• If painting or galvanizing isrequired, the fabricator/erectorneeds to know the specific require-ments, such as surface preparation,which members are to be painted,the type of paint, etc. This informa-tion should be expressed using stan-dard SSPC notation.

• Special attention should be given todetails where steelwork structurallyinteracts with the work of othertrades, such as web openings, supportfor fascia panels, support for metaldeck, etc.

One of the most perplexing sit-uations for fabricators/erectors iswhen designers don’t share the infor-

should be discussed at the pre-con-struction conference.)

• The fabricator and erector need toknow which beams, if any, are sub-ject to vibration loads such as frommachine rooms and elevator beams.

• Reactions for special load condi-tions—such as cantilevered members,two- and three-span beams, beamswith both uniform and concentratedloads and beams with non-uniformsnow-drift loads—should be shown.

• Specific column stiffener and dou-bler plate requirements should beshown—including sizes and locations.However, designers should considerthe oftentimes more economicaloption of increasing the column sizeto eliminate the need for stiffening.

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S uccessful projects require ateam effort, with the owner, designer,fabricator and erector workingtogether to create the finished struc-ture. Each of the key team membershave specific roles, and with theseroles come responsibilities to theother team members.

For example, one of the fabrica-tor’s and erector’s key roles is to cor-rectly interpret and comply with thedesigner’s instructions. In order toaccomplish this goal, however,he/she requires loads, dimensionsand member sizes to be summarizedas outlined below:

• Beam end reactions for gravity,axial and torsion loads, as well asmoments, should be shown.Likewise, the designer should indi-cate if live load reductions have orcan be taken. And, in LRFD, thedesigner should indicate whether ornot the reactions are factored.

• Column loads—not only axial butalso shear loads at splices and at thebase, plus any moments at beamends, brackets and splices—can beshown on the column schedule.

• The designer should indicate diago-nal axial loads and whether they arein tension, compression or both. Thefabricator also needs to know ifallowable stresses can be increased(ASD). If the designer has a prefer-ence for bracing work point locationit should be shown.

• The fabricator and erector need toknow all special floor and roof loadsand point loads for special equip-ment or service requirements such asbeams supporting constructionequipment storage areas or jumpcranes during erection. (Such items

Value Engineeringfor Steel Construction

Complete information is a key to success

Modern Steel Construction / April 2000

Figure 1: Mill Extras (as reported by Nucor Yamato Steel)

The following sections are available at the same cost for A36, A572 Gr. 50,A992, and CSA 40.21 Gr. 350W:

W24x68-103, W24x55-62, W21x62-93, W21x44-57, W18x50-71, W18x35-46, W16x67-77, W16x36-57, W16x26-31, W14x61-82, W14x43-53,W14x30-38, W14x22-26, W12x53-58, W12x40-50, W12x16-22, W10x49-77, W10x33-45, W10x22-30, W8x31-67, W8x24-28, W8x18-21, W6x15-25.

For other shapes, A572 Gr. 50, A992 and CSA 40.21 Gr. 350W require sur-charges as follow:

sections to 150 lbs./ft. inclusive ..........................................$1.25/CWTall sections over 150 lbs./ft. to 300 lbs./ft. inclusive............$2.00/CWTall section over 300 lbs./ft. ..................................................$2.25/CWT(note: CWT = 100 lbs)

Minimum item quantity requirementsA588 or equivalent

Mill 1 ......................................................................................InquireMill 2 ......................................................................................20 tons

ABS-AH36 ................................................................................20 tonsLength Requirements

stock lengths 30’-80’ inclusive ......................................................noneunder 30’-25’ ......................................................................$1.00/CWTnon-standard lengths >30’ - <80’ ........................................$0.25/CWTOver 80’ ..............................................................................$0.25/CWT

Standard lengths (30’, 35’, 40’, 45’, 50’, 55’, 60’, 65’ 70’ & 80’) are available inbundle quantities only.

Figure 3

in the range of 50% - 75%. Fullcomposite design is often inefficientand uneconomical. The cost of oneshear stud in place equals the cost ofapproximately 10 lbs. of steel. Unlessthis ratio can be attained, the addi-tion of more studs will prove uneco-nomical.• Take advantage of live-loadreductions if governing codes per-mit.• Select optimum bay sizes. Anexhaustive study by John Ruddy,P.E., of Structural AffiliatesInternational in Nashville (AISCEngineering Journal, Vol 20, #3,1983) indicated that a rectangularbay with a length-to-width ratio ofapproximately 1.25 to 1.50 was themost efficient. The filler membersshould span in the long directionwith the girder beams in the shortdirection (see figure 2).• Tailor the surface preparationand the painting requirements tothe project conditions—do not over-do or underdo the coating require-ments. An extensive examination of amultitude of aged structures withsteel frames indicates that the pres-ence or absence of a shop primer isimmaterial as long as the structuralsteel is kept dry (LRFD SpecificationCommentary Chapter M). Thesesame studies indicate that shopprimer alone affords very little pro-tection if a structure develops a seri-ous leak. In recent years, the trendhas gone toward not painting. Thereare many side benefits to be gainedby the omission of paint—no maskingaround bolt holes, better adhesionfor concrete and/or fire proofing,easier weldability, ease of inspection,ease of making field repairs/alter-ations, etc. If shop painting is neces-sary, bear in mind that a shop coat isby definition a temporary coat—usu-ally serving less than six months induration. As such, there is little justi-fication that the coat be perfect (thatis, of uniform thickness with nodrips, runs or sags).• Show all necessary loads on thedesign drawing to avoid costly over-designing of connections or—worseyet—underdesigning. The designerwho provides a complete design willfind that the subsequent review andapproval process of shop drawingswill be much quicker and more ositive.

mation developed during the designprocess. During the design process,the structural engineer develops allof the information required to fabri-cate and connect the structural steelmembers, including loads, reactions,stiffening, special conditions, etc. Butwhen it comes to the design drawing,the engineer all-to-often merelyshows the member sizes.

Skimping on the design drawingalways comes back to haunt thedesigner in the form of questions,higher bids, change orders, arbitrat-ing disputes, a slowerreview/approval process and a drag-ging construction schedule. If it is aquestion of time, then the designeris fooling himself or herself. Thetime the fabricator spends derivingall of the needed information ispassed back to the owner in the formof higher fees. And the engineer’sapproval reviewer has to spend addi-tional time analyzing the questionsand change orders.

The solution is greater teamworkand a consciousness of the impor-tance of value engineering. The team

member with the greatest impact onthe economic success of the project isthe designer. The team members alllive or die with the engineer’s design.The following is a checklist of itemsdesigners should consider whiledesigning a steel project.

• Capitalize on steel’s strengths.• Good weight-to-strength ratio• Efficiency of pre-assembly.• Speed of delivery and erection.• Strength in three directions.• Ease of modification/renovation.

• A designer should keep currenton the cost and availability of thevarious steel products he/she pre-scribes. A steel fabricator can supplybasic steel prices and mill extras (seefigure 1). A designer also should beaware of where the money is spenton steel construction: approximately30% on material, 30% on shop costs,30% on erection, and 10% of otheritems such as shop drawings, paintingand shipping. Labor is more than60%!• Consider using partial compositedesign of floor beams—something

Figure 2

• Make sure the general contractoror construction manager indicateswho is responsible for any “greyareas” such as loose lintels, masonryanchors, elevator sill angles, elevatorsheave beams, fastenings for precastconcrete spandrel beams, etc. Unlessthe responsibility is specifically dele-gated, it is likely that the cost ofthese items will be included in thebids of multiple contractors, whichmeans the owner will pay more thanonce for the same article.• Don’t require the steel sub-con-tractor to perform work normallydone by other trades , such asinstalling masonry anchors, ceilinghangers, toilet partition supports,window wall supports, etc.Information required to perform thiswork is often slow to develop, result-ing in needless delay to the fabrica-tor. The most efficient steel jobs arethose on which the fabricator anderector are allowed to concentrate onthe steel frame while unencumberedby the intricacies pertinent to othertrades. This reduces coordinationrequirements and allows the steelframework to be turned over to theother trades in far less time thanwould otherwise be possible.• Consider the use of cantileveredrafters and purlins to save weighton roof design (see figure 3).• Do not design for minimumweight alone. The savings in materi-al cost will often be negated by theneed for more members, more con-nections and more costly shop workand field erection. • Excessively stringent mill, fabri-cation and erection tolerancesbeyond state-of-the-art construc-tion practices will reduce thenumber of bidders and raise thecost of the project. ASTM A6 toler-ances and those established by AWSand AISC have served the industrywell for many years and should beadhered to except under extraordi-nary circumstances where some spe-cial condition dictates a more stricttreatment.• Design the proper type of high-strength bolt value. The correctapplication of each type is well-docu-mented in the current bolt specifica-tions. Do not specify “slip-critical”

bolt values for the pur-pose of obtaining anextra factor of safety.The trend in recentyears is toward the useof “snug-tight” boltsand bearing values.• Allow the use oftension control(twist-off) high-strength bolts. Thesebolts are as reliable asother methods of mea-suring bolt tension andsave labor costs in bothshop and field.• Where possible,specify fillet weldsrather than groovewelds. Groove weldsare more costlybecause of the jointpreparation requiredand the generallygreater volume of weld(see figure 4).• Use single-passwelds where possible.This involves keepingfillet welds to a maxi-mum of 5/16”.• Favor the horizon-tal and flat weldingpositions. These weldsare easier and quickerto make and are gener-ally of high quality(see figure 5).• Don’t specify more weld than isnecessary. Over-welding createsexcessive heat, which may contributeto warping and shrinkage of themembers resulting in costly straight-ening expense.• Grant the fabricator the optionof eliminating some columnsplices. The cost of one columnsplice equals the cost of approxi-mately 500 lbs. of A992 steel. Thefabricator should study the situationcarefully before he decides to omitthe column splice as the resultingcolumn may be too long for safeerection. Multi-tier columns shouldbe designed to have splices every twoor four floors. Three-floor columnsare to be avoided due to erection dif-ficulties. The higher up in a tallbuilding, the less desirable it is to use

Figure 4

Figure 5

Figure 6

four-floor columns due to higherwind speed and difficulties in guying.• Avoid designing column splicesat mid-story height. These are oftentoo high for the erector to reachwithout rigging a float or scaffold. Ifthe splice can be located no higherthan 5’ above the tops of the steelbeams, it saves the expense of theextra rigging and still will be in aregion of the column where bendingforces are relatively low (see figure6).

• Except where dictated by seismicconsiderations, do not design col-umn splices to “develop the fullbending strength of the governingcolumn size.” Seldom is the splicelocated at the point of maximumbending and seldom do the bendingstresses result in a condition that

• Avoid designing heavy or awk-ward members in remote hard-to-reach portions of the structure.This may eliminate the need for larg-er, more expensive hoisting equip-ment.• Reinforce beam-web penetra-tions only where necessary. It maybe less costly to use a beam with athicker web, to move the opening toa less critical location or to changethe proportions of the opening tosomething less demanding (see figure8). To help in designing web open-ings, AISC published Design Guide#2: Design of Steel and CompositeBeams with Web Openings. AISCalso offers a software program,Webopen, to help in designing webopenings. To order AISC publicationsand software, visit www.aisc.org orcall 800/644-2400 to order publica-tions and 312/670-5444 to ordersoftware.• Allow the prudent use of over-sized holes and slots to facilitatefit-up and erection. They may elim-inate or reduce the need for costlyreaming of holes or modification ofconnection parts in the field.• For ordinary structures, do notspecify that connection materialbe of one type to the exclusion ofother types. Allow the fabricator touse his stock to good advantage.However, the fabricator should rec-ognize that certain structural situa-tions require specific types of steel.The designer should identify thesespecial conditions.• Avoid calling for the indiscrimi-nate use of stiffeners. Allow partialdepth stiffeners where applicable.

Stiffeners are required to preventlocal deformation or to transfer loadfrom one part of a member to anoth-er (see figure 9). If the main mem-bers are capable of taking care ofthemselves, then the cost of stiffenerscan be saved.• Avoid odd sections that may notbe readily available or which areseldom rolled since it could result incostly delays. Consult with a fabrica-tor concerning the availability of spe-cific shapes.• In areas subject to snow driftloading, arrange the purlins paral-lel to the drift and space thepurlins closer together as the driftload increases so the same gageroof deck can be used throughout(see figure 10). • Space floor beams so as to avoidthe necessity for shoring duringthe concrete pour. The cost ofshoring is relatively expensive andcan easily be offset by varying thespan, gage or depth of the floor deck.• Avoid the “catch-all” specifica-tion that reads something like this:“Fabricate and erect all steel shownor implied necessary to complete thesteel framework.” The bids willundoubtedly be padded to coverwhatever might be “implied”. • Avoid the “nebulous” specifica-tion calling for stiffeners, roofframes, reinforcing of beam web pen-etrations, etc., “as required”. Thefabricator and erector are rarely fur-nished enough information at the bidstage to determine what is or is notrequired and therefore will includein the bid an allowance for investi-gating and furnishing the question-

Figure 7

Modern Steel Construction / April 2000

wold require a full-strength splice.The column has axial compressionstresses. The excess capacity is allot-ted to bending stress that occur ascompression in one flange and ten-sion in the other. The compressionforces are added to each other at oneflange while at the other flange thetension force is subtracted from thecompression force. Seldom does thisother side of the column ever go intotension and never into full allowabletension of the magnitude that wouldrequire a full-strength splice. Thus,except in high seismic constructionthere is little justification for everrequiring a full-strength columnsplice (see figure 6).• Consider using a heavier columnshaft to eliminate the need forweb doubler plates and/or columnstiffeners opposite the flanges ofmoment-connected beams. Onepair of stiffeners installed costsapproximately the same as 300 lbs. ofA992 steel if the stiffeners are fillet-welded. If they are groove welded,the cost skyrockets to the equivalentof 1000 lbs. of A992 steel. The costof one installed doubler plate isabout the same as 350 lbs. of A992steel (see figure 7). Considering thatfor an average two-floor columnthere could be as many as four pairof stiffeners and two or more doublerplates, at least 1900 lbs. of A992 steelcould be sacrificed in order to savethe time and expense of making thelighter shaft compliant. (For moreinformation, see AISC Design Guide#13: Wide-Flange Column Stiffeningat Moment Connections. To orderAISC publications and software, visitwww.aisc.org or call 800/644-2400.)

Figure 8

depths.• Do not call for non-parallel chordsfor “K” series joists.• Do not specify severe top chordslope for long-span joists and joistgirders.• Do not call for clip angles, bracketsor any such superficial attachementsto be fastened to the joists by themanufacturer, as this would disrupthis normal handling and shippingsystem. • Do not specify non-standard cam-ber (see Steel Joist InstituteSpecifications for more information—phone 843/626-1995; fax 843/626-5565; web: steeljoist.org.)• Do not specify a special joist paint,surface preparation or method ofpaint application.• Do not specify a special paint colorother than the manufacturer’s stan-dard (this is usually grey or reddishbrown).• Do not prescribe a special paintthickness.• Do not specify special chord or websizes.• Do not call for a special web pro-file.• Do not specify special steel materi-al. The SJI Specification permits abroad range of acceptable material.• Do not stipulate hot-rolled or cold-rolled material to the exclusion ofthe other. The SJI Specification per-mits both types.• Do not prohibit or limit the numberof joist chord splices, restrict thesplice locations or require the spliceto be made using a particular weld-ing procedure. The SJI prescribessplicing procedures that have passedthe test of time with flying colors.• Do not call for holes in highlystressed portions of joist chords.• Do not call for joist top chordextensions to be too long or tooheavily loaded. Follow manufactur-er’s recommendations.• Do not call for concentrated loadson joists that are beyond their capac-ity to resist. The SJI has establishedmaximum limits.• Do not specify bottom-bearing joistsif underslung ends will suffice.

Figure 9

Figure 10

able items whether they’re needed ornot.• Avoid overly restrictive specifi-cations. The more restrictions listedin the steel specifications, the greaterthe chance that no one will be ableto meet them all. This will eliminatesome competition and result in higher bids.• Design for duplication of beamsizes where possible since thisresults in economies of scale. Forexample, in a mezzanine the edgebeams often carry less load and couldbe made smaller but for the sake ofduplication make them the same. • Likewise, design for duplicationof connections. For example, if mostof the filler beams on a job can beconnected using a four-bolt shearplate but a few require only a three-bolt shear plate, make them all four-bolt. This miniscule “giveaway” ismore than made up by the efficien-cies of duplication—both for the shopand field. Connection material rarelyexceeds 5% of the job total weight.Trying to save a tiny percentage of5% is not cost effective if it leads tospecial handling, marking, sortingand other special treatment of themembers in question.

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T he engineer-of-record is notexpected to design steel joists orother proprietary products such aswindow walls, large atrium skylightsor modular storage towers. However,they must clearly state the project’srequirements regarding loads andperformance to enable the joist man-ufacturer to produce a compliantproduct.

The key to economical steel joistdesign is “standardization.” Openweb steel joists were originally con-ceived as single-span members carry-ing uniform loads and as such theyare at their best. Joists are a standardproduct with relatively few variables.

Departure from the standard willgenerally increase the cost of thejoist. The following is a list of “do-nots”:

• Do not specify non-standard joist

• Do not call for cross-bridging wherethe SJI Specifications permit the useof horizontal bridging.• Do not specify that the welds usedby the joist manufacturer be madeusing a special weld process or elec-trode.• Do not indicate “ceiling extensions”if the ceiling is “hung” below thejoists.• Do not require that modest concen-trated loads be delivered at a panelpoint. A joist top chord is designed tosupport a 400 lb. concentrated loadanywhere between panel points inaddition to the normal uniform load.

There are other ways to realizecost savings in joist construction.Sometimes it is less expensive to usea heavier joist if it reduces the bridg-ing requirements (see figure 11).Bridging installation is very laborintensive. For example, a 12K1 joist17’ long requires two lines of bridg-ing whereas a 12K3 joist of the samelength requires only one line ofbridging. This is a 50% reduction inbridging and installation and the costof the heavier joist is only about $3more.

When a span is so short as tomake it impractical or impossible touse an open web joist, a joist substi-tute can be used such as angles,channels, small wide-flanges, HSS orcombinations thereof. Figure 12shows approximate limitations forminimum lengths of short joists.These may vary among manufactur-ers. Figure 13 shows some of theshapes that can be utilized in place ofshort joists.

Today, some manufacturers arewilling to customize their product,often to an amazing degree.However, for ordinary joist construc-tion there are practical and economi-cal limitations on the amount of cus-tomization that can be performed ona joist. If the designer sees the steeljoist becoming too complex, chancesare he or she should consider using awide-flange alternative.

Figure 11

Figure 12: Approximate* Min. Joist Lengths

H & K Series Open Web Joists LH Series LongspansDepth (in.) Min. Length* (ft.) Depth (in.) Min. Length* (ft.)

8 4-0 18 6-410 4-6 20 7-012 5-7 24 8-414 5-11 28 9-816 6-10 32 11-018 7-6 36 12-420 7-10 40 13-822 8-2 44 15-024 8-6 48 16-426 8-10 52 17-828 9-2 56 19-030 9-6 60 20-4

*varies by manufacturer

Figure 13

Figure 14

Modern Steel Construction / April 2000

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Formed metal deck floors androofs play a significant role in steelbuilding construction. There areenough variables in deck design tomake it important for designers toput the right combination together tomaximize value.

Some of these variables include:

• Type (roof deck, centering,deformed floor cell, cell deck).

• Profile (narrow, intermediate,wide rib).

• Depth.• Gauge.• Finish.• Side laps.• End laps.• Span and deflection.• Fastening systems.• Acoustic or non-acoustic.

Roof Deck

Roof deck is generally available in1-1/2” and 3” depths. Deeper deck isavailable from a few manufacturers.Deck is available in thicknesses from16 ga through 22 ga and with paint-ed, G60 galvanized or G90 galva-nized finishes. Roof deck is availablein acoustic and non-acoustic styles,with or without cells. Three rib pro-files are available—narrow, interme-diate and wide. Side laps are eithernestable or interlocking (see figure14). Deck ends are usually over-lapped for a minimum of 2”. Die set(swaged) ends were offered at onetime as an aid to deck nesting butmodern deck profiles are such thatthis is no longer necessary. In fact,there are distinct disadvantagesregarding the erectability of deckpanels that have die set ends. Thespan is important because it has adirect effect on several other deckproperties, namely the profile, gauge,depth, stress and deflection limits.

Narrow-rib deck is so inefficientthat it is seldom used today.Intermediate-rib deck is competitive-ly priced with wide-rib deck; 24 gathickness intermediate-rib deck is

rib was not considered because theallowable span would have been soshort that it would have requiredmany more supporting members.

• 3”-deep deck was considered andwould have allowed the span toincrease to 10’ and the deck light-ened to 22 ga; however, the support-ing members increased in size andthe spacing did not adapt well to thechosen bay of 35’.

• 20 ga deck is among the most com-mon used, with most manufacturerscarrying a stock of 20 ga and 22 gacoils, which results in good availabili-ty and quick delivery.

• Painted deck was selected becausethe interior of the building is dry,well-ventilated and not subject tocorrosive atmosphere, condensation,humidity or any other condition thatwould have required a more expen-sive coating.

• The designer needed somediaphragm strength from his decksystem so he selected a deck withnestable side laps rather than inter-locking side laps. Interlocking sidelaps are normally fastened with abutton-punching devices but thismethod is unreliable in transmittingdiaphragm shear forces. Nestable sidelaps can be welded, screwed or popriveted. In 20 and 22 ga deck, thereis a danger of blowthroughs whenwelding side laps, so a self-drillingscrew system was selected. Plainrather than die set ends were stipu-lated since there was no reason torequire die set ends. As the probabili-ty existed that the deck might have to

offered by some manufacturers butshould only be used in special cases.For a given span and gauge, wide-ribdeck is stronger than intermediate-rib deck, which, in turn, is strongerthan narrow-rib deck. As a rule, allthings being equal thick deck costsmore than thin deck, and 3” deckcosts more than 1-1/2” deck. Also,G90 galvanized deck generally costsmore than G60, which costs morethan painted roof deck. Some deckmanufacturers offer other finishes,such as electro-galvanized, phospho-rized and galvanized/painted, whichmay be cost effective. Manufacturersshould be consulted regarding pric-ing and availability. Because of thevolatility of the deck industry, it isnot recommended that a specificmanufacturer be specified; rather, itis recommended that the manufac-turer be a member in good standingwith the Steel Deck Institute (ph:847-462-1930; fax: 847-462-1940;web: sdi.org).

The following example of valueengineering illustrates how severaldeck variables can be selected inorder to provide a suitable product ata good price:

• For the metal deck of a large ware-house, the designer has made severalefficiency and cost studies and deter-mined that a wide-rib, 20 ga, 1-1/2”-deep deck on a 7’ three-span condi-tion meets his requirements for loadcarrying ability and deflection.

• Wide-rib was selected becauseintermediate-rib would haverequired an 18 ga thickness. Narrow-

Figure 15

be laid in a patch-work manner anddie set ends would have created asevere hardship for the erectors sincedie set deck is normally laid out end-to-end all in one direction.

• Because the deck was supported bymembers with relatively thickflanges, it was decided that weldingwould be the most efficient mannerof fastening (see figure 15). If thesupporting material had been thin-ner, screw type or power-driven fas-teners would have been considered.As it was, the designer wisely permit-ted all three methods in the specifi-cation. Since the deck was thickerthan 0.028”, weld washer were notneeded or specified.

Floor Deck

Similar economical advantagescan be realized in the selection offloor deck.

Floor deck for the support ofpoured-in-place concrete is availablein several styles (see figure 16):

• Form deck (centering), which usu-ally comes in a modified corrugat-ed profile varying in nominaldepths from ½” to 1-1/4”;

• Composite (deformed) floor deck ;• Cellular deck;• Deck for use with shear studs;• Deck that cannot be used with

shear studs;• Vented or unvented floor deck;

and

Hollow structural sections havean advantage over wide-flange shapesin regard to painting and fireproof-ing, wind resistance and stiffnessabout the minor axis. Additionally,many architects prefer their aestheticquality.

Square, rectangular and roundHSS make economical columns.They are an excellent choice whenstiffness about both axes is required.They can be used as hollow membersor filled with concrete. There is nogreat strength advantage to fillingsmall HSS with concrete; however,for larger columns there is a distinctadvantage. For example, the designstrength of an HSS 3x3x1/4x10’ is alittle more than 10% higher whenfilled with 3000 psi concrete. But thedesign strength of an HSS8.625x0.322x12’ is about 40% higherwhen filled with 3000 psi concretethan unfilled.

HSS have less surface area thanequivalent wide-flange members,with round HSS having the least sur-face area. For example, listed hereare the surface areas per linear footof three common sizes:

• W8x31 = 3.89 sq. ft.• HSS 8x8x1/4 = 2.60 sq. ft.• HSS 8.625x0.233 = 2.26 sq. ft.

This can be a significant cost fac-tor if members require an exotic sur-face coating or fireproofing.

HSS offer excellent resistance totorsional forces and can be used toadvantage to support eccentric loadssuch as relieving angles for brickveneer, stone, or precast concretepanels (see figure 17).

• Floor deck with provisions forceiling hangers.

Floor deck is available in 1-1/2”,2” and 3” depths and some manufac-turers have special deeper decks.Inverted roof deck also can be usedas a form for placing wet concrete.Floor deck is available in thicknessesfrom 16 ga to 28 ga depending onthe type selected. It is available inuncoated, galvanized, painted andcertain combinations thereof, againdepending on the manufacturer andthe type of deck required. Floor deckcomes with either nestable or inter-locking side laps.

As with roof deck, cost-consciousdesigners will only specify those fea-tures deemed necessary for propermaintenance and performance andwill reject unnecessary features thatserve no particular fea-ture but add to the costof the project.

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Figure 16

Figure 17

HSS also make efficient bracingmembers. It is usually easier to hideHSS diagonal bracing systems withininterior walls than it is to concealwide-flange shapes, angles or chan-nels. Figure 18 shows various meth-ods of connecting HSS and steel pipe.They also can be combined withother structural shapes to producesome startling aesthetic effects (seefigure 19).

For more information on design-ing with HSS, AISC offers a HollowStructural Sections ConnectionManual (call 800/644-2400 or visitwww.aisc.org to order).

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A significant portion of a fabri-cator’s overhead is spent on estimat-ing. For every job, a fabricator mayprepare 20 or more unsuccessfulbids. Some recent project specifica-tions have been written in such a way

as to require the fabricator to per-form significant portions of the steeldesign in order to prepare an accu-rate cost estimate.

A complete design is the bestassurance that those who must usethat design will accurately interpretthe intent of the designer. There willbe far less chance for ambiguities,misinterpretations, errors and/oromissions.

David T. Ricker, P.E., began hiscareer in the American BridgeDivision of U.S. Steel and later movedto Berlin Steel (Berlin, CT), eventual-ly becoming the company’s chief engi-neer and then its vice president ofengineering. Now retired, he lives inPayson, AZ, and runs JavelinaExplorations.

Figure 18

Figure 19