摘要
抗剪性能是木材的基本力学属性之一,也是木结构设计的重要参数。国标测试方法中压剪试验获得的木材抗剪强度与纯剪强度存在一定差异,而常用的Iosipescu纯剪方法中的V形开口(V口)端部又可能存在应力集中。为此,该文通过有限元模型研究了V口和钥匙形开口(K口)试样受剪面剪应力的分布规律,并选取最优开口形式的试样开展了力学试验。研究表明:当V口在0°~90°范围时,随着开口角度的增大,受剪面两端的应力集中逐渐减弱,剪应力分布逐渐均匀;K口试样剪应力分布与开口角度、开口形式无关,仅与圆弧尺寸有关,且圆弧尺寸越小,剪应力变异系数越小;综合考虑加工难度、应力集中、破坏位置、应力分布以及中心应力等方面,90°V口试样相对合适,其次是3 mm圆弧半径的K口试样,二者受剪破坏模式、应力-位移曲线和应力-应变曲线形式相近,但剪切模量、抗剪强度仍有一定差异。
Shear capacity is one of the basic mechanical properties of wood,and is also an important parameter in the design of wood structures.There is a certain difference between the shear strength of wood obtained by the compression-shear test using the national standard test method and the pure shear test,and there may be stress concentration at the end of the V-notch opening in the commonly used Iosipescu shear test.Therefore,this study investigates the distribution of shear stress on the shear surface of V-notch and of Keyhole-shaped specimens using a finite element model,and selects the specimens with the optimal opening form to conduct mechanical tests.The research shows that when the V-notch opening is 0°~90°,the stress concentration phenomenon at both ends of the shear plane is gradually weakened and the shear stress distribution gradually become uniform with the increase of the opening angle.The shear stress distribution of Keyhole-shaped specimens is independent of the opening angle and form,but is related to the arc size,and the smaller the arc size,the smaller the shear stress variation coefficient.Comprehensively considering the processing difficulty,stress concentration,failure location,stress distribution,and central stress,the 90°V-notch specimen is relatively suitable,followed by the 3 mm arc radius Keyhole-shaped specimen.The shear failure modes,stress-displacement curves,and stress-strain curves of these two specimens are similar,but there are still some differences in shear modulus and shear strength.
作者
王忠铖
杨娜
李久林
WANG Zhong-cheng;YANG Na;LI Jiu-lin(Beijing Urban Construction Group Co.,Ltd.,Beijing 100088,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)
出处
《工程力学》
北大核心
2025年第9期115-123,共9页
Engineering Mechanics
基金
北京市博士后工作经费资助项目(2023-ZZ-129)
住建部研发项目(K20210032)
国家自然科学基金面上项目(51778045)。
作者简介
杨娜(1974-),女,辽宁人,教授,博士,博导,主要从事古建筑木结构、钢结构方面的研究(E-mail:nyang@bjtu.edu.cn);李久林(1968-),男,河北人,教授级高工,博士,总工,主要从事建筑施工、智慧建造方面的研究(E-mail:lijiulin@bjucd.com);通信作者:王忠铖(1990−),男,河北人,高工,博士,主要从事现代木结构、古建筑木结构方面的研究(E-mail:16115317@bjtu.edu.cn).
