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Pei S.,Colorado State University | Pei S.,South Dakota State University | van de Lindt J.W.,Colorado State University | van de Lindt J.W.,University of Alabama | And 2 more authors.
Canadian Journal of Civil Engineering | Year: 2010

In July 2009, a full-scale six-storey platform wood frame apartment building was subjected to a series of earthquakes at the world's largest shake table in Miki, Japan. Two double-midply shear wall stacks were installed in the building from the first storey through to the fifth storey. A continuous anchor tie-down system (ATS) was used to prevent overturning and allow the shear walls to develop their full lateral load capacities. This paper focuses on the behavior of the stacked double-midply shear wall in a full-scale midrise building during a series of triaxial shakes scaled for the city of Los Angeles, California. The stacked midply shear wall achieved a maximum interstorey deformation of 40.4 mm (equivalent to 1.64% drift). The uplift forces measured at the bottom storey of the stacked wall exceeded 760 kN, indicating the need for substantial tie-down systems for this type of wall when utilized in a midrise platform wood frame building. Source


Zhou C.,University of British Columbia | Zhou C.,University of New Brunswick | Dai C.,2665 East Mall | Smith G.D.,University of British Columbia
Composites Part B: Engineering | Year: 2011

As a continuation of previous paper on modeling vertical density profile (VDP) formation for wood strand composites, this paper presents typical prediction results from the VDP model and describes the experimental investigations. By taking into account the non-uniform mat structure, the model can predict not only the overall panel VDP but also the localized VDP of a given area within the panel. Thus it links the horizontal density distribution to the vertical density distribution within the panel. The proposed model was validated by comparing its predictions with experimental data. Also the model can predict the effects of some key pressing parameters on VDP formation. Longer press closing times or preheating of the mat is found to make the VDP of the panel more uniform. This study is valuable for improving the fundamental understanding of the relationship between pressing variables and panel properties for process optimization. © 2011 Elsevier Ltd. All rights reserved. Source


Zhou C.,University of British Columbia | Zhou C.,University of New Brunswick | Dai C.,2665 East Mall | Smith G.D.,University of British Columbia
Composites Part B: Engineering | Year: 2011

During the manufacturing of wood composites, mats of resinated fibers, particles or strands are consolidated under heat and pressure to produce panels with the necessary strength and stiffness properties. As the mat consolidates a vertical density profile (VDP) is established and it has a significant impact on panel properties. In order to tailor the VDP of the panel to various end-use applications, a means of describing of the effect of pressing variables on the development of the VDP is needed. In this paper, a comprehensive model is established to simulate the formation of VDP for strand-based wood composites. Based on the strand compression properties during hot pressing, this model can predict the in situ formation of density profile in combination with an existing heat and mass transfer model. As a structural model, it can predict the density distributions in both horizontal and vertical directions of the panel. Also it can help clarify the importance of pressing parameters and predict the effects of these parameters on VDP formation. © 2011 Elsevier Ltd. All rights reserved. Source


Zhao Y.,University of Toronto | Yan N.,University of Toronto | Feng M.W.,2665 East Mall
Current Organic Chemistry | Year: 2013

In this study, mountain pine beetle (MPB, Dendroctonus ponderosae Hopkins) infested lodgepole pine (Pinus contorta Dougl.) barks were liquefied in phenol using sulfuric acid as the catalyst. Results showed that liquefaction conditions, such as reaction time, reaction temperature, phenol/bark ratio, and catalyst loading had significant effects on the liquefaction yield, free phenol content of the liquefied bark fraction and the properties of the unliquefied bark residues. Higher reaction temperature and prolonged reaction time not only promoted the degradation of the bark components during the liquefaction but also induced recondensation reactions among the degraded bark components. Higher phenol/bark ratio increased the bark liquefaction yield by retarding the recondensation reactions among the degraded bark components. The liquefaction yield, free phenol content in the liquefied bark fraction and residues properties were found to be mostly affected by the catalyst loading, followed by the reaction temperature, reaction time and phenol/bark ratio. © 2013 Bentham Science Publishers. Source


Pan M.,Nanjing Forestry University | Zhang S.,2665 East Mall | Zhou D.,Nanjing Forestry University
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2010

Wheat straw fiber-polypropylene (PP) composites were prepared by means of the extrusion and moulded pressing process. The effects of the wheat straw fiber content, fiber size, MAPP concentration, and temperature on the melt rheological properties of PP composites were investigated. Adding wheat straw fiber to polymer matrix can increase the melt viscosity of the PP composites. The introduction of MAPP to the system increases the flow behavior of polymer and decreases the melt viscosity. The longer the wheat straw fibers, the lower the melt viscosity, and the finer the wheat straw fibers, the higher the melt viscosity. The melt viscosity of the PP composites decreases with increasing temperature from 170°C to 190°C, and increasing shear rate from 0.01 to 0.1 s -1. Source

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