Treesearch

This article reviews the performance of wood-frame buildings in recent earthquakes, and summarizes research performed to more fully understand their seismic behavior.

Recent work has identified ethanol toxicity as a major factor preventing continuous production of ethanol at the concentrations obtainable in batch culture. In this paper we investigate the use of a continuous two-stage bioreactor design to circumvent toxic effects of ethanol. Biomass is produced via continuous culture in the first stage reactor in which ethanol concentrations are either absent or maintained at low levels. The freshly grown cells are fed into the second bioreactor in which high ethanol concentrations are produced. The steady influx of fresh cells and continuous removal of...

Information on the performance of wood-based structural composite panels under long-term load is currently needed to permit their use in engineered assemblies and systems. A broad assessment of the time-dependent properties of panels is critical for creating databases and models of the creep-rupture phenomenon that lead to reliability-based design procedures. This paper presents a broad background of information on the creep-rupture phenomenon by describing the microscopic mechanisms of creep-rupture, presenting models commonly used to describe creep deformation and time-to-failure...

Recent failures of bolted connections have raised doubts about our knowledge of their design. Some of the design criteria are based on research conducted more than 50 years ago. This paper compares results found in the literature, using the European Yield Theory as a basis of comparison, to summarize what is known about bolted-connection design and what needs further research. By putting all this information in one place we hope to help engineers and architects design safer timber buildings and structures. In general, the strength is known for a single bolt in a wood side member connection...

Timber structures require adequate connections between components. Connection design is based on the performance criterion of a single fastener. This study is part of a research effort by the Forest Products Laboratory to establish a common basis design criteria for lateral strength of dowel-type fasteners that includes nails, screws, lag screws, and bolts. A general dowel lateral strength model is determined. It depends on specificgravity, dowel diameter, minimum penetration, and load direction to the angle of grain. The model is then used to determine the diameter at which parallel- and...

This paper was prepared for anyone who wants to know more about enhancing wood’s physical properties, from the amateur wood carver to the president of a forest products company. The authors describe chemical and physical treatments of wood that enhance the strength, stiffness, water repellency, and stability of wood. Five types of treatments are described: 1. water- soluble polymers or synthetic resins that become insoluble after curing, 2. organic chemicals or cross-linking agents that bond cell wall polymers, 3. liquid monomers that polymerize in the lumen of wood cells, 4. compression...

As many of you may not be familiar with Forest Products Laboratory, allow me to introduce it to you. The Forest Products Laboratory is a Federal government laboratory of the United States Department of Agriculture and, more specifically, of the Forest Service. The Laboratory was built in Madison, Wisconsin in close cooperation with the University of Wisconsin to serve as-the national center for wood utilization research. The broad mission of Forest Products Laboratory is “to improve utilization of wood through research that leads to improved management of the timber resource, thus meeting...

In many plants, a portion of the polysaccharides appears to have a very low degree of cross-linking with aromatic polymers such as lignin or flavolans. The proportion of cross-linked units may be enriched for study by enzymatically hydrolyzing the nonbonded carbohydrates. A convenient method is described for the simultaneous analysis of sugar content and apparent chain length of the oligosaccharidic fragments remaining after enzymatic hydrolysis. The analysis assumes attachment to the phenolic polymers by nonglycosidic linkages. The hemiacetal ends of the oligosaccharidic fragments are...

In a retention and drainage control strategy, it is necessary to monitor the concentration of dissolved inorganic material and the concentration of dissolved and colloidal organic material. Conductivity is successful as a sensor to monitor inorganic material. We studied TOC as a means to monitor dissolved and colloidal organic material and found it to work well. Both conductivity and TOC have limitations, and pH, consistency, and temperature need to be controlled.

A new design criterion for wood members under combined axial and bending loads is proposed. The new equation covers biaxial bending, axial load, and water ponding. It employs Ylinen's column formula for beam or column buckling, and replaces the linear interaction equation with more accurate equations based on recent test data and results of elastic stability analysis. Despite its simplicity, the proposed criterion is more general, more rational and more accurate than the existing design criterion.