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1.
A comprehensive research project has been carried out at the Swiss Federal Institute of Technology (ETH) on the fire behaviour of timber-concrete composite slabs (Frangi and Fontana 2000). The glued laminated timber beams used for the fire tests were bonded with a one-component polyurethane (1-K-PUR) adhesive. As one fire test on a slab showed an unexpected shear failure of a glued laminated timber beam, a series of tests was carried out to study the shear behaviour of different types of adhesives at high temperatures. The first part of the paper describes the results of the shear tests at elevated temperatures, in the second part the shear test results are compared to the fire test on a slab. 相似文献
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S. Hallström 《Wood Science and Technology》1996,30(5):323-337
Summary An experimental investigation of glass fibre reinforcement of glued laminated timber beams is presented. A polyester resin is used both as matrix and adhesive between the reinforcement and the wood. The main part of the work considers beams with large holes tested in three point bending. Circular and rectangular holes, centred at quarter length of the beams make the strength of wood perpendicular to the grain become critical. Great improvements of strength are obtained with the glass fibres. A comparison between various kinds and combinations of glass fibre reinforcement is made. Further, the reinforcement applied as repair of earlier cracked beams is investigated with positive results. One series of beams without holes is reinforced and tested in four-point bending.This reseach project was initiated to improve the ability of glued laminated timber to compete with steel and concrete, in large free span constructions. The project was funded by the Nordic Industrial Fund (NI), Svenskt Limträ AB and the Swedish National Board for Industrial and Technical Development (NUTEK) 相似文献
4.
采用铜氨(胺)季铵盐(ACQ-D)防腐剂处理马尾松木材,以水性高分子异氰酸酯(API)、聚氨酯(PUR)和间苯二酚-苯酚-甲醛树脂(RPF)为胶黏剂制备防腐材胶合试样,研究胶黏剂种类和防腐剂处理浓度对马尾松胶合强度的影响。结果表明:API、PUR、RPF适用于ACQ处理马尾松的胶合,平均剪切强度和木破率均达到GB/T 26899—2011《结构用集成材》要求。胶黏剂种类对防腐材胶合强度有显著影响,表现为PUR和RPF的剪切强度优于API。与未处理材相比,ACQ处理对API胶合有负面影响,对PUR胶合有增强效应,对RPF胶合没有显著影响。在ACQ浓度为0.1%～1.0%范围内,胶合强度没有显著变化。 相似文献
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Ciprian Pîrvu Hiroaki Yoshida Masahiro Inayama Motoi Yasumura Kinji Taki 《Journal of Wood Science》2000,46(3):193-201
In past years high priority was given to developing a seismic design for wood structures, including research on the response of wood structures to earthquakes. In this study a new type of portal frame with relatively large span was developed for the traditional Japanese wooden houses with large openings at the front to strengthen the structure. Stainless steel plates coated with zinc and glued with epoxy adhesives on laminated veneer lumber (LVL) members, composed of Douglas fir veneer and bonded with phenolformaldehyde resin, were used. The connection between the frame's beam and columns and between the columns and groundsills was mechanical, with bolts. The subject of this research was to analyze strength properties and failure behavior of glued LVL metal joints used as structural components and to evaluate the response of LVL portal frames under cyclic lateral loading. The results show that portal frames using glued LVL metal plates have a good multiplier for the shear walls and may be applied to traditional Japanese structures. The equivalent viscous damping provided good energy dissipation in the frames. The joints displayed good mechanical behavior during tests; moreover, the structures demonstrated high strength, stiffness, and ductility, which are necessary for a seismic design.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society, Kouchi, April 1997; and at the 5th world conference on timber engineering. Montreux, Switzerland, August 1998 相似文献
6.
Adhesively bonding of timber structural elements provides new opportunities as it is well adapted for the anisotropic and fibrous nature of the material. Experimental and numerical investigations were carried out on adhesively bonded full-scale double-lap joints composed of timber adherends (spruce) and adhesive layers. The influence of different geometric parameters and adhesives on the joint strength was studied. The investigated geometric parameters were the thickness of the adhesive layer (0.5–2.0?mm), the overlap length (40–280?mm), and the ductility of the adhesive (using three different adhesives). It was found that the joint strength was independent of the adhesive layer thickness (for the thickness range investigated) that the joint strength increased with the overlap length up to an apparent maximum of approximately 200?mm and that strength was almost independent of the adhesive stiffness. The numerical investigation was in good agreement with the experimental results and allows for the model to be used for strength prediction of the investigated joints. 相似文献
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D. Mannes S. Sanabria M. Funk R. Wimmer K. Kranitz P. Niemz 《Wood Science and Technology》2014,48(3):591-609
In this work, the sorption and moisture diffusion behaviour of historically relevant glutin-based adhesives (i.e. bone glue, hide glue, fish glue) is characterized. The adhesive’s sorption isotherms were assessed on thin film samples revealing fundamental differences between the glutin-based adhesives and the synthetic reference adhesive (polyurethane). Furthermore, the water vapour diffusion parallel to the fibre was examined by means of neutron imaging on bonded two-layer samples of Norway spruce wood. In contrast to previous studies using neutron imaging, a new evaluation approach is presented, which allows for nonzero initial moisture conditions and takes into account and compensates for the geometry changes in the sample caused by swelling and shrinkage, thus allowing for a characterization of the diffusion behaviour within the glue line. The diffusion coefficients determined with neutron imaging were interpreted in terms of a theoretical model which takes into account the glue line microstructure. Although the diffusion coefficients were on average larger values for the glutin-based adhesives compared to the reference polyurethane adhesive, the significant variation observed in the sorption measurement is not reflected. This can partially be ascribed to excessive penetration of the adhesives into the wood substrate in fibre direction, which impedes a continuous adhesive layer. Furthermore, deformation and densification of the wood structure was assessed in the vicinity of the adhesive joint. This effect can be ascribed to the surface roughness, which results in very high local stresses leading to buckling and deformation of the tracheids. This situation is similar to that found for adhesive joints in or close to the fibre direction such as finger or butt joints. 相似文献
8.
Antonio Pantaleo Domenico Ferri Achille Pellerano 《Wood material science & engineering》2016,11(1):25-35
The research focuses on the assessment of the performances of glued laminated wood corner joints for outdoor window profiles applications, proposing a methodology to appreciate the strength of 90° tenon mortise corner joints. The rationale relies on the potential damage (i.e. breaking of the frame) that can be caused by poor glueing processes and/or typology of adhesives. There is a number of standards for assessment of wood-adhesive bonds for outdoor windows; however, there is a lack of specific standards related to glueing assessment for outdoor wood frames, which can take into account all the factors influencing the glueing quality. The proposed methodology was tested on red oak window profiles. A commercially available polyvinyl acetate-based adhesive was used for corner joints. Bending strength of 90° tenon mortise corner joints was measured and compared with maximum admissible loads on the frame to limit its deformations within admissible ranges. The test results show that the 90° tenon mortise corner joints strength exceeds the admissible load to preserve the functionality of the frame. In order to appreciate the influence of conditioning processes on adhesion, shear strength tests of the flatwise glued joint samples (bond lines of lamellae) were carried out after different conditioning processes. 相似文献
9.
Improving the thermal stability of one-component polyurethane adhesives by adding filler material 总被引：1，自引：0，他引：1
Sebastian Clauβ Karin Allenspach Joseph Gabriel Peter Niemz 《Wood Science and Technology》2011,45(2):383-388
The aim of the current study is to improve the thermal stability of one-component moisture-curing polyurethane adhesives.
The approach here tends to add suitable filler materials to the adhesive and to study the resulting effects. The investigation
covers mechanical tests to determine the shear strength of the glued wood joints according to EN 302-1 (2004). Furthermore, the distribution of the filler material within the adhesive is shown by means of environmental scanning electron
microscopy combined with energy-dispersive X-ray spectroscopy analysis. The thermal stability of the glued wood joints could
be significantly improved by adding chalk with a volume fraction of 30% to the adhesive. 相似文献
10.
Eka Mulya Alamsyah Liu Chang Nan Masaaki Yamada Kinji Taki Hiroaki Yoshida 《Journal of Wood Science》2007,53(1):40-46
To estimate the potential bonding performance of bonded wood products from tropical fast-growing tree species, a study on
the bondability of Paraserianthes falcataria L. Nielsen, Pinus merkusii Jungh et. De. Vriese, and Acacia mangium Willd from Indonesia was conducted. Two-ply laminations were produced using polyvinyl acetate emulsion (PVAc), urea formaldehyde
(UF), resorcinol formaldehyde (RF), and water-based polymer isocyanate (API) adhesives. In order to determine the bonding
performance, the block-shear test was applied according to the Japanese Agricultural Standard for structural glued laminated
timber under normal conditions and after accelerated-aging treatments. To support this study, the wettability of each wood
species was also investigated through contact-angle measurement. The results showed that the bonding performance of low-density
P. falcataria was better than that of medium-density P. merkusii and medium-density A. mangium, while the bonding performance of medium-density P. merkusii was better than that of medium-density A. mangium. Furthermore, compared with A. mangium, the small contact angle and good wettability in P. falcataria and P. merkusii result in better adhesion and more intimate contact between the wood surfaces and adhesive. 相似文献
11.
竹质工程材料及构件的研发,不仅拓展了竹材在建筑、交通和桥梁等领域的应用,而且符合我国绿色发展、清洁生产、乡村振兴战略等重大政策需求。文中阐述了以竹集成材、竹篾集成材、竹重组材为代表的3种竹质工程材料的研究进展,在此基础上梳理归纳了竹集成材梁柱、竹篾集成材梁柱、重组竹材梁柱、复合竹质梁柱构件以及双拼梁柱等5种梁柱工程构件的结构特点,并从建立竹质工程材料与构件的评价分级方法、研发梁柱用竹质工程构件的长效绿色防护技术、制定相关的规范与标准等尚需解决的几个关键技术方面提出了将来的研究展望。 相似文献
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探讨了利用速生杨木单板层积材及科技木生产实木门的可行性,介绍了杨木单板实木门的制造工艺。速生杨木单板层积材压缩率、硬度、抗弯强度、尺寸稳定性等指标均远高于普通板材,是一种很好的结构用材,可用其替代高档硬质实木使用,以提升杨木产品的科技含量和附加值。 相似文献
13.
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. 相似文献
14.
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。 相似文献
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针对落叶松集成材中的木材干燥问题,阐述太阳能-热泵联合干燥系统,并对木材干燥室进行了设计研究,实现对木材干燥中温度、湿度、空气流动、加热时间等影响木材干燥的关键因素进行全程监测和精确控制。 相似文献
16.
《Wood material science & engineering》2013,8(4):185-189
Abstract One of the main disadvantages of wood is hygroscopicity resulting from its polar character. The sorption–desorption of water causes unwanted swelling and shrinkage in wood. Thermal modification substantially reduces this inconvenient feature. Unfortunately, the same chemical changes that reduce water sorption alter the polar character of the material and result in poorer wetting of thermally treated wood by waterborne adhesives. Gluability of thermally modified beech (Fagus silvatica L.) and birch (Betula pubescens Ehrh.) wood with two commercial amino resins, melamine–urea–formaldehyde (MUF) and melamine–formaldehyde (MF), and a two-component polyurethane (PUR) adhesive was investigated. Both wood species were modified according to two temperature regimes: 160°C and 190°C. Shear strengths of the joints were then determined according to EN 205:2003 standard. The results showed that thermally modified beech and birch wood can be effectively glued not only with commercially available PUR adhesives, but also with aqueous MF and MUF resins. The resultant shear strengths of the joints were limited by the strength of the thermally modified substrate. 相似文献
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Prediction of the load carrying capacity of bolted timber joints 总被引：1，自引：0，他引：1
Failure of bolted timber joints is analyzed experimentally and numerically. In this study, the prediction of the load-carrying
capacity of dowel-type joints with one dowel under static loading is based on the analysis of fracture in wood contrarily
to most engineering methods that are based on the yield theory. Mechanical joints consist of glued laminated spruce members
and steel dowels. In the different analyzed tests, the bolt loads the wood parallel or perpendicular to the grain. The wood
member thickness is chosen sufficiently thin to avoid the fastener from presenting plastic hinges. The influences of different
structural parameters such as the dowel diameter, the edge- and end-distances are investigated. The fracture propagation analysis
is carried out with the Finite Element (FE) method in the framework of Linear Elastic Fracture Mechanics (LEFM). The only
identified parameter is the critical energy release rate in mode I (GIc). The comparison between experimental and numerical results shows that the fracture must be considered for a correct prediction
of the ultimate load and that LEFM can help to improve design codes.
Received 11 August 1997 相似文献
19.
Air-coupled ultrasound as an accurate and reproducible method for bonding assessment of glued timber
Sergio J. Sanabria Christian Mueller Juerg Neuenschwander Peter Niemz Urs Sennhauser 《Wood Science and Technology》2011,45(4):645-659
Glued timber products are widely used in construction; therefore, it is necessary to develop non-destructive bonding quality
assessment methods for long-term structural health monitoring. Air-coupled ultrasound (ACU) inspection is a novel technique,
with phenomenal improvements in reproducibility compared to traditional contact ultrasonics, unlimited scanning possibilities,
and a high potential for delamination detection in wood products. As part of an ongoing project, glued timber samples of 10 mm
thickness with artificial glue line defects were inspected. A normal through-transmission set-up with 120 kHz transducers
allowed for successful and accurate imaging of the geometry of glued and non-glued areas in all inspected objects. The influence
of wood heterogeneity and the reproducibility of ACU amplitude measurements were analysed in detail, identifying the main
sources of variation. Future work is planned for the inspection of more complex glued timber objects. 相似文献
20.
Finger-jointing green softwood: Evaluation of the interaction between polyurethane adhesive and wood
《Wood material science & engineering》2006,1(3):127-137
Existing European standards for finger-jointing of load-bearing lumber require the wood to be dried before gluing. This article presents a study on the properties of green-glued finger joints, wet wood being bonded prior to drying. Issues to consider, in comparison to finger-jointing of dry wood, are mechanical performance of the joint, absorption of the polymer by the wood in its natural/wet state, and the chemical reactions of the adhesive on contact with water. Finger-jointed samples were tested in bending, and the glue joints analysed by optical microscopy, scanning electron microscopy and microdensitometry. A patented one-component polyurethane adhesive developed for gluing-green wood which has a moisture content usually higher than 70% was used in the study. The resulting green-glued joints showed improved strength properties in comparison to dry-jointed joints. The results confirm that green-glued joints provide a wide, continuous wood/adhesive interface from one substrate to the other. The adhesive penetrates several cells deep and the density of the wood adjacent to the joint surfaces is increased. The results also indicate that the patented adhesive forms covalent bonds to the wood substrate. 相似文献