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GlassEnclosurewithPyramidRoofDiagram

Figure:

Q9

18.0m

clearspan

SECTIONACROSSBUILDING

Areacoveredby

glazedroof

inequalglazed

segments.

Glazedpyramid.

6.0m Ground

Level

18.0m

9.0m

PLANOFBUILDING18.0m clearspan

Thevoid withinthesupportingwalls

androofistoremainclearofany

structure.

6.0m wideby4.0mhigh

removableglazingforaccess

StructureZone

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Question9: GlassEnclosurewithPyramidRoofClientsrequirements1. Anexhibitionhallistohaveafeatureglassroofandcladdingsurroundingadisplayarea. Thiscomprisesa

glazedpyramidsupportedonfourglazedwallsformingasquare. A6.0mby6.0mareainthemiddleofonewallisrequiredtobedemountableforaccess. SeeFigureQ9

2. Theglazingcomprisescavityglassunits30.5mmthick,weighing0.30kN/m2. Allglasselementshaveamaximum

size

of

1.5

m

by

1.5

m.

The

glass

units

and

panes

may

be

supported

by

partial

or

complete

framingorbepointfixed. Mountingmustbearrangedthatanyglassunitcanbeindependentlyremovedformaintenance.

3. Theclientrequiresastructuralframeandglasssupportsystemfortheglasswhichhasaminimumofinterruptiontothelightandenhancesthevisualaspectoftheenclosure. Thesupportsystemmustbeentirelyontheinsidefaceoftheglass,andisrestrictedtothestructurezoneindicatedinthediagram,suchthatthevoidwithinthebuildingremainsclearofanystructure.

4. Thedesignshallincorporateadescriptionofanappropriatefoundationscheme,butdetaileddesignofthefoundationsisnotrequired.

Imposedloading5. Imposedloadonroof: 0.6kN/m2,6. Amaintenancepointloadof0.5kNappliednormaltotheglassanywhereonthesupportsystem.Siteconditions7. Thesiteislocated2kmintoatown,over100kmfromthecoast. Basicwindvelocityis46m/sbasedona

3secondgust;theequivalentmeanhourlyspeedis23m/s.

8. Groundconditions:Groundlevel 0.9m Madeground0.9m1.5m Sandandgravel,Nvariesbetween3and5.Below1.5m Sandstone,allowablebearingpressure1,000kN/m

2

Groundwaterwasencounteredat2.5mbelowgroundlevel.

Omitfrom

consideration

9. Detaileddesignoftheglasspanes.

Detaileddesignofthefoundations.

SECTION1 (50marks)a. Prepareadesignappraisalwithappropriatesketchesindicatingtwodistinctandviablesolutionstothe

proposedstructure. Indicateclearlythefunctionalframing,loadtransferandstabilityaspectsofeachscheme. Identifythesolutionyourecommend,givingreasonsforyourchoice. (40marks)

b. Afteryourdesigniscomplete,theClientwritesthatalatermoredetailedsoilinvestigationrevealsthattherearetheremainsofaburiedrivervalleyacrossthecornerofthebuildingarea. Writealettertoyourclientadvisinghimoftheimplicationsofthisandhowtheeffectscanbemitigated. (10marks)

SECTION2 (50marks)ForthechosensolutioninSection1(a):

c. Preparesufficientdesigncalculationstoestablishtheformandsizeofalltheprincipalstructuralelementsandconnections. (20marks)

d. Preparegeneralarrangementplans,sectionsandelevationstoshowthedimensions,layoutanddispositionofthestructuralelementsandcriticaldetailsforestimatingpurposes,includingdetailsofhowtheglassunitsaretobesupported. (20marks)

e. Prepareadetailedmethodstatementforthesafeconstructionofthebuildingandanoutlineconstructionprogramme. (10marks)

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Question9: GlassEnclosurewithPyramidRoofExaminersappreciationThisquestionwillbebestansweredbythosewhohaveexperienceinenvelopedesign,especiallyinvolving

glass,thoughtheobviousstructuralaspectsmayattractothercandidates. Whilefoundationsareomitted,

greaterattentiontothedetailsandstructuralisexpectedofthecandidate. Solutionsthatdonotmeetthe

clientsrequirementsthatthestructureenhancesthevisualaspectoftheenclosurewillbepenalised.

Whiledesignoftheglasspanesisomitted,thecandidateisexpectedtodesigntheglasssupportsystemandthe

mainstructure

down

to

ground

level,

including

all

necessary

structure

for

load

support

and

stability.

Ithasbeenleftopenhowtheglassissupported. Thisquestionlendsitselftoeitheredgesupportedorpoint

fixedglazing. Itmaybethatsomesortofproprietaryglazingframingsystemisincorporatedintothedesignand

thiswillbeacceptableprovidingthatthestructuralrequirementsforthesystemareshownasmet. Inthis,

deflectionsareoftenthegoverningcriteria.

Possiblesolutionsforthestructureinclude:

EdgesupportedglassonglasscurtainwallframingspanningfromthegutterlinetoRHS/CHS/UB/CUBmainmembersformingthepyramidsupportedinturnonamainstructuretogroundlevel.

UnframedpointfixedglasssupportedonslenderopenwebgirderssupportedinturnonRHS/CHS/UB/CUBframing

forming

the

pyramid

supported

in

turn

on

amain

structure

to

ground

level.

Unframedpointfixedglasssupportedontriangularspaceframesformingthepyramidandbuildingwalls.Thereisconsiderableopportunityforcandidatestousetheirimaginationindesigningthestructure. Itis

acceptedthatitmaybesomecommonalityintheframingforthetwosolutions,butsimilardesignsindifferent

materialswillnotbeacceptable.

Candidatesareexpectedtoshowthattheyunderstandtheparticularproblemsoftolerancesandmovement

thatcanaffectabuildingofthistype. Alsothattheycanprovidedetailsthattaketheseaspectsintoaccount.

Carewillbeneededinassessingtheloadsinorderthatthemembersaresizedwithintherestrictionsgiven. The

stabilityoftheroofandthesupportingstructuremustbeconsidered. Thosewithexperienceof3dimensional

structures(cut

timber

roofs,

for

example)

will

be

able

to

reduce

the

size

of

the

main

members,

though

should

bewareofthehorizontalcomponentsofsupportforces.

Thenotethatthereisnostructurewithinthepyramidvoidistopreventacandidateusingsimplerstructureto

bracetheroof. Thestructurezoneisshownnotdimensioned,butcandidatesareexpectedtobereasonablein

theirinterpretation,thattheirstructuremeetsthisreasonablyandthatnomemberscrossthevoid.

Whilethoseexperiencedsolelyinenvelopestructureswillnormallyusesomeoneelsesstructureastheir

foundation,someknowledgeofbuildingfoundationsisexpectedofaCharteredEngineer. Whilenodesignis

askedfor,thecandidateisexpectedtohavesufficientknowledgetocomplywithClientsbrief4andanswer

part1b.

ForthecalculationsIexpectconsiderationofthememberdesignincludingnotonlytheappliedandselfweight

forcesbut

proper

consideration

of

element

stability

and

especially

deflection.

Thedrawingsshouldshowthegeneralarrangementsasnecessary. However,thereshouldalsobedetails

showinghowtheglassissupportedandhowthepyramidsarelinkedtothesupportingframe.

Iwouldexpecttheprogrammetotakeatleast6to9months,butthemethodstatementmustindicatehowthe

panes(weighingupto140kg)aresafelyhandled.