1、Designation:D289912Standard Practice forEstablishing Allowable Stresses for Round Timber Piles1This standard is issued under the fixed designation D2899;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A numb
2、er in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice contains procedures for establishing allow-able stresses for round timber piles starting with clear woodstrength properties.1.2 S
3、tresses established under this practice are applicable topiles conforming to the quality,straightness,spiral grain,knot,check,shake,and split provisions of Specification D25.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility
4、 of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D25 Specification for Round Timber PilesD245 Practice for Establishing Structural Grades and Re-lated
5、Allowable Properties for Visually Graded LumberD2555 Practice for Establishing Clear Wood Strength Values3.Terminology3.1 Definitions:3.1.1 allowable stressthe numeric value of pile strengththat is appropriate for use in structural analysis.3.1.2 end-bearingcompression-parallel-to-the-grain stressre
6、sulting when pile load is not carried to the soil through skinfriction.3.1.3 load sharingthe distribution of load in proportion topile stiffness.This results in piles that perform as a groupreducing effects of between-pile variability and increasingsystem reliability over that of piles which perform
7、 indepen-dently.3.1.4 skin frictionthe interaction between the pile surfaceand the soil which serves to distribute load either away from orinto a pile.A positive skin friction refers to pile loadsdistributed to the soil.Negative skin friction distributes load tothe pile when soil strata subside or c
8、onsolidate.3.2 Symbols:Ccp=adjustment for small clear compressionperp for annual ring orientation(1/1.67)Cct=conditioning factorCdol=adjustment for duration of load and factor of safetyCd=adjustment for density applied for Douglas fir andSouthern pine onlyCfs=combined adjustment for form and size(=0
9、.97)Cg=adjustment for grade characteristics applied to allspecies including bending(0.75),compression(0.93),andshear(0.50)Ch=adjustment for height in the tree(=0.96 if softwoodsand=1.0 for hardwoods)Chv=adjustment for height and for reduced variability(MOR=0.91 for softwoods,1.05 for hardwoods,C/=0.
10、91 forsoftwoods,1.05 for hardwoods,Shear=0.99 for softwoods,1.03 for hardwoods)Cls=load sharing adjustment(structural engineers option)Cs=size adjustmentCv=adjustment for shear deflection in calculation for bend-ing modulus of elasticity(=1.06)D=diameter of a round timber pileE=clear wood unseasoned
11、 average modulus of elasticityfrom Test Methods D2555MOE=modulus of elasticity(average)Fb=allowable stress for stress designated by the subscript bFc=allowable compression stress for pile tipsfc05=small clear lower 5%exclusion compression strengthin accordance with Test Methods D2555fi05=lower 5%exc
12、lusion value for stress“x”determinedusing the green,small clear strength and standard deviationvalues reported in Test Methods D2555b=stress value subscripts,c=compression parallel,cp=compression perpendicular,b=bending,v=shear4.Significance and Use4.1 This practice is intended for use by associatio
13、ns,tech-nical societies and other groups that develop national designstandards and use recommendations for round timber piles.4.2 In using allowable stresses established under this prac-tice,factors specific to each end use which may affect the1This practice is under the jurisdiction of ASTM Committ
14、ee D07 on Wood andis the direct responsibility of Subcommittee D07.04 on Pole and Pile Products.Current edition approved April 1,2012.Published April 2012.Originallyapproved in 1970 as D2899 70 T.Last previous edition approved in 2011 asD2899 11.DOI:10.1520/D2899-12.2For referenced ASTM standards,vi
15、sit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.Unit
16、ed States1 performance of the pile system shall be considered.Suchfactors include the location of the critical section,the bearingcapacity of the soil,the ability of the pile to withstand drivingforces and conditions of service.PRINCIPLES INVOLVED IN ESTABLISHINGALLOWABLE STRESSES5.Species5.1 This practice applies to any species of piles for whichclear wood strength values are given in Test Methods D2555.5.2 Where pile allowable stress is to be established for acombination of species and or regi
