ASTM_D_7381_-_07_2013.pdf

Designation:D738107(Reapproved 2013)Standard Practice forEstablishing Allowable Stresses for Round Timbers for Pilesfrom Tests of Full-Size Material1This standard is issued under the fixed designation D7381;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number 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 compression parallel to grain and bending stresses forround timbers used for piling,based on results from full-sizetests.NOTE1Allowable stresses for compression perpendicular to grain andshear properties are established in accordance with the provisions ofPractice D2899.1.2 Stresses established under this practice are applicable topiles conforming to the size,quality,straightness,spiral grain,knot,shake and split provisions of Specification D25.1.3 A commentary on the practice is available from ASTMInternational.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility 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 PilesD198 Test Methods of Static Tests of Lumber in StructuralSizesD245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded LumberD1036 Test Methods of Static Tests of Wood PolesD1990 Practice for Establishing Allowable Properties forVisually-Graded Dimension Lumber from In-Grade Testsof Full-Size SpecimensD2555 Practice for Establishing Clear Wood Strength ValuesD2899 Practice for Establishing Allowable Stresses forRound Timber PilesD2915 Practice for Sampling and Data-Analysis for Struc-tural Wood and Wood-Based ProductsD4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural MaterialD6555 Guide for Evaluating System Effects in Repetitive-Member Wood Assemblies3.Terminology3.1 Definitions:3.1.1 allowable stressthe numeric value of pile strengthappropriate for use in design.3.1.2 end-bearingcompression parallel to grain stressused in design when the pile load is not carried to the soilthrough skin friction.3.1.3 load sharingthe distribution of load that occurs intwo or more piles which are capped with a load-distributingelement that assures the piles deform as a group.The loaddistributed to the piles in such a group is in proportion to thestiffness of each pile.This distribution of loads to the piles inthe group reduces the effect of between pile variability andincreases system reliability over that of piles which perform assingle members.3.1.4 skin frictionthe interaction between the pile surfaceand the surrounding soil which serves to distribute load eitheraway from or into a pile.A positive skin friction refers to pileloads distributed to the soil.Negative skin friction refers toloads being distributed into the pile as a result of soilsubsidence or consolidation.3.2 Symbols:c=circumference of a round timber pileCcp=conditioning adjustmentCds=adjustment for duration of load and miscellaneousfactor of safetyCls=load sharing adjustmentCoc,Cob,Coe,Coeb,=adjustments to Fc,Fb,E and EMOEfor pile oversizing relative to Specification D25 specifiedminimum circumferences1This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.04 on Pole and Pile Products.Current edition approved April 1,2013.Published April 2013.Originallyapproved in 2007.Last previous edition approved in 2007 as D7381 07.DOI:10.1520/D7381-07R13.2For referenced ASTM standards,visit 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.United States1 Ct=adjustment of allowable compression parallel to grainstress at pile tip to critical section location LD=pile diameterEi=modulus of elasticity for individual member individualcompression parallel to grain specimenEa=average modulus of elasticity of butt and tip compres-sion parallel to grain specimens from the same pileE=sample mean modulus of elasticity in compressionE=allowable modulus of elasticity in compressionEMOEi=effective modulus of elasticity in bending for anindividual pileEMOE=sample mean effective modulus of elasticity inbendingEMOE=allowable effective modulus of elasticity in bend-ingFb=allowable stress in bendingFc=allowable stress in compression parallel to grainfcTL=compressio