Masonry Construction Manual - Masonry Details

Masonrydetails

Masonrydetails Konrad Zilch, Martin Schiitz

Wallsare notonlyenclosing, decorative elements.Theyalsohavemajorstructuraland buildingsciencefunctionsto perform.In terms of structure,we distinguishbetweenloadbearing,stiffening and non-loadbearing walls. Loadbearing wallscarryverticaland horizontal loadsand transfertheseto the subsoil.Stiffening wallsin the formof shearwallsguarantee the load-carrying capacityof the building,and in the formof crosswallsor returnwallsprovide lateralsupportto preventthe bucklingof loadbearingwalls,Therefore, theyare alwaysconwalls. sideredas loadbearing Non-loadbearing wallsgenerallyonlycarry theirownweightand havemerelyan enclosing function.Theyare not.calleduponto assistin stabilizing the buildingor to providesupportto otherloadbearing walls.However,non-loadbearingwallsmustbe ableto transferhorizontal loadsperpendicular to the face of the wall to loadbearingmembers. Thebuildingsciencefunctions of thewallare thermal(insulation and heatstorage),sound insulation, fire protection and protectionagainst drivingrain.Specialrequirements that may needto be fulfilledby a wall are protection againstwater(bothpressurized and non-pressurized), e.g.basement walls,and security functions(externalwallsof certainbuildings), Themany e.g.banks,militaryestablishments. demandsplacedon wallscan.leadto conflicts of interest,whichcan be solvedonlythrough carefuldetailingand selectionof materials. Basically, thefollowing criteriaapplywhen choosingthe type of masonry: Forfacingworkthe decisivefactorsare the surfacefinishand the strengthof the unitsor theirfrostresistanceand resistanceto mechanicaldamageand saturation. External walls,on theotherhand,areprimarily chosen depending whilefor on thermalrequirements, internalwallsit is soundinsulationand loadcarryingcapacitythatinfluence ourchoice, Whenselectingthe type of wall and type of material,otheraspectssuchas weight,opportunitiesfor rationalization on siteand the costs haveto be conof materialsand construction s i d e r e d1 3 27, 1 ,9 1 ,4 1 , 1 6 1 1 .

External walls External wallsmustbe designedand builtso thattheywithstand drivingrain.Thisrequireoccupied mentis mandatory for all buildings moreor lesspermanently by people.External wallsaredividedintosingle-and twin-leaf wall consistsof justone walls.The single-leaf wall of masonry,whereasthe twin-leafwall consistsof two parallelwallsup to 150mm apart,joinedtogetherwithwallties.As a rule, Froma theronlythe innerleafis loadbearing. mal pointof view,externalwallsare divided wallconintosingle-and double-or multi-layer wall is The masonryof a single-layer structions. wall,but apartfrom likethat of a single-leaf carryingthe loadsalsofulfilsthe necessary Thedouble-or multithermalrequirements. but the layerwall is a loadbearingconstruction masonryfulfilsonly partof the thermalrequirements.The otherlayersare madefrommaterialsthat generallyonlycontributeto the thermal wallwith insulation, e.g.single-leaf external thermalinsulationplasteringsystem.

Single-leaf external walls

The designof single-leafexternalwallsis these daysdeterminedmainlyby thermalrequire'1053paft 1, the miniments.Accordingto DIN mumthicknessfor a single-leafexternalwall is in commonly 115 mm.Thewallconstructions infig.2.4.1.Theregulations useare illustrated on thermalinsulationhaveled to the developmentof differentsolutionsto complywiththose monolithicexterregulations. So the single-leaf valnalwallwith everbetterthermalinsulation uesfor the masonryand mortarwill continueto And the be favouredfor certainapplications, useof insulatingplasterswill alsohelpto securethe use of monolithicmasonry.Adding to the loadbearingmasonry a layerof insulation allowsexternalwallsto satisfypracticallyall demands.Onlyin the caseof curtainwall facadesdo we haveto considerthe additional heatlossesvia the wallties betweenwall and facade.

Plasteredsing IeJeaf externalwalIs are builtwithoutadditionallayersof thermal insulationand are providedwitha coatof plasrendering ter on the insideand water-repellent on the outside.The renderingpreventsmoisthe masonryand subturefrom penetrating : sequentlyfreezing,and permitsthe useof masonryunits.In orderto non-frost-resistant requir:ecomplywiththe strictthermalinsulation mentsand, at the sametime,avoidunjustifiablythickwalls,whichalthoughsatisfying buildingsciencedemandsareusuallytoo and conexpensivein termsof construction sumptionof valuablespace.Suchwallsonly use masonryunitswithvery goodthermalinsuclay, lationproperlies(e.9.aeratedlightweight autoclavedaeratedconcrete,lightweig ht hollow concreteblocks,the formationof voids, cellsand slots,masonrywithoutmortarto the perpends)in conjunctionwiththermalinsulation plastersor plasteringsystems. f al]]e2.4.2showsthe thermaltransmittance valuesthat can be achievedfor masonry300., and 365 mm thick,and howthe thermalinsulation can be improvedby usinga thermalinsulationplaster. The use of thin-bedand lightweightmodars insteadof normalmortartogetherwith large-,. formatmasonryunitsand layingwithoutmortar ' to the perpendsfurtherreducesthe thermal bridgingeffectof the mortarjoints. of Thediagramsin fig.2.4.3showthe influence lengthof unitand type of perpendas well as thicknessof bed jointfor normal,LM 36 and LM 21 mortars.A medium-bedjointof LM 36 is practicallyidenticalwiththe thin-bedjoint.The or thin-bedmodarrepresents, useof lightweight in thermalinsulation a markedimorovement of the irrespective of the thermalconductivity masonryunits. In wallswith normalmortar,the thicknessof the bed jointand the lengthof the unitwith mortar to the perpendshas a noticeableeffecton the thermalconductivityof the masonry.Differ- ; enceswithinlightweightand thin-bedmodars merelyamountto the orderof magnitudeof the rangeof onethermalconductivityclass. this can be importantif, whendeterHowever',

122

i{

Externalwalls

2.4.1 Formsof single-leafexternalwalls

miningcharacteristic values,the measuredor calculatedresultfor the masonrybeingevaluatedlieson thethreshold of a class[A.1,p. 1161,

t >240

, > . 11 5

4 >115 .|f-f--

> 115

1 1 52 > 1 7 5 .t---.1+

Plastered Single-leafexternal Single-leaffacing Singleleafexternal Single-leafexternal Single-leafexternalwalls with thermalinsulamasonrywith 20 mm single-leaf wall with thermal wall with curtainwall wallwith internal tion compositesystems wall joint externalwall insulationcomposite facade insulation are.constructed frommasonryunitsperforming syslem structural and otherfunctionsbut exhibitingrelativelypoorthermalinsulationpropertiesin conjunction witha thermally insulating coating 2.4.2 fhermal transmittancevaluesfor sinole-leafmasonrv appliedto the externalwall surface.Thiswall Wallthick- Type of Rendering Designvaluefor thermalconductivityof masonry[WmK] systemis employedfor new buildingwork,as ness [mm] plaster 0.16 0.18 0.12 0.13 0.14 0.1 0.11 wellas for subsequently improving thethermal 0.52 300 LP 0.41 0.47 2 0.31 0.34 0.36 0.39 insulation of existingmasonry.The coating 0.41 WDP 4 0.33 0.34 0.38 o.27 o.29 0.31 consistsof threelayers:bondingcoat,thermal 366 0.44 LP 0.35 0.39 2 o.26 o.28 0.3 0.33 o.33 0.36 WDP 4 0.26 0.28 0.3 o.23 o.24 (hardpolystyrene insulation foamor mineral External:20 mm lightweightplaster(LP)or 40 mm thermalinsulationplaster(WDP) fibrebatts)and a two-coatplasterfinishcomlnternal:10 mm lime-dvoslJm nlaster prisingreinforcingand finalcoats. Railsystemsor dowelscreatean additionalfixingto the substrate.The heatlossescausedby thethermalbridgesformedby suchmechanicalfixingsaretakenintoaccountby increasing 2.43 fhermal conductivityof masonry in relationto thermal conductivity of masonry unit, type of mortar,thickness of thethermaltransmittance values.However,this bed jointand lengthof unit effectcan be ignoredwhenusingthermally 0.25 0.25 ootimized dowels. 12mm bedjoint As the thermalinsulationcompositesystemis 6 mm bed joint tl fullyresponsible for thethermalinsulation function,thistype of wall is oftenreferredto as a "thermoskin" and is usedwith masonrywith NM relatively lowthermalinsulation but highcomNM pressive strength(e.9.calciumsilicatemasona ,/ ry).Thissystemresultsin relatively thinwalls, LM 36: )< '/ whichgreatlybenefitsthe totalamountof inter- YF F LM 36 nalspaceavailable. vc In principle, thistypeof wallis an improvement = C _M t1 DIV = l on the thermalinsulationplasteringsystem LIV c C becauselayersof thermalinsulation with better ,/ 6 6 '// insulation valuesare used insteadof the olasE E '/ b ter. /): '= As the thermalinsulationcompositesystem .> ,/t I o b doesnot satisfythe requirement for decreasing l l tl c ! c strengthof the layersfromthe insideto the out- co o o o side,the materials usedin thethreelayers G E E E mustbe compatible in orderto avoidthe nega- o o c s (see"Plasters"). tiveconsequences Thisis F F 0.15 0.10 0.15 0.10 0.20 0.20 guaranteed by usingcompletesystems.Nevertheless,it shouldbe notedthatthistype of wall Thermalconductivityof masonry[WmK] Thermal conductivity of masonry [WmK]

v,

a

F

t

t

Masonrydetails

2,4.4 Sectionthrough375 mm single-leaffaced wall (sketchshowingprinciple) Outside

Walljointfilled withoutvoids

./tnsiae 20

-ff

-1 3 7 5 1 2.4.5 Formsof twin-leafexternalwalls Outside

lnside Cavitywall Walltie embedded >50mm Walltie with dripdisc

Outerleal

Cavity

MG ll (lla)

lnnerleaf Internalplaster > 9 0...].-....'.'.-..]T 1 6 0 < d < 1 5 O m m PaftialJillcavity wall

Loadbearing leaf Air space >40mm Internalplaster Wall tie with dripdisc >90

----T---- < 1 5 0 m m ....]T

>40

Full{illcavitywall Facing masonry MG ll (la)

>1501

-

I

r<150

Plaster-f illedcollar-jointed wall Minimal air space Plaster lnnerleaf Walltie >90 l_

't24

by the lowestunitstrengthclassusedin thewall. and attackby frostis assumedto Saturation onlyaffectthe outermasonryunitsin singleleaffaced walls.To avoidsaturationof the backing masonryin regionswith severeweather, everycourseof masonryshouldincludeat least two rowsof unitsof equalheightseparatedby a 20 mm wide walljoint (offsetin eachcourse to followthe bond)overthe full heightof the Single-leafexternal walls with curtain wall wall.Thismustbe filledwithoutvoidsusing facade lf externalwallsmadefromnon-frost-resistant waterproofmortaror, betterstill,run in liquid waterproofmortarcourseby course.By inmasonryunitsare not rendered,the external creasingthe thicknessof the walljointfrom wall can be protectedagainstthe weatherand '10 mm to 20 mm, guaranteedby the full mortar claddingto damageby addinga weatherproof becomes wallthickness filling,the minimum the outside.Thiscurtainwall can be attached eitherdirectlyto the externalwallor to external 310mm.Thisis dueto thefactthata 240mm insulation, which is thenprotectedby the venti- thickwallwouldmeanthatthe walljointcould latedcuftainwallfacade. only be formedin everysecondcourseand a continuousmoisturebarrierthe full heightof The mechanicalfixingsfor the curtainwall thewallwouldnotbe possible(seefig.2.4.4.). resultin additional heatlosseswhichcan be quiteconsiderable. Thicknesses of 375 and 500 mm are also feasible. Single-leafexternal walls with internal insulation The jointsin the exposedface- if flushpointing is not carriedout- shouldbe rakedout to a Thethermalinsulationeffectof a single-leaf depthof 15 mm and properlypointed.Subexternalwall can alsobe improvedby attaching insulationmadefrom hardpolystyrene sequentpointinghasthe advantagethat pigmentscan be addedto the pointingmortarto foamor mineralfibrebattsto the insideface. of thejoints(see"Pointing"). varythe appearance Thistype of wall is particularly suitablefor the It is very difficultto fulfilthe thermalinsulation refurbishment with of existingbuildings facingmasonry. with single-leaf requirements facadesworthyof preservation, and for those thesedaysfacingmasonryis almost roomsin newbuildingworkwhichare notper- Therefore, exclusivelybuiltas pad of a twin-leafmasonry manently heated(e.9.assemblyhalls).Owing wall. to the lossof the heatstorageeffectof the externalwalls,roomsinsulatedinternallyare quicklyheatedand storelessthermalenergy afterthe heatingis switchedoff.Condensation Twin-leaf external walls beingused problemswithinthe wall construction Twin-leafmasonryis increasingly can be a problemwith absorbentmasonry,particularly for externalwallsto achievethe necessary Thevariousfunctionsof a at junctionsbetweenfloorsand partitions.Like- thermalinsulation. wall are separatedin thistype of construction wise,the soundinsulation of adjacentrooms The leaves. to the individual and allocated can be impaired throughflankingtransmisinternal insulation innerleaf (backingmasonry)providesa solid sionscausedby unsuitable enclosureto the interiorand carriesthe vedical systems. and horizontalloads.The outerleaf (facing ihe masonryor renderedouterleaf)determines Single-leafexternalwallswithoutrendering (sing le-leaffaced wall) visualappearanceand servesas protection againstthe weatherand mechanicaldamage. The decisionto omitthe renderingfroman externalwall,i.e.the facademasonryremains Any thermalinsulationrequiredis fixedagainst the wholeof the outsideface of the innerleaf. exposed(facingbrickworketc.),dependson frostThe outerskin usesnon-efflorescent, the desiredapoearanceas well as localtradiunits resistantsolidmasonryunits.Perforated tionsand experience. The mainadvantageof - in single-or twin-leaf wallsare lesssuitablebecausetheycan become facingmasonry severelysaturated,whichcan be aggravated is the low cost of maintenance. A single-leaf facedwall consistsof an outer by possiblelackof careduringpointing. cavfac- We distinguishbetweencavity,partial-fill skinof frost-resistant, usuallysmall-format, collar-jointed ity,full{ill cavityand plaster-filled ingor engineering bricksor calciumsilicate (seefig.2.4.5). nonfacingbricksand a backingof, usually, of the innerleaf(min. frost-resistant masonryunits.The use of differ- Onlythethickness 115 mm) may be consideredin the structural ent masonry. materialsfor the backingand the the innerleafaccordWhenanalysing analysis. facingworkshouldbe avoidedbecauseof the possibledifferential deformation and the asso- ing to the simplifiedmethodof analysis,the 'l{5 of mm is onlysuitablefor buildciatedriskof cracking.Facingand backingare thickness of thantwo full storeysplusan ings of no more together together form the loadbonded and The permissiblestress attic;in addition,crosswallsmustbe provided bearingcross-section, whichmaybe usedin the designis governed for stabilitv.The minimumthicknessof the is vulnerable to mechanical damage.Apart fromthat,additionalsoftskinshavean unfavourable effecton the soundinsulation propertiesof the masonry. mustbe observed Fireorotectionreouirements whenusingflammable or notreadilyflammable thermalinsulation materials.

E{ernal walls

outerleafshouldbe 90 mm for reasonsof stabilityduringconstruction. SupporTing the outerleaf Theweightof the outerleafmustbe supported on the loadbearingleaf.The completeouter leafshouldbe supportedoverits full length (e.9.on nibs projectingfromthe floors,on steel sectionsboltedon or cast in). lf the supportis non-continuous (e.9.separatebrackets),every masonryunitmustbe supportedat bothends at the suppoftlevel. Usinga metalangleas a supportcreatesa continuous thermalbridgewhich,in the arrangement shownin 'fi7.2.4.6, meansan additionalheatflowto the outsideof 0.15 WmK [A.2]alongthe lengthof the angle. Forsupportovertwo storeysthis meansan increasein heatlossesof AU = 0.025WmrK comparedto a wallwithoutsuch supports.The influence of the supportcan be neglectedfor an outerleaf12 m high.Supportdetailswhich can no longerbe inspectedafterbeing builtin protectedagainstcorromustbe permanently sion. Outerleaves1 15 mm thickhaveorovedto be worthwhile in practice,Owingto theirgood stability, theseneedto be supportedonly every12 m in'height.Whensupportedat every secondfloor,a 115 mm outerleafcan project beyondits supportby up to one thirdof its thickness. Outerleaveslessthan115 mm thick mustbe supportedevery6 m in heightand maynot be builtmorethan20 m aboveground levelowingto theirlimitedresistanceto wind loads,Buildings comprising no morethantwo fullstoreysmayincludea triangular gableup to 4 m highwithoutanyadditional support.lf a 115mm leafis notprovidedwithflushpointing, weakeningdue to subsequentrakingout of the jointsmustbe takenintoaccount. Anchoringthe outer leaf Theouterleafis to be anchoredto the loadbearinginnerleafby meansof walltiesto preventit fromoverturning, bucklingand bulging as a resultof unequaltemperaturechanges.In addition,this anchoringservesto transferthe windloads.As the wind generatesbothpressureand suctionforces,the anchorsmustbe ableto resisttensionand compression. Wall tiesmustbe of stainlesssteelto DIN 17440. Theirshapeand dimensions mustbe as given inItg.2.4.7. Whenthe bondingof the loadbearing leafand theouterleafcoincide,thenZ-shapeties may be used.Otherwise the L-shaoeis moresuitablebecausethis can be bentto suit.lf the bedjointsof the two leavesare not in the same planeor if the outerleafis builtat a laterdate, tiesfor subsequentfixingintothe innerleafof masonryare necessary. Theuseof such anchorsis alsorecommended whenattachingan additionallayerof thermal insulation in orderto ensurethatthe insulation

is pressedtightlyagainstthe outsideface of the innerleaf. Wallties shouidbe soacedat max.500 m vertically,max.750mm horizontally. In additionto the requirements outlinedin table2.4.8,Ihree ties per metreof edge lengthare required aroundopeningsand at the cornersof the jointsand buildingas wellas alongmovement at the tops of outerleaves. The type,numberand arrangement of ties in curvedmasonryor masonrywith projections shouldbe specified, takingintoaccountthe deformation due to, for example,wind and/or temperature changes.' Table2.4.10showsthe influence of walltieson heattransmission for a numberof typicaltypes of wall.In cavitywallsthe ties are practically ineffective as thermalbridges. The useof additionallayersof insulationin the cavityincreasesthe heattransmission by up to 5% for optimum150mm thickcavityinsulation and 5 mm thickwallties;theseinfluences can be ignored.Therefore, to complywith DIN 4108part2, no analysis of thethermalbridge effecthasto be carriedout for minimumther mal insulation when usingconventional forms of fixing,e.g.wireties.Whenusinglightweight mortar,LM 36 is alwaysrequiredwhenwallties are to be builtin. Othertypesof tie are permissiblewhentheycan accommodate min.1.0kN tensionand compression at 1.0mm slipper tie.The numberof tiesmustbe increased if this valuecannotbe guaranteed,Othertypesof ties(e.9.flatsteel)and dowelledfixingsin the masonryare permissible whentheirserviceabilityis verifiedby a buildingauthoritycertificate. Walltiesshouldbe builtin so thattheycannot conveymoisturefromthe outerto the inner leaf.Thisis achievedby positioning theties horizontally and by fittinga plasticdisc (drip disc).The drip disc ensuresthatwaterpenetratingthe outerleafdoes not reachthe thermalinsulation or the loadbearing leaf,but is intercepted. Ad ditionalrequirements A dampproofcourse(dpc)shouldbe included at the bottomof the cavitybetweenthe leaves in orderto protectthe innerleafand the tloor from moisturewhichpenetratesthe outerleaf and collectsat the baseof the cavity.The damp proofcoursemustbe laidwith a fallto the outsidewithinthe cavityand horizontal underthe outerjeaf.The outerleafmustbe supportedin sucha way that it cannotslip. To do this,placethe firstrow of ties as low as possibleand ensurethatthe waterproofing complieswithDIN18195part4. Thedamp proofcourseshouldextendas far as the front edgeof the outerleafand shouldcontinue min.150mm up the innerleafon a firringpiece and be fixedto this leaf (see2.4.9). Openingsfor doors,windowsetc. in the outer leafareformedas transferstructures

2,4.6 Outer leaf supportdetails

Facing masonry

This joint sealedwith permanenlry elastic

Strips for distributing load Joinl seareo

Continuous stainless steelangle support

Movement joint

Masonrydetails

2.4.7 Wall ties for twin-leaf external masonry Plasticdisc 130 >cn

7 2.4.8 Minimumnumberand diameterof wall ties Der m2 of wall area Wallties: min. No. diameter

neitherof the followingtwo linesapply Wali sections > 12 m above groundlevel,or

distancebetween masonryreaves 70-120 mm

7 or5

4 5

A walltie diameterof 3 mm is adeouatefor a Dlaster f illedcollar-iointed wall.

2.4.9 Detailat base of twin-leaffacing masonry

I

115 >60 Tf Loadbearing leaf

MG ll (lla)

Freshair inlet,e.g. vraopen perpends '1st in and2nd courses

(e.9.individual as bracketsor steelsections), reinforcedmasonryor as lintels.The lattermay be constructedusingspecialsor in the formof camberedor semicircular arches. Referto "Jointdesign"for detailsof the arrangement of movementjoints. Cavity walls In contrastto the curtainwallfacade,in this type of wall,the cavitybetweenthe masonry to leavesmay be includedin calculations determinethe thermalinsulationbecausethe openvedicaljointsin the outerleafare not proRainwater or condensavidedfor ventilation. tion in the cavitycan drainawayor evaporate withoutcausingproblemsandwithoutthe inner leafbecomingsaturated.In addition,the cavity helpsthe outerleafto dry out faster.Thethermalinsulation is mainlydetermined by the innerleaf,although thisis usuallyonlyeconomwith innerleaveswithvery lcal in conjunction highinsulation values. The cavityshouldbe at least60 mm wide.This minimumdistanceis basedon the fact that of the air cannotbe adequatecirculation expectedif the gap is too small.However,the widthof the cavitymay be reducedto 40 mm if the mortaris struckoff flushon at leastone side of the cavlty,thus preventingmortar the cavity.The maxibridgesfrom interrupting mum distancebetweenthe two leavesis determinedby the load-carrying capacityof the wall and shouldbe no more tiesundercompression than150mm.Ventilation openings(e.9.open perpends) shouldbe includedat thetop and bottomof the cavityand at any intermediate supportsto guaranteecirculationof the air. Openingsat the bottomalsoserveto drainthe cavity(weepholes).Thisalsoappliesto spandrel panels.A totalof 7500mm2of ventilation openingsshouldbe providedfor every20 m2 of wallarea(including doorsandwindows). Thisfiguremeansthatfor a single-storey building and an outerleafof thin-formatunits everysecondperpendat the approximately baseand belowthe roofor the undersideof supportsin the outerleafmustbe leftopen. The damp proofcoursemustbe positioned exactlyin orderto preventthe masonrybelow the open perpendsbecomingsaturatedatthe baseof the wall.As watermay collectin certain areasat the base,the innerleafis to be protectedagainstrisingdamp by extending the damp proofcourseup the face of the inner leaf.Openingsmustbe at least100mm above groundlevel. Parlial-fill cavity walls Inthistypeof wallthefunctions of the individual layersare clearlydemarcatedunderoptiA layerof mumbuildingscienceconditions. thermalinsulationis attachedto the outside leafbuta ventifaceof the inner,loadbearing latedgap remainsbetweenthis and the outer and leaf.Thiscavitvmeansthat condensation

to the insidefaceof the drivingrain penetrating outerleafcan drainwithoutsaturatingthe therthe outerleaf Consequently, mal insulation. protectsthe layerof thermalinsulation against the directeffectsof the weatherand impactor material otherdamage.lf a vapour-permeable thenthe ciris usedfor the thermalinsulation, culatingair notonly driesout the outerleafbut dry,causinganyconalsokeepsthe insulation densationto evaporate. The maximumdistancebetweeninnerand outerleavesis 150mm (see"Cavitywalls"). Thisdoesnot needto be fullyexploitedif the innerleafhas good insulationproperties.But it is importantwhenthe innerleafmakesuseof masonrytypesthat exhibithighcompressive In thatcase, strengthbut lowthermalinsulation, the thermalpropertiesof the wall are provided Thiscan partly solelyby the layerof insulation. of the total compensatefor the disadvantage to necessary thicknessof the wall construction thermalinsulationpluscavity.A accommodate is the highcostof confurtherdisadvantage structingsuchwalls. Theminimum widthof the airspaceis 40 mm. lf we usethe maximumwidthof 150mm between the two leaves,we are leftwith 110 mm which However,owingto may be filledwith insulation. the unevenness of the surfacesof the two to includea reasonable leaves,it is advisable battsare tolerancein our planning.Insulating recommended; theseare buttjointedtogether andfixedby suitablemeans(e.9.clamping discson walltiesor wallanchorsetc.).Blankets,on the otherhand,tendto swellor expandand hencereducethe widthof the air they shouldnot be usedfor space.Therefore, thistypeof wall. The detailsat the top and bottomof the wall corre- ' regardingopeningsand waterproofing spondto thosefor cavitywalls. Full-fill cavity walls Theseare externalwallsin whichthe cavity betweenthe leavesis filledcompletelywith insulationmaterialin orderto increasethe value,or the cavityis omitted thermalinsulation in orderto reducethe overallthicknessof the wall.The outerleafshouldconsistof frostresistantmasonryunitsat least115 mm thick to drivingrain.The to increasethe resistance cleardistanceto the face of the loadbearing innerleafshouldnotexceed150mm.Glazed unitsor unitswith surfacecoatingsmustexhibit Thethermalinsulaenhancedfrostresistance. tion is installedbetweenthe leaveswithoutany air space.The insulationmaterialsusedmay be in the formof batts,blankets,granulates and loosematerialswhichare permanently (hydrophobic) as well as injectwater-repellent or ed cellularfoams(e.9.hardpolystyrene polyurethane), mineralwool,looseexpanded perliteor polyurethane or ureaformaldehyde resininjectedcellularfoams.Up to now,the of thesematerialshas had to be serviceabilitv

126 t

Externalwalls

2.4.10 lnfluenceof wall ties on thermaltransmittancevaluesof twin-leaf verifiedby a generalbuildingauthoritycertificate.In futurethe requirements theseinsulationmaterialshaveto meetlvill be coveredby corresponding standards. In practicalterms,it is virtuallyimpossibleto buildthe outerleafwithouta gap for the bricklayer'sfingerswhenusingbattsand blankets (notloosematerialsor injectedcellularfoams), However, this hasthe advantagethat any 1 7 5m m 1 7 5m m 1 7 5m m lnnerleaf waterwhichdoes penetratecan drainaway l. = 0.56 l. = 0.36 unhindered. 1 2 0m m 1 0 0m m Thermalinsulation Whenusedas full-fillcavityinsulation, waterl, = 0.040 l, = 0.040 proofor water-repellent 40 mm materialsdo not need 60 mm Cavity/Airspace 1 1 5m m 1 1 5m m 1 1 5m m Outer leaf to be treatedany differently to theiruse elseI = 0.81 ), = 0.81 l. = 0.81 wherewith resoectto theirthermalconductiv- Walltie 5 per m2 ity.However,full-fillcavityinsulationcan func4mmA 3mmtl) SmmA tioneffectively onlywhenthe amountof water 1.O23 0.006 0.009 penetrating 0.003 the insulationis not excessiveand, au. 0.282 0.312 1.026 aboveall,does not accumulateat certainposi- uc guaranteed tions.Thisis by ensuringthatthe outerleafis builtto a high standardof workmanship- whichmeanserectingthe masonry withfullyfilledjointscapableof transmitting stresses. Lime-cement mortarsof group ll or lla witha good stickyconsistencyare preferred.In addition,properbricklaying techniquesappropriateto the materialof the outer leafare essential(e.9.prewettinghighabsorbencyunits,reducingthe plasticityof the mortarfor low absorbencyunits).Furthermore, openingsin the outerleaftotallingat least 5000mm2per 20 m2of wallarea(including doorsand windows)mustbe includedat the baseof the wall so that any moisturethat does becometrappedin the cavityinsulation - can drainto the despitecarefulconstruction baseof the walland escapeto the outside. Mineralfibreinsulationmaterialsin the formof battsand blankets,or sheetsof foamedplastic andfoamedglassareto be fixedto the inner leafby,for example,plasticdiscsfittedto the wallties,in sucha way thatthe thicknessof the insulatlon remainsconstant.Blanketsof insulatingmaterialsare buttjointedtogetherbut the stifferbattsrequirejointsto be formed(e.9. rebate,tongueand groove)or fixedwith layers offsetso thatwatercannotpenetratethe joints. Missingsectionsof hardfoammaterials(e.9. wherewallties penetrate)mustbe made good witha suitablesealingcompound. Whenusingloosethermalinsulating materials (e.9.mineralfibregranulate,polystyrene foam beads,expandedperlite), it mustbe ensured externalwallswithoutmathematical 2.4.11 Max. permissiblesizesof infillpanelsin non-loadbearing thatthe insulatingmaterialcompletelyfillsthe uVallthicknebs Permissiblemax. size of infillpanelfor a heightabove ground levelof: cavitybetweenthe leaveswith a consistent 20to 100m 8to20m 0toBm e=1.0 e=1.0 e>2.01) packingdensityand alsothatthe drainage e=1.0 e>2.01) le>2.01) ' lm' mz m2 m2 mm openingsat the baseof wall remainunob4.0 6.0 8.0 5.0 115 12.0 8.0 structedby using,for example,a stainless 5.3 8.0 10.6 6.7 115r) 16.0 10.6 steelmesh,An inconsistent, incomplete filling 6.0 9.0 13.O 9.0 175 20.o 14.O 12.O to the cavityimpairsthe thermalinsulation 16.0 16:0 25.O 23.0 240 36.0 17.0 25.O 23.O 35.0 > 300 50.0 33.0 value.Thisis particularly so at the top of the = panel infill where e ratio of longer to shorter side of wallif the materialsettlesshortlyafterfillingor Max. permissiblesizesfor side ratios1.0 < e < 2.0 may be interpolatedlinearly. overthe courseof time,However,voidsand 1)The sizesmay be doubledfor masonryunitsof strengthclasses> 20 and ratiosM > 2.0 (whereh = heightof infill irregularities in fillingsof looseinsulating panel,| = lengthof infillpanel). 2)Permissible for masonrvunit comDressivestrenothclasses> 12 materialsand injectedfoamsare particularly

Masonrydetails

2.4.12

Slidingand elasticjointsat sides of infill panels

Jointmaskedby channel or anglesection

Wall recessedinto groove

A n c h o ri n s l o t ,e . g . of stainlesssteel

Slidingjoint at steelcolumn

Flator round bar in bed joint approx. every 400 mm

2.4.13 Detailat base of infilloanel

2,4.14 Junctionbetweeninfilloaneland timber oosl Internalplaster

Mortargroup ll or self-adhesive sealingstrips Stainlesssteelflat anchorbent to form angle Galvanizedclout nails

128

criticalas theseallowmoistureto penetrate uncheckedrightup to the innerleaf.Theonly way to avoidthls is to use provenequipment in the handsof experienced andtechniques personner. Plaster-fiIIed coIIar-jointed external waIIs makesuse of Thistype of twin-leafconstruction layerof plasterappliedto the outa continuous sidefaceof the innerleaf.Likethe cavitywall, the innerleafin thiscaseconsistsof masonry unitswith goodthermalinsulationproperties. preventswaterfrom Thistype of construction reachingthe innerleafand providesprotection againstdrivingrain.Theouterleaf(facing masonry)is erectedas closeas possibleto the plaster(gapfor bricklayer's fingers)withjoints fullyfilledwith mortar,In termsof construction thiswallis an improvement on and function, the single-leaf facedwallwithits continuous 20 mm walljoint.In contrastto the single-leaf externalwall,whichoftensuffersfromdamage to lackof carewhencastingthe attributable walljoint,plastering theoutsidefaceof the innerleafand hencethe standardof workmancoatof shipandfunctionof the continuous plastercan be easilyinspectedbeforethe the disadvantage outerleafis built.However, of thetwin-leaf wallcomparedto the single-leaf facedwallis thatthe verticalloadsmustbe to carriedsolelyby the innerleaf.Compared the cavitywall,thistypeof wallis thinneroverall.

lf a renderedouterleafis preferredto facing masonry,thenthe plastercoaton the outside innerleafmaybe omitfaceof the loadbearing, facingbricksare not necested. Frost-resistant sarywith such a renderedouterleaf. Drainage openings(e.9.weepholes)are requiredonlyat the baseof thewalltoallow waterwhichhas penetratedthe outerleafand draineddownto escape.Openingsat thetop of wall are not necessarybecauseventilationin the narrowgap betweeninnerand outerleaves Walltiesjust3 mmthick cannotbe expected. are adequateto connectthe two leaves.

walls lnternal

betweenoverlappingfittingsor attachedby way of stainlesssteelanchorsin slots(seefig. 2.4.12)in orderto achievethe slidingand elastic connection.Stripsof resilient,elastic,rotproofmaterial(e.9.mineralfibreor bitumen felt)are placedbetweeninfillpaneland adjoining component, outerand innerjointssealed joint materialor prefabricated with elastoplastic fillers.Thesidesof panelsareeasilyconnected to steelcolumnswhenthe overalldimensionsof the sectionsare selectedto suitthe thickness of the infillpanel(seefig.2.4.12). Stripsof foil are placedbetweensteelflange and mortarto achievea slidlngjoint.Mineral fibre pads betweenthe mortarand the web of the steelsectionhelpto improvesoundinsulaThetransferof forces tion and fire protection. betweenmasonryand columnis ensuredby completelyfillingthe void betweensteelsection and panelwith mortar.At the top of the panela 20 mm toleranceis generally sufficient. The gap is filledwith a soft,rotproofmaterial. Basisfor design adjoiningcomthe loadbearing According to DIN1053part1, the infillpanels Thisprevents ponentunintentionally transferringloadsto the of frameor cellularstructuresneed not be panelby way of deformation whenthe panelsare sup- non-loadbearing assessedstructurally portedon foursides(e,9.by bonding,tongue and subsequentdeflection.At the baseof the forcesfrom,for example,, and groovejointsor anchors),normalmortarof wallthe horizontal fromthe non-loadwind loads,are transferred at leastmortargrouplla or lightweightmortar comwallto the loadbearing bearingexternal LM36 or thin-bedmortaris usedand the conponentby friction.A layerof roofingfelt can be ditionsof DIN1053part1 table9 (seetable includedbetweenthewalland the loadbearing 2.4.11)aremaintained. The dimensions of the component(fig.2.4.13). infillpanelareto be takenas the cleardimenInfillpanelsto a timberframeshouldalwaysbe sionsbetweenthe supportingconstruction, Theheightsabovegroundlevelreferto the top completedwith a mortarjoint 10-20mm wide betweentimberand masonry.Thiscompenedgeof the respectiveinfillpanel.To classify in the to use satesfor tolerancesand deformations twin-leafmasonry,it is recommended to the A secureconnection timberconstruction. thethickness of the innerleafplushalfthe timberis providedby way of triangularfilletsto thicknessof the outerleafas the designwall steelnails.This In contrasttoloadbearing masonry, all sidesfixedwithstainless thickness. theconditions of table2.4.11takeintoaccount presupposesreliableadhesionbetweenmortar and masonryunits(e.9.providedby suitable the lowtensilestrengthperpendicular to the mortar the useof low-shrinkage bedjoints.Thisis possiblebecausefailureof a pretreatment, paneldoesnot leadto collapseof the entire stainlesssteelflat anchors etc.).Alternatively, structure.lf the aboveconditionsare not met or bentto forman anglecan be specifiedas a withlarge fixing,particularly mechanical openings are providedin non-loadbearing panels. externalwalls(e.9.windows,doors)which impairthe load-carrying ability,a structural is required. analysis

Non-loadbearing external walls

Gable walls

Non-loadbearing externalmasonrywallsare slab-likecomponentswhich,apartfromtheir ownweight,haveto carryloadsactingperpendicularto theirface (e.9,windloads)and loadbearing comtransfer theseto adjoining, ponents, e.g.shearwalls,floorplates.ln the structuralanalysisthey may not be takeninto accountwhenassessingthe stabilityof the buildingor as lateralrestraintto loadbearing walls.Thesewallsare popularfor the infillpanelsof frameor cellularstructuresof reinforced concrete,steelor timber.Suchpanelscan be form,withor without builtin single-or multi-leaf plaster, withadditional thermalinsulation renand/orcurtainwallfacade.Single-leaf, deredwallsmustbe min.115 mm thick,singleleaffacingmasonrymin.310mm. In a twin-leaf wallthe outerleafmustbe at least90 mm and the innerleafat least115 mm thick.

Gable wallswithoutverticalload on buildMasonrygablewallsarenecessary ingswith pitchedroofs.Withsteeproofslopes, areas suchwallscan constituteconsiderable of masonry.Coupleand collarroofsdo not transferany loadto the gablewall,which thereforeonlycarriesits ownweightand wind as nonloads.Theseshouldbe considered loadbearingexternalwalls.Theymay be or by comparisonwith analysedstructurally valuesfor infillpanelsaccordthe permissible ingto DIN1053part1 table9, providedthe gablewallis supportedat the edgesor by crosswallsor integralpiers.At the basethe wall is held in positionby the relnforcedconcreteflooreitherby meansof tensionanchors at thetop by a ring or viaadhesionandfriction, To do this,the beamor the roofconstruction. mustbe braced(e.9.timber roofconstruction or metaldiagonalbracing).The bettersolution in structuraltermsis the formationof a ring beam,whoseendsat leastmustbe connected by way of steelanchors. to the roofconstruction Thesimplersolutionis to supportthe gable wall at roof levelvia a connectionrigid in the Thisis usuallyachieved horizontal direction. by way of masonryanchors.

Connectionsto loadbearingcomponents Infillpanelsachievetheirstabilityby being The connecfixedto adjoiningcomponents. tionsmustbe ableto transferloadsactingon the infillpanelsto the loadbearingconstruction in the and alsoaccommodatedeformations Theymaybe rigidor adjoining construction. a rigidconnecslidingand elastic.However, tion,e.g. steelinserts,anchors,mortarjoints, bonding,shouldonlybe usedwhenexcessive restraintand deformation is not exoectedfrom loadbearing themasonryandthe surrounding The use of slidingconnections construction. meansthereis no opportunityto spanthe infill The wallsbetweenthe adjoiningcomponents. infillpanelis generally builtintoa groove,or

Gable walls with vertical load lf purlinsspanontothe gablewall,thena loadbearingmasonrypiercan be assumed beneaththe bearingfor the purlinas a resultof the verticalload.Apartfromcarryingthe roof the gablewall. load,thisalsostiffens the gablewall is dividedintoloadTherefore, areas.Theloadbearingand non-loadbearlng bearingsections(masonrypiers)beneaththe purlinshaveto be examinedaccordingto the moreaccuratemethodof analysis.In doingso, the clearheightof the piershouldbe usedas of load the bucklinglength.Thedistribution belowthe purlinsmay be assumedto be 60'. the mustaccommodate The roofconstruction horizontalsupportreactions,e.g. by way of diagonalbracingin the planeof the roof,arising fromthe provisionof supportto the pier. sectionsadjacentto the The non-loadbearing masonrypiersshouldbe analysedas gable wallswithoutverticalload.

lnternalwalls Loadbearing internal walls

ln the latesteditionof DIN1053pad 1, the miniwall internal for a loadbearing mumthickness has beenreducedtrom240mm to 115 mm. Thisreductionin thicknesshas resultedin a for usefulgainin floorspace,particularly buildingsin whichthe single-andtwo-storey eviThisis particularly loadsareonlyminimal. dentwhen it can be guaranteedthatthe crosssectionsof suchthinwallsare not reducedby Reducingthe minimum chasesand recesses.

129

Masonrydetails

2.4.15 Structuralloadingschemeaccordingto DIN 4103 part 1 for non-loadbearing internal partitions

--"j .:.

Horizontal load

\ --,7

Location 1: P, = 9.5 P57t Location2: P, = 1.6 L17t

wailthicknessto 115 mm has alsoallowed internalwalls,previouslyclassedas non-loadbearingon accountof theirthickness,to now be includedas loadbearing As a elements. result,stiffening to the buildingis improved, floorspansare shortened,connectionproblemsfor non-loadbearing wallsareminimized etc.ln somecircumstances, designand construction of the buildingis,on thewhole,made easier.

Location2: Locations withlargenumbersof people,e.g. largerassemblybuildingsand schools,lecture theatres,exhibitionhalls,retailpremisesand similarfacilities: horizontallineload Pz= 1.0kN/mat a heightof 900 mm abovethe baseof wall. lrrespective of location,a bracketloadof 0.4kN/mwalllength(see2.4.15)and an = 100kNm impactloadwith a forceof Euu"i" positionmustalsobe actingat an unfavourable Non-loadbearing internal walls allowedfor.The impactloadcan be causedby Whenbuiltfrommasonry,non-loadbearing a person(softimpact)or a hardobject(hard internalwalls- or non-loadbearing internalpar- impact). titions- are usuallybuiltas lightweightpartiAccordingto DIN 1055paft 3, the structural tionsin the senseof DIN1055part3. Nonfloorsuppodingsuch analysisof a loadbearing loadbearinginternalpaditionsare onlysubject- partitionsmay assume- insteadof a more - a uniformlydistributed ed to considerable windloadsin exceotional accuratecalculation wall cases,e.g.in shed-typebuildings withlarge additionalimoosedloadof 0.75kN/m'zfor plaster)< 1.0kN/m'zwall dooropeningswherethe pressure weights(including can build up insidethe building.ln suchcasestheyare areaand 1.25kN/m2for wallweights(including plaster)1.0-1.5 kN/m2wall area. to be treatedas non-loadbearing external par- Forwallweights> 1.5kN/m2wall area- or walls.Otherwise, non-loadbearing internal titionsnot subjectedto wind loadsare covered > 1.0 kN/m2wall areafor floorswithoutadequatetransversedistribution by the provisions of the loads- the of DIN4103.Therequirementsand analysesof DIN4103part 1 are not positionand magnitudeof the wall loadis to be guidelinesfor relatedto material.Construction takenintoaccountaccuratelywhenanalysing the floor. masonrypartitionsare stipulatedin DIN4103 paft 3. At presentthis standardonlyexistsin the formof an unpublisheddraft.Detailsgiven Materialsfor non-loadbearinginternalmasonry partitions hereare basedon the currentstateof knowledgewith respectto non-loadbearing masonry Onlymaterialscoveredby DINstandardsor partitionsbasedon the information may be usedfor sheetpubbuildingauthoritycertificates of masonryunits lishedby DeutscheGesellschaft fur Mauerbuildingpartitions.Partitions werksbau(GermanMasonryAssociation) or wall elementsmay use onlymortarof mortar [97, groupsll, lla or lll to DIN1053part1.Themor1721. firm in orderto Non-loadbearing internalpartitionsarewalls tar shouldnot be unnecessarily preservesufficientelasticityin the masonryto betweeninteriorspacesthat do notfulfilany Thin-bedmortar structuralfunctionfor the overallstructure,i.e. accommodatedeformation. theyare notcalleduponto stabilize the buildcoveredby buildingauthoritycertificatemay ing notto carryverticalloads.Consequently, and gaugedunits. be usedfor wallelements they may be removedwithoutadverselyaffectingthe stability of the building. Structuralanalysis An assessment of the abilityto carryhorizontal Requirements loadsaccordingto DIN4103part1 (see 'ti1.2.4.15) Apaftfromself-weightplus plasterand/or may be carriedout mathematically cladding,thesewallsmustbe ableto carry or by meansof tests.However,a mathematical lightloadsfrom bracketsand horizontal analysisis difficultbecausetensilestresses impactsfrom peopleor hardobjectsand trans- perpendicular to the bed jointmay not be fertheseloadsto adjoining, loadbearing com- takenintoaccounteventhoughtheyare preponents.Theygaintheirstabilityfrom being sentto a limitedextent. connectedto adjoining components. Maximumdimensionsthat satisfythe requireDIN4103part1 distinguishes betweenthefol- mentsof DIN4103part t havebeendeterlowinglocationsfor partitionswiththeirassoci- minedexperimentally[97]. ated loads: Thesemaximumdimensions(takenfrom[97]) aregivenin table2.4.16torvarioustypesof Location 1: masonryand supporlconditionsaccordingto Locations withlownumbersof people,e.g. location, thickness and height.Designers housing,hotels,offices,hospitalpatient adheringto thesedimensionsdo not needto accommodation and interiorswith similarfunc- carry
130

d

walls lnternal

internalpaftitionsof man-mademasonryunits 2,4.16 Max, dimensionsfor non-loadbearing Thetype of junctionbetweena partitionand thefloorabovedetermines whetherany load is Supported on Supportedon 3 sides Suppodedon fromthe floorto that partition. transferred 3 sideswith unwith 1 unsupported 4 sides supportedtop Therefore, we distinguishbetweenpartitions edge withand withoutverticalloading.Reinforced ratios concretefloorswith high slenderness Max. dimensionsfor walls suoportedon 4 sidesl)withoutverticalload'z) requireus to assumepartitionswith vertical Max.wall length[m] for wall height[m] for location1 (uppervalue)and location2 (lowervalue) d [mm] loading. Theminimum thickness of 50 mm in AA 4.O 3.5 3.0 2.5 h Iml thetablesis basedon practicalconsiderations. 50 4.O 3.5 3.0 Themaximumwall lengthis restrictedto 12 m 2.5 t.c 2.O /q 5.5 5.0 4.0 60 in orderto limitcracking.Loadtransferon 3.5 2.5 3.0 threesidesmay be assumedup to a 7.O 6.5 6.0 5.5 5.0 70 heighVlength ratioof h/l < 0.66.Smallerratios meanthatthe partitionis supportedonlytop 9o 5.5 5.0 4.s 4.O 3.5 and bottom.In this casetheremustbe a mortar jointbetweentop of wall and undersideof 7.0 6.5 6.0 5.5 5.0 floorslab. 10 . 0 10 . 0 10.0 10 . 0 10.0 \,6di^.1

6.0

Designand construction rules Following the recommendations belowwillhelp internal ensuregood qualitynon-loadbearing partitions:

6.5

odd6

7.O

7.5

8.0

8.0 7.5 7.O 6.0 6.5 no restrictionon length 12.O 12.0 12.0 12.O 12.0 1 ) T h e m a x . w a ll le n g t h s a r e t o b e h a l v e d f o r w a l l s s u p p o r l e d o n S s i d e su( 1n s u p p o r t e d v e r t i ceadl g e ) . 2)The valuesgiven hereapply to calciumsilicateand autoclavedaeratedconcreteunitswhen using MG lll or thin-bed mortar,Forwallthicknesses< 175 mm and MG llor lla, the valuesareto be halvedwhen usingthesetypesof masonryunits. 175

. Max.finalfloorslab deflectionl,/500 (lt= eQuivalent spandependingon structural system). Max. dimensionsfor walls suoportedon 4 sidesl)with verticalload2; . Reducethe floorslab deflectiondue to creep d Max.wall length[m] for wall lmml 4.5 4.0 andshrinkage by adheringto strikingtimes 3.5 3.0 2.5 h tml 6.5 6.0 and subsequently treatingthe concrete. 5.5 50 ' Buildnon-loadbearing 3.5 2.5 internalpartitionsafter 7.0 6.0 completionof the primarystructurewhenever 60 5.0 4.5 4.0 possibleso thatthe majorityof deformations 9.5 9.0 8.5 8.0 70 7.5 7.0 6.5 b.c o.u resultingfromshrinkageand creepof the 12.0 12.O 12.O 12.O 12.O 90 loadbearing construction are alreadycom9.0 8.5 8.0 7.5 7.O pleted.At the very least,the topmostcourse 12.O 12.O 12.O 12.0 12.O 100 of masonryunitsand the plasteringshouldbe 10.0 9.5 9.0 8.5 8.0 no restrictionon length carriedout as lateas possiblein orderto min- t t c 12.O 12.0 12.0 12.O imizethe riskof cracks. no restrictionon length 120 . Erectnon-loadbearing partitionsin sucha 12.0 12.O waythatfloorslab deformation due to the no restrictionon lenqth 175 1)The max.wall lengthsare to be halvedfor walls supportedon 3 sides (1 unsupportedverticaledge). weightof such partitionsdoes not introduce 2)The valuesgiven here apply to calciumsilicateand autoclavedaeratedconcreteunitswhen using MG lll or thin-bed anyadditional loadsintonon-loadbearing mortar,and also for MG ll or lla with wall thicknesses> 100 mm. Forwall thicknesses< 100 rpm and MG ll or lla, the partitionsin the storeybelow(if possible,start valuesare to be halvedwhen usingthesetypes of masonryunits. in the topmoststoreyand workdown). floorspanof l, = 7.66t, u Upto an equivalent partitioncan carrya load by non-loadbearing wayof archingactionwithoutdamage,providingthe recommendations are followedand it is guaranteed thatthe horizontal thrustcan be carriedby the supportsat the endsof the wall. Largerspansrequireadditionalmeasuresto be taken,e.g. separatingthe baseof wallfrom thefloorslabby meansof sandedbuilding paperor reinforcing the areasof wall at riskof cracking.

Max. dimensionsfor walls supportedon 3 sideswithoutverticalloadl)(top edge unsupported) dtmn'[ l v l a xw a l ll e n g t h [ m ]f o r w a l lh e i g h t [ m ]f o r l o c a t i o n l ( u p p e r v a l u ea) n d l o c a t i o n 2 ( l o w e r v a l u e ) AA 4.O 3.5 3.0 2.5 2.25 h Iml 2.0 6 4 5 3.5 3.0 50 t.c 2.5 2.O 9.0 8.0 7.O 6.0 5.5 60 5.0 4.O 3.5 3.0 2.5 2.5 10.0 10.0 10.0 9.0 8.0 7.O 7.5 70 7.O 6.0 5.0 4.O 3.5 3.5 12.O 12.O 10.0 10.0 9.0 8.5 90 8.0 9.0 8.0 7.O 6.0 5.0 4.O 4.0 12.O 12.O 12.O 12.0 10.0 10.0 10.0 100

115 1zo

5.0 11.5 6.0 a.0

5.0 8.0 6.0 9.0 6.0

6.0 9.0 7.0 10.0

7.0 10.0 8.0 12.O

8.0 10.0 9.0 12.O

9.0 12.0 1o.o 12.O

10.0 120 19.q 12.0

10.0 10.0 9.0 7,O 8.0 6.0 no restrictionon length 120.. 12.0 12.0. 12.0 10.0 9.0 8.0 @tomasonryunitSofc|ayorlightWeightconcreteWithnorma|mortaraSWe||aS autoclavedaeratedconcreteblocksor calciumsilicateunitswith thin-bedmodaror mortarsof mortargroup lll. When using unitsof autoclavedaeratedconcreteand calciumsilicatewith normalmortar,reducethe max.wall lengthsas follows:a) for walls56 and 70 mm thick reduceto 40%; b) for walls90 and 100 mm thick reduceto 50%; c) for walls 115 and 120 mm thick in location2 reduceto 50% (no reductionfor location1). The unitsshouldbe prewettedwhen using mortargroup lll. 175

131

Masonrydetails

2 . 4 . 1 7 S l i d i n gj o i n td e t a i l s Slidingjointsbetweenwalls

JTr*ro"n beadoredse ]

chamfered with trowel

Cast-in dovetail slot Mineralwool or similar

Anchor position can be adjusted veftically Elastoplastic seal

Slidingjointat undersideof floor

Mineralwool or similar* Aluminium or steel section as

- Incombustible materialif requiredto complywith fire protectionregulations

Slidingjointat intermediatecolumn lMortar Mineralfibre

Slidinglayer, Flator round bar in bed ioinl e.g. foil strip approx.every400 mm

Junctionswith adjoining,loadbearing components musttakeaccountof the possible Connections influencethat deformations in adjoiningcomponentsmay haveon the internalpartition. Accordingto DIN4103part'1, the serviceabilityof junctions mustbe guaranteed. Thejunctiondetailsshownin figs.2.4.'17 and 2.4.18do notnormally requirefurtherassessment. Rigidjunctions arethosewhicharefullybonded, filledwithmortaror employsimilarmeasures(anchors,dowelsor steelinserts).Such detailsare usedfor wallswhereno or very low restraintforcesfromthe adjoiningmembers are expectedto act on the wall. Rigidlateralconnectionsare usuallylimitedto (walllength| < 5.0 m).A rigid housebuilding junctionbetweentop of wall and undersideof floorslabcan be achievedby fillingthejoint with mortar,Introducinga stripof hardfoam reducesthe influenceof the deformation of the adjoiningloadbearing construction, but guaranteesthe transferof horizontal forcesdue to the hardfoamstrip beingcompressedas the floorslab deflects. Slidingjunctions are particularly suitablefor applicationswhereit is necessaryto reduce the riskof crackingdue to unintentional forces beingintroduced intothe non-loadbearing internalpartitionas a resultof the deformation of adjoiningcomponents. Slidingconnections areachievedby usingprofiles,groovesand stainlesssteelanchorsin slots,maybewiththe additionof foilto createa s l i d i n gb e a r i n g Thejointshouldbe filledwithmineralwoolin orderto improvefire protectionand sound (see"Non-loadbearing insulation external walls").

or recesses.In all othercases,the safetyfactor is increased to 1, = 2.5. The reductionfactoris consequently defined as ki = 2.0/2.5= 0.8.The useof divided masonryunitsor dividedunitswith> 35% perforationsmakesthe columnsmorevulnerable to irregularities and flawsin the construetion. for Unlikewalls,thesecannotbe compensated partsof the cross-section and by neighbouring so this high riskof structuralfailurehasto be takenintoaccountby way of an increased safetyfactor.

Free-standing masonry walls

masonrywall The problemof the free-standing is that it is suppodedonlyat its base,and so the systemmustspanvertically.The exception to thisruleis whensuitablemeasures, e.g. reinforcedconcretecolumns,masonrypiersor crosswallsat closespacing,are introducedto by way ensurethatthe wall spanshorizontally reinforced of archingactionor by employing masonry.Withoutsuchmeasures,the permissibleheightof the wall is very limitedowingto mayonlycrack the fact thatthe cross-section as far as the centreof the wall. wallsmustbe Masonryunitsfor free-standing frostresistantif theyare not rendered.Freestandingmasonrywallsare alwaysbuiltwitha properbondand withalljointsfilled. Thefoundationshouldbe takendownto a level whereit is not affectedby frost.A horizontal moftaror damp proofcourseof water-repellent waterproofpaintshouldbe includedabove groundlevelin orderto protectthe wall against risingdamp and splashingwater.Vertical facesof masonryin contactwiththe ground shouldalso be protectedagainstingressof moisture fromthe soil.Thelengthof an individual segmentof masonryshouldnot exceed 6-8m; longerlengthsshouldincludemoveGolumnsand free-standingmasonrywalls mentjoints.Theyare a numberof ways in which longwallsmay be segmentedattracThetop of thewallmust Columns tively(seefig.2.4.19). Columnsare elementswith a cross-sectional be coveredin sucha way thatwatercannot penetrate,indeedthat it drainsawayclearof area< 0.01m2.To act as a loadbearing element,a columnmusthavea minimumcrossthefaceof thewall.lf usedas a coping,a sectionof 0.004m2,Hence,the minimum brick-on-edge coursemustconsistof whole dimensions of a loadbearing columnare 115 x bricksand be carefullyjointed.Thejointbelow 365 mm or 175x 240 mm.Columnshavea low a brick-on-edge copingmustbe waterproof. momentof areaand thereforea lowstiffness Owingto the manyjoints,thistype of copingis El.Theirhelpin distributing Othertypesof cophorizontal loadsis limitedin its applications. negligible, and so theyare notcalleduponto ing includeclay rooftiles,corrugatedroofing cementor specially carryhorizontalloadsin the structuralanalysis. unitsof fibre-reinforced So columnscarryonlyverticalaxialloads.They designedcopingunits.Alsosuitableare preplastic may be analysedfor concentricor eccentric cast concreteunitswith permanently jointslaid in water-repellent mortaror on a compression usingeitherthe simplified or moreaccuratemethodof analysis.The simpli- damp proofcourse,or metalcappingsof galvanized fied methodmakesuse of the reductionfactor either steel,copperor aluminium kr = 1.0,andthe moreaccuratemethoduses nailedor screwedon. the safetyfactory* = 2.0. In this casethe columnshouldconsistof one or morewhole masonryunitsor dividedunitswith < 35% perforationsand shouldnotweakenedbv chases

132

d

Externalbasementwalls

Pafiwalls partywalls Forreasonsof soundinsulation, between adjoiningresidential buildings(terracedhouses,semi-detached houses)should be builtas twin-leafwallswith a continuous joint(cavity)fromfoundationto roof. separati.ng lf twin-leafexternalwallsare used,the separatingjointmustbe takenthroughthe outerleaf aswellin orderto avoidan acousticbridge. According to DIN1053part1, the minimum thickness of eachleafshouldbe 115 mm. lf the weightof the partywallexceeds100kg/m2wall plaster), area(including thewidthof thejoint mustbe at least50 mm: if over 150kg/m'z, then30 mm is permissible but50 mm is stillrecommended. To complywiththe soundinsulation requirements of DIN4109,the cavitymustbe completelyfilledwith mineral fibrebattsto DIN18165 part2. Closed-cell hardfoamsheetsor wood-fibreboardsare for soundinsulation. The insulation unsuitable mustalwaysextendabovethe leafbuiltlastin orderto preventmortarand debrisfallinginto the cavityand possiblyformingacoustic the insubridgesbetweenthe leaves.Installing lationin two layerswiththeirjointsoffsetis refor improving the soundinsulacommended jointalsopassesthrough tion.As the separating thefloors,the insulationshouldextendabove thethickness of thefloorduringcasting,be protectedby suitablemeansand supported againstthe pressureof concreteon one side. lf theweightof a singleleafexceeds2OOkglm2 wallarea,the separatingjointmay remain open.Specialcaremustbe takenhereto ensurethat mortaror debrisdoes not drop into the cavityand formacousticbridges.Thisis lessof a problemwhenusingthin-bedmortarif the mortaris appliedby way of mortarsledges. mortar- or concretewhencasting Otherwise, thefloors- can be preventedfromfallinginto the cavityby usingsuspendedbattensraised as the workproceedsor jointforms,which haveto be removedsubsequently.

Externalbasementwalls Basements are no longerrestrictedto subordinaterolessuchas the storageof food or fuel, butprovidespacefor diverseactivities, e.g. guest playroom, washing, hobbies,workshop, room,studyetc,Theyrepresenta relatively inexpensive way of extendingthe usefulfloor spaceavailable.At the sametime,they correspondto the conceptof dense,space-saving construction IB]. Basementroomsnormallyheatedrequireadditionalthermalinsulationif that of the masonry aloneis notsufficient.Externalthermalinsulationis recommended. Thisshouldconsistof materialscoveredby a standardbut with extra functionsregardingresistanceto water,irost and earthpressure coveredby a generalbuild-

ing authorityceftificateor by the provisionsof DIN4108part 4. Productssuitablefor external sheets, insulationincludeextrudedpolystyrene foamedglasssheetsand polystyrenebead foamsheetswith a minimumbulk densityof 30 kg/m3.

2 . 4 . 1 8 R i g i dj o i n td e t a i l s Rigidjointsbetweenwalls Bondedjoint

Externalbasementwallsare subjectedto verticalloadsin the planeof thewalland horizontal loadsresultingfrom,for example,earth pressure, perpendicular to the planeof the wall.Earthoressureloadsare assumedto be mainlyactiveearthpressures,providedthe thickerthanthe wallsare not substantially structuralanalysisrequires,and the backfill materialis only compactedto mediumdensity, an lf the backfillmaterialis highlycompacted, e.g.earthpressure increased earthpressure, at rest,mustbe assumed.The earthpressure generates bendingmomentsin thewallwhich areusuallythe decidingfactorin the designof thewall,

Jointwith anchors

a

Et Section b-b

Stability of external masonry basement walls

Joint plastered over (onlylocation1)

Verticaluniaxialloadbearingaction lf the basementwall is supportedtop and bottom,we can assumethatthe wall acts as a vermemberspanningin one ticalloadbearing directionbetweentwo supportswith a cracked sectionof no morethan halfthe wallthickness. to the bed Thetensilestressesperpendicular jointsmay not be takenintoaccount(see "Analysis of tensionand bendingtension"). by verticalloads. Theyare "neutralized" DIN1053part1 includestwo methodswhich may be appliedin orderto avoidthe needto analysethe wallfor earthpressure.Thefollowing conditionshaveto be satisfiedfor both methods(seefig.2.4.20) ' Clearheightof basement wallh" < 2.60m, thickness of walld >240 mm. . The roofto the basementmustact as a plate the forcesgenand be ableto accommodate eratedby the earthpressure, 'The imposedloadon the groundoverthe areain whichthe earthpressureinfluences the basementwall may not exceed5 kN/m2. At the sametime,the sudaceof the ground shouldnotslopeupwardsfromthe wall and the depthof fill h" mustbe lessthanthe clear wallh". heightof the basement

Rigidjoint at base of wall

7777777r'. Mortarjoint

2.4,19 Segmentationof free-standingmasonry walls (planviews)

ln the firstmethodthe decisivecriterionis the permanentload Noat the top of the basement wall belowthe basementroof,whichmustlie limits: withinthefollowing

_+-+-6

maxNo> No> minNo edge withthe permissible Compliance pressureis checkedusingthe equation

Wall builton loadbearingfloor

Wall builton bonded screed

to 8m

d=17.s to 96.5cm

_

-

max No= 0,45d oo 133

Masonrydetails

2,4,20 Loading assumptionsfor basement walls without mathematicalanalysis

whered = wallthicknessand oo = basicvalue of permissiblecompressivestress. Theminimumloadsmin.N^arelistedin DIN1053 part1 tableB (seetablei.+.211.Theseensure compliancewiththe permissibleeccentricityof the basementwall as a resultof axialforceand bendingmomentdue to earthpressure. The secondmethodis basedon the findingsof Mann/Bernhardt [9] and enablesthe wailto be analysedwith slightlylessverticalload.The loading axialforceN, resulting frompermanent at halfthe depthof fill mustliewithinthe following limits:

.forb 0.5 ffiiI No rn,"r,u, Nj > 0.5 ffiifl Nuniaxiar

.forb>2h.: No> min Nornia",", N., > min Nuniaxial

HorizontaI loadbearing action lf supportsare closelyspaced,then it is possibleto carrythe horizontalloadof earthpressureto the supportsby way of tensilebending stressesparallelto the bed joints.Owingto ihe lowtensilebendingstrengthof masonryparallelto the bed joints,thisformof horizontalloaddxBr/(3y)>Nr>minN bearingactionis, however,very limited,particwnere ularlywithwallswhichneedto be thinin order min N = (p"x h""x h"r)/ (20d) to maximizethe usableinteriorspace.lf the 2.4.21 Min. N^ for basementswallswithoutmathematicaianalysis verticalloadsare very lowowingto, for examcharacteristic compressivestrength Fo ple,largewindowopeningsor floorslabs Wall min Noin kN/m of masonry thicknessd for depth of bacKill heof wall,or if. spanningparallelto the basement safetyfactor v mm 1 . 0m 1 . 5m 2 . 0m 2 . 5m pe thereare segmentsof wallwith unsupported bulk densityof fill [kN/m3] 20 45 75 top edges,e.g.spandrelpanelsbeneathlarge 300 3 15 30 50 lf the vedicalloadsNoand N, do notliewithin basementwindows,the structuralsystemcan, 365 0 10 25 40 490051530 be takento be a horizontalarch.However,the the givenlimits,the basement wallmustbe designedaccordingto the moreaccurate externalbasementwall mustbe supportedby polation methodof analysistakingthe earthpressure the transverseelementsand at a closespacing intoaccount.This involvesanalysingthe comto guaranteethatthe arch is formedand the : At an interhorizontal thrustaccommodated. oressivestressesas well as the slab shear resultingfromthe shearforcegeneratedby the mediatesupportbetweentwo archeswith roughlyequalspansand loads,the arch earthpressure.Alternatively, the permissible thrustsin the planeof the wall canceleach upperand lowerlimitsmay be adjustedby 2.4.22 Waterproofing of basementwallsfor the "nonincreasing thethickness of thewall,reducing otherout and onlythe componentperpendichydrostaticpressure"loadingcase the heightof thewallby formingthe basein ularto wall hasto be resistedby the support. reinforcedconcrete,or choosinga uniVmortar But at an end supporl,resistanceto horizontal Masonry with normal Thick bitumen combination witha highercompressive shearhasto be proved.Thetype of construcmortar in bed joints coating with/withoutmortar to of tionwhichusuallyfulfilsthe requirements strength.This is alsonecessaryif the design perpends in accordance such an analysisis reinforcedmasonryusing accordingto the moreaccuratemethodof with DIN 1053 pt 1 Protective layer (e,9.drainageboard) reinforced,concrete-filled specials.The baseanalysistakingearthpressureintoaccountis Cement screed laid not possible. Finally, the load-carrying capacity mentwallmustbe as thickas possiblein order Horizontalwateron separatingmembrane to achievean adequate"rise"to ensurearchof the basementwall can be increasedby proofing at base of wall ing action.In addition,a crackedsectionup to usingreinforcedmasonryor by consideringit halfthe thicknessof the wall may be assumed to spanin two directions or horizontally [154]. at the centreof the arch in the calculations. The perpendsmustbe fullyfilledwith mortarin Biaxialloadbearingaction Separating membrane The characStabilitycan be checkedby assumingthatthe orderto transferthe compression. teristicvaluethat may be usedfor the strength externalbasementwall subjectedto earth pressurespansin two directionswhencrossof the masonryin the basementwall perpenwallsor structuralcomponents,e.g. piersor dicularto the perpendsis - basedon DIN valueBofor stiffeningcolumnsof reinforced,concrete-filled 1053part 3 - the characteristic valuepo solidunitsand halfthe characteristic channelblocks,supportthewallat a clear 2,4,23 Walerproofingof basement walls for the "temporarybuild-upof seepagewater" loadingcase to the verticalloads for compressivestrengthperpendicular spacingb < 2 hs.Thenecessary maythen be reducedas followsaccordingto bed jointfor perforatedsolidunitsand other perforatedunits. valuesmay be DIN1053part1 (intermediate Thickbitumen vuaur r9 obtainedthroughlinearinterpolation): Horizontalwaterproofing at baseof wall

Blinding Polyethylene foil > 0 . 2m m Protectivescreed

134

J

Naturalstonemasonry

construction of thefloor duringthe subsequent Reinforcedmasonry Reinforced externalbasementwallsare useful (seefig.2.4.22). The loadingcase"temporary build-upof whenthe verticalloadsare so lowthat a seepagewater"requiresa layerof blindingto crackedsectionlargerthan halfthe thickness be laidfirstwhichis thencoveredwitha min. occursunderverticalor biaxialloadbearing foil as a separating action,or whencarryingthe loadshorizontally 0.2 mm thick polyethylene membraneand thena screedto protectthis viatensilebendingstressesparallelto the bed jointsor via horizontalarchingactionleadsto damage.Thegroundslab againstmechanical tanking)(seefig. the rein- is thencaston this(internal uneconomically thickwalls.Generally, in the bed 2.4.23). forcementis placedhorizontally joints.However,verticalreinforcement is possiblein conjunction with specials.Pleaserefer' VerticaI waterp roofing Waterproofsheetingbondedto the wall or masonry"for detailsof the deto "Reinforced workedcold (modified sealingcompounds signand construction of reinforcedexternal syntheticbitumenthickcoatings)spreador basementwalls, sprayedon are suitablefor the verticalwaterproofing.The numberof layersof waterproof sheetingdependon thetypeof sheeting Waterproofing As theyare constantlyin contactwiththe soil, selected.Thickcoatingsmay be one-or twocomponentsealingsystemsand are always externalbasementwallsare permanently subjectedio especiallyarduousconditions.lf the appliedin two operations is an extension to the livingor ancil- Specialcare mustbe exercisedat the junction basement Thefoundawaterproofing. walls withthe horizontal laryspaceof a building, thenthe external protectedagainstthe tion/walltransitionshouldbe roundedoff with a mustbe permanently ingressof moisture. concavefillet(min.radius40 mm).Theoverlap shouldbe at least100mm and be formedas Togetherwiththe customarywaterproofing withoutelaboan overlappedwatercheckjoint. systems,masonrybasements, for ratetreatment, satisfythe requirements Protective layer designand construction to meetthe loading to the Thisprotectsthe verticalwaterproofing cases"grounddamp"to DIN18195part4, pressure"to DIN 18195part 5 basement damage "non-hydrostatic wallsagainstmechanical pressure"to DIN 18195part6 duringbacKillingand subsequent compaction and "hydrostatic Suitablematerialsare,for with"lowload"(temporarybuild-upof seepage of the excavation. example,texturedplasticsheeting,thermal water).Mostbasementwallsdesignedfor the insulationbattsor drainageboardsof no-fines loadingcase"hydrostaticpressure"with "high polystyrene. Thisprotective will continueto be conbitumen-bound load"(groundwater) thatthe verticalwaterproofing structedin concreteto ensureadeouatewater- layerguarantees proofing(external systemremainsfullyfunctional. tanking).The mostpopular waterproofing systemsfor externalbasement wallsare bitumenand polymerbitumensheet- Separatingmembrane fabricas a sepaThe inclusionof a non-woven ing;cold-application self-adhesive bitumen sheeting;and modifiedsyntheticbitumenthick ratingor slidingmembranebetweenwaterproofingand protectivelayerpreventsloads coatings.The latterare usedfor the majorityof due to settlementof the backfillfrom being waterproofing tasksin housebuilding and representthe mosteconomicsolution[93]. to the waterproofing, causingthisto transferred becomedetached. Horizontal waterproofing Horizontal waterproofing in the formof a comServicepenetrations pletesealingmembrane Buildingservices(e.9.wastewater,fresh is appliedto the groundslabfor the loadingcases"ground water,electricityetc.)mustbe routedin such a pressure". is not impaired.In lt is way thatthe waterproofing damp"and "non-hydrostatic mustbe ableto addition,servicepenetrations extendedto the outsideat the baseof the of the structurewithaccommodatesettlement elternalwallsbeneaththe firstcourseof masonryunitsto overlapwiththe vertical out damage. waterproofing. The groundslab mustproject Constructionjoints sufficiently beyondthe externalwallto ensure mustsafelybridgeover Thewaterproofing an adequateconnectionbetweenhorizontal joints.Any waterstopsthat are inPlacingthe waterconstruction andverticalwaterproofing. to the proofingbeneaththe firstcourseof masonry connected cludedmustbe permanently unitsmeansthatthe entirefloorconstruction, waterproofing. e.g.floatingscreed,is carriedout in the dry. Nofurtherhorizontal waterproofing is required. Transitionto superstructure,plinth - bothfroma visualand a It is undesirable materialare usually Sheetsof waterproofing technicalpointof view- to continuethe vertical usedbecausetheseare morerobustthan waterproofing abovegroundlevelat the base coatingswith regardto mechanicaldamage

A plinthmustbe waterof the superstructure. proofedand protectedagainstsplashingwater to a heightof about200 mm aboveground waterproofpaintor suitable level.Therefore, renderingis appliedto exposedsurfacesand by this mustoverlapthe verticalwaterproofing at least100mm. Intwinleafmasonrythewaterproofingis placedon the outsideface of the innerleaf.

Natural stone masonry Naturalstonemasonrycan be classedas dry variousformsof walling,rubblemasonry, coursedmasonry,ashlarmasonryor faced masonrydependingon the degreeto which the naturalstonesareworkedand theirresulting geometry. Drywalling is madefromrubblestonewithoutmortar.The stonesshouldbe laidwithminimaldressingin a properbond so thatjointsand voidsare as smallas possible.Smallerstonesareto be wedgedintothe voidsto createtension betweenthe mainstones.Thishelpsthe wallto keep its shapeand remainstable.Drywalling walls.In assessing is usedfor gravityretaining stability,the densityusedshouldbe takenas halfthe bulk densityof the naturalstone.When walls,the natural buildinggravityretaining stonesare allowedto pile up againstthe soil to be retainedin orderto improvethe stability of the wall.The largestand mostregular(rectangular)stonesare usedto framethe wallat the cornersand ends,and for the base (see ti7.2.4.24). Uncoursedrandomrubble masonry is madefromunworkedstonesas theyoccur in nature.The roundformof the stonesresultsin appearance. a highlyirregular to sliding Thefinishedwallis highlysusceptible compresand does not exhibitany noteworthy sivestrengthdespitethe hardrock used. To securethe masonrybond,the jointsmust be carefullyfilledwith mortarand smallpieces the cornersarebuiltusing of stone.In addition, stoneswith a moreregularshapeand the coursesheldtogetherwith headers(througheveryapprox. stones)trued up horizontally 1.0 m of wallheight(seefi1.2.4.25). Coursedrandomrubble masonry The bed facesofthesestones(150-300mm high)obtainedfromquarriesundergoonlyminimalworking.Naturalstonesof varioussizes are laid in moftarin approximatecourses. Coursedrandomrubblemasonryis truedup acrossits completethickness horizontally (>500 mm)everymax.1.5m of wallheight. of a damp Thesameappliesto the inclusion proofcourse,which shouldbe builtin approx. 150mm abovegroundlevel.Largestones 135

Masonrydetails

2,4.24 Dry walling

2.4.25 Uncoursedrandomrubble masonry

2.4.26 Coursedrandomrubble masonrv

2.4.28 lrregularcoursedmasonry

2.4.27 Hammer-dressedmasonrv

2.4.29 Regularcoursedmasonry

t_l[--'1t----l

[-lL] 2.4.31 Stonefacing with backingof man-made masonrvunitsor concrete

E[ --l-_l ][]n[

EE E[---]r

l

136

]E[

-]E[

]l

>g 1 0 0

> h/3 > 100 lf+ . >)40

> 24n +

Hammer-dressedmasonry The bed jointsand perpendsof the stonesin exposedfacesare workedto a depthof at least120 mm. However,the naturalstones beyondthis depthof wall are eithernotworked ' at all or onlyvery little.Verticaland horizontal jointsare.approximately at right-angles; Theheightof a coursemaychangewithina courseand betweencourses;however,the.. across masonryis to be trued up horizontally its completethicknesseverymax.1.5m of wall on mortarsand horizonheight,Forinformation tal damp proofcourses,referto "Coursedianabove(seettg.2.4.27), domrubblemasonry" Irregular coursedmasonry The bed jointsand perpendsof the stonesin exposedfacesare workedto a depthof at jointsare least150mm.Verticaland horizontal perpendicular to each otherand approximately to the surface. Perpendsand bed jointsmay not be thicker than30 mm.The heightof a coursemay changewithina courseand betweencourses, however,the masonryis to but not excessively; acrossits complete be trued up horizontally thickness everymax.1.50m of wallheight{see fig.2.4.28).

[--']E[][--l

2.4.30 Ashlarmasonry

shouldbe usedat the baseand at cornersin orderto securethe masonrybond.Normal on mortarof groupll or lla is useddepending the type of rock. Thesedays,coursedrandomrubblemasonry is only usedfor lessimportantbasementwalls, free-standing boundarywallsand for retaining wallsin vineyards(seefig.2.4.26).

.l

Openingsin walls

Regularcoursedmasonry Thestonesshouldbe workedas for irregular coursedmasonry.However,the heightof stonesmay not changewithina course.In addition,the heightof everycourseis to be truedup (seefig.2.4.29). Whenusedfor vaulting,domesand similar constructions, the bed jointsmustpass throughthe completethicknessof the curved element.Therefore, the bed jointsshouldbe workedoverthe full depth,whileperpends needonlybe workedto a depih of 150 mm. Ashlarmasonry. Thestonesfor ashlarmasonryshouldbe worked accurately to the specifieddimensionsand all perpendsand bed jointsworkedto the full depth.Theprinciplesfor bondingashlarmasonryare basicallythe sameas for masonry usingman-madeunits;all the differenttypes of bondsusingstretchersand headerscan be produced.Thejointthicknesscan be 4-30mm; mortaris difficultto applyto jointsthinnerthan 4 mm.Dryashlarmasonryrequiresthe bed facesto be groundand is hardlyusedthese days(see'fig.2.4.30). Stone-facedmasonry consistsof a skin of regularcoursedor ashlar masonryon a backingof man-madeunitsor concrete(seefig.2.4.31). Thestonefacingmay be consideredas part of the loadbearingcross-section when ' the stonefacingis builtat the sametime as the backingand is bondedto it, ' the stonefacingis bondedto the backingby at least30% headers, . the headersofthe stonefacingare at least 240mm deeo and are bondedat least 100mm intothe backing, . thethicknessof the stonefacingis > '1l3its h e i g hot r m i n .1 ' 1 5m m , ' withbackingsof man-madeunits,at least everythirdcourseof naturalstoneconsisis entirelyof headers.

Thethicknessof the totalwall construction shouldbe as determinedby the structural analysis, butthisis seldomlessthan500 mm for oracticalreasons.The conditionsdescribed aboveapplysimilarly whenthe backingis madefromconcrete.Here,the concreteis pouredand compactedaftereverycourseof facingstoneworkto preventvoidsbeing formedbeneaththe headerstones.The oermissiblestressfor the comoletewall construction is governedby the materialwiththe lowest permissiblestress.Stonefacingsthat do not complywiththe conditionsoutlinedabovemay notbe includedas partof the loadbearing cross-section. Coursedstonesmay be laid againsttheirstratification onlywhenthey exhibita minimumcompressivestrengthof 20 MN/m2parallelto theirstratification. A nonloadbearingstonefacingshouldbe anchored and supportedas for a non-loadbearing outer leafof a twin-leafwall.Claddingpanelsmay not be includedas part of the loadbearing cross-section of a column.

2.4.32 Atch actionover openingin wall Vertical load

2.4.33 Effectiveloadsover openingin wall with arch actron

Openingsin walls Openingsin wallsfor windows,doorsand largeritems,e.g. ventilation ductsand light wells,are bridgedoverby way of lintelsor "lintels"). arches(masonry

Arching action over openings

Whendesigninga lintelor arch,we can assumean archingactionin the masonry abovethe openingin the wall,providedthere are no openingsadjacentto and abovethe lintelor archand the associatedloadtriangle, and thatthe archthrust(horizontal support reactions)can be resistedat the sidesof the opening.Therefore, the lintelor arch carries the loadonlybelowthe assumedarch(seefig. 2.4.32). This is takenintoaccountby the (equilateral) loadtriangleof masonryabovethe lintelor arch.

137

Masonrydetails

2.4.34 Reinforcedconcrete lintel details

Reinforced concretelintel Reinforced concretelintelas withcast-inthermalinsulationupstandbeamwithchannel (onlysuitablefor certain blocksas permanentformwork applications) to outsideface

7)

(////)

w-n AL)T)

q7/)

I Reinforcedconcretelintel maskedby channelblocks for facing masonry

C a l c i u ms i l i cate channel blocks

Clay channel blocks

2,4,35 Shallowlinteldetails

compresston zone shallowlintelas tensionflange

v^z ''' Nttr

H)4

-L

ER 1 7 51 1 5

T-

tl | zDF a

n w,

J6

rH J= IT

| ) ""'

n #]o

rca

+1 7 5

2,4.36 Supportinga soldiercourse"fake"lintel

--__lrtl

4 1 2 3 4 5

5fl[

Bolt Angle bracket 6 mm dia. V4A steelanchor Continuousbar carryingsoldiers(10 dia. V4A steel) Continuoushole

138

Uniformlydistributedfloorloadsabovethe load triangleare nottakenintoaccountwhen designing the construction overthe openingin the wall.Forfloorloadsthat act withinthe load triangleas a uniformly distributed loadon the masonry(e.9.floorslabsand joistfloorswith joistspacing< 1,25m),onlythe sectionwhich lieswithinthe triangleis assumedto transfer loadontothe lintel.Pointloads,e.g.from beams,whichliewithinor nearthe loadtriangle are assumedto distributetheirloads at 60". If pointloadsoccuroutsidethe load triangle,they needbe takenintoaccountonly if they liewithinthe spanof the lintelor arch and belowa horizontalline250 mm abovethe apex of the loadtriangle.In this casethe self-weight of the wall belowthe pointloadalsohasto be takenintoaccount(seefig. 2.4.33). lf archingactioncannotbe establishedin the masonryabovethe loadtriangleoverthe opening in thewall,the lintelor archmustbe assumedto carrythe entireload abovethe opening.

it may needto be formedas an upstandbeam. Thereare channelblocksavailableto match the respectiveformatsand courseheightsof facingmasonryand thesemay be usedto form prefabricated lintelsand employedas formworkto the side of a reinforcedconcretelintel castin situ(seefig.2.4.34).

Shallow lintels with masonry above

reinShallowlintelsconsistof a prefabricated, forcedtensionflangeand onlyachievetheirfull witha load-carrying capacityin conjunction zoneof masonryor concreteor compression both (e.9.masonryand flooror cappingbeam) above.Thetensionflangemay be prefabricatedfromconcreteor fromchannelblocksof concrete, calciumsilicateetc.; clay,lightweight filledwith concretein whichthe reinforcement (prestressed if required)is placed.In contrast to beam-typelintels,shallowlintelscarrythe withthe loadsactingon them in conjunction wall abovelikea tied frame(a closedsystem). The shallowlintel(tie)resiststhe tensileforces fromthe arch (frame)in compression and Beam-type lintels thereforereplacesthe end supportswhich Beamsof, for example,timber,steelor reinwouldotherwisebe necessaryto accommo-. forcedconcretetransferthe loadsactingon datethe horizontal thrust themto theirsupportsat each end by way of The advantageof shallowlintelsis thatthey bending.Therefore, the beamsmustbe decan easilybe madefromthe samematerialas signedto resistbendingand shearforces. wall.Thisavoidscracksin and the surrounding Owingto theirexcellentmaterialproperties, damageto the plaster.By matchingthe dimenquitesmall,but sionsof the sl'lallowlintelto the modularsizes steelsectionscan be generally for reasonsoffire protectionhaveto be encased of the surrounding wall,thistype of construc' in concreteand to complywithbuildingscience tion can be integratedintothe masonrywithout requirements mustbe providedwiththermal havingto adaptor cut the masonryunitsadjacentthe openingin thewall.Thisleadsto insulation. Reinforcedconcretelintelsare usuallychosen moreeconomicand morerationalsiteoperawhenthe lintelcan be combinedwitha reintions.Forfurtherinformation, see "Reinforced forcedconcreteflooror in certainloadingsitu- masonry"and [35] (seefig. 2.4.35). ations.Theymay be precastunitsor cast in situwiththe reinforcedconcretefloor.A reinforcedconcretelintelmustalwaysbe provided Masonry lintels and arches with insulation to meetthermalinsulation Prefabricated or in-situlintelsof horizontally requirements. The problemwiththis is thatthe reinforcedmasonrymay be usedfor facing effectivecross-section of the lintelmustbe work.The loadbearingbehaviourcorresponds reducedin orderto accommodate the insulato the tied framemodelof the shallowlintelwith tion and this createsa substratefor plastering wall above.The horizontalreinforcement is placedeitherin trough-shaped whichis different to the surrounding wall. specialsor Despitethe provisionof a plasterbacking horizontalchannelblocksor perforatedunits spanningacrossthethermalinsulation, with a continuousholeto suitthe bond of the this type of detailoftenleadsto cracksin the renfacingmasonry.Designand construction deringand stainingof thefinish. withDIN1053oart3. shouldbe in accordance Onesolution to thisproblemis to providechan- Pleasealsoreferto "Reinforced masonry". nel blocksin the respectivetype of masonryas In twin-leaffacingmasonrythe outerleafabove permanentformworkinsteadof the reinforced the openingin thewallcan be carriedby nibs concrete.The reinforcedconcretelintel(preon the side of the floorslab or by supports cast or in situ)is then integratedintothis.This boltedto or cast intothe floorslab (e.9.steel can also be used in conjunctionwith a reinanglesor brackets).To satisfyarchitectural forcedconcretelintelcasttogetherwiththe we can alsoprovidea horizontal requirements floorslab.In thisdetaila prefabricated lintel lintelin theformof a soldiercoursein conjuncunitmadefromchannelblocks(withintegral tionwith bracketsand barspassingthrough insulation) formsone side of the formworkfor the masonryunits.The shear-and tensionthe reinforcedconcretelintel.As the structural- resistantconnectionto a reinforcedconcrete ly effectivewidthof this lintelis onlyverysmall, beambehindmeansthatthis is onlva "fake"

Vaultingandarchfloors

2.4.37 Semicircularand pointedarchesaccordingto [162]

2.4.38 Camberedand gauged archesaccordingto [162]

o

E o 'o I

Thespan (S)feasibledependson type of arch, compressionin arch and verticalloads.The width (M,fof the abutmentdependson the span;the valuesgivenhere apply to abutmentwidthsessentiallywithoutverticalload.All valuesare guidelineswhich may be exceededin an accurateanalysis.Camberedarchesin non-loadbearing facingwork can be builtfor spans up to approx,1.75m withoutthe need for a structuralanalysis.

lintelwithno loadbearing function(seefig. 2.4.36). Masonrylintelsin the formof archesare primarilyusedin the refurbishment of olderbuildings,butarealsobeingrediscovered as a moderndesignoptionin conjunctionwithfacingmasonry. Owingto the highlabourinput, thesearchesare oftenproducedas prefabricatedelements,whicharethen liftedintoplace on preparedabutments.Witha favourable rise/spanratioand predominantly permanent loads,i.e.deadloadsconsiderably higherthan imposedloads,the arch may be designed accordingto the lineof thrustmethod.This meansthatthe construction is subjectedonly to axialcompression and no shearor bending momentswhenthe axisof the arch coincides withthe lineof thrust.However,this idealcase is hardlypossiblein practicebecausechangingloads,and hencedifferent loadingcases, meanthatvariouslinesof thrusthaveto be considered whendesigning the arch.'Nevertheless,to ensurethat exclusivelycompressive stresseswithouta crackedsectionoccur in the cross-section of the arch,the geometryof the archshouldbe suchthat,if possible, the lines of thrustfor all possibleloadingcaseslie in the middlethirdof the cross-section. Linesof thrustcanthusbe usedindependently ofthe loadsin oiderto designa suitable, economic archfor masonrywhich,in theory,cannot accommodate anytension.In doingso, we assumethatthe structuralsystemis basedon determining the linesof thrustfor a three-pin archin whichthe pinsare positionedat the springingpointsand at the crownof the arch. Archeswithlongerspansand morepronounced changesof loadinghaveto be designed accordingto elastictheory.Providingresis-

Camberedand gauged arches haveinclined(skewback)abutmentsaligned withthe centreof the arch.The bed jointsalso pointto the centreof the arch.The riseof a camberedarch is max.1/50of the widthof the opening,thatof a gaugedarchmax.1/12.A camberedarchwithoutany risemay alsoact as an arch in comoressionif the soldiercourse deviatesslightlyfromthe verticaland is wedgedintoabutmentsbuiltat a veryslight angle. Thearchlintelis producedfroman odd numSemicircularand pointedarches ber of courses,whichcan makeit necessary Theradiusof a semicircular to insetthe abutmentsby halfthe widthof a archis eoualto halfthewidthof the opening,and for a pointed courseon the masonryat the sides.The extraarchequalto thefullwidthof the opening,with dos shouldalwaysend in a bed jointof the the centresof the radiibeingthe respective masonryabovein orderto avoidlargecompensatingcoursesabovethe archor unoppositespringingpoints.The abutmentsfor The sernicircular and pointedarchesare generally attractivegussetsabovethe abutments. positionedhorizontally requirements regardingjointthicknesses and at the levelof the springingpoints.Thearchesarenormally con- bondingcorrespondto thosefor semicircular structedwithtaperingbed joints.The thickness and pointedarches(seefig.2.4.38). of the jointsat the undersideof the arch (intrados)shouldnot be lessthan5 mm,at the outer ring of the arch (extrados)not greaterthan Vaultingand arch floors 20 mm.Specialtaperingunits(voussoirs) may be necessary for smallradii.Whenusingsmall- Vaults formatunits,the sizeof the bed jointsat the or also Theseare roof-like,one-way-spanning, extradosof the arch increaseas the arch bidirectional arch-like or sphericalcurvedroof becomesthicker.Therefore, thickarchesare constructions of masonry.The varioustypesof alsobuiltin individual rings,oneabovethe vaultingare basedon the two fundamental other.Archesare alwaysconstructedusingan types:barrelvaultswith cylindricalcurvature, odd numberof unitsso thatthereis nevera and domeswith sphericalcurvature.Besides jointat the crownbut ratheralwaysa keystone. the barrelvault,othercylindricalformsinclude Thebed jointsmustbe arrangedperpendicular the Prussiancap vault;the cloisteredvault;the to the lineof thrustand fllustrunthe full deoth troughvault;the cov; and the groinedvault. of the arch.The bondfor masonryarchesis to The dome is a sphericalformof vaultingwhose be producedaccordingto the bondingrules surfacesgenerallyform partof the surfaceof a for masonrypiers[32,141,1611(tig.2.4.37). sphere(seefig.2.4.39). tanceto the archthrustat the supportsalso hasto be takenintoaccountwhen designing an arch.Shallowarcheswith a low risegenerate a greaterhorizontal thrustthanarcheswith a smallerradiusand largerrise.The horizontal thrustmustbe resistedwithoutdisplacement at the supportsirrespective of the curvatureof the arch becausethe arch itselfundergoesa severeincreasein stressesdue to the reductionin the riSeevenwithonlvminimaldisolacementof the supoorts.

139

Masonrydetails

,'/a r-'ll

2.4.39 Types of masonryvaulting

6)

/(__ - - - - - - l ,_-_,__)

Barrelvault

Groinedvault

Hemispherical

,,iY--',

,4''\ / \/

/,' Trough vaull

Cove

Cloisteredvault

,2r-il 7

D-" Starvaulting

Sailvaull

2.4.40 Designrequirementsfor masonryarch floors Arch floor in masonrybond

Risef>1/10x1

Hetringbonebond

"Kuff" bond

-':

Steel beams

Steel -'/ oeams

2,4.41 Assumptionsfor arch thrustfor multi-bayarch floor

Lateral ..-..: support

i;f o-

-

Directionof span

lE

Lateral support

I

4

--

c

i,'I

I

c o o o !

o

E o

I T Length of anchor >1/3 | Detailsof end bay

140

17-7-7=7-71.

I

l

E c

Sidesupport >1/31 Structuralsystemfor transferring horizontal thrustfromend bay

Vaultswith smallerspans,a favourablespan/ permanent riseratio(f/l> 1/10)and essentially loadingcan be designedaccordingto the line of thrustmethod.Theyare builtfromtapered masonryunitsthat supporteachotherand are abutmentsin sucha supportedon immovable way thattheyare onlysubjectedto compression.The archthrustcan also be resistedby ties(intension)insteadof abutments. Vaultswithlargespansand pronounced changesof loadingaredesignedaccordingto elastictheory.

Masonry arch floors between beams

Thesearethe upperpartof an arch built betweensteelbeamsas verticalsuppotls(see for Thestructural systememployed tig.2,4.40). suppotl the verticaland horizontal determining reactionsfor archfloorsis a three-pinarchwith the centrepin at the crown.Withan essentially imposedloadaccordingto DIN1055 stationary part3, archfloorswith a thicknessbasedon rulesandwithbeamsspacedat max. empirical approx.2.50m do not needto be analysed thickInthiscase,the minimum structurally. nessmustbe 115 mm,theymustbe builtusing "Kuff"bond or herringbonebond,and the ratio of riseto span mustbe at least1/10.Centering for parallelarchesshould,likethe bricklaying in orderto itself,be carriedout simultaneously thrustcausedby the arches limitthe horizontal at the end baysof multi-bayfloors.Tiescan be thrustfrom integratedto transferthe horizontal the end baysof multi-bayfloorsto the side walls.Thesemustbe includedin the end bays parallelto the directionof spanof the floorat the endsof the beamsand at a spacingequal to the spanof the end bay but at leastat thirdpoints.In orderto considerthe end plate formedby ties as an adequateabutment(rigid horizontalolate)ableto transferthe horizontal thrustto the sides,the widthof the end plate mustbe equalto one thirdof its length.The tiesusedmustbe longerthanthe minimum widthof the plate.ln the caseof narrowend baysit is sometimesnecessaryto extendthe tiesoverseveralbays(seefig.2.4.41). The end baysmustbe providedwith supports at the sideswhichare in the positionto accept thrustof the middlebayseven the horizontal whenthe end baysarenotloaded.Thesupportsmay be securedby meansof masonry, permanentverticalload,anchorsor othersuitof buildings Inthe basements ablemeasures. stationaryimposedloadof with an essentially max.2.0 kN/m2we can assume,withouta thrust structuralanalysis,thatthe horizontal fromarchfloorsup to 1.3m spancan be accommodatedby meansof 2 m long,240 mm at a spacingof max.6.0m. thickcrosswalls mustbe builtsimultaneously Thecrosswalls with and fully bondedto the end bay support wallsor - in the caseof toothing- via a non(seefig.2.4.42). connection mechanical

Connections

Pointloads Masonrycan be subjectedto point(concentrated)loadsfrom beams(e.9.windowlintels); joists(e.9.joistfloors);or columns(e.9.windowmullions,roofposts).Thesegenerateverticalconcentrations of stresson the bearing surfacesand horizontalspittingtensileforces in the loaddispersionzone.The spittingtensile forcescan be accommodatedby the tensile strengthof the masonrybond, by reinforcementor by reinforcedconcreteelements. A padstoneor similaris alwaysintegratedinto the masonryto distributethe loadfromheavy pointloads.Thisis usuallyof reinforcedconcretebut may be of steel.The reinforcedconcretering beamor the suppor/floorstrip is oftenused.lt may alsocomprisemasonryunits of higherstrengthincorporatedin the masonry bondbelowthe pointload.In bothcasesthe designermusttakeaccountof possiblecracking in the masonryas a resultof restraints causedby the changein material(seefig. 2.4.43).A loaddistribution of 60" may be assumedwithina sectionof wall strengthened withunitsof higherstrength.The strength requiredfor this masonryis determinedby the bearingstressesbeneaththe pointload.The heightoverwhichthe wall mustbe strengthenedis determinedby the fact thatthe normal masonryof the wall (of lowerstrength)mustbe ableto carrythe load beneaththe 60" loaddispersion. Thepermissible stressesfor masonrybelow pointloadsare greaterthanfor the restof the wallbecausethe inclined"struts"createdby generate the60'load dispersion a biaxialcompressionconditionat the pointof actionof the pointloadwhichincreasesthe load-carrying capacityof the masonrylocally.However,the inclinedstrutsmeanthattherearealsohorizontal "ties"in the lowercoursesof thewall,the tensionin whichhasto be resistedby horizontal reinforcement or by thefloorslabactingas a tie. Pointloadsthat act at the end of a wall create an inclinedstrut,whichis balancedby a horizontaltensionat the top of the wall.Thistensionleadsto verticalcracks,to tearingof the masonrybearing,if it cannotbe accommodated by the masonrybond,the reinforcedconcretefloorslab or ring beamactingas a tie or by horizontal reinforcement in the masonry. Whenanalysing the pointloadandthe dispersion of the loadaccordingto DIN1053 part1, the positionof the pointload is taken intoaccountthroughthe dimensionsof the pointof actionof the load(seefig.2.4.43). Pointloadsperpendicular to the planeof the wall,e.g.fromhorizontalimpacts,shouldnot exceed0.5p*accordingto the moreaccurate methodof analysisin DIN 1053part 1 and 0,5x2.67 oo = 1.33ooaccordingto the simplifiedmethodof analysis. In addition, the shear stressesin the bed jointsof the individual masonryunitsunderloadmustbe analysedfor

horizontalpointloadsperpendicular to the planeof the wallwhereF > 3 kN. Perforated and cellularunitsrequirea plateor similarto be incorporated underneathso thatthe horizontalload is transferredto at leasttwo webs in orderto avoidoverloadinq the webs of individualmasonryunits.

2.4.42

Accommodatingthe arch thrust without structuralanalysisfor a multi-bayarch floor over basement

Connections Wallsmustbe connectedto floorsand roof framesin orderto guaranteetransferof forces and provisionof horizontalsupportfor loadbearingand stiffening walls.Thiscan be achievedeitherby anchorsor throughadhesionand friction. In orderto alsoachievethree-dimensional stability for the building,ringbeamsmustbe placedin all externaland crosswallswhichact as verticalplatesfor carryinghorizontalloads (e.9.wind).Thispresupposes thatthefloors act as horizontalplates.Floorsthat do not act as plates(e,9.timberjoistfloors),or those whicharesupportedon thewallsviasliding bearingsin orderthat deformations are not restrained(e.9.roofslabs)requirethatthe walls,and hencethe building,gainhorizontal restraintby way of cappingbeamsor other eouivalentstructuralmeasures.

2.4.43 Load dispersionbelowpoint load

Masonryof higherstrength 01 from point load (beam,column,joist)

Connecting walls to floors and roof frames

In principle, walls allwalls- includinginternal - mustbe or paftywallsseparating buildings connectedto floorssuchthatforcescan be transferred,providedthe floorsare intended to providelateralsupportto the walls. Connectionusing anchors Anchors(withverticalstrapsin the caseof timber joistfloors)mustalwaysbe includedin loadbearingareasof wallsand neverin nonloadbearing spandrelpanels.Onlyby providing verticalloadis the wall in a positionto accommodate the anchorforcesand guarantee the transferof forcesto the floor.A lackof verticalloadmightdictatethe useof a dng beam.Generally, the spacingbetweenanchors shouldnot exceed2.0 m in orderto limitthe forcesplacedon them.However,the spacing may be increasedto max.4.0 m in exceptional circumstances if the particularconstruction does not permitany othersolution. Wallsparallelto the directionof spanof the floorrequirestrapswhichextendat least1.0m intothe floorand are fixedto at leasttwo floor ribs or Mo beams(threejoistsin the caseof timberfloors).Thisdistribution of loadover severalribs or beams/joists is necessarybecauseotherwisethe restraintforcessubjectthe floormembersto lateralbending(seefig. 2.4.46).Beamssplicedoverinternal wallsand tied to the perimeterwallsmusthavea tensionresistantspliceconnection. Thisis necessary

Masonry of lower strength or : to be carriedby masonryof higherstrength oz : to be carried by masonry of lower strength

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Masonrydetails

2.4.44 Supportoptionsfor gable walls

Unbracedgable wall Anchorat apex

Suooort via braced roof frame

Supportvia integralcolumn

2.4,45 Load distributionof a ring beam for building stiffened bv floor olates

142

Ringbeamsmay be madefromtimber,steel, reinforcedmasonryor reinforcedconcrete. Theyare to be designedfor a tensileforceof 30 kN underserviceloads.Thisfigurecorrespondsto the forcesto be expectedin buildThebeamsshould ingsof normaldimensions. be designedfor greatertensileforceswhena structuralanalysisof the wall plate,floorplate resultsin largerfigdeformation or differential ures.Ringbeamsof reinforcedmasonrymust complywiththe corrosionprotection,reinforceConnectionusing adhesionand friction and mortaror concrete mentarrangement Securesupportfor wallsby way of adhesion of DIN1053paft3. Ring coverrequirements and frictionis providedby concretefloors beamsof reinforcedconcretemusthaveat whenthe depthof bearingof the slab on the leasttwo continuous10 mm reinforcingbarsto wall is at least'100mm;anchorsarethen lapsshouldbe in unnecessary. An adhesion/friction connection DIN1045.Thereinforcement if withDIN1045,and staggered assumesthat a connectioncaoableof transfer- accordance ringforcesis generatedby the adhesionalone, oossible. requiredfor ring beamsof The reinforcement and is only reinforcedby the frictionarising reinforcedmasonryor reinforcedconcretemay fromverticalloadsif necessary;however,the presenceof frictionis not absolutelyessential. includethe full cross-section of continuous notfullyutilizedin floorslabsor reinforcement We can alsoassumethis situationat the juncwindowlintelsno morethan500 mm fromthe tionbetweena walland a cappingbeam. centrelineof the wall or floorparallelto the Theuseof different beam(seetig.2.4.47). materialsfor the masonryand the ring beam Ring beams and capping beams can leadto damageto masonry.Aboveall, Theseare horizontalstraightmembersin the in ring planeof the wall.Ringbeamsaccommodate severetemperaturedeformations of as wellas the shrinkage tensionwithinthewallplate,whichensuesas a beamsgenerally resultof externalloadsor differential deforma- reinforcedconcretering beamsin padicular can leadto cracksin the masonry.Temperation,and henceincreasesthe stabilityof the can be minimizedby includture deformations wallsand that of the wholestructure. shrinkage ing adequatethermalinsulation, Cappingbeamsalsoserveas ringbeams reducedby latestrikingof the formworkand by whentheyforma completering aroundthe treatingthe concrete.To miniwholebuilding.Furthermore, theirreinforcesubsequently mizecrackingin rendering,a reinforcedconmentarrangement allowsthemto accommocretering beamshouldmakeuse of fabric to the planeof the dateloadsperpendicular shouldbe fabrior, alternatively, reinforcement wallby way of bending. catedfrom channelblocksto matchthe surroundingwall and henceprovidea consistent Ring beams substratefor the rendering.Thisor the useof act as tiesto holdthe structuretogether.They are requiredin buildingswith morethantwo full reinforcedmasonryas a ring beammeansthat of changingthe material the disadvantages storeys,or thoselongerthan 1Bm at wall eleare,on thewhole,avoided. mentsprovidedfor stabilizingthe structure (external walls,twin-leafpartywalls,crosswalls Cappingbeams etc.)at or immediately beloweveryfloorlevel. Ringbeamsmay be interrupted onlywhentheir are subjectednot onlyto tensileforcesbut also to bendingmomentsfrom horizontalloads. is guaranteedby othercompoeffectiveness nents,e.g.windowlintelsor landingsin thecase Cappingbeamsare necessarywhenfloorsdo not act as plates,e.g.timberjoistfloors,or are of continuouswindowsto a staircase. It is alsonecessary to holdthe structure together providedwithslidingbearingswhereiheyare supporledon the wallsand so do not provide by way of ring beamsin the caseof wallswith lateralrestraintat floorlevel.The ring beam manyor particularly largeopenings; thisis especiallythe casewhenthe sum of the widths becomesa cappingbeamand takeson a stabilizingtask.As a rigid horizontalbeamit transof the openingsexceed60% of the lengthof the wall or 40%;o in the caseof windowsgreater fersthe horizontalloadsfromwind,reversalof etc.to the shearwalls(see forces,earthquakes thanA3 of the storeyheight. 'fi7.2.4.48). Otherfunctionsof ringbeamsareto act as a tie to the The cappingbeamand its connections floor for the compressionarch in a horizontal plate;to act as a tie for the vedicalmasonry shearwallsshouldbe designedfor a horizontal plate;and to accommodate loadequalto 1/100of the verticalloadof the tensilestressesin deforma- wallsand for a proportionof the wind loads.In the masonryas a resultof differential addition,cappingbeamsbeneathslidingbeartion causedby temperature fluctuations, ings musttakeaccountof tensileforcesfrom of the subshrinkageor differential settlement the residualfrictionforcesof the floors. soil[54] (seefig.2.4.45). in orderto linkopposingexternalwallstogether and ensurean effectiveconnectionbetween externalwallsand floors. Gablewallscan be connectedvia anchorsto they gain a bracedroofframe.Alternatively, theirstabilityby way of crosswallsor other (e.9.reinforced measures concretecolumns restrainedby the floorslab,masonrypiers) (seefig.2.4.44).

Connections

2.4.46 Fixinglensionanchorsin masonry Shearwallsmustbe analysed to ensurethey >240 canaccommodate the supportreactionsof > 240 t--| TT cappingbeams,and thattheyadequately transferthe forcesto the foundations. lf a cappingbeamdoesnotfulfilringbeam Strap> 15 x 50 mm functionsat the sametime,it needsonlyto Gable anchormust be fixed to 3 joists extendas far as necessaryto iransferits supO N portreactionsto anotherelement.Capping beamsmaybe madeof timber,steelor rein: O 6 forcedconcrete.Theymustbe rigid enoughto preventany cracksin the masonrydue to deformations. Thisreouirement meansthatthe feasible spanof sucha beamis sometimes limited. Reinforced concretecappingbeams Strutting musthaveshearlinksand at leastone longitudinalreinforcing bar in eachcornerof the link. Fixingto masonryin directionof span of floor Fixingto masonryat right-anglesto span of floor Cappingbeamsshouldbe treatedlikering beamswithregardto the problemof the riskof 2.4.47 Delailsof ring beamstaking into accountparallelreinforcement cracksin masonrycausedby a changeof materialbetweenwall and beam,Thisalso applies to the useof channelblocksto achieve Reinforcement plastersubstrate. r a consistent betweenplanks

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Timberjoistfloorwith reinforced concretering beam

Precastfloor with reinforced concretering beam

Reinforcedmasonryas ring beam

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2.4.48 Capping beam action

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