STRUCTURAL CONCEPTS (2)WEE

K 6

# 640263 KATHRYN RANDALL-DZERDZ...and Hamish’s workshop

Hamish’s workshopGroup: 2Materials: 1200x3.9x90mmPly Qualities:flexibility 1200x42x18mm Pine Qualities: free of knots = high structural integrity Parameters:Mustspan1000mmandandresistthegreatestappliedforcepossible.

Ply-wood attached with nailsWhen the structure is loaded, the ply-wood warps revealing the tension along its upper edge as it ‘folds’underthisstress.Thenailsheremaybepulledthroughthethinwoodor‘pop’out,unableto resist the forces that are distorting the ply.

Pineframe(affixedwithnails)Twolengthsofpinehavebeenusedtocreateaload-bearingframe,reinforcedatintervalstodistributeloads placed upon it. This type of framing is more practicalunderdistributedloads,butfailedquickly(fig.1)underalive,concentratedload(fig.2)asthestresscouldnotbetransmittedthroughthestructureefficiently(fig.3).

Ply-wood attached with screwsThis wood also demonstrates distortion as it warps under compressive and tensile forces. Unlike the nails however, the screws used here provide more resistance to the applied loads. Thedistributionandfrequencyoffixingsdeterminestheabil-ity of the ply-wood to remain in contact with the pine frame, butcaremustbetakennottoweakenthepinestructureinthisprocess(‘Hamish’2013,pers.comm.,6September).

Figure 1: An example of the fracture of pine and ply. Source: G. Lewis 2013.

Figure 2: An exam-ple of the concen-trated loading of a structure. Source: G. Lewis 2013.

APPLIED LOAD

COMPRESSION

TENSIONFRACTURE POINT/SFigure 3: The forces within a struc-

ture under an applied load.

Figure4:Sectiondrawingofroofingstructure.

Figure 5: Modelled section.

CASE STUDY - MODELDuetothecomplexityofthebuilding(EasternResourceCentrelink),asmallsubsection,determinedtobeofstructuralsignificance(fig.4)wasrecreatedusingbalsawoodandcard(fig.5).

Theendplatesandthefixingoftheroofspanstotheexistingconcretewall(fig.6)wasanareaofparticularinterest,andwererecreatedindetail(fig.7).

Figure 6: Detailed section drawing of the end plate and fixings.

Figure7:Modelledendplateandcleats.

A

A

I-beams

Existing ERC building

Glossary Plasterboard

Plasterboardisacommonwallandceilingliningmaterialmadeofagyp-sum(hydratedcalciumsulphate(WordNetSearch–3.1n.d.))coresur-roundedbya“heavy-dutypaperliner”(Boral2012).

Thehydratednatureofthegypsummaterialhelpspreventrapidfirespread, and may give up to 4 hours protection in certain applications. Plasterboardmayalsoacttodampennoise,andmaybemanufacturedtoenhancethisfunction.Typically,plasterboardisavailablein1200mm-wide sheets to suit standard 600mm stud spacing commonly found in modernhousingstructures.Whileitdoesnotresistwater,itcanbesealedforuseinwet-areas.Overall,plasterboardisaversatilematerialthatcansuitanumberofapplicationsdependingonthemanufacturingprocess(BritishGypsum2013).

References:

Boral2002,ExportPlasterboardSheetProducts,Available:http://www.boral.com.au/plasterboardexport/export_plasterboard_sheet_products.asp[2013,11September].

BritishGypsum2013,10thingsyoushouldknowaboutplasterboard,Available:http://www.british-gypsum.com/Technical-Advice/Installation-Guidance/10-things-you-should-know-about-plasterboard[2013,11September].

WordNetSearch–3.1n.d.‘Gypsum’,Available:http://wordnetweb.princeton.edu/perl/webwn?s=gypsum[2013,11September].