Development of wooden portal frame structures with improved columns

In Japan, the lifetime cycle of most housing lasts around 20–30 years. A governing factor in this respect is poor durability due to old-fashioned use of the house. As a solution of this problem, houses can be built with a skeleton structure that allows free partition of spaces by future owners. To develop the skeleton structure effectively, multistory frames with spans of 6 to 10 m are required. For this reason, attention has been focused on the behavior of multistory timber frame structures. In this article, two types of wooden portal frame structures are proposed. Both structures have improved vertical columns with short horizontal members glued in. The aim of this study was to investigate structurally effective solutions with these types of columns. The first type of the new structure changed the location of the moment-transmitting ductile connection with the improved columns. The second type of structure used an extended panel zone. Nine portal frame specimens were tested. The stiffness values were improved by around 1.7 and 3.5 times when compared with the control, and the strength was improved by around 1.25 and 1.45 times.     

A feasibility study of using two-component polyurethane adhesive in constructing wooden structures

This investigation was conducted to determine the feasibility of using a two-component polyurethane （PUR） adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted tests to compare the shear strength and adhesion performance of PUR with polyvinyl acetate （PVAc） adhesive on block-shear specimens constructed of oriental beech （Fagus orientalis L.）, fir （Abies alba Mill.）, poplar （Populus deltoides Bartr.）, white oak （Quercus alba L.）, sycamore （Platanus orientalis L.） and white walnut （Juglans cinerea L.）. The values of the percentage of wood failure were also determined in specimens constructed with each adhesive. The highest shear strength values of both adhesives were obtained in specimens constructed of beech, while the lowest shear strength values were obtained in fir and poplar specimens. Average shear strength of the PUR adhesive was 16.5% higher than that of the PVAc adhesive. Specimens constructed of fir, poplar and sycamore were characterised by the highest percentages of wood failure, whereas the lowest average percentages of wood failure were obtained in beech and oak specimens. With the exception of oak specimens, there was no statistically significant difference between percentage of wood failure among the PUR and PVAc adhesives. Generally, the PUR adhesive showed an acceptable adhesion performance on wood materials used in our study.     

Pseudodynamic tests and earthquake response analysis of timber structures III: three-dimensional conventional wooden structures with plywood-sheathed shear walls

Pseudodynamic (PSD) tests were conducted on plywood-sheathed conventional Japanese three-dimensional (3D) wooden structures. Lateral load was applied to the edge beam of specimen structures to generate eccentricity loading. Specimens were based on a combination of shear walls with openings in the loading direction and horizontal diaphragms with different shear stiffness. The principle deformation of the horizontal diaphragm was torsion for rigid diaphragms and shear deformation for flexible diaphragms. Lumped-mass time-history earthquake response analysis was conducted on the tested structures, and additional calculations were conducted on structures with different eccentricity rates. Dynamic analyses were conducted by varying the masses and the resistance of the walls in the loading direction. The simulated peak displacement response in the loading plane agreed comparatively well with the PSD test results. The maximum displacement response on changing the wall resistant ratio showed almost the same tendency as that obtained by changing the mass ratio up to an eccentricity rate of 0.3; however, the maximum displacement response increased markedly beyond an eccentricity rate of 0.4. It was proved that the lumped-mass 3D model proposed in this study was appropriate for conducting a parameter study on the 3D dynamic behavior of timber structures.     

Pseudodynamic tests and earthquake response analysis of timber structures II: two-level conventional wooden structures with plywood sheathed shear walls

Pseudodynamic (PSD) tests were conducted on two-level timber structures with plywood-sheathed shear walls, which each had an opening of different configuration, to study the effects of the mechanical properties of the first and second levels on the earthquake response of the structure. The specimens had two-level conventional post and beam frames that were 3 m wide, 3 m deep, and 6 m high with plywood sheathings nailed on one face of the structure. The first and second levels had different opening configurations of window, door, or slit. Lateral forces were applied at the top of the first and second levels, calculating step by step the next displacement based on the North-South (NS) components of the 1940 El Centro earthquake. The test results were compared with those of the time-history earthquake response analysis using the lumped mass model and hysteresis model presented in the companion article (part I). The experimental and simulated results showed that the simulation by means of the lumped mass time-history earthquake response analysis predicted quite well the response of the first level, but tended to underestimate the response of the second level, and that the PSD tests of an individual wall system with the mass supported by that particular wall generally show a conservative estimate of the response.     

Collapsing process simulations of timber structures under dynamic loading III: numerical simulations of real-size wooden houses

In this study, we developed a new analysis method that enables numerical simulations of the collapse process of real-size wooden houses and evaluated the accuracy thereof by carrying out numerical simulations by shaking table tests. The distinct element method was adopted as the basic theory of our numerical analysis. This research is the first approach in which the extended distinct element method was used for Japanese timber post-and-beam construction. The size of the analysis model is a 5.5 m × 5.5 m, two-story real-size wooden house. The three analytical models were developed in terms of the strength of exterior mortar walls. The simulation results were compared with the shaking table test results. One of the collapsing processes of the numerical simulation corresponds well to the experiment results. Assessment of the possibility of collapse for real-size wooden houses was determined to be possible using our newly developed numerical analysis method.     

Pseudodynamic tests and earthquake response analysis of timber structures I: plywood-sheathed conventional wooden walls with opening

Pseudodynamic (PSD) lateral loading tests were conducted on conventional post and beam timber frames with plywood-sheathed shear walls to validate the dynamic model of wall panels, each with an opening of a different configuration. The lateral forces were applied step by step at the top of the wooden frames by the computer-controlled actuator, and the displacement response for the next step was computed on the basis of the input accelerogram of the 1940 El Centro earthquake scaled up to 0.4g. The test results were compared with those of the lumped mass time-history earthquake response analysis using the hysteresis model with pinching. The results of the dynamic analysis with this global model consisting of the envelope curves, unloading and reloading with pinching agreed well with the experimental results of the PSD tests of this type of earthquake record. Some parametric studies may be necessary, however, to validate the model with different earthquake records. The hysteretical parameters obtained in this study showed similar values for each of the wall panels with different opening configurations. This makes it possible to use the model and parameters for the plywood-sheathed shear walls to estimate the dynamic behavior of entire structures without conducting expensive PSD tests or shaking table tests.     

Mechano-sorptive effects in wooden material

Summary The effects on wood of simultaneous mechanical and moisture loading are studied. In order to clarify the mechano-sorptive behaviour of wood, a review of different phenomena presented in the literature is included. Based on this review a constitutive model is proposed for the case of uniaxial stress in the longitudinal direction. The validity of the model is checked independently against test results. The calculations show that the model is capable of describing the response of wood with reasonable accuracy. Simulations indicate that the response of small test specimens is more difficult to describe than that of larger beams. Some differences in behaviour are found to depend on loading mode and nature of moisture cycling. Very large and fast moisture cycles seem to give larger mechano-sorption than smaller variations. The results of the simulations show that there is a significant influence of strain on the shrinkage and swelling response.     

2009地板行业那点事

前言：2009年,对地板行业来讲,是不同寻常的一年。但究竟如何,春江水暧,企业感触最有发言权。为此,为了全景式地展现地板行业的2009年的发展态势,我们编辑部走访众多地板企业。这些企业有行业标兵,有黑马新贵,有区域强势品牌,更有新兴品牌。对于这些企业家,我们抛向了同样的采访问题。也许企业情况不一样,站在的角度不一样,我们＂回收＂的解答也不尽一致,甚至出现相左的解析。但我们在本次专题中仍然将这些声音原汁原味地收入,因为我们相信正是由于对话企业家这样的多角度、多层次、真性情的回答,客观构成了行业发展的原生态画卷。     

Hygromechanical behaviour of wooden composites

Summary The objective of this research is to study the moisture deformation of densified in technological pressing wooden composite materials. By generalizing Cosserat's couple-stress theory a structural model for determination of mid-surface strains and curvatures of composite board taking into account asymmetric structure and nonuniform distribution of moisture as well as nonlinear swelling functions of the wooden stuff and dependence of strain characteristics on moisture content is developed. On the basis of a laminate analogy the optimum flake or veneer alignment in board has been estimated for the real composite production process. According to analysis performed, the optimum alignment for hygromechanical properties may not coincide with that for mechanical properties, and for every type of loading, material with a definite structure should be used.     

Difficulties of wooden housing production sector in Brazil

ABSTRACT

This research identified the central hindrances found in Brazilian wooden housing scenario in the fields of finished product, producer, and sector. Thus, a questionnaire with three qualitative questions based on multiple-choice answers allowed investigating the difficulties faced by these producers in Brazil. This sector still faces obstacles in the three observed fields, especially for the negative aspects of house financing, housing technique certification, skilled hand labour, general costs incurred in local production, tax exemptions, public policies, utilization of wooden houses in public works, and other factors. These obstacles in wooden housing sector have created limitations of production potential and restrictions of its market. A current panorama from these obstacles was formed, which could contribute with sectoral development. Actions such as creation and institution of incentives and specific policies should consolidate as the main direction to reduce these difficulties faced by the wooden housing producers.     

木地板厂的粉尘控制研究

针对国内外对环境保护日益重视的特点，从木地板厂产生的木粉尘的特性及危害，收集和再利用3个方面简述了对木地板厂粉尘的控制。     

Thermal bridges in a prefabricated wooden house: comparison between evaluation methods

The major aim of this study was to create a numerical model of thermal bridges in a wooden structure and to discover differences between factual values of linear thermal transmittance utilized in the finite-element (FE) modelling and values given by the European normative method (EN ISO 14683). Thermal bridges of wooden structures were detected using thermocamera FLIR S65 for infrared detection. These measurements allow displaying the temperature distribution of the thermal scan and proving the positive correlation between heat flux and change in the evaluated temperatures of a thermal bridge. A three-dimensional FE model of the structure was prepared for the thermal analysis using the engineering software ANSYS Workbench 13. The transmission heat loss coefficients of a prefabricated wooden house were established based on the Czech normative method (?SN 730540-4). Linear thermal transmittance values calculated from the thermal analysis and the normative method given by EN ISO 10211 were compared. The results show that even if the transmission heat loss coefficients meet the requirements designated by standards, the real heat losses are increased by thermal bridges involved in the construction. Their influence is determined by the linear transmittance value which is usually not exactly established.     

Natural vibration analysis of clear wooden beams: a theoretical review

 In wood science, natural vibration analysis is being used to an increasing extent to characterise the longitudinal and the shear modulus of elacticity of various geometrical types of prismatic beams. A lateral or a axial percussion at one end of a beam set up on elastic support produces bending or longitudinal vibrations. Considering the hypothesis of the homogeneity of geometrical and mechanical properties of the beam, basic dynamics theorems can be applied to obtain the motion equations of longitudinal and transverse vibrations. The resolution of the differential equation for transverse motion leads to a search for solutions to the frequency equation. Because no exact analytical solution can be found, several approximate results are analysed. The application and validity range have to be defined to be able to achieve realistic results. The effects of the elastic support, the shear modulus and the height to length ratio are discussed. The conceptual bases help in understanding the analytical results and accuracy calculations can then be developed for practical applications. We present the most common theoretical models and define their validity range, application conditions, and accuracy levels with respect to measured values. Received 26 June 2000     

浅谈木粉燃烧机在林产工业中的应用

中密度纤维板、刨花板及木材加工生产过程中产生大量砂光粉尘、废料等。尤其是砂光粉尘,颗粒径一般在50um以下,若不合理利用,对环境污染特别严重,对能量也是一种浪费。本文介绍了砂光粉尘的产生、特性、危害及如何处理过程,并做了经济效益分析。     

木本植物多倍体育种研究进展

该文论述了木本植物多倍体的特征、形成途径,展望了多倍体未来发展的方向。     

木质纤维柔性地板的生产工艺

主要阐述了木质纤维柔性地板的性能及技术参数、生产工艺、市场前景与经济效益、项目产业化优势。该产品可广泛用于办公场所、公共场所及家庭住宅的地面铺装。生产过程低碳节能、对环境无污染;使用过程中无甲醛、苯等有害物质释放。其市场前景十分广阔,并具有显著的经济效益,是一种资源节约、环境友好、低碳节能的新型材料。     

The dynamics of innovation in Malaysia's wooden furniture industry: Innovation actors and linkages

As a low-tech, labour intensive and supplier-dominated industry, the wooden furniture industry's pattern of innovation is widely acknowledged as business driven. This paper's main objective is to ascertain the roles played by the various innovation actors and their linkages to the process of technological innovations in the wooden furniture industry. Empirical evidence is derived from a narrative case study of the Muar furniture cluster in Malaysia. The main findings from this study indicate that the dynamics of innovation in Malaysia's wooden furniture industry are mainly business-led and are characterised as collective innovation. In this regard, the roles played by the immediate business environment such as suppliers, customers, competitors, and retailers are of paramount importance. These innovation actors have been linked closely to firms in their surge for technological advancement. Universities and government organisations do not feature in the operations of these firms.     

伊春市一次性木质卫生筷子未来的出路

筷子是我国人民必备的餐具之一，历史悠久。随着经济的发展，生活水平的提高，人们对餐具的要求也越来越趋向于向高品位的工艺和健康卫生的方向发展。自八十年代以来，我国生产的一次性木质卫生筷子，不仅遍及全国，而且出口到日本、韩国、东南亚及港、澳、台等国家和地区。一次性木质卫生筷子厂家的大批上马，虽然在短时期内取得了一定的经济效益，但同时也给濒临枯竭的森林资源带来大量的资源浪费。为保护生态环境，使有限的资源合理配置、高效发挥作用，作对伊春市的一次性木质卫生筷子企业进行了调查，并提出了相应的解决办法。     

核桃1年生枝条的抗寒性

为了减少全国范围内不断出现的低温、晚霜等对核桃生产造成的危害,尤其是核桃栽培中普遍存在的新梢冻害现象,通过电导法和人工诱导法,对核桃1年生枝条的抗寒性做了初步研究。研究结果表明:核桃1年生枝条上各器官抗寒力表现为:木质部叶芽花芽;芽体的抗寒力在早、晚实品种间存在较大差异;成龄树枝条活性在-20℃低温时开始发生改变;不同低温伤害下早、晚实品种成龄树的枝条反应各有差异,-30℃时差异最明显。