木结构钢板螺栓连接节点承载力计算分析及试验研究

为便于木结构工程设计,提出了钢板螺栓连接承载力计算式,并提出了受弯螺栓连接节点承载力上限和下限的计算方法。设计制作了钢填板螺栓连接节点试件,并进行了复合受力节点承载力试验研究。试验结果表明,各受力工况下试验节点的承载力平均值均介于所计算的承载力上、下限之间,且基本等于所计算的承载力上、下限的平均值。从而验证了所提出的钢板螺栓连接承载力计算式和连接节点承载力计算方法的正确性和适用性,为设计提供了可靠依据。     

木结构钢板螺栓连接节点承载力计算分析及试验研究

为便于木结构工程设计,提出了钢板螺栓连接承载力计算式,并提出了受弯螺栓连接节点承载力上限和下限的计算方法。设计制作了钢填板螺栓连接节点试件,并进行了复合受力节点承载力试验研究。试验结果表明,各受力工况下试验节点的承载力平均值均介于所计算的承载力上、下限之间,且基本等于所计算的承载力上、下限的平均值。从而验证了所提出的钢板螺栓连接承载力计算式和连接节点承载力计算方法的正确性和适用性,为设计提供了可靠依据。     

胶合竹结构梁柱螺栓连接节点承载力试验研究

对胶合竹(格鲁斑Glubam)材料应用于框架结构房屋进行简要介绍,根据实际工程选取代表性框架,进行了4榀螺栓连接胶合竹梁柱框架试件的水平加载试验,获得单调及往复荷载作用下试件承载力与变形关系,研究螺栓连接节点的受力性能。试验结果表明,节点螺杆群中的螺杆受力不均,而节点的破坏是由作为基材的胶合竹撕裂引起。在构造合理的条件下,受力较小的螺杆也可参与抗震耗能。参照GB 50005—2003《木结构设计规范》以及美国规范ANSI/AFPA NDS-2012等方法分析了节点承载力,与试验结果对比表明,中国及美国木结构规范的设计值均与试验结果差异较大,但在设计中可以参考,且可比较偏于保守地按规范取值。     

桉木制单板条斜向组合胶合木材料及连接性能试验研究

为研究一种桉木制单板条斜向组合胶合木,开展了7组木材力学性能试验,得到其顺纹抗拉强度、顺纹抗压强度、横纹抗拉强度、全部及局部横纹抗压强度和销槽承压强度;开展了12组共72个厚径比较大的单螺栓连接试验,研究受力与纹理方向、厚径比和木材种类对破坏模式的影响,采用GB/T50708—2012和欧洲规范Eurocode 5对承载力设计值及标准值进行计算,以SPF胶合木试验结果为参考,结果表明:桉木制单板条斜向组合工程木内嵌钢板单螺栓连接试件有单个塑性铰与两个塑性铰两种破坏模式,顺纹试件极限荷载平均值较SPF胶合木大5%~56%,等效屈服荷载相当;横纹试件极限荷载平均值与等效屈服荷载平均值较SPF胶合木大4%~34%。对于单个塑性铰与两个塑性铰破坏,依据GB/T 50708—2012及欧洲规范Eurocode 5对内嵌钢板单螺栓连接节点设计有较高的安全性,但单个塑性铰破坏计算值较高,两个塑性铰破坏计算值较低。     

层板胶合木梁柱钢填板-螺栓连接节点横纹受力性能试验研究

为研究层板胶合木梁柱钢填板-螺栓连接节点横纹受力性能，对6组20个足尺节点试件进行抗剪试验，获得了节点的受剪性能指标和特征曲线。结果表明：节点的破坏均表现为木材的横纹劈裂脆性破坏，且第一条贯穿裂缝基本出现在靠近加载侧的螺栓孔处；相比于加载边边距e2，非加载边边距e1对节点的力学性能影响更为显著，非加载边边距e1取30~70mm时节点的屈服荷载和弹性刚度的变化幅值分别达16.6%和60.8%。总体上，试验所得受剪承载力与理论公式计算的相差较大，但相对而言，由van der Put计算公式计算的受剪承载力与试验结果最为接近，且偏于保守。     

自攻螺钉增强胶合木梁柱螺栓节点受力性能试验研究

设计制作了9个胶合木梁柱螺栓节点试件,其中7个螺栓节点采用自攻螺钉进行增强。进行了单调和低周反复加载试验,研究胶合木梁柱螺栓节点采用自攻螺钉增强后的受力性能。试验研究表明,胶合木梁柱螺栓节点易产生木材撕裂破坏,采用自攻螺钉增强后的节点由于自攻螺钉咬合力作用,有效抑制了木材纹理的开裂;当螺栓边距、端距小于GB/T50708—2012《胶合木结构技术规范》限值时,节点试件的承载力及延性仍有明显提高,其中,螺栓直径20 mm的节点试件承载力最大提高了112%,螺栓直径14 mm的节点试件承载力提高了81%。     

带翼缘钢填板-螺栓连接胶合木梁-柱节点转动性能试验研究

针对钢填板-螺栓胶合木梁-柱连接节点易发生木材横纹劈裂脆性破坏的问题,提出在钢填板上下端增设翼缘以降低木材横纹拉应力或约束木材横纹裂缝扩展,形成带翼缘钢填板-螺栓连接胶合木梁-柱节点形式。通过对其进行单调加载试验,获得了该连接节点的弯矩-转角关系曲线,对比分析了该类连接节点和采用不同加固技术的普通钢填板-螺栓连接节点的受弯承载力。研究表明：带翼缘钢填板-螺栓连接节点具有良好的变形能力,其相对受弯承载力较普通钢填板-螺栓连接节点提高最多可达129%,且高于采用自攻螺钉、碳纤维布和交叉胶合木等技术加固的普通钢填板-螺栓连接节点的受弯承载力。     

木材横纹销槽承压强度研究

设计了3种共计290个木材横纹销槽试件,分析了试验方法、判定方法、有效承压高度、试件尺寸及螺栓直径等因素对木材横纹销槽承压强度的影响,并将试验结果与规范计算结果进行对比.结果表明：现行规范中的木材横纹销槽承压强度试验方法和计算方法均存在一定的局限性;基于本文提出的标准试验方法所得到的木材横纹销槽承压强度,木结构螺栓连接横纹屈服承载力计算结果与试验结果比值的平均值为0.92.     

干节点连接装配式混凝土梁静力性能试验研究

为了解决装配式混凝土预制构件连接时节点湿作业带来的施工不便,设计制作了7根混凝土简支梁,其中包括1根现浇混凝土简支梁、1根按《装配式混凝土结构连接节点构造》中湿节点连接而成的预制混凝土简支梁以及5根由构造不同干节点连接而成的预制混凝土简支梁,对梁进行两点加载,完成了简支梁静载作用下力学性能试验,获得承载力、变形及裂缝分布等试验数据。结果表明:采用钢板焊接连接和钢板螺栓连接的干节点混凝土试验梁的承载力不弱于现浇混凝土梁,而采用钢板对焊连接、预应力连接和植筋连接的干节点试验梁承载力稍弱于现浇混凝土梁,且其挠度实测值与最大裂缝宽度实测值均比现浇混凝土梁略大。     

碳纤维增强胶合木钢填板螺栓连接节点横纹受力性能研究

胶合木钢填板螺栓连接节点横纹受力会出现脆性破坏的现象。为研究碳纤维(CFRP)增强对胶合木钢填板螺栓连接节点的横纹受力破坏模式、承载能力和变形能力的影响,考虑CFRP铺设位置和层数,开展销槽承压强度试验,再以螺栓边距、中距、数目、排列方式和CFRP增强方式为参数,开展节点的横纹受拉试验和有限元分析。结果表明：双面或四面粘贴2层或4层CFRP布,销槽承压强度最大可提高171%,离散系数最大可降低84%;CFRP增强节点的破坏模式由脆性破坏转变为延性破坏,极限载荷最大可提高181%,位移延性系数最大可提高625%;增强后螺栓横纹边距和中距可适当减小。基于试验结果及相关规范,给出CFRP增强横纹销槽承压强度和CFRP增强胶合木钢填板螺栓连接节点的横纹受拉承载力表达式,可为工程设计提供参考。     

带齿夹板钢木连接节点受力机理

为解决胶合木网壳螺栓连接节点初始刚度低、木梁螺栓孔易发生劈裂的问题,提出一种带齿夹板钢木连接节点。通过试验研究了带齿夹板节点(JD-2)在单调荷载作用下的力学性能和破坏模式,并与同尺寸下不含钢齿的普通夹板节点(JD-1)进行对比分析。为深入研究带齿夹板节点的受力机理,对带齿夹板节点进行有限元模拟。结果表明:JD-1的破坏模式为木梁沿螺栓孔水平连线方向的横纹劈裂破坏,JD-2的破坏模式为夹板屈服破坏; 与JD-1相比,JD-2的初始刚度提高了47.18%,极限承载力提高了31.4%,延性系数提高了19.83%; 钢齿与木梁之间的机械咬合作用可以有效减少木梁螺栓孔初始间隙对节点刚度的不利影响; 在弯矩与剪力联合作用下,荷载通过钢齿及螺栓共同传递给木梁,减少了木梁螺栓孔的应力,因此延缓了木梁螺栓孔的开裂; 随着夹板翼缘厚度的增加,节点的受弯性能呈现增大的趋势; 增加夹板布齿率,木梁螺栓孔受到螺栓挤压应力减小,钢齿阻止夹板与木梁之间的相对滑动能力增强,建议夹板布齿率取0.46%～0.65%。     

Tests and models for engineered wood product connections using small steel tube fasteners

Laminated Strand Lumber (LSL) is a type of engineered wood product widely used as a substitute for sawn structural lumber. This is because LSL can be manufactured to have superior mechanical and physical performance to competing products, including high resistance to splitting, high strength and dimensional stability. The authors studied connections in LSL with behaviour of similar connections in sawn Spruce lumber as a benchmark. Proneness to splitting is the Achilles heel of most wood-based construction materials and especially products like sawn lumber and glued-laminated-timber. This characteristic makes it especially difficult to make connections that are mechanically efficient. However, when constructing with LSL it is possible to create connections that not only have desirable response characteristics, but also achieve labour efficiencies. The particular type of connection studied by the authors uses small diameter steel tube fasteners inserted in tight-fitting holes in conjunction with steel plate elements located in slots in ends of joined members and links them together. Tube fasteners are driven perpendicular to the axes of wood members and pass through both those members and steel link elements. Tests were conducted under static tensile loads with multiple-fastener arrangements obeying spaced and end distance rules typical for solid bolts in sawn softwood lumber. The response was highly ductile and failure occurred mainly in the fasteners. Consequently the so-called European Yield Model (EYM) for doweled timber connections yields good predictions of connection strengths. A detailed finite element analysis was also performed to assist interpretation of test results and validate predictions from the EYM beyond the range of test data. The finite element model was developed using the ABAQUS software and results from that model agreed closely with experimental findings in both qualitative and quantitative aspects.     

工程木梁的受弯性能试验研究

以江苏速生意杨为原材料加工的工程木材,包括层板胶合木(Glulam)和旋切板胶合木(LVL)等,提出几种新型的构件截面形式,对受弯构件的结构性能影响因素进行了详细分析。研究的主要目的是充分利用我国速生林资源,并将其应用于现代木结构建筑。首先,通过材料的材性试验,探讨了Glulam和LVL的主要物理力学性能;在此基础上,对31个工程木梁模型试件进行了弯曲性能的试验研究,分析了工程木梁的破坏形态和破坏机理,探讨了其极限承载力和抗弯刚度等弯曲性能,并对构件性能进行了对比;最后,分析了影响工程木梁结构性能的各种因素,包括层板组合方式、荷载方向、单板厚度(LVL构件)以及构件尺寸等。结果表明:工程木梁的结构性能远远超出了建筑中常用锯材梁的结构性能,其强度比樟子松锯材构件高出39.0%~90.0%,刚度高出35.0%~45.0%,若将Glulam与LVL进行优化组合,会取得更好的效果;构件横截面平均应变基本上呈线性分布,构件的极限拉应变约为0.006,而其破坏时的压应变最大为0.009左右;     

自攻螺钉参数设置对胶合木梁柱节点受力性能的影响

采用自攻螺钉对胶合木梁柱节点进行横纹加强可有效传递木材的横纹拉应力和顺纹剪应力,从而延缓木材开裂、提高节点性能。为了研究自攻螺钉的布置间距、直径和个数等参数对加强节点受力性能的影响,对4组采用不同布置间距、直径和个数的自攻螺钉加强胶合木螺栓连接梁柱节点进行单调和低周往复加载试验,得到各组节点的刚度、延性、承载力、破坏模式和抗震性能。结果表明：自攻螺钉个数增加、直径增大,节点的承载力、破坏转角、延性系数以及节点总耗能增大;自攻螺钉布置间距的变化对节点在单调荷载作用下的承载力和延性系数无明显影响;而节点在往复荷载作用下时,随着自攻螺钉布置间距的减小,节点承载力和总耗能降低。     

胶合木梁柱角钢混合连接静力与抗震性能试验研究

为解决传统的木结构销栓连接刚度低、震后可恢复功能弱等问题,将钢结构梁柱翼缘角钢连接方法应用于木结构,提出了一种胶合木梁柱角钢混合连接形式。为研究此类木结构节点的静力与抗震性能,对节点试件进行了单调与低周反复荷载试验。研究结果表明：当梁柱截面尺寸分别为135mm×420mm和150mm×350mm,连接角钢规格为∟180×110×12时,胶合木梁柱角钢混合连接的极限弯矩达到95.3kN·m,最大转角接近0.096rad,初始刚度达4073kN·m/rad。低周反复荷载作用下,混合连接的变形能力与延性良好,梁端弯矩-转角滞回曲线呈反“S”形,角钢屈服后的大变形使其短肢底部与柱面产生了明显的分离,滞回曲线出现捏缩效应;角钢的短肢翘曲严重,从而使混合连接的耗能能力和等效黏滞阻尼系数均下降。     

Ductility aspects of reinforced and non-reinforced timber joints

Even though brittle failure modes in timber joints may be avoided by the proper design of the connection, the use of minimum timber dimensions and minimum spacing and distances of fasteners often leads to timber splitting in the connection area. Due to the highly nonlinear behaviour of timber loaded in compression as well as the steel used for mechanical fasteners, timber joints can behave in a rather ductile manner. Ductile behaviour is preferable in timber structures.Technical innovations regarding engineered wood products as well as fastener and steel technology led to the development of high-performance timber connections. In these high-performance connections, brittle failure modes are prevented by reinforcing the timber in the connection area perpendicular to the grain or using cross-laminated timber members. The improvement of the ductility levels is shown based on several experimental studies comparing non-reinforced to reinforced connections.     

Determination of fire resistance ratings for glulam connectors within US high rise timber buildings

Multi-storey mass timber buildings constructed with cross laminated timber and glulam are being developed globally. Where engineered timber such as glulam is utilized, the column to beam connections need to be constructed with a fire resistance rating equal to that of the connecting members. The preferred glulam connectors are either a concealed steel plate with bolts and dowels; or a concealed proprietary screw-in sleeve type connector. The fire resistance of connectors for glulam members is an unresolved design issue, as there is no clear methodology to assess their capacity under fire, when the timber is exposed and not clad behind fire protective plasterboard. There is limited fire test data on concealed connectors under shear forces, which is the normal loading condition within a constructed building. Fire test data is also limited on full-size specimens. Correlations developed to date to calculate concealed connector fire resistance have only limited application.A methodology for the design of glulam beam to column connections has been developed based on an extensive literature review, examining the key issues for connection failure. It has been determined that char rate for the timber at the connection needs to be increased above the normally accepted design values, due to the influence of the steel connectors. Secondly, the reduction in timber strength behind the char layer needs to be accounted for, by including a greater depth of reduced strength and stiffness timber, such that the connection can effectively transfer the applied forces through the timber to the steel connector. The methodology detailed within this paper provides a simple approach to evaluate the timber cover to the concealed steel connector, where the timber strength and stiffness are effective.     

LY315钢材带悬臂梁段拼接梁柱节点抗震性能试验研究

带悬臂梁段拼接梁柱节点是我国GB 50011—2010《建筑抗震设计规范》推荐的节点设计形式之一,为研究LY315钢材带悬臂梁段拼接梁柱节点的抗震性能,开展了高强度螺栓抗滑移系数试验及梁柱节点循环加载试验,试验获得了该类型节点的破坏模式、滞回曲线、骨架曲线及延性系数等,探讨了悬臂梁段长度对该类型节点抗震性能的影响。试验研究结果表明：对于LY315钢材,采用钢丝刷清除浮锈的表面处理方式所得螺栓抗滑移系数为0.29;以此钢材制作的带悬臂梁段拼接梁柱节点试件滞回曲线饱满,具有良好的耗能能力;3个试件在加载终止时转角均超过0.04rad且试件的延性系数均大于4,表明该类型节点具有良好的变形性能及延性;随着悬臂梁段长度的增加,试件的累积耗能能力有所降低,这是螺栓的滑移耗能造成的;随着悬臂梁段长度的增加,节点的承载力则略有提高,而悬臂梁段长度的变化对试件的延性及刚度退化影响不大。