High Temperature Material Laws of High Strength (S460) Steel

Transcription

1 High Temperature Material Laws of High Strength (S460) Steel Prof. Dr.-Ing. Jörg Lange Institute for Steel Structures and Fracture Mechanics Technische Universität Darmstadt STAHLBAU

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3 1981 BMW AG in Berlin 15,0 15,0 15,0 15,0 Penthouse 7,8 8,2

4 120,0 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 7,5 B 15,0 Tensile forces H resulting from sagging composite beams A 60,0 15,0 15,0 2,5 2,5 2,5 2,5 2,5 1,25 Protected beams carrying compressive forces A 15,0 1,25 B H H Protected beams Unprotected beams sagging under fire Protected beams Beams and girders level above ground floor

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6 Paint shop for Airbus A380 Hamburg 2004

7 Frame of the main door Door Airplane

8 Deflections under self weight and fire A m /V mostly less than 30

9 Fire load Airplane - Paintshop according to DIN (May 1998) Fire load for one A380 painting area Kind of fire load: Mass (KG) m - Factor Heating value (kwh/kg) Energy contents (kwh) Airplane primary structure , Hydraulic Oil , Tires , Chairs , Additional plastic , Additional load inside building , Kerosine (after emptying) , Paint , Tools etc , Sum This results in a specific fire load q r = 273,4 kwh/m 2, in an area of m 2. = 17 kg/m² wood

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11 Reduction of the yield strength of S460 fy(θ) / fy(20 C) [-] 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 SFB 148 (1986): StE 47 Winter (1990): StE 460 TM Arbed (1989): StE 460 TM Outinen (2000): S460 M EC Θ [ C]

12 Chemical composition Fine grain built due to Nb, Ti, V S460 N: Final rolling at 900 C S460 M: Final rolling at 800 C Austenite cannot re-crystallize due to Niob fine grain ferrite reduction of carbon

13 S460 N Equal grain size (G = 8) S460 N: Round grain, linear distribution of perlite (dark) S460 M S460 M: Uneven distribution, Distorted grain less perlite (less carbon)

14 Test methods Institute for Steel Structures and Fracture Mechanics Steady State Tests (+ creep): Θ = const. ε s, ε k, ε th separated F σ ε s Θ = const F ε

15 Test methods Institute for Steel Structures and Fracture Mechanics Steady State Tests (+ creep): Θ = const. ε s, ε k, ε th separated F σ ε s ε s + ε k Θ = const F ε

16 Test methods Institute for Steel Structures and Fracture Mechanics Steady State Tests (+ creep): Θ = const. ε s, ε k, ε th separated Transient State Tests Θ const ε s, ε k and ε th included F σ ε s ε s + ε k Θ F = const Θ = const F F ε

17 Test methods Institute for Steel Structures and Fracture Mechanics Steady State Tests (+ creep): Θ = const. ε s, ε k, ε th separated Transient State Tests Θ const. ε s, ε k and ε th included F F = const σ ε s ε s + ε k Θ Θ = const F F ε ε th = ε s + ε k ε

18 Comparison S460N - direkter steady Vergleich state tests stationär-instationär transient state test S pannung [N/m m ²] stat 600-stat 700-stat 800-stat ,5 1 1,5 2 2,5 3 Dehnung [%]

19 Curve fitting using a nonlinear function according to Anderberg (1983) and Rubert/Schaumann (1985) σ Ellipse: b σ = a a 2 ( ε y,θ + d ε) 2 + f p,θ c f y,θ E V,Θ b f p,θ f p,θ - c c a d E 0,Θ ε p,θ ε y,θ ε y,θ + d ε

20 Analytical Stress-Strain-Relationship ε εp, Θ : σ = ε E 0, Θ b 2 2 p : σ = a ( ε y, Θ + d ε) + fp, Θ c a ε y, Θ < ε 0,03 : σ = f y, Θ + ( ε ε y, Θ) EV, Θ ε, Θ < ε εy, Θ Geometry of the ellipse: ψ a = ψ b = (E 0, (E Θ + EV, Θ ) ( ε y, Θ εp, Θ) δ 0, δ λ Θ + EV, Θ ) (f y, Θ fp, Θ) λ δ λ E V, Θ ( εy, Θ εp, Θ ) (f y, Θ fp, Θ ) + (f y, Θ fp, Θ) c = δ EV, Θ ( ε y, Θ εp, Θ ) (f y, Θ fp, Θ) E V, Θ E0, Θ ( εy, Θ εp, Θ ) d = λ 2 2 mit ε p, Θ = f p, Θ / E0, Θ Hilfswerte δ, λ, ψ = f (E, Θ;EV, Θ; ε y, Θ; εp, Θ;fy, Θ;fp, 0 Θ Fitting of parameters according to least square method )

21 Examples for curve fitting 600 Spannung [N/mm 2 ] S460 N mit Berücksichtigung des Fließplateaus 200 C 500 C C 0 0 0,005 0,01 0,015 0,02 0,025 0,03 Dehnung [-]

22 Analytical Stress-Strain-Curve for S460 N 500 Spannung [N/mm 2 ] C 200 C 300 C 400 C 500 C 600 C 700 C C 900 C 0 0,005 0,01 0,015 0,02 0,025 0,03 Dehnung [-]

23 Analytical Stress-Strain-Curve for S460 M C 200 C 300 C 400 C 500 C Spannung [N/mm 2 ] C 700 C 800 C 900 C 0 0,005 0,01 0,015 0,02 0,025 0,03 Dehnung [-]

24 Comparison of examples for S460 N und S460 M Spannung [N/mm 2 ] S460 N S460 M EC ,005 0,01 0,015 0,02 0,025 0,03 Dehnung [-] 500 C 600 C 800 C

25 Comparison of results for S460 N und S460 M Rt2,0 / fy(20 C) [-] 1,1 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0, Temperatur [ C] S460 N S460 M EC3-1-2 increased strength of S460 M compared to S460 N (yielding at higher temperatures)

26 Comparison to EC3-1-2 Rt2,0 / fy(20 C) [-] 1,1 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0, Temperatur [ C] S460 N S460 M EC3-1-2 EC3-1-2 overestimates the S460 N Will this lead to unsafe structures?

27 Ultimate Load Design Calculation of the ultimate load at various temperatures and various slendernesses. Comparison of the new model to EC3-1-2 N N V 0 w 0 = L/1000 w 0 Θ q 0 Θ L = s K q 0 = 8 N w 0 / L 2 V 0 = 4 N w 0 / L N b,fi,θ,rk =?

28 Calculation of Ultimate Load 800 C Buckling perpendicular to y-axis (HEA 300) 1 κfi (bez. auf N fi,800 C,Rk,EC3 ) 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 y z λ = L/i y eigenes Werkstoffmodell - S460 N Werkstoffmodell nach EC3-1-2

29 Summary Institute for Steel Structures and Fracture Mechanics Higher strength of S460 M compared to S460 N at 400 C Θ 900 C. Material laws according to EC3-1-2 are ok for S460 M but not for S460 N.