EN Eurocode 1 Accidental Actions. Ton Vrouwenvelder TNO Bouw / TU Delft. EUROCODES Background and Applications

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1 Brussels, February 2008 Dissemination of information workshop 1 EN Eurocode 1 Accidental Actions Ton Vrouwenvelder TNO Bouw / TU Delft

2 Brussels, February 2008 Dissemination of information workshop 2 EN 1990 Section 2.1 Basic Requirements (4)P A structure shall be designed and executed in such a way that it will not be damaged by events like -explosion - impact and - consequences of human errors to an extent disproportionate to the original cause Note: Further information is given in EN

3 Brussels, February 2008 Dissemination of information workshop 3 EN 1990 guidance: reducing hazards low sensitive structural form survival of local damage sufficient warning at collapse tying members

4 Brussels, February 2008 Dissemination of information workshop 4

5 Brussels, February 2008 Dissemination of information workshop 5 World Trade Center USA, 2001

6 Brussels, February 2008 Dissemination of information workshop 6 Eurocode EN General 2. Classification 3. Design situations 4. Impact 5. Explosions Annexes A. Design for localised failure B. Risk analysis C. Dynamics D. Explosions

7 Brussels, February 2008 Dissemination of information workshop 7 3 Design strategies

8 4. Impact Brussels, February 2008 Dissemination of information workshop 8 Type of road Vehicle type F d,x [kn] Motorway Country roads Urban area Parking place Parking place Truck Truck Truck Truck Passenger car

9 Brussels, February 2008 Dissemination of information workshop 9 Annex B: scenario model

10 Annex C: force model Brussels, February 2008 Dissemination of information workshop F[kN] upper lower theorie E [knm] F=v (km) model en experiment

11 Brussels, February 2008 Dissemination of information workshop 11 Table 4.2.1: Data for probabilistic collision force calculation variable designation type mean stand dev n number of lorries/day deterministic T reference time deterministic 100 years - λ accident rate deterministic m -1 - b width of a vehicle deterministic 2.50 m - α angle of collision course rayleigh 10 o 10 o v vehicle velocity lognormal 80 km/hr 10 km/hr a deceleration lognormal 4 m 2 /s 1.3 m/s 2 m vehicle mass normal 20 ton 12 ton k vehicle stiffness deterministic 300 kn/m -

12 Brussels, February 2008 Dissemination of information workshop force [kn] 2500 eq distance [m] Life time exceedence probability: 10-3

13 Design example: bridge column in motorway Brussels, February 2008 Dissemination of information workshop 13 x F dy H h y a b b width 0.50 m h thickness 1.00 m H column height 5 m f y yield stress steel 300 MPa f c concrete strength 50 MPa ρ reinforcement ratio 0.01

14 Brussels, February 2008 Dissemination of information workshop 14 Bending moment: M dx = a( H a ) H F dx = 1.25 ( ) = 940 knm Resistance: M Rdx = 0.8 ω h 2 b f y = = 1200 knm > 940 knm

15 Brussels, February 2008 Dissemination of information workshop Annex D: gas explosions in buildings gas explosions in tunnels dust explosions

16 Brussels, February 2008 Dissemination of information workshop 16 INTERNAL NATURAL GAS EXPLOSIONS The design pressure is the maximum of: p d = 3 + p v p d = p v +0,04/(A v /V) 2 p d = nominal equivalent static pressure [kn/m 2 ] A v = area of venting components [m 2 ] V = volume of room [m 3 ] Validity: V < 1000 m 3 ; 0,05 m -1 < A v / V < 0,15 m -1 Annex B: load duration = 0.2 s

17 Design Example: Compartment in a multi story building Brussels, February 2008 Dissemination of information workshop 17 H = 3m p d B = 8 m Compartment: 3 x 8 x 14 m Two glass walls (p v =3 kn/m 2 ) and two concrete walls

18 Brussels, February 2008 Dissemination of information workshop 18 explosion pressure: p Ed =3+ p v /2 + 0,04/(A v /V) 2 = / = 6.5 kn/m 2 self weight = 3.0 kn/m 2 live load = 2.0 kn/m 2 Design load combination (bottom floor): p da = p SW + p E + ψ 1LL p LL = *2.00 = kn/m 2

19 Dynamic increase in load carrying capacity Brussels, February 2008 Dissemination of information workshop 19 ϕ d = 1 + p p SW Rd 2 u g ( Δ t Δt = 0.2 s = load duration g = 10 m/s 2 u max = 0.20 m = midspan deflection at collapse p sw = 3,0 kn/m 2 and p Rd =7.7 kn/m 2 max ) 2 ϕ d = [ * 0.20 (0.2 ) 2 ] = 1.6 p REd = ϕ d p Rd = 1.6 * 7.7 = 12.5 kn/m 2 > 10.5 kn/m2 Conclusion: bottom floor system okay

20 Brussels, February 2008 Dissemination of information workshop 20 Be careful for upper floors and columns P sw p E edge centre column column B

21 Brussels, February 2008 Dissemination of information workshop 21 BLEVE in een overkluizing

22 Brussels, February 2008 Dissemination of information workshop 22 Y X Y Z X

23 Brussels, February 2008 Dissemination of information workshop 23 Z Y X.1E-1.9E-2.8E-2.7E-2.6E-2.5E-2.4E-2.3E-2.2E-2.1E-2 0

24 Brussels, February 2008 Dissemination of information workshop 24 Annex A: Classification of buildings Consequences class class 1 class 2, lower group class 2, upper group class 3 Example structures low rise buildings where only few people are present most buildings up to 4 stories most buildings up to 15 stories high rise building, grand stands etc.

25 Brussels, February 2008 Dissemination of information workshop 25 Annex A: What to do Class 1 Class 2, Lower Group Frames Class 2, Lower group Wall structures Class 2, Upper Group Class 3 No special considerations Horizontal ties in floors Full cellular shapes Floor to wall anchoring. Horizontal ties and effective vertical ties OR limited damage on notional removal OR special design of key elements Risk analysis and/or advanced mechanical analysis recommended

26 Brussels, February 2008 Dissemination of information workshop 26 Class 2a (lower group) s = 4 m s = 4 m interne trekbandt i L = 5 m alle liggers kunnen worden ontworpen om als trekband te dienen omtrek trekband T p interne trekband T i randkolom

27 Class 2a (lower group) Brussels, February 2008 Dissemination of information workshop 27 s = 4 m s = 4 m interne trekband 2Ø12 L = 5 m omtrek trekband 2Ø12 interne trekband 2Ø12 randkolom T i = 0.8 (g k +Ψ q k )sl = 0.8{3+0.5*3}x4x5=88 kn>75 kn FeB 500: A = 202 mm 2 or 2 Ø12mm

28 Background horizontal typings Brussels, February 2008 Dissemination of information workshop 28 total load on center column R = (g k + ψ q k ) L s = p L s s s L L T i = 0,8 s L p T i T i T i middenkolom

29 Background typing forces Brussels, February 2008 Dissemination of information workshop 29 T i = 0.75 p s L Equilibirum for δ = (s+l)/6 drukkrachten R trekkrachten verplaatsing δ δ X R X T i

30 Brussels, February 2008 Dissemination of information workshop 30 Suggestion: design corner column as a key element.

31 Brussels, February 2008 Dissemination of information workshop 31 Example structure, Class 2, Upper Group, Framed L =7.2 m, s =6 m, q k =g k =4 kn/m 2, Ψ=1.0 internal ties L perimeter tie s

32 Brussels, February 2008 Dissemination of information workshop 32 Example structure Internal horizontal tie force T i = 0.8 (g k + Ψ q k ) s L = 0.8 {4+4} (6 x 7.2) = 276 kn FeB 500: A = 550 mm 2 or 2 ø18 mm. Vertical tying force: T i = (g k + Ψ q k ) s L = {4+4} (6 x 7.2) = 350 kn FeB 500: A = 700 mm 2 or 3 ø18 mm.

33 Brussels, February 2008 Dissemination of information workshop 33 Class 2 higher class walls 1,2 m z interne trekband T i omtrek trekband T p interne trekband T i dragende wand

34 Class 2 higher class walls Brussels, February 2008 Dissemination of information workshop 34 Tyings Horizontal: T i = F t (g k + ψq k ) /7,5 z/5 kn/m > F t Periphery: T p = F t Vertical: T = 34 A / 8000 (H/t)² in N > 100 kn/m F t n s z A H t = n s kn/m < 60 kn/m = number of storeys = span = horizontal cross section of wall [mm²] = free storey height = wall thickness

35 Class 2 higher class walls Brussels, February 2008 Dissemination of information workshop 35 Design Example: L = 7,2 m, H = 2,8 m en t = 250 mm T = /8000 (2800/250)² = = ³ N = 960 kn > 720 kn maximal distance 5 m maximal distance from edge: 2.5 m Result: 2 tyings of 480 kn

36 Brussels, February 2008 Dissemination of information workshop 36 Effect of tyings in walls

37 Brussels, February 2008 Dissemination of information workshop 37 Effect of vertical tyings gaping

38 class 3: Risk analysis Brussels, February 2008 Dissemination of information workshop 38 Guidance can be found in Annex B: Definition of scope and limitations Qualitative Risk analysis hazard identification hazard scenarios description of consequences Reconsideration definition of measures of scope and assumptions Quantitative Risk Analyisis inventory of uncertainties modelling of uncertatinties probabilistic calculations quantification of consequences calculation of risks Risk management risk acceptance criteria decision on measures Presentation

39 Brussels, February 2008 Dissemination of information workshop 39 Risk Analysis Eastern Scheldt Storm Surge Barrier (1980)

40 Brussels, February 2008 Dissemination of information workshop 40 Office building Zwolle (The Netherlands) London Eye

41 Brussels, February 2008 Dissemination of information workshop 41 Points of attention in risk analysis list of hazards irregular structural shapes new construction types or materials number of potential casualties strategic role (lifelines)

42 hazards Brussels, February 2008 Dissemination of information workshop 42 Earthquake Landslide Tornado Avalanche Rock fall High groundwater Flood Volcano eruption Internal explosion External explosion Internal fire External fire Impact by vehicle etc Mining subsidence Environmental attack Vandalism Demonstrations Terrorist attack Design error Material error Construction error User error Lack of maintenance

43 Brussels, February 2008 Dissemination of information workshop 43 Step 1 Step 2 Step 3 Identifical and modelling of relevant accidental hazards Assessment of damage states to structure from different hazards Assessment of the performance of the damaged structure Assessment of the probability of occurence of different hazards with different intensities Assessment of the probability of different states of damage and corresponding consequences for given hazards Assessment of the probability of inadequate performance(s) of the damaged structure together with the corresponding consequence(s)

44 Brussels, February 2008 Dissemination of information workshop 44 Risk calculation: Step 1: identification of hazard H i Step 2: damage D j at given hazard Step 3: structural behavour S k and cpmsequences C(S k ) Risk = p( H i ) p( D j H i ) p( S k D j )C( S k ) Take sum over all hazards and damage types

45 Conclusions Brussels, February 2008 Dissemination of information workshop 45 EN : valuable document, but not a masterpiece of European harmonisation Reasons: large prior differences member state autonomy in safety matters legal status different in every country It will be interesting to see the National Annexes and NDP s.

46 Brussels, February 2008 Dissemination of information workshop 46 Relevant Background Documents ISO-documents COST actions C28 and TU0601 Background document for the ENV-version of EC1 Part 2-7 (TNO, The Netherlands, 1999) Leonardo da Vinci Project CZ/02/B/F/PP Handbooks Implementtion of Eurocodes (2005)