Assignment 2 final Steel Truss Design PDF

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Assignment-2 Construction Materials hepls with understanding....

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STEEL%TRUSS%DESIGN%FOR%RODEO% ARENA% !

Nafisa!Nishandar(12932339),!Jeongmin!Sin!(99173130),!Kyaw!Nyi!Nyi!Thein!(12508521)

Contents% Contents%%% 1. Introduction!.…………………………………………………………………! Pg. 2 2. Steel0Roof0Trusses!...………………….………………………………….! Pg. 2-4 2.1 Selection!of!Steel!Roof!Truss!……………………………………! Pg. 3 2.2 Truss!Components!…………………………………………………..!! Pg. 4 3. Truss0and0Column0Section0Specification!.……………………...! Pg. 5-7 3.1 Sketch!1:!Rodeo!Arena!Plan!……………………………………..! Pg .5 3.2 Sketch!2:!Overall!truss!Shape!…………………………………..! Pg. 5 3.3 Sketch!3:!Pin!Connection!Detail!……………………………….! Pg. 6 Pg. 6 3.4 Sketch!4:!Truss!to!Truss!Connection!…………………………! Pg. 7 3.5 Sketch!5:!Sliding!Connection!Detail!………………………….! 4. Material0Specification!…………………………………………………! Pg. 8 4.1 Structural!Steel!Hollow!Section!Specification!..…………! Pg .8 4.2 Welding!Consideration!for!Steel!………………………………! Pg. 8 4.3 Bolt!Specification!…………………………………………………….! Pg. 9 Pg. 9 4.4 Corrosion!Protection………………………………………………..! Pg. 9 4.5 Fire!Protection!…………………………………………………………! Pg. 10 4.6 Comparison!of!Black!Mild!Steel!&!Structural!Steel!! Pg. 10 5. Bibliography!………………………………………………………………….! Pg. 11 Appendix:0Lab!Results!for!Black!Mild!Steel00

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1. 1.%%Introduction% 0 Trusses!are!an!integral!part!of!roof!design!and!provide!structure!and!support!to!the!roof.!Long! span! truss! design! can! create! flexible! and! column! free! internal! space! making! them! ideal! for! buildings!such!as!arenas,!stadiums!and!exhibition!centres(SteelConstruction.info).!This!report!is! an!overview!of!the!roof!truss! design!for!a!Rodeo!Arena! (116m! x!68m)! having!a!span!of! 68m.!It! highlights!the!specifications!for!the!truss!in!terms!of!its!overall!shape,!column!type,!connection! details!(column!to!truss,!truss!to!truss!connections),!material!specification!and!the!use!of!specific! corrosion!and!fire!protection!techniques.!!!!

2.% 2.%Steel%Roof Steel%Roof Steel%Roof%%Trusses Trusses%% A!truss!is!primarily!a!triangulated!arrangement!of!interconnected!structural!elements.!The!top! and! bottom! cord! undergo! tension! and! compression! while! the! bracings! in! between! the! cords! resist!shear!forces!(StealConstruction.info,!N/A).!!The!following!table!gives!a!brief!summary!of! the!type!of!truss!and!its!purpose.!! ! Type0of0Truss0 Purpose0 Diagram00 • Short!span!workshop!buildings! North0light0 Truss0 • Useful!for!natural!lighting!! • Risk!of!over!heating!

! Pratt0Truss0(N)0 0

• Long!span!buildings!20-100m!span!! • If! slope! added! to! top! chord! a! Duopitch!Pratt!truss!is!achieved! • Limited!to!having!straight!cladding! • Not!aesthetically!pleasing!!!

Pratt!Truss!!

! ! Duo!Pitched!Pratt!Truss! Bow0String00

• Arched! top! chord! with! flat! bottom! chord! • Large!height!difference!between!top! and!bottom!chord!

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Barrel0Truss0

• Arched!top!and!bottom!chord!! • Minimum! difference! between! top! and! bottom! chord! therefore! less! wastage!of!material!! • Pleasing!aesthetics! ! • Suitable!for!long!spans!!

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2.1$Selection$of$S 2.1$Selection$of$Steel$ teel$ teel$R Roof oof$T $Truss$$ From!the!above!truss!types,!we!have!chosen!the!Barrel!Truss!as!the!steel!roof!truss!for!the!Rodeo! Arena.!This!fits!the!project!requirement!of!an!arched!truss!and!is!able!to!strike!a!balance!between! serviceability!and!minimum!material!costs,!due!to!the!reduced!gap!size!between!the!two!chords.! Sketches!1-5!provide!the!details!of!the!truss!design.!! !

2.2$Truss$Components$ 2.2$Truss$Components$$$ According!to!A.!Gudadhe,! Circular!Hollow!Section!(CHS)!is!among!the!best! between!Rectangle! Hollow! Section!(RHS)! and! Squared! Hollow! Section! (SHS)! due! to! its! high! load!carrying! capacity! which!is!achieved!by!having!the!greatest!moment!of!inertia!as!compared!to!other!shapes!(Figure! 1).! From! figure! 1! it! can! also! be! seen! that! CHS! has! the! highest! buckling! and! torsional! stress! compared!to!other!hollow,!I!and!Channel!sections,!which!will!ensure!that!the!structure!is!suitable! to!carry!large!loads.!!stable!and!strong!structure.!Furthermore,!the!rounded!shape!ensures!that! there!is!less!chance!of!moisture!and!dust!being!deposited!on!the!surface!which!makes!CHS!less! susceptible!to!corrosion!attack(A.!Gudadhe,!2015).! ! !!

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Figure01:0Illustrates!the!mechanical!properties!of! different!sections00 Page!3!of!12!

Concrete-filled0Steel0tubular0columns ! In! order! to! support! the! huge! loads,! high! strength,! small! cross-sectional! area! columns! are! required.! Concrete! filled! steel! tube! (CFT)! section! have! characteristics! such! as! high! strength,! reduction! material!cost,!large!energy!absorption!capacity!and! enough!ductility!of!steels,!making!them!suitable!to! be! used! as! columns! for! trusses! (Zhao! Hua! et! al.! 2017).! For! this! reason,! the! concrete! filled! square! steel!tube!is!going!to!be!used!as!columns!to!support! roof! truss! for! the! arena. 300! (outside! width! of! the! square! section)! x! 3.70(wall! thickness!of!steel!tube)!!x!900(length!of!the!specimens)! specimen!could!withstand!load!around!3700!KN.!So!as! to! construct! the! square! shape,! Q235! steel! plates! is! going!to!be!bent!and!the!connection!between!steels!will! be!welded.!Commercial!concretes!,C50,!will!be!filled!in! the!column!(Ding!et!al.!2015).!

Figure02:0Cross-section!of!Column!

! Figure03:0Axial!Displacement!due!to!load0 Sliding0Connection0for0one0end00 A!number!of!civil!structures!including!steel!truss!roofs,! steel! domes! and! so! forth! have! been! affected! by! unexpected! environmental! characteristics! such! as! change! of! temperature.! Both! cracking! and! buckling! would! appear! in! structural! components! once! increasing! or! decreasing! length! are! restrained! by! support!because!there!is!large!thermal!stress.!In!order! to! get! rid! of! constraint! effect! to! the! components! of! structures!and!facilities,!sliding!supports!are!universally! Figure04:0change!in!length!due!to! chosen(Zhao!&!Xu!2006).!This!truss!has!a!sliding!support! thermal!expansion!! which!consists!of!an!upper!structure,!sliding!pad!made! of! Poly! Tetra! Fluoro! Ethylene! (PTFE)! and! support! structure.! PTFE! has! a! special! feature! of! low! coefficient!of!friction,!PTFE!called!Teflon!is!used!so!to!produce!many!of!the!sliding!pads!(Rae!&! Dattelbaum! 2004).! Before! the! truss! and! the! concrete! filled! steel! column! are! connected,! the! column!would!be!combined!with!bigger!size!steel!plate!and!PTFE!panels!at!the!pin!connection.! Four!bolts!40!mm! in! diameter!are!connected!to!the!panels!in!a!way!that!accommodates!slight! movement!of!the!truss!due!to!temperature!changes.!After!installing!them,!the!friction!constant! is!able!to!be!around!0.04!and!uniform!distribution!load!could!be!considered!in!this!system!(Zhao! &! Xu! 2006).! ! !

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4.% 4.%Material’s%Specification% Material’s%Specification% Material’s%Specification%%% 4.1$ 4.1$Structural$Steel$Hol Structural$Steel$Hol Structural$Steel$Hollow$Section$Specification low$Section$Specification low$Section$Specification$$ • •

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CHS!from!AS1163!structural!steel!hollow!sections!will!be!used!for!the!truss!members.! Yield!stresses!for!these!sections!are!between!250-450!MPa!with!tensile!strengths!between!320500MPa!(Figure!2)!.!This!range!will!be!suitable!for!the!required!span!of!the!Rodeo!Arena!as!ASTM! A572! (AS350)! grade! steel! was! used! for! a! larger! 91m! x! 140m! Boston! Garden! Roof! design.! (P.! Cheever!&K!Wiesner)!! The! hollow! sections! under! this! standard! are! manufactured!by! cold-forming! and! by! the! use! of! electric!resistance!welding!(EWR)!!

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Figure04:0Australian!Standard!steel!grades!and!their!potential!strengths.!

$ 4.2$ 4.2$Welding Welding Welding$$Consideration$for$ for$Steel$ Steel$ Steel$$$$$ Since!sections!of!the!truss!are!pre-fabricated,!on!site!welding!and!bolting!is!going!to!require!for!connection! purposes!and!hence!its!important!to!ensure!that!the!composition!of!steel!is!suitable!for!these!processes.!! ! In! basic! terms,! steel! is! a! metal! made! from! alloying! iron! (Fe) ! and! carbon! (C).! Hence! carbon! is! a! very! important!element!in!steel!and!directly!links!to!its!properties!of!strength,!hardness!and!ductility.!There!is! an!inverse!relation!between!the!effect!of!carbon!on!steel’s! strength!and!ductility.!The!higher!the!carbon! content!the!greater!the!strength!and!lower!the!ductility.!The!chemical!composition!of!the!structural!steel! hollow!section!would!determine!its!weldability.!According!to!D.!Dutta!et!al,!steels!with!fine!grain!microstructures!are!better!for!weldability!as!they!are!less!likely!to!develop!cracks!and!fracture.!In!addition,!for! weld!able!steel,!the!carbon!content! has!to!be!limited!to!less!than!0.2%! and!can!be!substituted!by!other! elements!such!as!manganese,!silicon,!vanadium,!aluminum,!chromium,!nickel,!niobium!and!titanium.!The! use!of!Carbon!Equivalent!Value!(CEV)!is!a!commonly!used!technique!to!set!the!criteria!for!weldability!for! a!certain!type!of!steel.!The!lower!the!CEV!value!the!better!the!steel!is!able!to!be!weld.!! &'

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+ 2. !!(The!International!Institute!of!Welding)! 𝐶𝐸𝑉 = 𝐶 + ( + . Restrictions!having!to!be!made!on!the!phosphorus!and!sulfur!contents!as!these!elements!are!undesirable! and!cause!major!issues!for!welding.!Sulfur!can!segregate!the!steel!matrix!making!it!weaker!and!along!with! phosphorus! it! reduces! ductility.! Hence! their! contents! have! to! be! limited! to! less! than! 0.04%! -! 0.05%.! Overall,!the!steel!chosen!for!the!truss!design!needs!to!have!a!minimum!content!of!carbon!required!for!the! desired!strength!(250!to!450!MPa),!so!that!it!doesn’t!get!too!brittle!and!prone!to!fractures!due!to!welding.!!! ! There!are!different!types!of!welding!that!are!suitable!for!steel.!The!first!type!of!steel!is!called!stick!welding! or! known! as!SMAW! (shielded!metal! arc! welding).!It! is!the! most! commonly! used! type! of! welding.!Stick! welding!is!used!on!construction!sites!and!in!the!field.!It!is!mobile,!simple!and!cost!less.!Furthermore,!it! Page!8!of!12!

produces!good!welds.!Two!stick!welding!rods!6011!and!7018!both!on!alternate!and!direct!current.!The! second!type!of!steel!for!welding!is!Mig!welding!steel.!Mig!welding!is!mainly!used!for!manufacturing!e.g.! for!shop!products.!Unlike!stick!welding,!it!is!harder!to!transfer!from!carbon!to!steel!as!the!process!involves! alternating!shielding!gas!and!the!spool!of!wire!as!stated!in!(!).!! !

4.3$Bolt$Specification 4.3$Bolt$Specification$$ • •

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Class!8.8,!high!strength!structural!bolts!under!AS/NZS!1252!can!used!for!the!connection! bolts!at! the!columns.!! They!are!made!of!medium!carbon!steel!through!the!process!of!quenching!and!tempering!(heating! material! followed! by! rapid! cooling! in! water,! oil! or! gas).! This! process! strengthens! the! element! making!it!less!brittle!and!more!ductile.!This!is!offers!abrasion!resistant,!high!yield!strength!element! which!is!perfect!for!bolts!as!they!support!huge!loads!of!the!whole!structure.!(A.Syam!et!al,!2005).!! They!come!in!nominal!sizes!of!M12,!M16,!M20,!M24,!M30!and!M36.!The!connection!bolts!for! the!truss!would!be!M30.!!!

4.4$C 4.4$Corrosion$ orrosion$ orrosion$P Protection$ rotection$$$ Corrosion0protection0technique0 ! There!are!many!ways!to!ensure!that!steel!is!protected!from!corrosion.!Even!before!steel!members!are! produced,!careful!consideration!on!the!composition!of!steel!can!produce!stable!and!long-lasting!products.! The!elements!chromium,!nickel!and!copper!in!structural!steel!are!important!corrosion!resistive!materials! and!contents!of!aluminum!and!silicon!(deoxidizers)!make!steel!a!durable!metal.!!! ! Other!corrosion!prevention!techniques!include;!Painting/Spraying!and!metal!coating!(galvanizing).! Painting/Spraying0 (zinc0 rich0 paints):! organic! bonded! agents! and! inorganic! pigments! can! be! used! for! painting!exterior!steel!sections.!The!paint!has!three!coatings,!first!a!primer!coat!which!acts!as!a! physical! barrier!so!that!the!corrosive!materials!cannot!interfere!with!the!structure,!chemically!inert!intermediate! coat!to!help!bond!with!the!final!top!coat,!which!is!impervious!to!any!chemical!or!mechanical!actions.!The! paint!or!sprays!thickness!is!limited!to!15-20µm. This!is!done!before!the!truss!sections!(4!sections:!two!20m! and!two!6m!long)!are!brought!to!site,!in!order!to!prevent!corrosion!during!transportation,!storage!and! fabrication.!(D.!Dutta,!1998).!For!hollow!sections!the!internal!corrosion!isn’t!a!big!issue!are!they!as!long!as! there!are!no!pores!for!air!or!water!to!seep!as!most!sections!are!sealed!with!weld!caps.!Inspections!have! to!be!done!to!ensure!that!water!isn’t!settling!inside!the!CHS!due!to!freeze-thaw!action!cause!of!changing! night!and!day!temperatures.!(D.!Dutta,!1998).! ! Hot0dip0galvanizing:!it’s!an!economical!form!of!protection!for!both!external!and!internal!section.!Cleaned! and!chemical!pickled!steel!members!are!immersed!in!molten!zinc!at!470ºC,!this!causes!a!non-porous!zinc! layer!to!form!over!the!steel!surface!providing!protection!to!the!structure.!(D.!Dutta,!1998).! !

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4.5$ 4.5$Fire$Protection$ Fire$Protection$ Fire$Protection$$$ !

Figure05:0Intumescent!Coating!use!for!protecting! against!fire00

The!main!type!of!fire!protection!consumed!for! structural! hollow! sections! is! thin! film! intumescent! coatings.! Intumescent! is! a! substance! that! expands! when! exposed! to! heat!increasing!volume!and!reducing!density.! As! the! temperature! reaches! above! 250ºC! a! thick! layer! of! insulating! layer! of! char! is! created!on!the!steel!(S.!Jones,!N/A).!Typically,! for!a!fire!rating!of!2!hours,!5mm!coating!has! to!be!applied!to!the!structure.! ! ! !

4.6$ 4.6$Comparison$of$Black$mild$s Comparison$of$Black$mild$s Comparison$of$Black$mild$steel$to$structural$steel$ teel$to$structural$steel$ teel$to$structural$steel$$$ • •

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Black!mild!steel!is!a!form!of!low!carbon!steel!that!is!suitable!for!welding!! From!our!results!and!research!it!can!be!seen!that!Structural!Steel!AS1163!has!a!greater! ductility! and!strength!than!Black!Mild!Steel.!You!may!refer!to!the!appendix!for!details.!

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𝑀𝑒𝑎𝑛7𝐷𝑢𝑐𝑡𝑖𝑙𝑖𝑡𝑦 = 32.2%!

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Bibliography % Books

Ding Fa-xing, Lu Jing, Liu Xue-mei, Yu Zhi-wu & Li Da-wen 2015, ‘Mechanical behavior of circular and square concrete filled steel tube stub columns under local compression’, Thin-walled Structure, vol.94, pp. 155-166 Dutta D & Wardenier J, 1998, Design Guide for Fabrication, Assembly and Erection of Hollow Sections, pg 17,140, TUV VERLAG. Gorenc B, Tinyou B, Syam A, Steel Designer Handbook, Pg 18, 208, UNSW Press

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Liu Dalin 2006, ‘Behaviour of eccentrically loaded high-strength rectangular concretefilled steel tubular columns’, Journal of constructional steel research, vol. 62, pp. 839846 Zhao Hua, Sun Yuping, Takeuchi Takashi & Zhao Shichun 2017, ‘Comprehensive stress-strain model of square steel tube stub columns under compression’, Engineering Structures, vol. 131, pp. 503-512 Zhao.X & Xu.Y.L 2006, ‘Finite element-based force identification of sliding support systems: Part I—Theory’, Finite Element in Analysis and Design, vol 42, pp. 229-248 Rae.P.J & Dattelbaum. D.M 2004, ‘The properties of poly(tetrafluoroethylene) (PTFT) in compression’, Polymer, vol. 45, pp. 7615-7625 Websites Cheever P & Wiesner K, N/A, Structural Design of the New Boston Garden, viewed on 2nd Oct 2017

Gudadhe A, 2015, Design of Long Span Exhibition Hall of Steel Structure, viewed on 2nd Oct 2017

% Welding tipsandtricks, 2017, Welding steel, viewed 8 October 2017,

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Appendix Appendix%%:%Lab%Result%for%Black%Mild%Steel% ! ! !

LD

50.08 mm

LE

67.60 mm

DD

9.97 mm

DE

6.48 mm

σGHIJK7LMJNO

23.00 kN

σPQR

37.70 kN

σSQMNTKJ

26.80 kN

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