Bolted Connection in Glass Structure

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ADVANCED DESIGN OF GLASS STRUCTURES Lecture L4_ME Bolted connection in glass structures Martina Eliášová European Erasmus Mundus Master Course

Sustainable Constructions under Natural Hazards and Catastrophic Events 520121-1-2011-1-CZ-ERA 520121-1-2011-1-CZ-ERA MUNDUS-EMMC

Objectives Objectives of the lecture

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Objectives

•

Introduction

Structural design of bolted connections

•

Stru St ruct ctur ural al de desi sign gn of bo bolt lted ed co conn nnec ecti tion ons s

Typology and technology

•

Typ Typology and technology

Behaviour under loading

•


Experimental research

•

Experimental re research

•

Design concepts

Introduction

Design concepts

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Examples of bolted connections Objectives Introduction

Bolted Connection in horizontal Glass Beams

Structural design of bolted connections Typology and technology Behaviour under loading Experimental research Design concepts

Allied Irish Banks, Bank c entre, Dublin Architect: RKD Architects

Facade:

Gartner Steel and Glass, Germany

Structure Specialist Glazing, Curtain Wall,

Steel- and Glass roof Surface:

20,000 m²

Completion: 2008

Wellershoff F., F., Schreiter D., Schmitt F., F., 2008 3

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Examples of bolted connections Objectives

Bolted Connection in horizontal glass beams

Introduction

Structural design of bolted connections Typology and technology © F. Wellershoff

Behaviour under loading Experimental research Design concepts

© Gartner Steel and Glass

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Practical examples Objectives

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Bolted Connection in horizontal glass beams

Introduction


Glass roof for university of Glasgow, 2002

• fricti friction on grip grip conn connect ection ion • soft interlay interlayer er replaced replaced by by aluminium aluminium alloy • prestr prestress essed ed M2 M20 0 bolts bolts • spe specia ciall fricti friction on laye layers rs 5

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Bolted connection in vertical fins


River City - Danube house, Prague

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Trump Tower, Chicago (SOM Architects, 2008) 7

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Museum of history – Luxembourg Glass fins: height - 12 m, thickness – 19 mm 8

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Museum of history – Luxembourg 9

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Bolted connection in vertical fins wind

Structural design of bolted connections Typology and technology Behaviour under loading

compression A tension in steel tie glass fin divided into pieces of 4m and 2m s t u n h t i w s e i t l e e t s

Experimental research Design concepts

t c a t n o c t c e r i d

Detail A

Natural museum in Rotterdam, 1997 • glass façade of 6m height is stabilized by glass fins • depth of fin 400mm, distance 2.5m 10

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Bolted connection in glass bridges


Glass footbridge, Rotterdam, 1994

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beam: span 3,5 m, depth 300 mm, composition 3 x 10 mm float glass, parabolic shape = architectural reasons

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floor plates – float glass 2 x 15 mm

•

walls: laminated glass - external:10 mm toughened glass, internal: 6 mm heat-strengthened glass 11

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Glass footbridge, Rotterdam, 1994

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beam: span 3,5 m, depth 300 mm, composition 3 x 10 mm float glass, parabolic shape = architectural reasons

•

floor plates – float glass 2 x 15 mm

•

walls: laminated glass - external:10 mm toughened glass, internal: 6 mm heat-strengthened glass 11

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Structural design of bolted connections Typology and technology

high modulus structural silicone sealant

4mm,  180mm steel plate

15mm thick,  130mm steel plate


M16 countersunk screw

low modulus silicone sealant

8mm heat strengthened glass


round polished edge hole  142mm

1,52mm thick PVB interlayer nylatron bush

1mm thick vulcanised cellulose fibre gaskets

15mm toughened glass ground and arrissed hole  12mm, steel 28mm plate,  180mm

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Eaton Center, Calgary (MMC International Architects, Toronto, 2010) 13

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Structural design of bolted connections Objectives Introduction

Stress Analysis with FE-Methods


Typology and technology Behaviour under loading Experimental research Design concepts

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Kravis Center, LA (Gartner, 2011)



© Rafael Vinoly Architects

Client

Claremont MC Kenna College

Architect

Rafael Vinoly, NY

Façade

Gartner Steel and Glass, Germany

Structure

Structural glass columns, steel roof, glass walls

Completion

2011 17

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Kravis Center, LA (Gartner, 2011)




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Stress Analysis with FE-Methods


X

0.9 Y

X Y Z Z


Spannungen

 1,+ [kN/cm 2] 0 . 0 4 1


2.33 2.01

0 . 0 8

0 . 0 5

1.69


1.37 1.04 0.72

Design concepts

0.40 0.08 -0.25 -0.57 -0.89 48.90 48.91

48.90 48.91

-1.21

34.25 34.26

34.25 34.26

Max : Min : 10.16 10.16 10.66 10.66

10.16 10.16 10.66 10.66

40.24 40.25 57.68 57.68

0 . 0 8

7.51 8.74 8.74 7.51

7.51 8.74 8.74 7.51

191.0 14 6.0

2.33 -1.21

40.24 40.25 57.68 57.68

0 . 0 5

8.74 8.74

0 . 6 4 1

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Structural design of bolted connections Objectives Introduction Structural design of bolted connections

Detail tests of the connection force resistance


Stützenkräfte Lastkombination nach ASCE-07

N [kN]

Kraftresultierende je Bolzenpaar

V [kN]

R druck [kN]

R zug [kN]

DL + LLR

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DL + 0,7 EL

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66,5

195

178

10,5

66,5

191,5

181

0,6 DL + 0,7 EL

DL (Dead Load), LLR (L ife Load), EL (Earthquake Load)

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© F. Wellershoff

© F. Wellershoff

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Detail tests of the connection force resistance

Typology and technology Behaviour under loading Experimental research

Test sample

Breakage force of glass layer

First layer

Design concepts

Max. force

Safety coefficient

Second All layer layer

2

719,5

755,0

4,17

3

682,0

682,0

3,77

733,2

800,0

4,42

476,7

578,9

3,20

7

798,0

801,4

4,43

8

742,8

742,8

4,10

4

775,9

5

449,2

1) Global

1)

578,9

safety factor related to characteristic connection force (181 kN)

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Full scale test for overall behavior of the column



© F. Wellershoff

© F. Wellershoff

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Typology and technology Objectives Introduction Structural design of bolted connections Typology and technology

Great number of point fittings on market •

Glass connectors, cylindrical flat shape, round-head

•

Behaviour under loading Experimental research

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Glass connectors, countersunk flat-head, round-head

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Slideable glass connectors, countersunk

•

Glass connectors for round pipe mounting

•

Hinged glass connectors

•

3D-glass connectors

•

Countersunk glass connector, tapered

Design concepts

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Objectives Introduction

Hole shapes

Structural design of bolted connections Typology and technology


cylindrical hole

conical hole

undercut hole

•

no universally accepted rules for positioning or dimensioning of drilled holes

•

hole diameter at least glass thickness, preferable twice of the glass thickness

Design concepts

A ≥ 2T

D≥T

A edge distance B distance between holes (from hole edge to hole edge) C distance to corner D hole diameter T glass thickness

D≥T

B ≥ 2T

C ≥ 6T

A ≥ 2T

recommended distances between holes and edges

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Typology and technology Objectives Introduction Structural design of bolted connections Typology and technology


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Standard bolt - simplest type of fixing • load transfer by direct bearing of the glass on the shank of the bolt • small contact area limits capacity, liner between glass and bolt increase bearing surface • little provision for rotation to the fixing under applied out-of plane loads


fibre washers

steel washer

steel washer

liner

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Typology and technology Objectives Introduction Structural design of bolted connections

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Simple countersunk bolt – bolt head is flush with glazing • liners enhance the in-plane load capacity • little provision for rotation of the glass relative to the fixing under applied out-of plane loads



liner

Design concepts

steel washer fibre washer

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Bolted connection with steel splices • bearing or friction bolts (bolts are tightened to a specific torque in order to achieve a friction connection) • increased contact area and wider load spread provide high load carrying capacity



fibre gasket


steel washer

Design concepts

steel washer plate

plate

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Bearing bolt connection with steel splices •

stress concentrations around the bolt hole → necessity of tempered or heat strengthened glass

•

ultimate breaking stress depends on the number and diameter of bolts


•

maximum force about 30kN per bolt

Design concepts

•

load is transferred into the plane of glass by contact between suitable interlayer and bolt bearing surface

•

use of single splice plate avoided due to load eccentricities

•

important is quality of edge treatment



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Typology and technology Objectives

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Friction bolt connection with steel splices

Introduction Structural design of bolted connections Typology and technology

•

normally double shear connection

•

friction forces resist the shear forces between the components of joint

•

magnitude of stresses, which friction grip connection can carry, depends on the contact pressure and friction coefficient

•

special friction layers → greater load capacity in comparison to bearing connection


•

normally used ONLY with monolithic glass → creep behaviour of PVB foil

•

laminated glass – PVB foil can be replaced in area of load transfer by insert of stiffer material, i.e. aluminium

elastomer sleeve

friction layer

spring washer

steel splice plate

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Typology and technology Objectives

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Bolted connections with steel splices



• bolt groups and multiply bolt connection are typical • example of internal splice plate design of friction grip connection • friction grip connection with more than one individual splice plate 31

Behaviour under loading Objectives

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Basic Parameters in Bolted Connections

Introduction Structural design of bolted connections Typology and technology Behaviour under loading


•

Glass thickness

•

Glass type (pre stress)

•

Glass surface quality in the borehole

•

Borehole offset in laminated glass

•

Borehole diameter

•

Bolt diameter

•

Bushing diameter and tolerances to bolt diameter

•

Contact material (thickness and tolerances, Young's modulus, viscosity, creeping performance, compression strength, adhesion to glass surface, UV-stability, moisture-stability,…..)

•

Load eccentricity (additional bending moment)

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Distances (between boreholes and from boreholes to glass edges)

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Behaviour under loading Objectives

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Stress distribution around the hole


1. bearing bolt connection with steel splices 2. compressive stress in the glass pane 3. tensile stress in the glass pane



stress distribution around the bolt 33

Behaviour under loading Objectives Introduction Structural design of bolted connections

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Description of contact compression with Fourier formula (Girkmann, 1978) Centric Load

Typology and technology Behaviour under loading


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Experimental research Objectives Introduction Structural design of bolted connections Typology and technology

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Research and concepts • Example of original beam with a splice connection and the isolated detail Ioad q Belastung qd


Design concepts

Isolated Beispiel Detail für to be bauteilähnlichen tested in laboratory Ausschnittsversuch

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Experimental research Objectives Introduction Structural design of bolted connections

Bolted Connection – Tests RWTH Aachen Test set up Centric Load


Design concepts

0 0 2

0 0 0 0 6 2

0 0 2

e t a l p l e e t S

Eccentric Load M = F  e

Load F Load F Load introduction material Side view: Glass bore hole Ø 35 (cylindrical)

Steel bolt Ø 25 e t a l p l e e t S

[ mm ]

Glass sample 600 * 400

Steel bolt e e = 0 / 4 / 5 / 6 cm

400 200

200 36

Experimental research Objectives Introduction Structural design of bolted connections Typology and technology Behaviour under loading Experimental research

Design concepts

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Bolted Connection – Tests RWTH Aachen Tested Materials: Polyamide 6 with 30% glass fibers (PA6 GF30) Polyethereethereketone (PEEK) PolySulfone (PSU)

Treatment: Pre fabricated bushes Fill out the gap between the bush and the glass without compression Fill out the gap between the bush and the glass with compression

Rein Aluminum AlMgSi (toughened) POM Hilti Hit Hy50 epple easy glass mortar epple easy 5610

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Experimental research Objectives Introduction Structural design of bolted connections Typology and technology Behaviour under loading Experimental research

Design concepts

Bolted Connection – Tests RWTH Aachen Test results – centric load

Tests with bolted connections; Glass Lochleibungsversuch, ESG d = Tempered 10 mm und 15 mm 100 PSU

Alu (weichgeglüht)

90

] N k ] 80 [ N e k [ r u 70 n l i i t a f f a t r 60 k a h e c c u r r 50 o B f e l n a 40 e m s i s x 30 e a m M e

PEEK

PA6 GF30

POM

Hilti nur Stahl epple 5610 epple Glasmörtel

g 20

d = 10 mm d = 15 mm

10 0 0

10

20

30

40

50

60

70

80

90

100

110

Versuchsnummer Number of test

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Experimental research Objectives Introduction

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Application of photoelastic method - CTU in Prague F

F


Steel splice


Glass specimen


Design concepts

F

• • •

Testing machine

F

Nominal dimensions of the specimens: 680 x 300 x 12 mm, float glass Insert from hard plastic between glass and bolts M16, quality 8.8 Special steel hinge - from one side of the glass specimen 39

Experimental research Objectives Introduction

F = 0 kN

F = 5 kN

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F = 10 kN

Structural design of bolted connections Typology and technology Behaviour under loading Experimental research

Design concepts

Numerical study – comparison with experiments

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Design Concepts Objectives

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Design Formula

Introduction Structural design of bolted connections

  ,max,d


 K  P  k 1  k 2  k 3  k 4  k 5   1,2  2,2 m   d   d bm  d 0  t 


Pd

design load at relevant bore hole

d0

bore hole diameter

t

glass thickness (one layer for laminated glass)

ki

factors for design and production parameters

bm

relevant width in [d0]

Km factor to consider load balance at multiple bore holes

Baitinger M., 2009

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Design Concepts Objectives Introduction

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Definition of relevant pane width


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Factor Km to consider load balance at multiple bore holes


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Design Concepts

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Objectives Introduction

Factor Km to consider load balance at multiple bore holes


Baitinger M., 2009

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Design Concepts Objectives Introduction Structural design of bolted connections

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Factors for design and production parameters Factor to consider unequal distribution of compression


Factor to consider little relevant width


Design formula is not applicable for b m < 3 d0

Factor to consider little edge distances e1=e2

k3=1.0 for e 1≠e2 Baitinger M., 2009

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Factors for design and production parameters Factor to consider little bore hole distances p1


Factor to consider offset in laminated glass

Design concepts

The maximum allowed offset is 50% of the mortar thickness

Baitinger M., 2009

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Design Concepts Objectives

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Example: Splice connection in the point of zero shear load

Introduction Structural design of bolted connections

glass panels


steel splices


Characteristic bending moment MEk = 2.3 kNm

Required glass thickness?

Bolted connection Baitinger M., 2009

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geometric parameters

factors


centric load


2 layers laminated glass

Baitinger M., 2009

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Determination of P d:

Structural design of bolted connections Typology and technology Behaviour under loading

Determination of t required:


Baitinger M., 2009

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References

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Educational pack of COSTActin TU0905 „Structural Glass - Novel design methods and next generation products“ TECHEN, H. Fügetechnik für den konstruktiven Glasbau, Institut für Statik, TU Darmstadt, PhD 1997. WELLERSHOFF, F.; SEDLACEK, G. Glass Pavilion Rheinbach – Stability of Glass Columns; Proceedings of the Glass Processing Days 2003, page 316-318. MOCIBOB, D. Glass Panel under Shear Loading - Use of Glass Envelopes in Buildi ng Stabilization, EPFL Lausanne, PhD 2008. VENCL, R., ELIASOVA, M. “Bolted Connections of Glass Structures by means of Two Holes In-line”. In: proceedings “Challenging Glass”, Conference on Architectural and Structural Applications of Glass, Faculty of Architecture, Delft University of Technology, May 2008, s. 279 – 284, IOS Press, ISBN 978-1-58603-866-3. VENCL, R., ELIASOVA, M., NETUSIL, M. „Connections of Glass Structures by Used Shear Bolts in a Row“. In: proceedings „Eurosteel 2008 – Volume A”, 5th European Conference on Steel and Composite Structures, Graz, Austria, 3rd – 5th September 2008, ECCS, s. 923 -928, 2008, ISBN 92-0147-000-90. BAITINGER, M. Zur Bemessung von SL-belasteten Anschlüssen im konstruktiven Glasbau, RWTH Aachen, PhD 2009. WELLERSHOFF, F., SENDELBACH, M.; SCHMITT, F. Glass Colunms and Glass Beams – Projects of 2010, engineered transparency at glastec 2010. Conference Proceedings, page 349- 357.

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Bolted Connection in Glass Structure

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