节子对落叶松胶合木胶合性能的影响

采用水性高分子-异氰酸酯(API)胶黏剂对含有木节的兴安落叶松(Larix gmelinii)层板按照工程胶合木的胶合工艺进行常温加压胶合,探讨木节及其大小对兴安落叶松工程胶合木胶合性能的影响。通过对试件进行胶缝剪切强度试验和浸渍剥离与煮沸剥离试验,发现节子对胶缝常态剪切强度、木破率、浸渍剥离率和煮沸剥离率均有显著的影响,随着木节直径的增大其胶缝剪切强度和木破率可下降40%和67%以上,浸渍二次总剥离率和煮沸二次总剥离率可增大至16%和37%以上。研究表明:两胶合面中仅一面有小木节(占板宽1/7~1/6),只能用于室内结构用集成材,不能用于室外结构用集成材;只有尺寸小于木板宽度1/10的木节与无节面胶合才能满足室外用工程胶合木的要求。     

结构用锯材分等及胶合木制备工艺研究进展

以锯材为基本单元制成的胶合木正部分取代钢筋混凝土和砖混结构应用于木结构建筑行业。主要介绍了国内外结构用锯材等级评价及其胶合木制备工艺相关研究;结合我国实际,就胶合木的进一步发展提出建议,以期为我国胶合木工业化生产提供借鉴与参考。     

正交胶合木胶合耐久性能研究进展

胶合耐久性是正交胶合木(CLT)最基本的性能之一,正交组坯结构和层板间缝隙等构造特征增加了CLT胶合耐久性评估方法的复杂性。同时,胶黏剂种类、胶合工艺参数、试件大小及形状和层板处理等均会影响胶合耐久性能的评价结果。比较分析了不同CLT胶合耐久性测试方法,并对CLT胶合耐久性能主要影响因素相关研究进行总结,为后续CLT胶合耐久性能研究提供参考。     

不同胶黏剂对俄罗斯落叶松木材胶合性能的影响研究

为验证进口俄罗斯落叶松木材胶合性能,选用4种具代表性的结构用室温固化胶黏剂,根据GB/T 26899—2011《结构用集成材》进行胶合性能试验,对俄罗斯落叶松及胶黏剂的胶合性能进行分析研究。结果表明:对于俄罗斯落叶松,单组份聚氨酯、双组份聚氨酯和水性高分子异氰酸酯3种胶黏剂的胶层剪切强度和胶层剥离率均满足标准要求,其中双组份聚氨酯和水性高分子异氰酸酯胶黏剂胶合性能优异,单组份聚氨酯胶黏剂胶合性能良好;间苯二酚-甲醛树脂胶黏剂的胶合性能虽能达到标准要求,但不推荐作为结构用胶黏剂。     

正交胶合木胶合性能研究现状及展望

胶合性能是胶合木制品的重要性能之一。在正交胶合木（CLT）中木材特征、胶黏剂性能以及木材与胶黏剂之间界面性能共同决定了正交胶合木的胶合性能。木材作为一种天然各向异性材料,其纹理方向不同,造成组坯方式对于胶合性能影响巨大。在胶合性能测试中,取样尺寸、取样形状对于胶合性能的测试结果都有一定的影响。胶合界面性能表征方面的研究正逐渐兴起,但是针对CLT胶合界面性能表征的相关研究报道并不多。有关CLT胶合的研究多集中在胶黏剂和胶合工艺方面,而针对不同锯材单元的特性对胶合性能尤其是耐久性影响的研究尚少有报道。文中基于现有研究对CLT胶合界面性能影响因素进行总结,梳理对比CLT胶合性能测试方法以及胶合界面性能表征技术,并对今后研究方向提出意见和建议。     

兴安落叶松胶合木胶黏剂的选择

论述单组份聚氨酯(PURd)、双组份异氰酸酯(MDI-A和MDI-B)以及间苯二酚(PRF)4种胶黏剂对兴安落叶松胶合木耐久性和力学性能方面的影响,对比、分析不同胶合木的剪切强度和剥离率。结果表明:耐久性方面,间苯二酚类胶黏剂胶合性能明显优于聚氨酯类胶黏剂;在抗剪方面,间苯二酚胶黏剂略优于聚氨酯类胶黏剂;不同来源的同种类胶黏剂由于参数不同胶合强度存在差异。以上研究可为选择和使用胶黏剂提供技术参考。     

结构用高含水率木材的胶合研究概况

湿材胶合,即高含水率木材的胶合,在20世纪80年代初就已实现商业化。笔者介绍了国内外热固性胶黏剂、常温固化胶黏剂在高含水率木材胶合中的应用,以及单组分聚氨酯胶黏剂在结构用胶合材方面应用的研究概况,为我国结构材的研究和制造提供参考。     

高温热处理木材胶合性能的研究

笔者研究了桦木、落叶松和樟子松高温热处理材的胶合性能,并与常规干燥材进行了对比。测试结果表明木材的胶合剪切强度与所用的胶黏剂有关,聚氨酯胶合的三个树种木材的剪切强度普遍大于白乳胶胶合的木材。无论是室内用的白乳胶或室外木结构用的聚氨酯胶都能与三个树种的高温热处理材很好地胶合,胶合试件的浸渍剥离率或煮沸剥离率皆为零。木材经高温热处理后,其剪切强度均有不同程度的降低,阔叶材桦木下降幅度最大,针叶材落叶松下降幅度最小。     

木材线型胶拼技术研究

利用线型涂胶的方式对松木单板进行加压胶合。研究了不同线型施胶方式和表面处理对松木单板胶合性能的影响。研究结果表明,与传统的全界面涂胶工艺相比,线型胶拼不仅可以降低施胶量和木材的胶拼成本,而且在低施胶量的情况下可以保证松木的胶合强度;对松木进行微孔预处理,可以有效提高木材的胶拼强度。采用线型胶拼工艺制备胶合木是可行的。     

胶合木构件胶接性能及耐久性研究

以层板胶合木为研究对象,采用ASTM D1037、BS EN1087-1,CAN/CSA-0188,ASTM D3434四种人工加速老化方法对单组份聚氨酯胶黏剂胶合而成的层板胶合木构件进行处理。老化处理后,试材的胶合剪切强度下降幅度在27.8%~44.9%之间,下降程度明显高于吸水厚度膨胀率、静曲强度和弹性模量,据此建议将胶合剪切强度作为判定层板胶合木构件耐老化性能的指标。BS EN1087-1老化处理后试材的性能变化情况SASTM D1037较为相似,且用时短,认为是研究层板胶合木构件耐久性较优的人工加速老化处理方法。     

胶合木桥的设计、制备及其结构性能试验研究

在做出设计方案,包括技术条件、设计规范、材料参数及桥梁选型等的基础上,利用通用有限元软件MIDAS／Gen对木桥进行了结构分析,主要的计算工况包括全跨活荷载、半跨活荷载及人致振动等。分析结果表明,该桥的应力水平及结构刚度等均满足承载能力及正常使用要求。同时简要介绍了胶合木加工工艺及木桥的装配过程,并且通过静力堆我试验对整桥进行了结构性能测试,试验结果与有限元分析结果吻合较好。     

木结构集成材自动上下料装备研究现状与展望

木结构用集成材作为现代木结构建筑的重要材料之一，主要用于制作建筑结构的承重构件。由于木结构用集成材外形尺寸较大、质量较重，存在着人工搬运效率低、劳动强度大等弊端。为提高木结构用集成材的加工效率，国内外设计开发了适用于木结构集成材自动上下料装备。文中针对木结构集成材自动上下料装备的关键核心技术——自动上下料、码垛装置、自动上下料码垛最优轨迹规划等技术研究进行综述，指出现阶段木结构集成材自动上下料装备研究存在的问题并提出未来发展趋势。     

Shear tests of double shear plate connector joints in sugi—Japanese larch composite glulam beams

To study the shear strength of structural joints in sugi (Cryptomeria japonica D. Don) — Japanese larch (Larix kaempferi Carriere) composite glulam beams using structural connectors with double shear plates, shear tests were conducted on two types of joint (post-beam and girder-beam). Two types of the composite beam (240 and 300 mm depth) were prepared for the tests. Ordinary sugi glulam beam and Japanese larch glulam beam were also used as control specimens. The load—displacement curves of joints in composite beams were somewhere between those of sugi and Japanese larch glulam beams. The shear strength of joints in composite beams was higher than that in the sugi glulam beam control. However, the allowable loads of the joints in composite beams were lower than those in the sugi beam with 240 mm depth. Large variation of maximum load of the joints in the composite beams resulted in lower allowable load.     

Prediction of bending properties for structural glulam using optimized distributions of knot characteristics and laminar MOE

This study established a prediction model for bending properties of glued-laminated timber (glulam) using optimized knot and modulus of elasticity (MOE) distributions of lumber laminate as the main input variables. For this purpose, knot and MOE data were investigated for all pieces of lumber that were prepared for glulam manufacturing, and statistical distributions of knot size, knot number in one lumber, and MOE of each laminate were optimized as distribution functions. These knot and MOE data were used as input variables in the prediction model for bending properties, and were also used in generating virtual glulam using the inverse transform method. Prediction of bending properties for glulam was carried out using the transformed section method, which is partially provided in ASTM D 3737 (Annex A4). Predicted values were compared with those from full-scale four-point bending tests for 60 six-layered glulams with 10 different laminar combinations. Finally, the allowable bending properties of glulam for each specific laminate combination were determined by calculating the fifth percentile of the modulus of rupture and the average modulus of elasticity from virtual test results of more than 1000 virtual glulams. From the results of this study, predicted bending properties for glulam and their distributions could be used for structural design in both allowable stress design and limit state design.     

Fire resistance of sugi covering materials for structural steel

Glued laminated timbers (glulam) or planks 50mm thick were added to structural steel columns and beams as covering materials. The wood used in the glulam was sugi (Cryptomeria japonica D. Don) laminated with resorcinol resin adhesive between woods and epoxy resin adhesive between wood and steel. The 50mm thick planks of sugi around the steel were fixed with spirally threaded nails (screws), and 25mm long wood plugs were used to cover the tops of the nails. The 50mm thick glulam showed 1h of fire resistance. The temperatures of the flanges and webs of steel were 100°C at 1h and 200°C after 4h. The epoxy resin used to bond the wood and steel was an appropriate adhesive from a recycling perspective because it is easy to separate or peel from the steel.     

Theoretical and experimental deflections of glued laminated timber beams made from a tropical hardwood

Abstract

Nondestructive testing (NDT) can play an important role in improving the quality and reliability of tropical hardwood as an engineering material. By means of these methods, the stiffness of the material can be determined and the information used to improve its structural performance. Although, it is a usual approach for qualifying the material used to manufacture engineered wood products made mainly from softwoods, it is not so common for tropical hardwoods. Additionally, the lack of information regarding properties of glulam beam made from these kinds of wood is evident. In this context, the paper aimed at evaluating the theoretical and experimental deflection of glulam beams made from the Brazilian hardwood louro-vermelho (Sextonia rubra). Initially, the stiffness of each lamina was determined nondestructively using transverse vibration method (E _dtv), which has been demonstrated to be the most suitable method for this wood species. Then, ten 5-lamina glulam beams were assembled according to descending lamina E _dtv values. The experimental evaluation was performed using a four-point bending schedule. In general, the theoretical values of deflection were 2% higher than the experimental ones. The transverse vibration showed to be a suitable method to both measure lamina stiffness and predict glulam beam deflection.     

工程结构材概述

介绍了工程结构材（包括单板层积材，胶合木，定向刨花板，重组木和单板条层积材）的性质，生产和应用现状及发展前景。     

MATLAB在落叶松结构用集成材胶合工艺技术研究中的初步应用

对MATLAB在落叶松结构用集成材胶合工艺技术研究中的应用进行了初步尝试。应用MATLAB软件。通过对数据统计主成分进行分析,得到7项指标在整体效果中占有的比重,进而证明了极差分析、方差分析中根据干态剪切强度、湿态剪切强度、干态剪切木破率和湿态剪切木破率的情况来选取最佳工艺参教是可行的。     

集成材及玻璃纤维增强复合材料的发展动态研究

通过对集成材、玻璃纤维增强复合材料的国内外研究历史及现状的概述,总结了研究成果,分析了其未来的发展趋势。研究结果认为,集成材作为优良建筑木构件材料将会得到广泛的应用,玻璃纤维增强复合材料具有广阔的应用前景和发展空间,木材与玻璃纤维等极性不同材料胶合机理、胶粘剂的开发、集成材的产品标准等方面的研究将是未来的发展方向。