Design of Joints in Steel Structures

Design of Joints in SteelStructuresInternational SeminarNorwegian Structural Steel AssociationOslo – 20 April 2005

How Designers can take Profitof the (German) Experiencewith Eurocode 3Dr.-Ing. Klaus WeynandPSP - Prof. Sedlacek & PartnerTechnologien im Bauwesen GmbH, Aachen

Contents• Economy considerations• Economy studies• Strategies• Applications• Examples for bad and good design• Design tools• Publications• Software• Worked Example4

Economy ConsiderationsTraditional approach:frame analysisassumptions for joint behaviourMMrigidcheck of memberspinnedφφdesign of joints satisfy assumptioncheck of joint stiffness ?often uneconomical solutions !5

Economy ConsiderationsModern standards (e.g. Eurocode 3):Joint designstiffness modelclassification systemsemi-rigid jointsModern design concept:Integrate joints as structural elementsin the design process6

Economy ConsiderationsStrategies for optimum solutionsSavings of fabrication and erection costsSavings of material costsEconomy studiesFrance/USABelgiumGermanyThe Netherlands7

Savings of Fabrication CostsOptimal detailing of rigid jointsOptimize the joint detailing such that the joint stiffnesscomes close to the ‘rigid’ classifiaction boundaryMactual stiffnessrigiddomain‘rigid’ classificationboundaryφ8

Savings of Fabrication CostsExample:Variationsin detailingStiffnessclassificationSavings infabrication costsPortal frame2-3 %IPE 360rigid 13 %7 m5 mHEA 300IPE 36020 m65 140 6546 590909090360,2IPE 360HEA 300rigid27 %HEA 300200120135 135270/716/2535010,8Initial joint detailingIPE 360HEA 300rigid28 %9

Savings of Fabrication or Material CostsEconomical benefits from semi-rigid jointsUse semi-rigid jointsin order to have any freedomto optimize the global frameand the joint designM‘rigid’ classification boundarysemi-rigidsimple joint ?Simple joints may haveφsome inherent stiffness andmay transfer moments - take profit of that actual behaviour10

Economy StudiesFrance /USA (1991)by Colson & BjorhovdeSystemunbraced framebraced frameJointsrigid *semi-rigidnominally pinned *semi-rigidrigid*reference systemFranceCosts100 %82 % 80 % 18 % 20 %100 %USAFranceSavingsUSA96 % 105 % 4 % -5 %120 % 115 % -20 % -15 %11

Economy StudiesBelgium(1995)by Jaspart &GuissebracedbuildingframeSystemflange cleatsext. end-platestiff. ext.end-plateJointssemi-rigidsemi-rigidrigidSavings3,6 %-12,5 %- 48,5 %unbracedbuildingframeext. end-platesemi-rigid20,6 %braced industrialframeflange cleatsext. end-platesemi-rigidsemi-rigid0,7 %- 2,4 %reference systemsstiff. ext.end-platerigid- 18,4 %12

Economy StudiesGermany (1997)by Weynandunbraced frame (office building)wg + sg + p4,0SystemunbracedframeJoints Companysimplesemi-rigid 1semi-rigid 2Costs100 %76 %97 %Savings24 %3 %11,0 m4,0bracedframerigidsemi-rigid1100 %96 %4 %g = permanent loadp = variable loads = snow loadw = wind loadsemi-rigid292 %8 %13

Economy Studiesin GermanyJoint detailing14

Economy StudiesThe Netherlands (1992)by SteenhuisInvestigated frame (braced)IPE 300 (pinned)IPE 270 (partial strength)4,5 m4,5 mIPE 550 (pinned)IPE 500 (partial strength)HE220AHE180A5,0 m12 m12 m12 m15

Economy StudiesThe Netherlandspinned jointspartial-strength jointsIPE 300IPE 270HE 220 AHE 220 ASavings =9 %IPE 550IPE 500HE 220 AHE 220 A16

Economy Considerationscosts(not to scale)total19802000pinnedlabourmaterialS=S Lj bEI brigidS optS(not to scale)17

Economy ConsiderationsConclusions:Two strategies to minimize the costsSimplification of joint detailingReduction of fabrication costsReduction of profile dimensionsReduction of material costsEconomy studiesSavings in costs of 3 - 20%dependent ontype of frame (bracing)type of framing (simple/continuous)steel construction companiesResults confirmed by many studies in various countriesDetailed evaluation of actual costs necessary18

Contents• Economy considerations• Economy studies• Strategies• Applications• Examples for bad and good design• Design tools• Publications• Software• Worked Example19

Good and bad designHE 180 BV = 62,72 kN4 x M 20HE 180 B3 x M 20V = 68,41 kN20

Good and bad designV = 35 kNV = 35 kN21

Good and bad designM = 98,4 kNM = 193,9 kN22

Good and bad designM = 65,4 kNM = 48,2 kN23

Contents• Economy considerations• Economy studies• Strategies• Applications• Examples for bad and good design• Design tools• Publications• Software• Worked Example24

Design ToolsNeeds for practice:• Design standards as a basis• Background information• Worked examples• Design tools- Tables- Design sheets- Software Eurocode 3 Publications Seminars Standardised joints Simplified rules General application25

Design ToolsDesign Books:ECSC Design Manual„Frame Design Including Joint Behaviour“to be published by ECCS• Background• Design methods & philosophies• Design sheets• Design tables• Worked examples26

Design ToolsDesign Books:have been prepared recently in:UK:Germany:‘Green Books’ on- Joints in Simple Constructions- Moment ConnectionsDSTV ‘Ringbuch’ on„Standardised Joints in Building Frames“- Simple Joints- Moment Resistant JointsCologne Design ToolsThe Netherlands: - Design Manual for Simple Joints- Design Manual for Moment ResistantJoints27

Design ToolsKölnerBemessungs-hilfeneBook, , PDFfree download:www.psp-tech.de→ Publikationen28

Design ToolsNew issue of DSTV publication onstandardised joints in steel building framesso-called“Ringbuch”:„TypisierteAnschlüssesseim Stahlhochbau“29

DSTV Design Tables• The new DSTV “Ringbuch”• Update of the old books from 1974• Implementation of new design concepts• Eurocode 3 (DIN V ENV 1993)• new DIN 18 800 (November 1990)• Extend scope for new material grades• Steel S 355 (St 52)• Bolt grade 8.8• User friendliness• New layout of design tables based on Europeanrecommendations30

DSTV Design Tables• Content of the new DSTV “Ringbuch”:Volume 1• Simple joints• Web cleated connections• Header plate connections• Notched beams• Load introduction• Unstiffened supports31

DSTV Design Tables• Content of the new DSTV “Ringbuch”:Volume 2• Moment resistant joints• End plate connections• Purlins (splices)• Simple joints• Continuous jointsV zV zM yM y32

DSTV Design Tables• Content of the new DSTV “Ringbuch”:Unified content for all types• General information, background• Design sheets (formulae)• Design tables33

DSTV Design Tables1. General information- Design model- Background- Range of validity- User instructions34

DSTV Design Tables1. General information- Design model- Background- Range of validity- User instructions2. Design Sheets- General formulae- Hand calculationacc. Eurocode & DIN- Component methodComponentsRequired dataDesign equations35

DSTV Design Tables1. General information- Design model- Background- Range of validity- User instructions2. Design Sheets- General formulae- Hand calculationacc. Eurocode & DIN- Component method3. Design Tables- Standard configurations- Dimension details- Design resistance- Failure mode- Eurocode & DINConfigurationDimensions36

DSTV Design TablesM y,1,RdkNmGrenzzust.EC erf. Stütze (S 235)M y,2,RdkNmV z,RdkN IPE HEA HEB HEM274,3 BFC 156,0 412,8 St St St St 100219,4 CWS 152,8 412,8 St St St 240 80164,6 CWC 114,3 412,8 500 340 260 200 60109,7 CWC 86,10 412,8 400 240 200 180 40%St = Stiffeners requiredwhere? see failure modeUnstiffened columnpossible from HEM 24038

Comparison EC 3 - DIN0,5Simple joints, e.g. doubleweb cleated jointsx = 1,06Profilreihe IPESchraubenfestigkeitsklasse 4.6F EC3 /F DIN,neu1,751,51,25HoleHolebearingbearing10,75Anzahl: 123BoltsBoltsininshearshearF RdFailure modes:• Hole bearing (Trägersteg)• Bolt shear (Schrauben)minor important:Block shear (EC 3)Beam in shear (DIN)0,250100 200 300 400 500 600Profilhöhe in mm39

Comparison EC 3 - DINMoment resistant joints(end plate connection)x = 0,97bündige StirnplatteProfilreihe IPEM RdM EC3 /M DIN,neu1,5BT1,25BT1BWTBWT0,75M 16BFCM 200,5 BFCM 240,250M 27M 30100 200 300 400 500 600Profilhöhe in mmBFCBFCFailure modes (EC 3):Bolts in tensionBWTBWTBTBTBeam web in tensionBeam flange in compression40

Design ToolsSoftwareJoint propertiesIndividual jointlayoutM - φ -curve41

Design ToolsSoftware:• Easy input for engineers42

Design ToolsSoftware:• Easy input for engineers• Data check1. Description of errors2. Reference to EC 33. Possible corrections43

Design ToolsSoftware:• Easy input for engineers• Data check• Calculation notes44

Design ToolsSoftware:• Easy input for engineers• Data check• Calculation notes• Individual language foruser interface / output45

Design ToolsSoftware:• Easy input for engineers• Data check• Calculation notes• Individual language foruser interface / output• Standard tables includes46

Design ToolsSoftware:• Easy input for engineers• Data check• Calculation notes• Individual language foruser interface / output• Standard tables includes• Further components andflexible configurations- Haunched beams- Stiffeners- Single sided- Double sided- Backing plates- Suppl. . web plates- Simple joints- Notched beams47

Design ToolsSoftware:• Easy input for engineers• Data check• Calculation notes• Individual language foruser interface / output• Standard tables includes• Further components andflexible configurations• Optimisation routines48

Contents• Economy considerations• Economy studies• Strategies• Applications• Examples for bad and good design• Design tools• Publications• Software• Worked Example49

Worked ExampleSoftware:ExampleConfiguration• Beam IPE 500• Column HEA 340• End plate connectionDesign assumption• Rigid jointFrame analysis• M Sd = 220 kNm50

Worked ExampleDesign resistance:Classification:Failure mode:M Rd= 196 kNm < 220 kNmSemi-rigidColumn web in compression51

Worked ExampleFailure mode:End plate in bending52

Worked ExampleFailure mode:Column web panel in shear53

Worked ExampleFailure mode:Column web panel in shear54

Worked ExampleGrenzzustand:Stützensteg auf Schub55

Conclusions Eurocode 3 is an accepted modern standard Tools are available and will be further developedJoint design can become• economic due to advanced design methods• easy and quick due to simple tools56