jointing of hollow section steel tubes

7/29/2019 Jointing of Hollow Section Steel Tubes

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SHS Jointing

Corus Tubes

Structural & Conveyance Business


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SHS JointingContents

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Contents

IntroductionButt JointsFlange ConnectionsSplice JointsEnd Fittings, Cleats & BracketsLattice JointsBeam to Column ConnectionsSlab to Column ConnectionsCast JointsMechanical Joints

Flowdrill & Hollo-Bolt JointingFlowdrillHollo-Bolt


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Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Introduction

SHS JointingIntroduction

Connections with hollow sections are often considered tobe complicated and expensive but in reality theycan be simple and cost effective. Any connectioncan be designed in two ways, either as a basic connectionor as an architectural connection.

Basic connections serve to join two or more componentsin the cheapest and simplest way. Plates are cut bycropping or profile burning and, whilst sharp edges andburrs are removed, no additional shaping is made.

Connections are made in the most accessible way forshop fabrication or site erection and will normally be leftexposed. Given freedom of choice and considering that, intodays economic climate, its the lowest bid that usuallywins, fabricators will, unless detailed otherwise, plan forbasic connections.

Architectural connections are designed to give the bestappearance generally requiring additional workmanshipand extra cost. However one should not focus ondesigning architectural connections which have

diminished visual impact, when considered as a part ofthe final structure.

Frequently hollow sections are employed for theiraesthetic appearance and in such cases it is importantthat the connection used has the necessary strength. It isthus necessary to strike a balance between workmanshipand cost. This document is intended to show that, the useof good architectural detailing can, provided a sense ofproportion or scale is maintained, be achieved without

incurring substantial extra costs.

A wide range of joint details are shown in thispublication. Many details will automatically seal a hollowsection and in this situation no internal protection isrequired. Where however the jointing system penetratesthe tube wall without sealing or leaves the section open,consideration must be given to the question of wateringress and internal corrosion protection. This aspectis particularly relevant to external structures.


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SHS JointingButt Joints

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Butt Joints 01

As most structures are higher or wider

in dimension than an individualcomponent, they will need to be jointed.A common connection will be an in-lineoint of two similar sized or possibly

different sized hollow sections. In-lineoints of equal size members are easily

made by full penetration butt joints.

Full use should be made of the fact that for agiven size of section the thickness change isinternal and not external thus a constant

external dimension can be achieved evenwhen differing thicknesses are being joined.For full welding details refer to Corus DesignGuide: SHS Welding CT15.

CHS Butt Joint

SHS Butt Joint

Up to 6mm

Up to 3mm

Over 3mm

Up to 20mm

Full Penetration In-Line Butt Welds


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SHS JointingButt Joints

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Butt Joints 02

Use of these techniques, especially when

used at natural joint positions (i.e. at ends ofindividual mill length members), can achieveclean lines with economy. In-line joints needcareful alignment and jigging to ensurecorrect fit-up. This is not a problem in thework shop where equipment is readilyavailable, but special provision is required forsite work. Site work will also be affected byweather conditions and care must be takenwhen welding. As a result most fabricatorswould prefer bolted site joints.

CHS Butt Joint Bolts applied to hold joint together for welding, oncewelded the bolts and cleats are removed.


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SHS JointingFlange Connections

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Flange Connections 01

Drainage blank

20mm min

Blank flange

Ring Flange

3t min

20mm min

Min PCD

Typical flange details Typical drainage details

2t min

Pb

Pb = 1.2Ft/ no bolts

1.25 x bolt dia

Ft

t

Flanges are the simplest type of in-line

bolted connections and can be of any shapeor size but those most generally used arerectangular, square, round or triangular.

They should be kept as small as possible but ofsufficient thickness to give adequate jointstrength and prevent distortion during welding.Flanges can be of the blank or ring type, thelatter being useful for external elements suchas tubular towers that require galvanizing bothinternally and externally.

NB. Attention must be paid to water drainagein external structures.

The following recommendations wereestablished for circular tower leg members(under static load conditions) and assume thesame grade of material for the flange and thetube. Thickness is based on strength and mayneed increasing to control distortion.

SHS Flange Connection


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Similar joints can be used in RHS and CHSlattice construction remember that, whilstclose up these can look bulky, in overallperspective their effect is diminished.

SHS Howe / x Girder lattice construction with bolted flangeconnections

SHS with flanges, connected to I beam


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Flange joints can equally be used in lattice

or multi-storey construction with either thesame or different size members. For multi-storey construction the flange joint cannormally be accommodated within the floorconstruction depth. Flanges can be blank orprovided with holes for bolting access, toconnect floor beams and/or concrete fillingof the column.

Base plates can either be plain orstiffened dependent on thickness andloading.

Similarly flanges are used as either capor base connections for columns.


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CHS with bolted ring flange connections

CHS with bolted flangeconnections

CHS and SHS with bolted flange connections


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SHS JointingSplice Joints

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Splice Joints 01

As an alternative to flanges, in-line

oints can be made by bolted spliceplates which can be either left exposedor used in conjunction with cover platesto give a smooth external appearance.

Splice Joint with cover plate removed -CHS

Splice Joint with cover plate removed - SHS Splice joint with Cover Plate -

CHS


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Exposed Splice Joint - CHS

Exposed Splice Joint - SHS


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SHS Splice Joint with cover plate removed &exposed RHS splice joint

Exposed Splice Joint - CHS

Splice Joint preparation


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SHS JointingEnd Fittings, Cleats & Brackets

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: End Fittings 01

Double fork end fitting, pinned ontocolumn head cruciform plate

Longitudinal gusset plate with singleforked pinned joint

Bolted single forked plate end fittings

End fittings, cleats and brackets form a

part of any connection whether for maincomponents or secondary items.

They can vary from simple flat platesor off-cuts of rolled sections, to complicatedbrackets. As has been previously said,simplicity is the key and simple connectionsare often the most economical and can bevisually acceptable. As a further bonus, asimple connection usually creates a directload path between the elements.


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End forks with single or multiple bolts or

pins can be made from standard rolledsections or from plates.

As an alternative to adding plates, ends ofCHS members may be fully flattened.Cold flattening may be used, but repair bywelding may be required on the weld andouter edges of the tube due to the amountof cold working carried out.

Double forks reduce plate thickness andput bolts or pins into double shear.Single forks can be either on or off thecenter line, and end plates or sections sealthe SHS member and negate internalcorrosion.

N.B. Sealed SHS members must bevented if galvanized.

End of SHS can be left open but internal

protection must be considered especiallyfor external structures.

Extended plates reduce crowding at joint.

Bolted single forked plate end fittings


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Column bases, bracing and main chord

connections shown here, are all based onthe continuing theme of simple plates witheither single pin or bolt connections.Shaping and relative dimensions of theplates combine to create their ownarchitectural style.

Pinned double forked columnbase

General Photograph showing column base and bracing

ointing

Pinned double forked bracing joints

Pinned double forked

bracing joints


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Longitudinal gusset plates, with double forkedpinned joint

Column base supporting a single forked pinned joint

SHS bolted into a double forked bracket


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Double forked end fitting on stiffening plate Double forked end fitting, pinned ontocolumn base

Simple flange welded onto SHS, ready to bebolted onto another section

Single forked end fitting


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Longitudinal gusset platewith pinned double forkedend fittings

CHS with plated end fitting, bolted to longitudinal cleat

Double forked fabricated bracket bolted to column


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Transverse cleat bolted to plate end fitting onCHS. Also a fabricated bracket supporting an Ibeam

Fabricatedbracket attachingbeam to a column

Transverse cleat


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Longitudinal gusset plate

Double forked end fittings, pinned to fabricated bracket


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Longitudinal gusset plate, pinned to a double forked fabricated column head

Double forked end fitting pinnedto ring cleat


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SHS bracing bolted to double forkedlongitudinal gusset plate

Cast end fittings welded to SHS, pinned to fabricatedbracket


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Transverse gusset plate Transverse gusset plate, used to join thetwo sections

Double forked end fittings pinned to a longitudinal gussetplate


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SHS JointingLattice Joints

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Lattice Joints 01

Structural hollow sections are highly

efficient in compression as well astension and the added fact of a clean,slender appearance means they areregularly used in lattice construction.

A warren bracing system is generallypreferred, as the compressive strength ofSHS bracings allow longer strut lengthsto be used, thus reducing the number ofbracings and joints, when compared toan equivalent N Brace system.

Additional struts can be added at non-nodal purlin positions to reduce chordbending if required.

Care in selecting member sizes andadjusting the joint eccentricity canminimise the complexity.

N Brace system used for roof structure


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CHS Warren brace system (One near vertical brace)

Warren brace system


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Design Notes

1 Design rules have been establishedfor most of the common range ofjoints in lattice construction. SeeCorus Tubes publication CT16Design of Welded Joints.

2 The strength of such joints isdependent on the relative size of thebracing and chord members, theangles of the bracings, whether thebracings have a gap between oroverlap each other, and thethickness of the chord and anycompressive load in it. As aconsequence, when selectingmember sizes the engineer pre-determines the strength of the joint.

Warren Brace system for CHS truss withmultiplanar gap joints

Multiplanar gap joint


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There are two basic types of lattice bracing

oints, gap and overlap. The gap joint isthe easiest for fabrication as it confines thework to a single bevel cut or end profiling.A minimum bracing angle of 30 should beused to ensure welding access.

The joint strength can be increased byoverlapping the bracings. This will howeverincrease the fabrication work due to thedouble shaping required unless a full overlapis made.

A combination of the chosen member sizesand gap or overlap condition may create aneccentricity. This must be included in thechord design check. In both cases thephysical dimensions will affect the jointstrength and this should be checked.See Corus Tubes design guides.

CHS overlap joint

CHS overlap joint, for arched roof trusses


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When two or more bracings overlapthe shaping required can be reducedby using a central division plate. Thisis especially useful for overlappedCHS bracings or where additionalvertical bracing is required, to allow adivision cap plate to be addedforming a T connection.

If at the design stage joints need tobe strengthened this can often be

achieved by increasing the bracingmember size or thickness.

Alternatively, extra strength can beachieved by adding plates to thechord face or the use of SHS filletpieces between bracings. It shouldalso be noted that 100% overlap willincrease joint strength and reduceend shaping.

Overlap joint, with central division plate and end cap plateforming a T connection, supporting additional verticalbracing, creating a KT joint


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For joints with CHS members the requirement

of end profiling must be considered.

However, not all bracings need to be profiledor saddled. When bracings are between1/3rd to 2/3rds of the chord diameter partialprofiling is needed, when over 2/3rds of thediameter full end profiling is required to achievethe weld fit up requirement. For bracingssmaller than 1/3rd of the chord diameter asingle end cut will normally achieve therequired fit up.

With CHS bracings the technique of partialflattening can be used to increase weldingaccess and reduce/avoid profiling or doubleshaping. This method will however increasethe bracing width and the resultant fit upshould be considered.

Profiled CHS, for close toleranceconnection.

CHS end profiling


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Joint complexity can increase when bracings

exist in more than one plane (multi-planar) asthose found in triangulated girders.

In these cases necessary weld clearancecan be obtained by partial flattening theends of the bracings, double shaping thebracings or alternatively the main memberdiameter may be increased to ensurenecessary weld clearance is obtainedwithout complex forming.

Multiplanar K-K overlap joint

Howe girder with X jointsand multiplanar KT joints


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When RHS members are used in

triangulated girders the selection of membersizes for the bracings and chords must bedone by considering their relative sizes andfit up. Failure to do this can cause extrafabrication and complicate details.

Additional work can often be eliminated byrotating the chord member and avoidingexpensive bird mouthing. It should alwaysbe remembered that chords can be made oftwin members. This can reduce the bracing

complexity and also allows the girders to besplit for fabrication and transport.

Triangular girder with N side bracing and Warren bracingbetween bottom chords


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Where multiple bracings occur thebracing connection can be moved backfrom the intersection point creating asimple joint . This can be achieved byintroducing a short length of CHS, or byemploying hollow spheres. Spheres givethe advantage of a square cut bracingend regardless of the intersection anglebut are limited in their source.

Short length of CHS, used foroining multiple bracings

Short length of CHS for joining multiple

bracings

Sphere joint used in space frame roofstructure


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SHS overlap joint, with central divisionplate and an end cap plate, forming aT connection

CHS overlap Joint, with central division plate

Warren Brace system, for SHS and RHS roof truss


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Triangular girder with N side bracing and warren bracing onlan/between to chords

KX joints for a CHS truss


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SHS JointingBeam to Column Connections

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Beam to ColumnConnections 01

It is impossible to illustrate all the varieties ofend-plates and shoes which may be usedwith structural hollow sections to fabricatetrusses and lattice girders.

The designer has a wide scope to exercise hisingenuity, to produce aesthetically pleasingconnections, which will keep fabrication tominimum, but which are adequate to perform thetask for which they are required.

Some connections use the flange of theuniversal column to transmit the loads fromthe girder or truss, which are more or less,simple plate flanges. They are probably thecheapest type of joint. However, great caremust be taken during design and fabricationto avoid cumulative tolerances which maygive rise to difficulties during erection andnecessitate an excessive amount ofshimming. It should also be borne in mindthat the connecting bolts transmit all the loadsfrom the truss or girder.

Transverse beam to column connection (in horizontal plane)


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When RHS columns are used it is not

always possible to bolt through the columnas with open sections. Alternative faceconnections can be made by combinationof plates or section off cuts.

RHS warren braced trussoined to RHS column


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Combinations of simple connections, oftenexposed, can with ingenuity create aesthetic

and visually pleasing structures.

Fabricated bracket to attachthe beam to the column

CHS bracing with end fittings bolted to aflange, which is welded onto the column

I section beams welded tocolumn


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As with lattice construction, connection of

rolled beams to RHS columns can be madevia simple plate details. Beams can be twinchannels (for access of vertical services)or single universal beam sections.

Face plates welded onto column, allow twin channels to be

bolted to the column, supporting secondary I beams


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In all cases it is the joint area that

requires the work. In many cases preassembled joint locations can be madeand added to the overall column - henceminimising the need to handle the totalcolumn length.

Single forked pin joint, joining the warren

brace truss to the column

Fabricated L shape brackets, join together the I beam to the RHScolumn


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Beams can be joined to SHS columns viaend plates or angle cleats in conjunction

with proprietary mechanical methods suchas Hollo-bolt or bolted systems such asFlowdrill (See Flowdrill and Hollo-BoltJointing). Where joints are located at the endof the section hand access for installation andtightening can be obtained and a single sidefixing made.

For joints at other locations a joint boxtechnique using a heavier wall insert andhand access hole can be adopted. Where 4

way beams connect the final face will requirecaptive nuts, threaded column wall or a onesided mechanical fixing to be used.

SHS with fabricated access slotto allow internal access, for boltapplication

Use of SHS with fabricatedaccess slots in construction.


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Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Slab to ColumnConnections 01

SHS JointingSlab to Column Connections

SHS columns can be used inconjunction with insitu concrete floorsor either a beam and slab or flat slabconstruction. Plates or cleats can beadded to provide shear resistance atunctions as an alternative to using the

column flange connection.

Reinforcing bars can be continued around thecolumn, welded to the face or passed throughthe section to give moment continuity. Where

a column head is required to be extended soas to reduce the shear in the slab, this can beachieved by addition of steel sections weldedto the column.

Extended column heads, welded tothe column reinforcing plates.


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Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Cast Joints 01

SHS JointingCast Joints

Castings can be effectively used intubular jointing, they can be designed tolocate the hollow section ready forwelding.

They allow graceful joints to be madeeconomically, only a few castings arerequired for economy over a fabricatedoption.

Advice and guidance on castings can befound in SCI publication: SCI-P-172:Castings in Construction

Cast joint, pinned to single forked column head,supporting CHS roof structure

Cast joint pinned to column head, supporting CHS roofstructure


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SHS JointingMechanical Joints

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Mechanical Joints 01

A range of mechanical fixings are availablefrom specialist suppliers. Such mechanicalfixings may be used with CHS (e.g. using aprofiled washer) but the flat surfaces ofRHS are better suited to their use.

Generally fixings can be put into twocategories, those that require special tools andthose that can be used in normal clearanceholes without special tools.

As an alternative to single side fixings, throughbolting can be used. The section is drilled andspacer tubes welded in position. This methodprevents distortion of the RHS and sealsagainst water ingress.

Lindapter - Lindibolt

The Lindibolt is a self heading bolt suitable formaking connections to cavity steel structures insimilar applications to the Hollo-Bolt but wherethe specific nature of the application precludesthe Hollo-Bolts use.

Lindapter

Welded Spacer Tubes


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Huck BOM Fasteners

High strength blind fasteners for structuralapplications, offering excellent pull together andhigh clamping force. Installation is a quiet andfast process that requires minimum skill levels.

Clufix Blind Rivet Nuts

A range of fasteners with different properties,dependant on their application. Such as thebody and screw diameter; head form (flush,cylindrical, countersunk); type of the body(open / closed); options choice (brake ofscrew); thickness and material.

Clufix

Huck


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Lindapter Hollo-Bolt

Hollo-Bolt is a pre-assembled three or five partfitting consisting of body, cone and bolt (thecollar and the body being seperated by acollapse mechanism in the five part fitting).

The pre-assembled unit is inserted throughnormal tolerance holes in both the attachmentplate and the RHS. As the bolt is tightened thecone is drawn into the body, spreading the legs,and forming a secure fixing. Once installed only

the Hollo-Bolt head and collar are visible.

Flowdrilling is a thermal drilling process whichmakes a hole through the wall of a structuralhollow section without the removal of metalnormally associated with a drilling process.

The formed hole is then threaded by the useof a roll thread forming tool, leaving athreaded hole which will accept a standardfully threaded bolt.

Flowdrill

Lindapter

Flowdrill


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Molabolt Peg Anchor Bolt

The innovation behind the Molabolt is itsability to expand to provide a firm bite thatdoes not rely on a good thread or being tightlyfitted.

Installation is a fast process that requiresminimum skill levels, and it does not require aclearance hole.

It can be used for all blind applications intohollow steel sections.

Molabolt


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As an alternative to mechanical fixings the

walls of thicker sections may be drilled andtapped (Fig 1), or, if the section thicknessis insufficient, threaded pads or nuts canbe welded on (Fig 2).

Buildex Super Teks Series 500

Fig. 1

Fig. 5 Fig. 6

Fig. 2

Studs can be welded onto the section

face. Some methods leave a collar atthe root. Holes must be recessed toclear the collar or clearance washersfitted (Fig 3).

Cladding may be fixed direct to hollowsections by using self drilling self tappingfasteners (Fig 4). It is important thatthese use twin seal washers to avoidwater penetration and should be fastenedat 90 degrees or perpendicular otherwisethe screw may skid off center and or the

drill point break.

A wide range of other fixings including J(Fig 5) and U (Fig 6) bolts are available.

Fig. 3

Fig. 4


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SHS JointingFlowdrill & Hollo-Bolt Jointing (for Hollow Sections)

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing Flowdrill & Hollo-Bolt 01

Flowdrill and Hollo-Bolt gives a choice of two

methods to produce bolted joints in HollowSections. Both systems offer the followingbenefits:

They produce bolted joints of structuralcapacity in Hot Finished Structural HollowSections (HFRHS).

They minimise the change in the fabricationprocess by using connection details which arestandard in the construction industry.

They reduce fabrication by removing the needto weld plates or other fittings onto the outside

surface of the RHS. They simplify erection by using fully threaded

bolts - an increasing practice in theconstruction industry.

They maintain aesthetics by producing a flushface on the RHS after fabrication.

They only require access from one side.

Design Guidance

The design guidance for Flowdrill and Hollo-Bolt

systems with grade 8.8 bolts in conjunction withCorus Tubes hot finished structural hollow sectionsis given in BCSA/SCI Joints in Steel Construction(Ref 1).

The design guidance, for joints in simpleconstruction, result from Corus Tubes initialresearch work undertaken in connections withCIDECT. The guidance has been consolidated intothe information published by the BCSA/SCI Jointsin Steel Construction (Ref 1).

Further test work is being undertaken to establish

design guidance for moment resisting joints.

Procedural checks are given for bearing, shear andlocal bolt pull out of the RHS wall and for thecombined effect of the column axial load and thestructural integrity tensile load of BS 5950 : Part 1.

The combined check for the column axial load andthe structural integrity tensile load recognises thatthe flexibility of the RHS face caused by the tensileload can, in the presence of the column axial load,reduce the overall joint capacity.


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Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing Flowdrill & Hollo-Bolt 02

SHS JointingFlowdrill & Hollo-Bolt Jointing (for Hollow Sections)

Fabrication and Construction

General detailing recommendations for beams toSHS columns, are given in the BCSA/SCIpublication: Joints in Steel Construction (Ref 1).

Both Flowdrill and Hollo-Bolt use fully threaded boltswhich allows standardisation of bolt lengthsthroughout the construction. Where beams areconnected to adjacent faces of an RHS column acheck must be made with the chosen bolt length toensure that assembly is possible (see Fig 3:

Flowdrill and Fig 6: Hollo-bolt).Both Flowdrill and Hollo-Bolt are suitable for usewith the two standard grades of Corus TubesCelsius SHS, EN10210 S275J2H and S355J2H.

At present, application of the Flowdrill process islimited to RHS thicknesses up to and including12.5mm. For thicknesses of 16mm and over,conventional drill and tap methods arerecommended, although due to the RHS materialstrength being lower than that of the grade 8.8 bolts,pull out strengths may be below the bolt tension

capacity.

Flowdrill

Hollo-Bolt

Reference

1. BCSA/SCI publication: P212Joints in Steel Construction:Simple Connections

Published jointly by:

The Steel Construction InstituteSilwood ParkAscotSL5 7QN

Telephone: 01344 623345

Fax: 01344 622944

The British Construction SteelworkAssociation Limited4 Whitehall CourtLondonSW1A 2ES

Telephone: 020 7839 8566

Fax: 020 7976 1634

Flowdrill


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SHS JointingFlowdrill

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing Flowdrill 01

Flowdrilling is a thermal drilling process

which makes a hole through the wall of astructural hollow section without theremoval of metal normally associated with adrilling process. The formed hole is thenthreaded by the use of a roll thread formingtool, leaving a threaded hole which willaccept a standard fully threaded bolt.

The Tools

The initial hole is made by a flowdrill tool consisting of atungsten carbide bit held in a Flowdrill Morsetaper collet

adaptor (fig. 1). The tool can be used in a conventional drillingmachine or CNC machine as found in fabricators works,provided it has adequate horsepower and spindle speed.

1st Stage

The tungsten carbide bit is brought into contactwith the RHS wall where it generates sufficientheat to soften the steel. The bit is thenadvanced through the wall and in so doing themetal is redistributed (or flows) to form aninternal bush. As well as drilling the initial hole,the tool is fitted with the means of removing anysurplus material which may arise on the outsideof the RHS section. The cycle time forFlowdrilling is similar to that for conventionaldrilling. However, if done on CNC machines thefeed rate can be slow at the beginning, rapidly

increasing as the material softens to improveefficiency.

2nd Stage

The 2nd and final stage is to tap the Flowdrillbush. This is done by roll threading the bush witha Coldform Flowtap. The complete cycle is shownin figure 2.

Fig 1

Fig 2


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Drilling machine parameters :

Table 1 gives a guide to requiredmachine parameters for producingFlowdrill holes for M12 to M24 bolts:

Note: The Flowdrill process is notsuitable for hand held or magneticclamp type drilling equipment whenused in the sizes shown.

Drill length: The recommended lengthof Flowdrill bits varies with the threadsize and thickness of material as givenin Table 2.

Drill care: Flowdrills are made fromtungsten carbide. They are extremelyhard but cannot withstand shock loads.After drilling each hole, FD KS pasteshould be applied to the Flowdrill whilst itis still hot, so minimising oxidation and

preventing build up on the surface.

Flat surface: the raised rim on the outersurface of the RHS material causedduring Flowdrilling should be removedusing Flowdrills with cutting edgesprovided on the collar. One rotation ofthe cutter is all this is required to removethe rim.


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Flowdrill detailing requirements.See Fig. 3 and Table 3

Note:

Flowdrilled joints used atlocations exposed to theweather should not beconsidered as water tight.

Flowdrilling is not suitable forus with pre-galvanisedmaterials.

Flowdrill data :

Further information on thermal drilling, including drilling machine parameters and tool sizes can be obtainedfrom the companies given below:

Flowdrill (U.K.) LimitedUnit 7, Hopewell Business Centre105 Hopewell DriveChathamKentME5 7NP

Tel: 01634 309422

www.flowdrill.com

FormdrillRobert Speck Ltd,Little Ridge,Whittlebury Road,Silverstone,NorthantsNN12 8UD,Tel: 01327 857307,

Contact: Mr Mike Carpenter.


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SHS JointingHollo-Bolt

Corus Tubes, Structural & Conveyance Business www.corustubes.com SHS Jointing: Hollo-Bolt 01

HOLLO-BOLT is a pre-assembled three or fivepart fitting consisting of body, cone and bolt

(the collar and the body being seperated by acollapse mechanism in the five part fitting).

The pre-assembled unit (fig. 4) is inserted throughnormal tolerance holes in both the attachment plateand the RHS. As the bolt is tightened the cone isdrawn into the body, spreading the legs, and forming asecure fixing. Once installed only the Hollo-Bolt headand collar are visible (fig. 5).

Installed 3-part Hollo-Bolt (M8, M10 & M12)

Collapsemechanism

Location Flats

Body

Cone Knurling

Installed 5-part Hollo-Bolt (M16, M20)


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Drilling requirements:

Hollo-Bolt uses a plain drilled hole which can be madeon site or in the fabrication shop using all normaldrilling equipment. The finished hole should have atolerance of -0.2mm to +1.0mm from the nominal givenin the data table (table 4).

Boltsize

(size1)

Boltlength

(V)

mm

Fixingthickness

(W)

Min Maxmm

Boltcentres

(X)

Minmm

Internalmin. edgedistance

(Y)mm

Edgedistance

(E1)

mm

Boltholedia.

(dh)mm

Acrossflatsmain

bodymm

Nominalboltdia.

mm

Tighteningtorque

Nm

M8 50 3 22 35 13 50 tp 14 19 8 21

M10 55 3 22 40 15 55 tp 18 24 10 40

M12 60 3 25 50 18 60 tp 20 30 12 78

M16 75 8 29 55 20 65 tp 28 36 16 190

M20 90 8 34 70 25 90 tp 35 46 20 300

Table 4 (See Fig. 6 for nomenclature)


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Material Options

The standard product is manufactured from mild steel and is electro-zincplated with the addition of JS500 1000 hour saltspray corrosionprotection. The central fastener is a grade 8.8 bolt.

For special applications, the Hollo-Bolt is available manufactured from316 stainless steel, with a grade A4-80 central bolt. This will not be astocked item, and would be manufactured to order.

Installation

The only tools required to fit Hollo-Bolt are two spanners - an openended spanner to hold the collar and a torque wrench to tighten thecentral bolt. Alternatively a power operated electric hand bolt is indevelopment.

Should the steelwork need to be adjusted, the fixing can simply beremoved and the hole reused with another Hollo-Bolt.

Step 1Drill holes in required position (see table 4 forrecommended hole size). Offer up the Hollo-Bolt

and fixture to the steelwork. Insert product throughboth fixture and steelwork, cone end first.

Step 2Grip the Hollo-Bolt collar with an open endedspanner. Using a torque wrench, tighten the centralbolt to the recommended torque given in the tableabove.

Step 3The Hollo-Bolt cone is drawn up into the body,spreading the product legs and providing a securefixing.


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Sealing Options

In certain applications, it may be necessaryto seal the Hollo-Bolt to prevent ingress of

water or other corrosive agents. For detailsof sealing options available, please contactLindapter.

Special Options(manufactured to order)

Stainless steel

Button head setscrew

Socket head capscrew

Countersunk setscrew/body

Special body lengths

Further information on Hollo-Bolt is available from:

Lindapter International,A Division of Victaulic plc,Lindsay House,Brackenbeck Road, Bradford,West Yorkshire,England,BD7 2NF

Tel: +44 (0) 1274 521444

Fax: +44 (0) 1274 521130


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www.corusgroup.com

Care has been taken to ensure that thisinformation is accurate, but Corus Group plc,including its subsidiaries, does not acceptresponsibility or liability for errors or informationwhich is found to be misleading.

Corus TubesStructural & Conveyance BusinessSales Enquiries contact:UK Sales officePO Box 6024,Weldon RoadCorby, NorthantsNN17 5ZNUnited Kingdom

Corus TubesStructural & Conveyance BusinessSales Enquiries contact:Netherlands Sales officePostbus 394900 BB OosterhoutThe NetherlandsT +31 (0)162 482300F +31 (0)162 466161

jointing of hollow section steel tubes

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