1、Designation:C1812/C1812M151Standard Practice forDesign of Journal Bearing Supports to be Used in FiberReinforced Concrete Beam Tests1This standard is issued under the fixed designation C1812/C1812M;the number immediately following the designation indicates theyear of original adoption or,in the case
2、 of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEThe designation was corrected editorially in June 2016 to conform with the units statement(1.2).1.Scope1
3、.1 This practice prescribes the design of journal-bearingtype rollers to support each end of fiber-reinforced concretebeams tested using Test Method C1399/C1399M or TestMethod C1609/C1609M.The roller design is intended toprovide a consistent and relatively low value of effectivecoefficient of fricti
4、on at the beam supports.The bearing designincorporates metal-on-metal sliding surfaces lubricated withgrease.NOTE1During the progress of a test,a crack or cracks open on theunderside of the beam between the loaded third points causing theunderside of each portion of the beam to move away from the ce
5、nter.Thedesign is intended to provide for unlimited rotation of the roller at thepoint of contact with the test beam in response to this motion.NOTE2The design of the supporting rollers is a significant factor indetermining the magnitude of the arching forces that cause error inflexural test results
6、.2Improperly designed supporting rollers can influencethe apparent flexural behavior of fiber-reinforced concrete beams.3Theeffective coefficient of friction can be determined using a method similarto that described by Bernard.41.2 UnitsThe values stated in either SI units or inch-pound units are to
7、 be regarded separately as standard.Thevalues stated in each system may not be exact equivalents;therefore,each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of t
8、hesafety 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:5C125 Terminology Relating to C
9、oncrete and Concrete Ag-gregatesC1399/C1399M Test Method for Obtaining AverageResidual-Strength of Fiber-Reinforced ConcreteC1609/C1609M Test Method for Flexural Performance ofFiber-Reinforced Concrete(Using Beam With Third-PointLoading)D4950 Classification and Specification for Automotive Ser-vice
10、Greases2.2 SAE International Standard:6J 404 Chemical Composition of SAE Alloy Steels3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice,refer toTerminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 effective coeffcient of friction,na dimensionlessra
11、tio of the horizontal force required to initiate rotation of theroller support applied at the contact point between the rollerand test beam divided by the normal force applied at the samepoint(see Fig.1).3.2.2 roller,na journal bearing capable of continuousrotation without exhibiting a significant v
12、ariation in resistanceto rotation.4.Significance and Use4.1 The presence of friction in the supporting rollers usedwhen testing a fiber-reinforced concrete beam will increase the1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct respons
13、ibility of Subcommittee C09.42 onFiber-Reinforced Concrete.Current edition approved July 1,2015.Published September 2015.DOI:10.1520/C1812_C1812M-15E01.2Zollo,R.F.,2013.“Analysis of SupportApparatus for Flexural Load-deflectionTesting:Minimizing Bias,”Journal of Testing and Evaluation,ASTM Internati
14、onal,Vol.41,No.1,pp.1-6.3Wille,K.and Parra-Montesinos,G.J.,2012.“Effect of Beam Size,CastingMethod,and Support Conditions on Flexural Behavior of Ultra-High-PerformanceFiber-Reinforced Concrete,”ACI Journal of Materials,Vol.109,No.3,pp.379-388.4Bernard,E.S.,2014.“Influence of friction in supporting
15、rollers on the apparentflexural performance of third-point loaded fibre reinforced concrete beams,”Advanced Civil Engineering Materials,ASTM International Vol.2,No.1,pp.158-176.5For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For A
16、nnual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.6Available from SAE International(SAE),400 Commonwealth Dr.,Warrendale,PA 15096,http:/aerospace.sae.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 apparent load resistance of the beam.Roller supports designedin accordance with this practice will provide a relatively lowand consistent value of friction at the supports.4.2
