2012 ASD/LRFD Manual for Engineered Wood Construction

26 M6: ROUND TIMBER POLES AND PILESM6.4 Special Design ConsiderationsWith proper detailing and protection, timber poles andpiles can perform well in a variety of environments. Onekey to proper detailing is planning for the natural shrinkageand swelling of wood products as they are subjectedto various drying and wetting cycles. While moisturechanges have the largest impact on product dimensions,some designs must also check the effects of temperature.See M4.4 for design information on dimensional changesdue to moisture and temperature.Durability issues related to piles are generally bothmore critical and more easily accommodated. Since pilesare in constant ground contact, they cannot be “insulated”from contact with moisture – thus, the standard conditionfor piles is preservatively treated. The importance of propertreatment processing of piles cannot be overemphasized.See M4.4 for more information about durability.In addition to designing to accommodate dimensionalchanges and detailing for durability, another significantissue in the planning of wood structures is that of fireperformance, which is discussed in Chapter M16.AMERICAN WOOD COUNCIL