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原文传递 EfTect of Incipient Decay in Compressive Strength and Stiffness of Timber Piles

题名：	EfTect of Incipient Decay in Compressive Strength and Stiffness of Timber Piles
作者：	R. Richard Avent, Ph.D., P.E. Vijaya K. A. Gopn, Ph D., P.E.
关键词：	timber, piles, decay, stifihess, compressive strength, chemkai analysis
摘要：	There are two key factors that control strength properties of the seemingly undamaged sections of a given pile in service. They are: (a) the amount of cellulose material in the wood; and (b) the quality of the resin bond between the wood fibers. Piles which appear to be undamaged can exhibit a significant loss in strength due to incipient damage occurring in the piles. This incipient damage is generally due to fungus infestation which is not obvious to the naked eye. If the infestation is widespread the pile could suffer a loss of the cellulose material which can explain the decrease in the strength properties. Also, the leaching of the creosote into the interior of the piles can contribute to some loss in strength. Small coupons were taken from most of the piles to determine the basic physical and mechanical properties. Several chemical analysis tests were conducted on specimens taken from pile cross-section to determine the level of creosote, lignin, holoceilulose, and the degradation of the holoceilulose. These tests were conducted in accordance with specified ASTM standards. The mechanical properties obtained from the coupon tests were compared with those obtained from the full-scale pile tests and formula for estimating the pile strength and stiffness from the coupon properties were developed. The investigation has led to the following conclusions; (1) The pile strength and stiffness are correlated to the strength and stiffness. respectively of the coupons; (2) The mechanical properties of the solid coupons are independent of their location in the pile cross-section; (3) The compressive strength of the coupons was independent of the specific gravity of the coupons; (4) The creosote level in the pile decreased towards the center of the pile;- (5) The lignin level remained unchanged across the cross section of the pile indicating that this level is not influenced by other ^ decay or the service life of the pile; (6) the holocellulose content indicates that degradation occurred in the outer portions of the pile which is most exposed to the environment; and (7) The decay level was unrelated to the compressive strength of the coupons.
报告类型：	科技报告