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Glued laminated timber, also called glulam, is a type of structural timber product comprising a number of layers of dimensioned timber bonded together with durable, moisture-resistant structural adhesives. In North America the material providing the laminations is termed ''laminating stock'' or ''lamstock''. By laminating a number of smaller pieces of timber, a single large, strong, structural member is manufactured from smaller pieces. These structural members are used as vertical columns or horizontal beams, as well as curved, arched shapes. Glulam is readily produced in curved shapes and it is available in a range of species and appearance characteristics to meet varied end-use requirements. Connections are usually made with bolts or plain steel dowels and steel plates. Glulam optimizes the structural values of a renewable resource – wood. Because of their composition, large glulam members can be manufactured from a variety of smaller trees harvested from second- and third-growth forests and plantations. Glulam provides the strength and versatility of large wood members without relying on the old growth-dependent solid-sawn timbers. As with other engineered wood products, it reduces the overall amount of wood used when compared to solid sawn timbers by diminishing the negative impact of knots and other small defects in each component board. Glulam has much lower embodied energy than reinforced concrete and steel, although of course it does entail more embodied energy than solid timber. However, the laminating process allows timber to be used for much longer spans, heavier loads, and complex shapes. Glulam is two-thirds the weight of steel and one sixth the weight of concrete – the embodied energy to produce it is six times less than the same suitable strength of steel.〔(Timber Engineering Europe Ltd. Glulam beams ). Timberengineeringeurope.com. Retrieved on 2015-09-27.〕 Glulam can be manufactured to a variety of straight and curved configurations so it offers architects artistic freedom without sacrificing structural requirements.〔(Canadian Wood Council Glulam )〕 The high strength and stiffness of laminated timbers enable glulam beams and arches to span large distances without intermediate columns, allowing more design flexibility than with traditional timber construction. The size is limited only by transportation and handling constraints.〔(【引用サイトリンク】title=About Glulam )〕 == Glulam versus steel == A 2002 case study comparing energy use, greenhouse gas emissions and costs for roof beams found it takes two to three times more energy and six to twelve times more fossil fuels to manufacture steel beams than it does to manufacture glulam beams. It compared two options for a roof structure of a new airport in Oslo, Norway – steel beams and glulam spruce wood beams. The life cycle greenhouse gas emission is lower for the glulam beams. If they are burned at the end of their service life, more energy can be recovered than was used to manufacture them. If they are landfilled, the glulam beams result in greater greenhouse gas emissions than the steel beams. The cost of the glulam beams is slightly lower than the steel beams.〔(FPInnovations A Synthesis of Research on Wood Products and Greenhouse Gas Impacts page 61 ). Forintek.ca. Retrieved on 2015-09-27.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「glued laminated timber」の詳細全文を読む スポンサード リンク
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