Treesearch

While wood has been used as a building material for millennia, "mass timber" buildings have only been realized within the past few years within North America. Mass timber refers to a class of wood composites that include glue-laminated timber (glulam), structural composite lumber, and cross laminated timber (CL T). These composites allow multi-story residential and non-residential buildings to be constructed more efficiently than traditional light-framed wood systems. While there are a host of environmental and other benefits to building with mass timber, these buildings are different from...

The increasing use of cross laminated timber (CLT) panels in large multi-story buildings has highlighted the structural performance of CLT in fire as a critical issue concerning life safety and serviceability. It is well-known that wood material strength decreases when exposed to elevated temperature for an extended period of time. For CLT panels, another level of complexity lies in the mechanical properties of the glued interface under high temperature. In this study, the tensile strength of typical North American wood species and shear strength of the glued interface of commonly used...

A novel class of high performance polymer porous aerogel flm-based triboelectric nanogenerators (A-NGs) is demonstrated. The A-NGs, made of a pair of highly porous polymer flms, exhibit much higher triboelectric outputs than the corresponding dense polymer flm-based triboelectric nanogenerators (D-NGs) under the same mechanical stress. The triboelectric outputs of the A-NGs increase signifcantly with increasing porosity, which can be attributed to the increase in contact area and the electrostatic induction in the porous structure, thereby leading to additional charges on the porous...

Structural insulated panels (SIPs) were creep-tested to determine the magnitude of long-term deflection and recovery, as well as changes to strength and stiffness, compared with a control group. This report documents the second phase of a two-phase testing process. The first phase was reported in FPL–RN–0332. In this second phase, 56 SIP control specimens were tested in static bending to failure. Of these, 28 were 12 in. wide by 12.25 in. deep by 19 ft long and 28 were 12 in. wide by 6.5 in. deep by 10 ft long. A matching set of 56 specimens were instrumented for deflection and subjected...

This paper focuses on the material study (radiocarbon dating, wood identification and strontium isotope analyses) of four large ‘India occidentali’ clubs, part of the founding collections of the Ashmolean Museum, in Oxford, and originally part of John Tradescant’s ‘Ark’,in Lambeth (1656). During the seventeenth century, the term ‘India occidentali/occidentales’ referred not only to the ‘West Indies’ (its literal translation), but to the Americas as a whole; hence, the Ashmolean clubs and, indeed, the c forty examples of similarly large, decorated clubs known in international museum...

Reliability calculations for lumber products ultimately depend on the statistical distributions that we use to model lumber stiffness and strength. Fits of statistical distributions to empirical data allow researchers to estimate the probability of failure in service. For these fits to be useful, the theoretical statistical distributions must be good matches for the empirical lumber property populations. It has been common practice to assume that the MOE of a grade of lumber is well-fit by a normal distribution, and the MOR of a grade of lumber is well-fit by a normal, lognormal, or...

This work reports a study on the effects of different types and aspect ratios of cellulose nanocrystals (CNCs) on properties of poly (vinyl alcohol) (PVA) composite fibers. CNCs were extracted from wood pulp and cotton and reinforced into PVA to produce fibers by dry-jet-wet spinning. The fibers were collected as-spun and with the first stage drawing up to draw ratio 2. The elastic modulus and tensile strength of the fibers improved with increasing CNC content (5–15 wt. %) at the expense of their strain-to-failure. It was also observed that the mechanical properties of fibers reinforced...

This paper reports on the ground-contact durability of lesser-used wood species of the northeastern United States after treatment with copper-based preservatives. Stakes (19 x 19 x 457 mm) cut from balsam-fir (Abies balsamea), eastern hemlock (Tsuga canadensis), eastern spruce (mixture of Picea glauca, Picea mariana and Picea rubens), red maple (Acer rubrum) or eastern white pine (Pinus strobus) were treated with one of four concentrations of chromated copper arsenate type C (CCA-C), copper citrate (CC), alkaline copper quat type C (ACQ-C) or copper azole type A (CBA-A) and placed into the...

Impact of planetary ball milling on pre-milled wood fiber was studied to improve efficiency of energy consumption for bioconversion using post-harvest forest residuals. Crystalline cellulose decreased from 40.73% to 11.70% by ball milling. Crystallinity index of ball milled wood samples had a negative correlation with glucose yield (r=−0.97, p < .01), xylose/mannose (r=−0.96, p < .01), and a positive correlation with median particle size (r=0.77, p < .01). Range of glucose yield and xylose/mannose yield for ball milled samples was found to be 24.45–59.67% and from 11.92% to 23.82%,...

To accelerate development of new and improved wood adhesives for engineered wood products, the optimal adhesive penetration into wood needs to be better understood for specific products and applications. Adhesive penetration includes both flow of adhesives into wood micron-scale voids and infiltration into the polymer components of the wood cell wall layers. In this work, X-ray computed tomography (XCT) and X-ray fluorescence microscopy (XFM) were used to study adhesive flow and infiltration. Model wood–adhesive bondlines were made using loblolly pine(Pinus taeda)latewood substrates and...