正交胶合木(CLT)在我国的应用前景

正交胶合木(CLT)在国内木结构行业的发展中具有潜在的推动作用,并且符合我国的绿色生态方针。本文阐述了正交胶合木的特点和国内外研究现状,展望了CLT板在国内木建筑中的应用前景。     

浅谈古建筑木结构修复中新型材料的应用

中国的古建筑作为中国建筑中的一笔重要的财富,其文化底蕴深厚,并且以独特的结构在世界独领风骚。我国大多数古典建筑的主流形式是木结构建筑,其优点是抗震性能优越以及能够起到保温的作用,但是木材由于在众多自然因素以及人文因素的作用下而发生腐蚀、变形甚至会遭到坍塌。因此,用科学的方法对古建筑进行修复和保护显得至关重要。随着科学技术的不断进步,一些新型的材料逐渐被应用到古建筑木结构的修复中去。本文简要介绍了对木结构修复的原则以及多种新型材料在木结构修复中的应用。     

复合塑料建筑模板的应用研究进展

综述了建筑模板的发展历程和使用概况。木质胶合模板、组合钢模板以及竹胶模板存在高能耗、高物耗、高污染等不同程度的弊端,而复合塑料建筑模板不仅符合绿色施工的要求,也是节约资源的一项重要措施,更是我国建筑模板行业未来的发展趋势。通过分析复合塑料建筑模板的特点及优势,指出了我国复合塑料建筑模板的巨大发展空间。因此,复合塑料建筑模板的应用前景广阔,将成为模板行业今后发展的主要方向。     

首届中国绿色轮胎安全周正式启动

<正>6月15日,首届"中国绿色轮胎安全周"在大连正式启动,拉开了为期一周的绿色轮胎安全宣传活动。这是中国橡胶工业协会首次举办的大型公益活动。本次活动的主题是"绿色环保,安全出行"。同时,首届安全周相关活动将在大连和上海两个城市展开。商务部贸易救济局、工信部原材料工业司、大连市政府等有关领导出席了首届"中国绿色轮胎安全周"的启动仪式。国内大型轮胎生产企业、原材料供应商以及     

利用天然物质胶合技术在秸秆人造板材中的应用研究

综述了人造板材生产中的无胶胶合技术的机理、种类及无胶胶合技术国内外的研究进展,还介绍了利用无胶胶合技术生产的人造板材的优势,并对无胶胶合技术未来的研究和发展提出展望。无胶胶合人造板材生产和使用过程无毒无害、环境友好,也解决了农林废弃物综合利用难题,在人造板材生产中大力发展无胶胶合技术具有重要的意义。     

菲律宾科学家用鸡毛研发新型建筑材料

菲律宾科学家创造出一种以鸡毛为原料的新复合板，这项新产品可能是亚洲建筑业的一个重大突破。据报道，新复合板是由水泥和鸡毛压缩而成的，能够取代现有的碎木胶合木板广泛用于建造房屋。由于羽毛不宜食用，因此新产品能够更好地防止白蚁的侵蚀，同时也比碎木胶合木板更能防火。该产品可用于隔板、天花板和隔热材料，但不能用作墙壁或支柱。     

大型玻璃钢板的模具设计与计算

自一九七五年至一九七九年的五年中,我们曾先后研制出七种不同规格大型玻璃钢板及相应的模具.其中钢木结构球形阳模三种,石膏水泥阴模四种。实践证明用这几种模具生产的各种玻璃钢板的质量均达到使用要求.     

金晖兆隆深化创新实践

<正>携绿色科技成果亮相2014中国国际橡塑展中国大型多元化企业山西金晖能源集团有限公司(简称"金晖集团")旗下先进塑料材料制造商——金晖兆隆高新科技有限公司,成功亮相2014中国国际塑料橡胶展,集中展示其创新的系列绿色科技成果及商业转化项目。近年来,我国因环境污染和生态破坏造成的经济损失每年高达2 000亿元,白色污染、雾霾天气等突出问题促使中国政府与民间治理环境污染,推动低碳与可持续性经济发展的意志愈发坚定。而这一需求不仅仅激发了众多国际性化工企业的积极响应,更为中国本土化工企业提供了新     

新型木结构防腐涂料的制备及性能研究

采用自制水性丙烯酸酯改性聚氨酯脂肪族交联型树脂、纳米粉体及助剂制备了一种新型的木结构防腐涂料。该涂料不但具有丙烯酸涂料具备的高耐光性、户外曝晒耐久性、耐酸碱盐腐蚀性及良好的柔韧性,而且具有聚氨酯涂料具备的抗拉伸性、优良附着力等性能。纳米粉体的引入提高了涂料的耐磨性及耐候性。最终测试结果表明:户外曝晒自然老化、耐人工合成海水盐雾腐蚀及耐磨性随着纳米氧化物含量的增加而提高,最佳的添加量为2%,实际使用效果可以防护户外木结构3~5 a。     

2014第五届中国(天津)国际绿色建筑与节能技术产品展览会

正时间:2014年9月13日—2014年9月16日地点:天津滨海国际会展中心展出内容:绿色建筑设计:规划设计、概念设计、施工设计、景观绿化设计、节能咨询、改造方案及改造设计等;环保节能房、木塑产品:低能耗环保建筑、移动模块房、轻钢结构全方位节能房建设,轻型木制住宅、原水屋、木结构景观、木结构建筑材料及构件、     

Glued joints in hardwood timber

The use of glued joints offers an option with ample aesthetic and functional possibilities in the design of wood structures. This type of joint is used since years 1970 in countries of North and Central Europe, for the design and construction of glulam (glued laminated timber) structures. This has led to diverse investigations in the experimental analysis of joints made with steel bars glued-in glulam subjected to axial loads. It led to diverse formulae of empirical base for the design of the same ones. Of these empirical formulae, the proposal of Riberholt is considered to be a pioneer. Likewise, the Eurocode 5 has included in more recent years a formula for the design of these unions, though only as an Informative Annex.From these precedents, our research equipment has developed an extensive experimental campaign directed to evaluating the adjustment of these proposals to the design of joints in elements made with hardwood saw timber. This can be of great usefulness in works of restoration, because glued joints have an enormous potential for repairing old structures.In this paper, diverse experimental campaigns made with threaded steel bars glued-in hardwood saw timber of high density are described.     

Withdrawal strength of threaded steel rods glued with epoxy in wood

In this study, the axial strength of joints made with threaded steel rods glued in timber with epoxy is investigated. Although numerous experimental studies have investigated these joints made in glued laminated timber (glulam) from softwood, experimental data concerning tests on a whole range of hardwood species are still lacking. Thus, to evaluate the influence of timber characteristics on the behaviour of the joint, test results from different species are presented and discussed in this paper. The experimental results from samples using softwood as well as high-density hardwood glued laminated timber are compared. Diverse geometries of the joint are studied in both cases. From this experimental analysis, a formula to predict the strength of the glued-in bars is proposed. The prediction of the strength is made from two parameters that are easily quantifiable the density of the timber and the slenderness of the glued joint. This model shows a good accuracy with the test results of joints made on different species both from softwood and hardwood.     

Intermittent and Continuous Drying of Red Beech Timber From the Green Condition

Intermittent and continuous schedules for drying New Zealand's indigenous red beech timber (Nothofagus fusca) from the green condition have been compared. Both schedules can be used to dry red beech with good timber quality. Continuous schedules are appropriate for use in conventional kilns, where better humidity control can be used to minimize timber degrade and equalize moisture contents. Intermittent schedules can be adapted for use in dehumidifiers, where the lower achievable humidities—often a result of poor insulation and air leakages—can be compensated for by the relaxation periods, when the fans and heaters are switched off intermittently to relieve drying-induced stresses. However, equalization cannot be easily applied in a dehumidifier. In this case, a presort of the green timber into two classes—a heartwood heavy class and a mixed heartwood light and sapwood class—would then prove beneficial to address the issue of significant timber property and green moisture content variations that occur in red beech timber.     

FRP增强胶合木梁弯曲变形的解析分析

在胶合木梁的受拉区设置纤维增强复合材料(FRP)是提高胶合木(glulam)梁结构性能的有效方法。通过力学模型分析,给出了FRP glulam简支梁变形的解析解。根据相关的力学机理并结合试验数据,对解析解进行了修正;修正系数是通过对某些参数进行回归分析得到的,将其与已有的试验结果进行对比,证实了模型具有较高精度,可以很好地模拟梁的全过程变形与刚度变化。此外,模型还广泛适用于多种常见简支梁的变形分析或刚度分析。     

The impact of defects on the capacity of timber joints with glued-in rods

Glued-in rods are an increasingly used technical solution for numerous structural applications in timber engineering, and demonstrate the potential of adhesively bonded connections. During the insertion process the adhesive fills a very narrow gap over significant anchorage contact area, raising concerns that manufacturing defects may impact the structural performance of the bonded joint, namely the possible lack of adhesion resulting from inadequate preparation of the joint on site. Previous studies on the effect of bonding defects on the capacity of bonded joints identified a nuanced relationship that depends on the ductility of the adhesive.This paper presents experimental evidence that sheds light on the relationship between defects and capacity of glued timber joints. Joints composed of softwood glulam members and mild steel glued-in threaded rods were manufactured with two types of defects likely to be encountered on-site: i) rods placed at an angle inside drill hole instead of aligned with the joint axis, and ii) rod placed against the side of the drill hole instead of fully centered. To establish performance benchmarks a first phase studied the influence of the anchorage length and the rod diameter using three different adhesives. The effect of these defects on joint capacity was investigated with three different adhesives in combination with three different rod anchorage lengths. The investigations demonstrated that joints with sufficient rod anchorage (herein 10 times the rod diameter) do not exhibit a statistically significant loss of capacity, if compared to defect free joints. These results can contribute towards better understanding of the influence that the studied parameters have on the performance on timber joints with glued-in rods, as well as to translate this information to promote the development of further applications.     

Shear tests of glulam at elevated temperatures

Experimental investigations are conducted to characterize the evolution with temperature of the shear strength of glulam wood. To realize the tests, an original specimen with cylindrical shape has been developed and justified by a numerical study. The geometry allows obtaining thermal gradient within material to represent the real combustion of timber members, while keeping constant the temperature of sheared section. The experimental programs consider various parameters such as the presence or absence of moisture and the thermal gradient within the specimen. The experimental results are discussed and analyzed. They show the correlation between the density of the material and the reduction of its strength at high temperatures. The experimental failure loads are used to evaluate the reduction factors for wood strength depending on the temperature. These factors are compared with those given by EN1995‐1‐2 for the advanced calculations methods in fire situation. The comparisons show that the reduction factors given by EN1995‐1‐2 are conservative in comparison with the experimental results. Copyright © 2014 John Wiley & Sons, Ltd.     

三聚氰胺-尿素-甲醛共缩聚树脂的性能研究

合成了三聚氰胺-尿素-甲醛(MUF)共缩聚树脂,考察了不同施胶量、固化剂用量及木材种类对胶合木性能的影响。结果表明,MUF共缩聚树脂用量为300g/m2,双面施胶,固化剂用量在1~2%时,生产的胶合木性能最优。     

GFRP-to-timber bonded joints: Adhesive selection

Recent research at the University of Queensland (UQ) has led to the development of a new type of structures called “Hybrid Fiber Reinforced Polymer (FRP)-Timber structures” (“HFT”). In HFT structures, FRP is combined with timber veneers to create high-performance, lightweight, easy-to-construct structural members. These HFT members take advantage (i) of the orthotropic properties of both, timber and FRP to orientate the fiber direction to produce optimal composite properties, and (ii) of the geometry of the cross sections to maximize the load bearing capacity for a given amount of material. While preliminary experimental work has revealed as such the effectiveness of HFT structural members, no work has been carried out so far to investigate the behavior of these HFT structures. Performance of these new HFT members relies significantly on the bond between FRP and timber. This paper presents the results of an experimental study aimed at selecting a suitable commercially available adhesive for glass fiber reinforced polymer (GFRP)-to-timber bonded joints. The experimental program included 393 single lap joint tests covering four different commercially available adhesives, two different curing temperatures, and two test methods (dry and moisture cycle tests). The test results revealed that both, polyurethane (PUR) and cross-linking polyvinyl acetate emulsion (PVAx) performed as the best under dry conditions, while PUR was shown to be superior to all other adhesives when subjected to moisture cycles. Epoxy and phenol resorcinol formaldehyde adhesive (PRF) commonly used in FRP structures and laminated timber structures, resp., were found to be less performing structural adhesives for HFT structures.     

Predicting the thermal response of timber structures in natural fires using computational ‘heat of hydration’ principles

The thermo‐physical response of timber structures in fire is complex. For this reason, debate still exists today as to the best approaches for simulating thermal response in fire using tools such as finite element analysis (FEA) modelling. Much of the debate is concerned with the thermal properties of timber, for example, conductivity, specific heat and density, at elevated temperature and how such properties should be implemented or interpreted in numerical calculations. For practitioners intending to use modelling as a fire design tool for timber buildings, guidance exists on the thermal properties of softwood in Annex B of EN 1995‐1‐2. These properties are limited for use under standard fire exposure conditions because of the way in which they were derived from calibration against focussed test data. As a result, they cannot be applied to non‐standard fires, which are more representative of real fires due to a combination of varying heating rates and the decay phase of fire development. The limitations of the standard fire test (and associated curve) are widely understood. As a result, much recent structures in fire research has focussed on the ‘performance based design’ of buildings subject to increasingly realistic fire conditions. Such an approach allows engineers to quantify the level of safety that can be achieved in a building should a fire occur. In addition, the design of buildings to withstand fires proportionate to the risks foreseen and also the geometry present results in better value buildings that are inherently more robust. For the same approaches and associated benefits to be realised for timber buildings, then a number of barriers must be overcome. The most obvious of these is engineers' ability to determine timber structure temperatures as a result of fires other than the standard fire curve. This however presents a number of challenges. Upon heating, the moisture bound within begins to evaporate, volatiles begin to flow from the heated surface and char forms. The rate of which these behaviours occur and the nature of the char that forms depends on a number of factors, but most notably the rate of heating. Upon cooling, the timber member continues to generate heat energy as the surface oxidises. As a result, any models intended to simulate temperature development must consider the relationship not only between temperature and thermo‐physical characteristics but also between heating rate and the process of heat generation. Many models have been developed for this purpose; however, they are extremely complex and are some way from being ready for implementation as design tools. This paper proposes implementing ‘heat of hydration’ routines, intended for the curing of concrete structures, to simulate the heating and cooling process in timber structures. Such routines are available in many commercial FEA software packages. The adoption of the hydration routines allows the heat generation process, as a result of oxidation, to be considered in parallel with solid phase heat transfer using apparent thermal properties. The approach is shown to be very effective in simulating temperature development in timber members subject to parametric design fires. The models developed are benchmarked against experiments conducted in the 1990s by SP Trätek. Predictably, a number of the heat generation parameters adopted are shown to depend on the fire dynamics considered. However, recommended parameters are given that provide an acceptable level of accuracy for most design purposes. Copyright © 2012 John Wiley & Sons, Ltd.     

Small-scale assessment method for the fire resistance of historic plaster system and timber structures

The primary protection against the charring of timber is ensured by protection materials. Today, there are only a limited number of materials given in design codes as fire protection materials for timber. Historic surface finish materials such as plasters have rarely been studied with respect to fire; no design values exist in the current fire part of Eurocode 5. Full-scale fire testing is costly to assess the fire performance of material combinations, thus this study presents a useful tool that is specifically tailored to evaluate the fire protection ability of materials in small-scale. A review of conducted tests demonstrate that the cone heater of a cone calorimeter is a dependable device to estimate the charring performance of protected timber specimens as the test results approximate the ones obtained from furnace tests. This work contributes to the assessment of fire resistance performance of various combinations and types of plaster systems found in existing timber buildings that often require an individual approach for an adequate fire risk analysis and design decisions to meet current fire safety regulations with respect to the load-bearing capacity and compartmentation of building structures. Increased knowledge on the fire protection performance of traditional plasters is believed to facilitate their wider use in timber buildings, primarily to preserve their significance as part of the cultural built heritage.