under localized fire Authors: R. Zanon ArcelorMittal R&D, O. - - PowerPoint PPT Presentation

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under localized fire Authors: R. Zanon ArcelorMittal R&D, O. - - PowerPoint PPT Presentation

Oct 23, 2022 161 likes •537 views

Analysis of steel-framed open car parks under localized fire Authors: R. Zanon ArcelorMittal R&D, O. Vassart Luxembourg L.-G. Cajot M. Sommavilla R. Zandonini University of Trento, F. Gadotti Italy 16 September 2010, Naples Open

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Analysis of steel-framed open car parks under localized fire

16 September 2010, Naples

Authors:

  • R. Zanon

ArcelorMittal R&D,

  • O. Vassart

Luxembourg

L.-G. Cajot

  • M. Sommavilla
  • R. Zandonini

University of Trento,

  • F. Gadotti

Italy

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1 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Dorneind, Helmond (NL) Wölfsburg (DE) Arnhem (NL) Amershan (UK) Erfurt (DE)

Open Steel – framed Car Parks in Europe

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2 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Architectural layout of Open Car Parks

~16 m

To allow a better functionality of the building it is advised to avoid columns between the parking lots. This increases greatly the dynamic capacity of the car park. Such a layout requires rather considerable spans (about 16 m), which are most suited for steel–framed structures. Open = natural ventilation through permanent

  • penings in the facades
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3 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Common structural solutions

  • Steel beam + traditional composite slab

(shallow steel decking, slab span 2.5 ... 3.3 m)

Parking Centre Hospedalier, GD-Luxembourg

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4 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Common structural solutions

  • Steel beam + traditional composite slab

(shallow steel decking, slab span 2.5 ... 3.3 m)

  • Steel beam + innovative composite slab

(deep steel decking, slab span 5.0 m)

Parking Bouillon, GD-Luxembourg

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5 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Common structural solutions

  • Steel beam + traditional composite slab

(shallow steel decking, slab span 2.5 ... 3.3 m)

  • Steel beam + innovative composite slab

(deep steel decking, slab span 5.0 m)

  • Steel beam + concrete slab

(in-situ or precast concrete units, slab span 2.5 ... 5.0 m)

Parking Auchan Kirchberg, GD-Luxembourg

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6 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Common structural solutions

  • Steel beam + traditional composite slab

(shallow steel decking, slab span 2.5 ... 3.3 m)

  • Steel beam + innovative composite slab

(deep steel decking, slab span 5.0 m)

  • Steel beam + concrete slab

(in-situ or precast concrete units, slab span 2.5 ... 5.0 m)

  • Integrated floor beam solutions (Slim Floor)

(Hollowcore slabs up to 16.0 m span)

Parking City Esch, GD-Luxembourg

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7 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Fire Resistance requirement in Open Car Parks

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8 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Single element Whole structure Nominal fire

Prescriptive approach

Natural fire

Performance based approach

Structural Fire design approaches

Actions Resistance

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10 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Steps of the performance–based approach

1 - Definition of fire actions according to the combustion of vehicles

simplified model from experimental tests

2 - Definition of fire scenarios with flame development and propagation

simplified model from experimental tests

3 - Thermal Analysis with localised fire model

analytical model based on experimental results

4 - Mechanical Analysis of the structure

numerical model validated by experimental results

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11 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 1. Test on cars to determine the RHR - curve

0 min. 5 min. 16 min. 34 min. 37 min. 49 min.

In the scope of various national and european projects, a total of 20 cars were burnt at CTICM laboratory in Maizieres-les-Metz in

  • rder to assess the combustion

process of standard vehicles. The cars were ignited with 1.5 litres of petrol in an open tray under the gear lever. All doors and windows were closed. A hood was built to collect smokes, combustion products and pollutants emitted during the fire. At the same time, the car was placed on a weighting platform that recorded the mass loss during the test.

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12 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Experimental RHR curves Design RHR curves

  • 1. Results of the tests on single vehicles
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13 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 2. Full scale test in Open Car Park

8 min. 15 min. 30 min. 36 min.

In a recent European project a real steel-framed car park was built in Vernon (France) in the scope to validate experimentally natural fire scenarios to be applied and to determinate the way to calculate the heat flux which the structure is submitted. Three big full scale tests involving several cars were run. No structural damage could be observed, and the deflection occurred during the fire could be fully recovered after cooling. From this experience the fire scenarios of several cars was confirmed. A propagation time of 12 minutes between a burning car and the ignition of the adjacent one was found to be a reasonable conservative hypothesis for fire modeling.

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14 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 2. Fire propagation to many vehicles

RHR Cars RHR of Special vehicles

12 min.

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15 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 2. Practical design: First fire scenario

1 vehicle burning below beam mid-span

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16 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 2. Practical design: Second fire scenario

4 vehicles burning around a central column

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17 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 2. Practical design: Third fire scenario

Burning wave: 7 vehicles burning along the border

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18 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 3. Thermal analysis

Currently two models are available in the EN1991-1-2 Annex C to describe the effects of localised fire to the structure: In the case of open Car Parks, the experimental campaign has been used to validate the Hasemi model as design tool able to reproduce with sufficient safety margin the temperature field in the structure caused by burning cars.

D 3.91m c 35 W m2 K m 0.7 f 1

Heskestad model for fire not impacting the ceiling Hasemi model for fire impacting the ceiling

Parameters for the thermal analysis Fire diameter: Convection factor: Steel emissivity factor: Fire emissivity factor: Stephan-Boltzmannconstant:

D 3.91m c 35 W m2 K m 0.7 f 1 5.6710 8 W m2 K4

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19 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 4. Mechanical analysis – FEM model

Columns Beams Ribs Slab

Restraints Cold part of the structure Heated part of the structure

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20 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Validation of the numerical model on tests

The comparison between experiments and numerical simulations has been showed the need to use 3D models to describe properly the structural behaviour under fire exposure. Such models are able to reproduce in reliable way the complex load-paths (in particular the membrane action) which developes under severe fire conditions and which allows for the structural stability.

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21 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Calculation example – First fire scenario

5.0m 16.0m 16.0m 5.0m 5.0m 5.0m IPE400 S355 IPE400 S355 IPE400 S355 IPE400 S355 IPE400 S355 IPE400 S355 Load:

  • 2.2 kN/m2 selfweight
  • 1.0 kN/m2 permanent loading
  • 2.5 kN/m2 variable loading

Slab:

  • composite slab, total thickness 120 mm, C30/37
  • open trapezoidal steel sheeting rib height 60 mm, S280GD
  • reinforcing mesh Q257, B500C

HEB200 S355 2 levels car park

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22 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 1. Cold

situation

  • 2. Heating

phase

  • 3. Temperature peak
  • 4. Cooling phase
  • 1. Slab in

compression

  • 2. Slab in tension

In central part

  • 3. Slab in tension with

compression ring

  • 4. Slab in compression in

cooling phase

Calculation example – Third fire scenario

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23 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Calculation example – Second fire scenario

5.0m 16.0m 16.0m 5.0m 5.0m 5.0m IPE400 S355 IPE400 S355 IPE400 S355 IPE400 S355 IPE400 S355 IPE400 S355 Load:

  • 2.2 kN/m2 selfweight
  • 1.0 kN/m2 permanent loading
  • 2.5 kN/m2 variable loading

Slab:

  • composite slab, total thickness 120 mm, C30/37
  • open trapezoidal steel sheeting rib height 60 mm, S280GD
  • reinforcing mesh Q257, B500C

0 min 12 min 12 min HEB200 S355 2 levels car park

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24 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Calculation example – Second fire scenario

3° phase: collapse, the displacement grows indefinitely 2° phase: column buckles and the slab displaces downwards 1° phase: due to thermal expansion of the column, the slab displaces upwards

1° phase 2° phase 3° phase

Column buckling about weak axis

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25 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

  • 0.3
  • 0.25
  • 0.2
  • 0.15
  • 0.1
  • 0.05

0.05 600 1200 1800 2400 3000 3600 Time of fire [s] Vertical displacement [m]

Post-critical behaviour Buckling of the column Pre-critical behaviour

Robustness – postcritical reserves

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26 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

General results for fire design

In comparison to the design of the Car Park in cold situation, the following general results can be stated for common steel-concrete composite structures: 1 – Composite Beams may be left unprotected (provided full shear connection in cold situation) 2 – Steel Columns may be left unprotected if overdesigned (otherwise they can be protected or traditional fire-resistant solutions) 3 – Composite Slabs need to be executed as continuous (design according to prescriptive rules in EC4 for the cold condition is sufficient) 4 – Connections may be left unprotected if properly designed (traditional simple joint solutions with correct ductile details are suitable)

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27 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Detail: expansion joint

e.g. Solution: overdesign

  • f the primary beam in

correspondance of the expansion joint

Expansion joint

In large car parks expansion joints have to be provided in a distance of about 100m. For the fire analysis they are structural weak points because of the discontinuity of the slab.

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32 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Additional costs of fire design measures [%]

  • 16.5%
  • 16.4%
  • 9.3%
  • 7.9%
  • 9.6%

With the performance based approach is possible to demonstrate that most the fire protection is usually not needed in well-designed open car parks. This result leads to a sensible cost reduction in the building erection in the range of 10 – 20%.

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33 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Thank You for Your kind attention

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35 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Centinatura

Workshop beam finishing

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36 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Different solutions for exposed columns

HEM profiles without any protection HEB profiles with external hollow section HEA profiles with partial concrete encasement

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37 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Temperature for most exposed column (1st scenario)

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38 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Partially encased profiles

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39 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Close Car Park: Commercial Centre Auchan

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40 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

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41 Analysis of steel-framed open car parks under localized fire Naples - 16 September 2010

Thank You for Your kind attention!