Comparative Study of Glass Design Standards

Transcription

1 Comparative Study of Glass Design Standards Mathieu Meur November 2017

2 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of glass fins Design of bolted glass Beyond standards

3 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of glass fins Design of bolted glass Beyond standards

4 Glass Behaviour Brittle material (theory v/s actual) E. Premalatha, Dr. C. Umarani University of Texas Arlington

5 Glass Behaviour Gang Deng and Tsutomu Nakanishi Breakage initiated from micro-cracks

6 E. Premalatha, Dr. C. Umarani Glass Behaviour Large deflections non-linear behaviour

7 Glass Behaviour Behaviour changes with duration of loading (creep)

8 Glass Behaviour Laminated glass behaviour changes with temperature Shear modulus, G (MPa) G PVB (MPa) 20 C C C C Poisson ratio, v 3s 1min. 1 hr. 1 day 1 mo. > 1yr. n PVB 3s 1min. 1 hr. 1 day 1 mo. > 1yr. 20 C C C C

9 Glass Behaviour Laminated glass behaviour changes with temperature

10 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of bolted glass Design of glass fins Beyond standards

11 Glass Design Standards Standards covered: ASTM E1300 US standard AS 1288 Australia standard BS 6262/ 5516 Bristish standard TRLV German technical regulation pren 16612/16613 proposed European standard (not approved) JGJ 102 Chinese standard

12 Glass Design Standards Other standards not covered: IS India standard Inspired from AS 1288 and BS 6262 NF DTU 39 French norm CAN/CGSB 12 Canadian standard NBN S Belgium standard

13 Glass Design Standards Focus on structural design aspects Impact safety not covered Thermal and visual performance not covered Aesthetics not covered

14 Glass Design Standards Definitions of AN, HS and FT Deflection limits at centre / edges Stress limits Load distribution (laminated / IGU) Mixed thickness glass consideration Point-fixed glass consideration Design of glass fins Design of curved glass Design breakage rate

15 Glass Design Standards Definitions ANNEALED GLASS HEAT-STRENGTHENED FULLY TEMPERED ASTM E1300 Surface compression of 24- Residual surface stress near 0 52MPa Surface compression >69MPa AS Surface compression Surface compression of 24-69MPa >69MPa BS 6262/ TRLV pren 16612/16613 Glass which has been treated during manufacture to minimise the residual stress in the glass, allowing it to be cut by scoring and snapping JGJ Glass which has been subjected to a strengthening treatment, by heat or chemicals, which induce compressive surface stress into the whole surface, balanced by tensile stress within the body of the glass Surface compression of 24-60MPa Glass which has been subjected to a strengthening treatment, by heat or chemicals, which induce compressive surface stress into the whole surface, balanced by tensile stress within the body of the glass >90MPa

16 Glass Design Standards Definitions Deflection limit Glass edge deflection limit Ultimate limit state ASTM E1300 N.A L/175 Unfactored AS 1288 L/60 for typical L/ G+1.5Q L/30 for cantilevered BS 6262/ 5516 Min. (L 2 /125x1000) for <=3m L/125 for monolitic --- Min. (L 2 /175x , 40mm) for >3m L/175 for DGU Min. (L 2 /175x1000, 20mm) for DGU TRLV L/100 min (L/200, 15mm) Unfactored pren 16612/16613 min (L/65, 50mm) G+1.2Q

17 Glass Design Standards Definitions Allowable stress (MPa) (Short-term load) Away from edge At edge AN HS FT AN HS FT ASTM E AS 1288 c 1.[ -9.85ln t ] c 1.[ -7.88ln t ] c 1 =1 c 1 =1.6 c 1 =2.5 c 1 =1 c 1 =1.6 c 1 =2.5 BS 6262/ TRLV pren 16612/ JGJ

18 Glass Design Standards Definitions Short-term load Laminated Load distribution Medium/ long-term load ASTM E1300 Total thickness DGU AS 1288 Total minimum thickness t 3 / t i Qt 3 / t i 3 BS 6262/ TRLV Total thickness Total thickness t 3 / t i 3 pren 16612/16613 Effective thickness δ 1 +φδ 2 h e,sls = 3 [ k h k3 +12ω(h k h 2 )] m,k where δ i =h i3 / h 3 ; h e,uls,j = [h e,sls3 /(h j +2ωh m,j )] φ=1/[1+a/a*] 4 ; a=shorter length of the pane; a*=28.9[sh 13 h 23 /(h 13 +h 23 )k 5 JGJ 102 t e,w = 3 (t 13 +t ΤI s ) w k,1 = 1.1Qt 3 / t 3 i (outer lite) t 1e,σ = [t e,w3 /(t 1 +2Τt s,2 )], Τ=0 for PVB w k,2 = Qt 3 / t i 3 (inner lite)

19 Glass Design Standards Definitions Mixed thicknesses for laminated and DGU Width : height limit for 4 sided Design thickness ASTM E1300 Yes (for lami only) --- Minimum thickness AS 1288 Yes 1:5 Minimum thickness BS 6262/ 5516 No 1: TRLV Yes pren 16612/16613 Yes JGJ 102 Yes (< 3mm)

20 Glass Design Standards Definitions Design of overhead glass Design of point-fixed glass Design of Glass fin ASTM E AS 1288 Angle < 75 o to the horizontal --- Fin thickness > 12mm 1.1kN distributed over a circular area of 0.01m 2 Friction grip joint for glass fin Deflection limit L/240 Appendix C for LTB BS 6262/ Annealed glass is not allowed Fin thickness > 15mm Glass hole edge distance > 2x thickness Friction grip joint for glass fin; Bolt spacing > 100mm TRLV Angle < 80 o to the horizontal Only laminated for the lower pane Free edge protrudes < 300mm pren 16612/ JGJ Thickness > 6mm for flat cap Deflection < L/200 routel Thickness > 8mm for coutersunk routel Edge distant >70mm Gap between fin and facial glass >8mm Fin thickness >12mm, breadth > 100mm

21 Glass Design Standards Definitions Climatic loads Design of curved glass Design breakage rate ASTM E1300 No No 8 : 1000 AS 1288 No Yes 1 : 1000 BS 6262/ 5516 No No Not indicated TRLV Yes Yes p f = 10-6 per year (0.05 : 1000 based on 50 year return) pren 16612/16613 Yes Yes Not indicated JGJ 102 Yes Yes Not indicated

22 Glass Design Standards Definitions ASTM E x1.8x2=2.88kPa>2kPa

23 Glass Design Standards Definitions AS 1288 LC 1: Q Global Deformations u Global Deformations u [mm] Isometric RF-GLASS CA1 Layer No. 1, Bottom Stresses for CO3 Sigma-x Stresses for CO3 x [MPa] Isometric Max : Min : 0.0 Max : Min : Z Z X Y X Y Max u: 14.2, Min u: 0.0 mm Factor of deformations: Max Sigma-x: , Min Sigma-x: [MPa]

24 Glass Design Standards Definitions BS mm

25 Glass Design Standards Definitions TRLV LC 1: Q Global Deformations u Global Deformations u [mm] Isometric RF-GLASS CA1 Layer No. 1, Bottom Stresses for LC1 Sigma-x Stresses for LC1 x [MPa] Isometric Max : 12.9 Min : Max : Min : Z Z X Y X Y Max u: 12.9, Min u: 0.0 mm Factor of deformations: Max Sigma-x: , Min Sigma-x: [MPa]

26 Glass Design Standards Definitions JGJ 102 LC 1: Q Global Deformations u Global Deformations u [mm] Isometric RF-GLASS CA1 Layer No. 1, Bottom Stresses for CO2 Sigma-x Stresses for CO2 x [MPa] Isometric Max : 14.0 Min : Max : Min : Z Z X Y X Y Max u: 14.0, Min u: 0.0 mm Factor of deformations: Max Sigma-x: , Min Sigma-x: [MPa]

27 Glass Design Standards 1.5mx3.5m panel in 2kPa with monolithic heat-strengthened glass Example Cases 1.6mx3.5m panel in 2.5kPa with laminated heat strengthened glass 1.4mx3.5m panel in 2.0kPa with DGU heat strengthened glass ASTM E1300 Glass thickness required = 8mm Glass thickness required = 5+5mm Glass thickness required = 6+6mm *Deflection limit is not specified *Deflection limit is not specified *Deflection limit is not specified AS 1288 Glass thickness required = 10mm Glass thickness required = 6+6mm Glass thickness required = 8+8mm (8mm glass fails in stress) (5+5mm glass fail in stress) (6+8mm glass fail in stress) BS 6262/ 5516 Glass thickness required = 10mm Glass thickness required = 8+8mm Glass thickness required = 8+8mm TRLV Glass thickness required = 12mm Glass thickness required = 6+6mm Glass thickness required = 8+8mm (10mm glass fails in deflection) (5+5mm glass fail in deflection) (6+8mm glass fail in deflection) pren 16612/16613 Glass thickness required = 10mm Glass thickness required = 6+6mm Glass thickness required = 6+8mm (8mm glass fails in stress & deflection) (5+5mm glass fails in stress & deflection) (6+6mm glass fails in deflection) JGJ 102 Glass thickness required = 10mm Glass thickness required = 8+8mm Glass thickness required = 8+8mm (8mm glass fails in stress) (6+8mm glass fails in stress) (6+8mm glass fails in stress)

28 Glass Design Standards AS 1288 and JGJ 102 generally most comprehensive and balanced ASTM E 1300 least conservative BS 6262 not very comprehensive or flexible

29 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of glass fins Design of bolted glass Beyond standards

30 Design of Glass Fins Lateral torsional buckling check not covered except in AS 1288 Does not take the non-linear load carrying behaviour due to imperfections, the glass strength and the interlayer Also possible to use buckling curves derived from buckling tests and numerical FEA models Buckling curves give reduction factors LT for design as a function of the slenderness ratio l LT A. Luible

31 Design of Glass Fins Lateral torsional buckling check M CR = g 2 L ay EI y GJ 1.7 g 3 y h L ay EI y GJ

32 Design of Glass Fins Lateral torsional buckling restraint Glass as a restraint? Restraint capacity?

33 Design of Glass Fins Redundancy check Laminated glass Prevent progressive collapse Check fins with one ply broken and reduced safety factors (accidental loading)

34 Design of Glass Fins Interstorey movement allowance (vertical restraint release)

35 Design of Glass Fins Spliced connections

36 Design of Glass Fins Spliced connections

37 Design of Glass Fins Clamped or bolted design

38 Design of Glass Fins Clamped or bolted design

39 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of glass fins Design of bolted glass Beyond standards

40 Bolted glass Stress concentration at bolt holes

41 Bolted glass Stress concentration at bolt holes Mascha Baitinger, Markus Feldmann

42 Bolted glass Simple theoretical approach Multiply stress by a factor

43 Bolted glass Simple FEA model No holes

44 Bolted glass Simple FEA model No holes

45 Bolted glass Simple FEA model No holes

46 Bolted glass More refined approach Hole and fitting

47 Bolted glass More refined approach Hole and fitting

48 Bolted glass More refined approach Hole and fitting

49 Bolted glass More refined approach Hole and fitting

50 Bolted glass Stress concentration at bolt holes Local mesh refinement

51 Bolted glass Load amplification factor is inaccurate (over-conservative) High sensitivity of results to mesh size Results sensibly the same between simple and complex models

52 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of bolted glass Design of glass fins Beyond standards

53 Beyond Standards Direct glass-to-glass connections

54 Beyond Standards Laminated connections

55 Beyond Standards Laminated connections Eckersley O Callaghan

56 Beyond Standards Laminated connections Eckersley O Callaghan

57 Beyond Standards All glass structures Eckersley O Callaghan

58 Beyond Standards Glued connections Eckersley O Callaghan

59 Beyond Standards Chemically tempered glass JSJ Jodeit

60 Beyond Standards Chemically tempered glass

61 Beyond Standards Glass connections

62 Comparative Study of Glass Design Standards Review of glass behaviour Design standards for glass sheets Design of glass fins Design of bolted glass Beyond standards