ASTM_D_6555_-_03_2014.pdf

Designation:D655503(Reapproved 2014)Standard Guide forEvaluating System Effects in Repetitive-Member WoodAssemblies1This standard is issued under the fixed designation D6555;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.INTRODUCTIONThe apparent stiffness and strength of repetitive-member wood assemblies is generally greater thanthe stiffness and strength of the members in the assembly acting alone.The enhanced performance isa result of load sharing,partial composite action,and residual capacity obtained through the joiningof members with sheathing or cladding,or by connections directly.The contributions of these effectsare quantified by comparing the response of a particular assembly under an applied load to theresponse of the members of the assembly under the same load.This guide defines the individual effectsresponsible for enhanced repetitive-member performance and provides general information on thevariables that should be considered in the evaluation of the magnitude of such performance.The influence of load sharing,composite action,and residual capacity on assembly performancevaries with assembly configuration and individual member properties,as well as other variables.Therelationship between such variables and the effects of load sharing and composite action is discussedin engineering literature.Consensus committees have recognized design stress increases forassemblies based on the contribution of these effects individually or on their combined effect.The development of a standardized approach to recognize“system effects”in the design ofrepetitive-member assemblies requires standardized analyses of the effects of assembly constructionand performance.1.Scope1.1 This guide identifies variables to consider when evalu-ating repetitive-member assembly performance for parallelframing systems.1.2 This guide defines terms commonly used to describeinteraction mechanisms.1.3 This guide discusses general approaches to quantifyingan assembly adjustment including limitations of methods andmaterials when evaluating repetitive-member assembly perfor-mance.1.4 This guide does not detail the techniques for modelingor testing repetitive-member assembly performance.1.5 The analysis and discussion presented in this guidelineare based on the assumption that a means exists for distributingapplied loads among adjacent,parallel supporting members ofthe system.1.6 Evaluation of creep effects is beyond the scope of thisguide.1.7 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:2D245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded LumberD1990 Practice for Establishing Allowable Properties forVisually-Graded Dimension Lumber from In-Grade Testsof Full-Size SpecimensD2915 Practice for Sampling and Data-Analysis for Struc-tural Wood and Wood-Based ProductsD5055 Specification for Establishing and Monitoring Struc-tural Capacities of Prefabricated Wood I-Joists1This guide is under the jurisdiction of ASTM Committee D07 on Wood and isthe direct responsibility of Subcommittee D07.05 on Wood Assemblies.Current edition approved Aug.1,2014.Published August 2014.Originallyapproved in 2000.Last previous edition approved in 2008 as D6555 03(2008).DOI:10.1520/D6555-03R14.2For 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 3.Terminology3.1 Definitions:3.1.1 composite action,ninteraction of two or more con-nected wood members that increases the effective sectionproperties over that determined for the individual members.3.1.2 element,na discrete physical piece of a membersuch as a truss chord.3.1.3 global correlation,ncorrelation of member proper-ties based on analysis of property data representative of thespecies or species group for a large defined area or regionrather than mill-by-mill or lot-by-lot data.The area representedmay be defined by political,ecological,or other boundaries.3.1.4 load sharing,ndistribution of load among adjacent,parallel members in proportion to relative member stiffness.3.1.5 member,na structural wood element or elementssuch as studs,joists,rafters,tresses,that carry load directly toassembly supports.A member may consist of one element ormultiple elements.3.1.6 parallel fr