DESIGNOrrREE STANDINGWALLS

1 A. KORFFBScCEngFIStructE MICEDESIGNOrrREESTANDINGWALLSe l/SfS' (21)'F',February1984 THEBRICKDEVELOPMENTASSOCIATIONI nformationnotes prepared in August 1995 relevant toDESIGNOF FREESTAND INGWALLSByJ .O. A. KorffBDA Design Guide 12, February 1984 IntroductionThe Designof FreestandingWallsDG12 was firstpublished by BDAin February1983 andsubsequentlyrevised to itspopularitywithdesignersandbecausemuch of theguidanceis still relevant, DG 12 is beingretained in theBDA's , Standardsand other reference material havechanged during the intervening 12 years since the guidewasreprintedin1984, and thepurposeoftheseinformationnotesis tohighlightthoseimportantreferencechange swhich have asignificantinfluenceon the use of the guide.

2 These updatedreferences willneedto befullyconsideredbydesignersin theinterpretationand use ofDG is not possible to issue a teJduralline-by-lineaddendumsheet to the guide and noattemptis being made to duecoursewhen all theessentialCodes,Standardsandotherrefer encesourceswhicharecurrentlychanginghave comeintoeffect, it is theAssociation's intention tocompletelyrevise b ilityPages 4 to 8inclusiveof DG 12provideadviceonexposure,durabilityanda ssociateddetailingconsiderationsfor the of thisguidancehas beensupersededby moreup-to-dateinformation "special" and"ordinary"qualitiesclassificationof claybricks is nowredundantand has should be made to BS39211'),BS 187(2) ,BS 4729(3) and BS 6649(13)and to BS5628:Use ofMasonry:Part3: 1985:Mat eri al s andcomponents ,designandworkm an ship(14).

3 Thoseclausesof BS5628:Part3:1985which are of particularrelevance tobrickworkmasonryare: Clause 21-ExclusionofMois tu re( and ), Clause22 -Durability, Clause 23 -Selection of mortars , furthersource ofinformationregardingdurabilityofbrickm asonryconstructionisBDAD esign Note 7-BrickworkDurability(15).W i n dLoad sDG 12deriveswind loadings in accordancewithBSCP3:ChapterV:Part2:1972: WindLoads. At the presenttime this Code is still relevant to wind loading derivation,although the current versionhas beenamendedfromthe 1972 on page11ofDG12 -BasicwindspeedInmls requiresrevisinginaccordancewith the latestamendmentof 1995 it is expected that BS 6399:Loadi n g forBulldings :Pa rt 2: 1995:Cod e ofpracticef o r windl o ad s, will be publishedby theBritishStandardsInstitution.

4 This new windload code will be acompleterevision 6399:Part2 is likely tocoexistalongsideCP3:Chapter V:Part2 for about12 months,afterwhich time CP3 willbe withdrawn. BS6399: Part2 will containspecific informationfor the derivationofwind loads on can be used in eitherthecontextof CP3:ChapterV:Part2 orBS6399:Part 2. If windloadingderivationisin accordancewithBS6399:Part2 then Table 2 (page12) of DG 12 becomesredundantwhilstFigure 7 (page18) of DG12continuesto be relevantif "p. , the designwind pressure is derived fully inaccordancewith BS6399:Part2 andincorporates theappropriatepartialfactor of safety for loading(YI)from BS 5628 (usuallyYI= ).

5 Thislatter requirementalso applies to DG12guidance in respect of the use of"p". the designwindpressure, referenced on pages 17, 18, 19,20,21and23 forunreinforcedbrickworkdesignand tosimilardesignwindpressurereferencesfor reinforcedbrickwork, (pages 26 to 34 inclusiveof DG12).StructuralMasonryDesignCodesAll references inDG12 to BS 5628:Use of Masonry:Part 1:1978:St ructuraluseof unrel nforcedmasonry,should be replaced by reference to BS 5628:UseofMasonry:Part1:1992:St ruct uraluseofunreinforcedmasonry. For brickworkfreestandingwall design toDG 12 the 1992version of BS 5628:Part1 isidentical tothe 1978 editionwith theexception that the characteristicshear strengthof unreinforcedmasonry in designationiii)mortaris reduced to (from ).

6 Page 21 ofDG12 shows ashearstrength calculationfor piers and if the revisedcharacteristicshearstrengthof N/mm2is taken into account the pier designdemonstrated remains to 34inclusiveof DG 12demonstratereinforcedbrickworkdesignus ing twoalternativemethods. The first is a permissiblestress design methodbased on CP111:Part 2:1970, while the second is limitstates based to SP91. Reference toSP91should bereplacedby BS5628:UseofMasonry:Part2:1985:Structura luse 5628:Part 2 became availableafter DG12was published. The detailed design approach andworked examples for limit states design shown in DG12from pages 29 to 34 inclusive need to be modified inrespectof therecommendationsof BS 5628: Part2:1985 ,although the basic principles of reinforcedmasonry design using this Code remain the same asthose given a forerunner to BS5628:Part amended version of BS 5628:Part 2is expected tobe publishedin the Autumn of 1995.

7 Upon publicationby the British Standards Institution this Code should besubstituted for the 1985 edition. Major changes willinclude guidance on design for durability of reinforcingsteels (cover and infill concrete quality) and changes todesignmethods for laterally loaded masonry panelsincorporating bed-jointreinforcement. References willalso be brought fully list of references on page 35 of DG12 should beamendedasfollows(others not amended remaincurrent):(1)BS3921 Standards that in due course CP3:Chapter V:Part 2is likely to be withdrawn.(10)BS5628:UseofMasonry:Part1: 1992 Standards Institution.

8 (12)Replacereferenceto SP91:1977by:BS5628:UseofMasonry:Part2:19 85 Standards that in due course BS5628:Part2:1995willsupersede BS 5628:Part 2 :(13)BS 6649 Institution.(14)BS5628:UseofMasonry:Part 3:1985:Materialsandcomponents, Standards Institution.(15)JR Harding&R A Smith. Design Note 7 BOA.(16)M Hammell&JMorton. The Design of BOA.(17)B A Haseltine&JN Tull. Handbook to BS5628:Part2:Section1:BackgroundandMater ials. 1991. BOA.(18)B A Haseltine&JN Tull. Handbook to BS5628:Part 2:Section2:ReinforcedMasonryDesign. 1992. BOA.(3)(4)(6)BS 4729:1990. Specificationfordimensionsofbricksofspec ialshapesand sizes.

9 BritishStandards reference to BS 3798:1964 which is awithdrawn standard and add in its place:BS5642:SillsandCopings:Part2:1983: Specificationforcopingsofprecastconcrete , caststone,clayware,slateandnaturalstone. British Standards additionalreference to BS6399:LoadingforBuildings:Part2:1995:Co deofpracticeforwindloads, when available from the BritishStandards following two references may be of interest andare published by BRE. They are compatible with DG12andits recommendations.(19) (20) ,DiaphragmandWidePlanFreestandingWalls. March 1994. BuildingResearch 1995eBrickDevelopmentAssociationLimitedF irst publishedFebruary1983 RevisedandreprintedFebruary1984(s e eEditor'sNoteopposite) nliSePhDCEng MIC El\lInstMDesignoffl' chi te c tu r eand Civ icDesignThe BrickDevelopmentAssociation1 INTRODUCTIONIThis docu me beenprepa redfo rthe guidanceo f civil a ndstru ctura l engineer s withthe design and useofplaina nd reinfor ced free-sta nd ing brickwalls notforming partof a ee-standingbrick walls are widely usedfor bounda rydemarcatio n.

10 Landscaping. scree ning. secur nd perly constr ucted. free-stan di ngbr ick wall shave pr ovedto beextremelydurabl e and pleasing inappeara nce. There are manyexamplesofbr ick wall s of yea rs o ld .whicha pa rt from occas iona l po int inganda tte ntion to copingrequire no other ern sta nda rds. mo stofthese by ruleofthumb. a re clea rlyove r-des since the turnofthece nt nd pa rt icu la rlyafterthe SecondWorldWa r . fina ncia lcon str aint s and the phenom en al growthofmasshou sing esta tes produced somevery unsat isfactor yexa mplesoffree-sta nd ing wallin g.