钢木组合结构自攻螺钉单剪节点试验研究

刘佳迪; 牛相元; 陈志华; 张安玲

doi:10.13206/j.gjgS21070602

钢木组合结构自攻螺钉单剪节点试验研究

doi: 10.13206/j.gjgS21070602

1. 天津大学建筑工程学院, 天津 300072;
2. 天津大学滨海土木工程结构与安全教育部重点实验室, 天津 300072;
3. 天津大学土木工程结构及新材料天津市重点实验室, 天津 300072;
4. 天津城建大学, 天津 300384

基金项目:

国家重点研发计划资助(2019YFD1101001-03)。

详细信息

作者简介:
刘佳迪,男,1986年出生,博士,讲师。Email:jdliu@tju.edu.cn

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出版历程
- 收稿日期: 2021-07-06

Experimental Study on Single-Shear Joint of Self-Tapping Screw of Steel-Timber Composite Structure

1. School of Civil Engineering, Tianjin University, Tianjin 300072, China;
2. Key Laboratory of the Ministry of Education on BinhaiCivil Engineering Structure and Security, Tianjin University, Tianjin 300072, China;
3. Key Laboratory of Tianjin of Civil EngineeringStructure and New Materials, Tianjin University, Tianjin 300072, China;
4. Tianjin Chengjian University, Tianjin 300384, China

摘要

摘要: 钢木组合体系兼具了两种材料的优势,在村镇住宅、大跨度结构等建筑体系中均有一定的应用前景。销轴类节点是钢木组合体系中常见的连接形式,其力学特性显著影响结构体系的性能,其中螺栓和钉为销轴的常见形式。为准确评估薄壁钢——木的自攻螺钉连接节点的抗剪性能,从节点抗剪试验、理论推导两个方面进行了研究。同时对潜在的结构材——速生木的力学性能进行了校核。
为研究木材与薄壁型钢(2 mm)小直径自攻螺钉(直径<6 mm)连接节点的抗剪性能,设计了 11种单调荷载下的单剪连接节点并进行了相关试验。对木材种类、钉的尺寸、连接方向等参数进行分析,得到了自攻螺钉连接节点的破坏模式、承载力及刚度、延性系数、割线刚度等力学特性。在 GB 50005-2017《木结构设计标准》的基础上,对薄壁钢-木自攻螺钉连接节点典型破坏模式的承载力进行了分析。
结果表明:速生木材的强度可满足连接需求,木材种类的变化对自攻螺钉连接节点的抗剪性能有一定的影响,但钉尺寸、类型、嵌入长度的改变显著影响节点的破坏模式、峰值承载力,国产杉木、杨木以及辐射虽低于常见建材——花旗松、樟子松,但仍有足够的连接强度;自攻螺钉-钢木组合连接节点主要有自攻螺钉钉杆剪断、钉拔出、木材破坏三种破坏模式,其中自攻螺钉剪断是最为常见的破坏情况,在螺钉的嵌入长度较小时,易发生自攻螺钉拔出的破坏情况,木材横纹钉节点时,易因横纹受拉发生脆性断裂,实际情况应避免;燕尾自攻螺钉连接节点在钢板 -木结构构件中有着较好的峰值承载力(3 kN左右),但其因螺钉的脆性断裂延性较差,平均延性系数为 2,减小嵌入长度可增加连接节点的延性;对自攻螺钉连接节点的抗剪承载力进行了理论推导和机理分析,基于 GB 50005-2017等国内规范基础上的分析和校核结果表明,现有标准因未充分考虑绳效应,承载力均小于试验实测值,且不同于纯钢或纯木的销轴类连接节点,薄壁钢-木自攻螺钉连接节点以弯剪破坏为主,由 GB 50005-2017得出的设计值约占承载力实际值的 30%~45%。
- 钢木组合结构 /
- 自攻螺钉 /
- 抗剪性能
Abstract: The steel-timber composite system combines the advantages of both materials and has prospects for application in village houses,long-span structures and other building systems.Pin connections are common connection forms in steel-timber systems,and their mechanical properties significantly affect the performance of the structural system.Among them,bolts and screws are the common forms of pins connections.In order to accurately evaluate the shear resistance of thin-walled steel-timber self-tapping screw connections,connection shear tests and theoretical derivation were investigated in the paper.The mechanical properties of the potential structural material,fast-growing wood,were also calibrated.
To investigate the shear performance of the connections between timber and thin-walled section steel (2 mm) with small diameter self-tapping screws (diameter ＜ 6 mm),11 groups of single shear connections under monotonic loading were designed and tested.Timber type,dimension of connections,and connection direction are the main parameters explored.The mechanical properties such as damage mode,bearing capacity and stiffness,ductility coefficient,and cut line stiffness of the self-tapping screw connections were obtained.On the basis of Standard for Design of Timber Structure(GB 50005-2017),the bearing capacity of typical damage modes of thin-walled steel-timber self-tapping screw connections was analyzed.
The results include:the strength of fast-growing timber can meet the connection requirements,the change of timber species has a certain effect on the shear performance of self-tapping screw connections,but the change of screw size,type and embedment length significantly affects the damage mode and peak load capacity of the connections.The performance of Chinese fir,poplar and pinus radiata is lower than that of common building materials such as douglas fir and pinus sylvestris,but they still have sufficient connection strength.The self-tapping screw connections in the paper mainly occur in three damage modes:self-tapping screw rod shearing,screw pull-out and timber damage.Among them,self-tapping screw shearing is the most common damage.When the embedded length of the screw is small,the connection is prone to damage from self-tapping screw pull-out,in addition,the timber cross-grain connection specimen is prone to brittle fracture due to cross-grain tension,the actual situation should be avoided.Self-tapping screw connection has a good peak bearing capacity (about 3 kN) in steel-timber composite structures and members,but the ductility is poor due to the brittle fracture of the screw,the average ductility coefficient is 2,reducing the embedment length can increase the ductility of the connection.Through the theoretical derivation and mechanism analysis of the shear bearing capacity of self-tapping screw connections,as well as the analysis and calibration based on GB 50005-2017 and other domestic codes,it shows that the existing standards do not fully consider the rope effect,the bearing capacity are less than the actual measured value of the test.Different from the steel or wood pin-type connections,the thin-walled steel-timber composite self-tapping screw connections are dominated by bending and shear damage,and the design values derived from GB 50005-2017 account for about 30%-45% of the actual value of the bearing capacity.
- steel-wood composite structure (STC) /
- self-tapping screw /
- shear resistance

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