New applications for sandwich panel

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  • Oct 28, 2011
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1 Newapplicationsforsandwichpanels: stabilizationandloadtransfer Dipl.Ing.SaskiaKpplein,Dr.Ing.ThomasMisiek 22/09/2011 1

2 Applicationsofsandwichpanels Commonapplicationofsandwichpanels Transferoftransverseloads(wind,snow)tothesubstructure Additionalpossibilitiestousesandwichpanels Stabilisationofbeamsandcolumnsagainstbucklingandlateral torsionalbuckling Transferofhorizontal(wind)loads=stabilisationofstructuresand buildings Buildingswithoutsubstructure Transferofaxialloads Transferofhorizontalwindloadsandstabilisationofbuilding 22/09/2011 2

3 Overview Torsional restraint Diaphragm action Axial loads Horizontal loads and stabilisation of buildings Introduction of tensile forces 22/09/2011 3

4 Stabilisationofbeamsbytorsionalrestraint Lateraltorsionalbuckling 22/09/2011 4

5 Stabilisationofbeamsbytorsionalrestraint Torsionalrestraint Sandwichpanelscanrestrainrotation IncreaseofcriticalbucklingmomentMcr Restrainingeffectsareconsideredbysprings RotationalspringwithstiffnessC Stiffnessofspringsdependsonstiffnessofpanels andconnections 22/09/2011 5

6 Stabilisationofbeamsbytorsionalrestraint StiffnessC consistsofthreecomponents 1 1 1 1 = + + C CA CB CC CB:distortionalstiffnessofthebeam easy to calculate CC:bendingstiffnessoftheattachedpanel CA:stiffnessoftheconnection object of investigations of EASIE project 22/09/2011 6

7 Stabilisationofbeamsbytorsionalrestraint Momentrotationrelation Downwardloading Upliftloading CA = 0 22/09/2011 8

8 Stabilisationofbeamsbytorsionalrestraint Momentrotationrelation downwardloading b mK = qd 2 mK CA = (mK ) CA = f (q d ) 22/09/2011 9

9 Overview Torsional restraint Diaphragm action Axial loads Horizontal loads and stabilisation of buildings Introduction of tensile forces 22/09/2011 10

10 Diaphragmaction loadtransfer Transferofhorizontal(wind)loadsbydiaphragmaction or sandwichpanelscanreplacewindbracings 22/09/2011 11

11 Diaphragmaction loadtransfer Example 22/09/2011 12

12 Diaphragmaction Stabilisationofbeamsandcolumns Stabilityfailuremodes Buckling Lateraltorsional buckling 22/09/2011 13

13 Diaphragmaction Stabilisationofbeamsandcolumns Lateralrestraint Sandwichpanelscanrestraindisplacementv IncreaseofcriticalbucklingmomentMcr andcriticalbucklingforceNcr Restrainingeffectsareconsideredbysprings longitudinalspringwithstiffnessK StiffnessKdependsonshearstiffnessSofthediaphragm 2 forsinusoidaldeflection K = S i l 22/09/2011 14

14 Diaphragmaction stiffnessofdiaphragm Definition:StiffnessSofasheardiaphragm F S= 22/09/2011 15

15 Diaphragmaction Generalassumptions Stiffpanelswithflexibleconnections Panelrotatesaroundareference pointP Panelsareparalleltoeachother Panelsremainparalleltothe longitudinaledges Atallfasteningsonlyforcesand displacementsinlongitudinal direction 22/09/2011 16

16 Stiffnessoffastenings Mechanicalmodelofaconnectiontothesubstructure 1 D t sup D t sup 2 1 kF 2 2C 8 EI kv = xF = 1 xF t 2 + 2 (1 x F ) D t sup 3 (1 x F ) D t sup 2 + t sup 3 1 D 2 D (2 D + 3 t sup ) 2 + sup + + + kF 2 4C 24 EI kF 2 C 6 EI 22/09/2011 17

17 Stiffnessoffastenings Threecomponents Bendingstiffnessofthefastener 2 dS 4 EI = 200.000 N / mm 64 Rotationalstiffnessofclampinginthesubstructure C = 2400 N / mm 2 t sup d15 Stiffnessofinternalfacesheet(holeelongation) f u , F 2 t F3 2 d 1 k F 2 = 6,93 0,26mm + 0,8 t F 2 Fasteningsatlongitudinaljoints N k v = 1900 3 t F1 d mm 22/09/2011 18

18 Overview Torsional restraint Diaphragm action Axial loads Horizontal loads and stabilisation of buildings Introduction of tensile forces 22/09/2011 19

19 Axialloads Newapplication: Buildingsmadeofsandwichpanelsbutwithoutsubstructure wallpanelstransfernormalforces newquestions: Globalloadbearingcapacityof axiallyloadedsandwichpanels Localloadbearingcapacityof loadapplicationarea 22/09/2011 20

20 Axialloads globalloadbearingcapacity Elasticbucklingload N ki N cr = N 1 + ki GA Elasticbucklingloadofthefaces:Nki Elasticbucklingloadofthecore:GA Axialload,atwhichwrinklingofbothfacesoccurs N w = 2 AF w Slendernessofasandwichpanel Nw = = 2ki + GA 2 N cr 22/09/2011 21

21 Axialloads globalloadbearingcapacity DesignmodelbasedupontheexistingmodelofEN14509 Considerationof 2nd ordereffects creepeffects 22/09/2011 22

22 Axialloads globalloadbearingcapacity Bucklingtests Longtermtests 22/09/2011 23

23 Axialloads globalloadbearingcapacity Ultimatestressofaxiallyloadedpanels WrinklingstressaccordingtoEN14509 Considerationofcreeping CreepcoefficientsdeterminedaccordingtoEN14509 Advantage: Determinationbybendingtests Formostsandwichpanelsalreadyknown 22/09/2011 24

24 Axialloads globalloadbearingcapacity 2nd OrderEffects 1 amplificationfactor = N 1 N cr Creepeffects sandwichcreepcoefficient k St = t 1+ k wv BS VV dx k= = wb GA MMdx 22/09/2011 25

25 Axialloads globalloadbearingcapacity BendingMoment ( ) M tII = M WI + M I T + M SI (1 + S 2000 ) + M GI (1 + S100.000 ) wind temperature snow permanent difference load Stressofthefacesheet M tII N = + w AF D 2 AF 22/09/2011 26

26 Axialloads globalloadbearingcapacity Alternative:Designbybucklingcurves EquationfollowingEC3 N M + k yy 1 Nw Mw Reductionfactor = 1 + 2 + 2 = 0 . 5 + [ 1 + 2 2 GA + 2 ] Imperfectioncoefficientforsandwichpanels 2e0 BS = D Nw 22/09/2011 27

27 Axialloads globalloadbearingcapacity Alternative:Designbybucklingcurves [ = 0.5 + 1 + 2 GA 2 + 2 ] 22/09/2011 28

28 Axialloads localloadbearingcapacity Loadapplicationarea: Connectionbetweenwallandroof Loadisintroducedinthecutedgebycontact Failuremode:Cripplingofthefreecutedge 22/09/2011 29

29 Axialloads localloadbearingcapacity Loadapplicationarea: Failuremodeisrelatedtowrinklingofacompressedface Loadapplicationarea:elasticallysupportedbeamwithafreeend 22/09/2011 30

30 Axialloads localloadbearingcapacity Imperfectionsatloadapplicationarea Unevencutedge contactimperfections Cracksbetweencoreandface Deflectionofroofpanel Introductionofloadnotexactlyvertical Reductionofultimatestress 22/09/2011 31

31 Overview Torsional restraint Diaphragm action Axial loads Horizontal loads and stabilisation of buildings Introduction of tensile forces 22/09/2011 32

32 Horizontalloadsandstabilisationofbuildings Newapplication: Buildingsmadeofsandwichpanelsbutwithoutsubstructure panelstransferhorizontalwindloads panelsstabilizethebuilding Transferofforces: directlyloadedwalls roof(circumferentialshearforce) walls foundation 22/09/2011 33

33 Horizontalloadsandstabilisationofbuildings Panelsareloadedbyinplaneshearforces Highinplaneshearstiffnessandcapacityofthepanels fasteningsaredecisive fasteningshavetobedesignedforthehorizontalwindload Determinationofforcesatfastenings bynumericalcalculationwithasimplemodel rigidpanelsandflexiblefastenings fasteningsareconsideredbysprings forsimpleapplicationsalsoanalyticaldeterminationpossible 22/09/2011 34

34 Overview Torsional restraint Diaphragm action Axial loads Horizontal loads and stabilisation of buildings Introduction of tensile forces 22/09/2011 35

35 Introductionoftensileforces Introductionoftensileforcesinonlyoneface tensilestressesinthebondingbetweencoreandface possiblefailuremode: delaminationoftheface fromthecorematerial/ tensilefailureofthecore 22/09/2011 36

36 Introductionoftensileforces Tensileforces: Minimumedgedistance:Pull Smalleredgedistances: outfailure Delamination ofthefacefromthe corematerial/tensilefailureof thecorematerial 22/09/2011 37

37 Introductionofforces Tensileforces: Forsufficientedgedistances Faceiselasticallysupportedbythecorematerial Stiffnessoftheelasticfoundationisinfluencedbymaterialparametersof thecore Stiffnessofthefaceisinfluencedbythicknessandelasticmodulus Concentratedtensileforce 22/09/2011 38

38 Forfurtherinformation www.easie.eu DeliverablesofWorkpackage3(examples) D3.3 part1:Torsionalrestraint D3.3 part2:Sheardiaphragms D3.3 part3:Stiffnessoffastenings D3.3 part4:Axiallyloadedsandwichpanels 22/09/2011 39

39 Thankyouforyourattention 22/09/2011 40

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