening phenomenon.The characteristics of the cyclic compression skeleton curves are similar to the monotonic compression curves of wood.The stiffness of the reverse reloading curves after unloading is significantly degraded.On this basis,the monotonic and cyclic constitutive model of wood was established,and its correctness was verified by experiments.The research results can provide a good basis for the mechanical analysis of timber structures subjected to cyclic loading.

关 键 词：木材 横纹 循环荷载 受力试验 力学性能 本构模型 

分 类 号：TU366.2[建筑科学—结构工程] TU317.1