Fire Safety Engineering for open and closed car parks: C.A ...fire.fsv.cvut.cz/ifer/2012-Training_school/Student-presentations/... · Fire Safety Engineering for open and closed car

Giuseppe Cefarelli

D.I.ST. – Department of Structural EngineeringUniversity of Naples “Federico II”, Italy

Fire Safety Engineering for open and closed car parks: C.A.S.E. Project for L’Aquila

Training School for Young Researcher

11-14 April 2012, Sliema, Malta

Fire Safety Engineering for open and closed car parks: C.A.S.E. Project for L’Aquilaeng. Giuseppe Cefarelli, [email protected]

Introduction: Fire Safety Engineering

The “Fire Safety Engineering” (FSE) is the application of engineeringprinciples, rules and expert judgement based on a scientificassessment of the fire phenomena, the effects of fire and both thereaction and behaviour of peoples, in order to:

A branch of Fire Safety Engineering is Structural Fire Engineering.

Structural Fire Engineering deals with specific aspects of passive fire protection in terms of analysing the thermal effects of fires on buildings and designing members for adequate load bearing resistance and to control the spread of fire (C. Bailey).

- save life, protect property and preserve the environment and heritage,

- quantify the hazards and risks of fire and its effects,- evaluate analytically the optimum protective and prevention

measures necessary to limit, within prescribed levels, the consequences of fire (ISO/TR 13387-1).


FSE: Layout

Modify of the Active and Passive Fire

Protection

Design and Structural Model

Building description: Analysis of the structural characteristics

Choose of the Safety Performance Levels

Choose of the Active and Passive Fire Protection

Fire Model Fire Design Scenario

The model meets the safety levels choose?

Were tested all scenarios?

Static and fire design load calculation

Modify of the size or ty-pology of structural ele-

ments

Or

Thermal and structural analysis (for each fire design scenario)

YES

NO

END

YES

NO



Protection










ments

Or


YES

NO

END

YES

NO

Case Study: Car Parks of C.A.S.E. Project for L’Aquila

Car Park located at the ground floor

steel column

Concrete slab

Isolationdevice

The “C.A.S.E. Project for L’Aquila” was developed in L’Aquila (province of Abruzzo, Italy), after the seismic event of 06/04/2009, in response to the housing emergency. It was characterised by the construction of several seismically isolated buildings.


The structural safety during the fire exposure, in the lack of protective

coatings on steel columns, was evaluated through the application of

performance-based approach

58 m

22 m

uncertainties on the effectiveness

of coatings maintenance

Park Description: Below each isolation interface is located the parking

area for about 34 cars; Each concrete base slab, with thickness 50 cm, is

supported by steel columns (260 cm in height) withintervening seismic isolators;

The size of the plant compartment in garage amountedto 22m × 58m; in fact, the perimeter walls, when present,are offset by 50 cm beyond the vertical projection of theplate isolated;

The circular hollow steel sections have a capital at thetop, which is designed to transfer load from the isolatorunit and to allow the isolator replacement.

CLOSED CAR PARK

OPEN CAR PARK

Italian prescriptive code (D. M. 01/02/1986)

R90


Sprayedgypsum

The objective of fire safety design concerns the mechanical resistance and stability, in firesituation, of the primary structural elements in the zone below the seismically isolatedplate.


Performace levelA limited damage after the fire exposure.


Protection










ments

Or


YES

NO

END

YES

NO


The damage is quantified in terms of relative vertical displacements between the top of two adjacent columns: in order to limit the finishing damage in the superstructure, the relative vertical displacement must not exceed the limit value, chosen cautiously equals to L/200 (5.0 ‰), where L is the distance between two adjacent columns (L=6000mm).


Protection systemsNo specific protection systems (active and/or passive) are provided.


Protection










ments

Or


YES

NO

END

YES

NO



Fire design load combinationModify of the

Active and Passive Fire Protection










ments

Or


YES

NO

END

YES

NO


n

ikiikkdd QGGAF

1221

Combinations of actions for accidental design situations



Protection










ments

Or


YES

NO

END

YES

NO


Fire Scenarioqualitative description of the course of a firewith time identifying key events that characterise the fire and differentiate it from other possible fires. It typically defines the ignition and fire growth process, the fully developed stage, decay stage together with the building environment and systems that will impact on the course of the fire (EN1991-1-2)


Technical References and GuidelineCEC Agreement 7215 - PP/025: “Demonstration of Real Fire Tests in Car Parks and HighBuildings”, by CITCM (France), PROFIL-ARBED Recherches (Luxembourg) e TNO (Netherlands),closed 2001INERIS Guideline: “Parcs de stationnement en superstructure largement ventiles. Avis d’expert sur les scénarios d’incendie”, Final Report 2001 by INERIS (Institut National de l’Environnement Industriel et des Risques) and by CTICM (Centre Technique Industriel de la Construction Metallique).REPORT PARCHEGGI (REPORT ON ITALIAN CAR PARKS): “Approccio ingegneristico per la sicurezza strutturale in caso di incendio di parcheggi aerati realizzati con struttura di acciaio”, Rapporto Interno Finale del 2010. Commissione per la Sicurezza delle Costruzioni di Acciaio in caso di Incendio.

Case Study: Car Parks of C.A.S.E. Project for L’AquilaThe fire scenario is significantly affected, among other things, by:- the geometry and- ventilation conditions of the compartment. As regards the evaluation of number of vehicles involved in the fire and the timing of fire initiation by a car to adjacent one, reference is made to the information provided by following Technical References and Guideline.


Open Car ParksCEC Agreement 7215 - PP/025:

Resultslocalised fire, that is “pre-flashover” fire;

limited number of vehicles burn;fire propagation times by a car to adjacent

one is about 12 min

Calorimetric Hood tests.

The research consisted in:

Full-scale tests

INERIS Guideline

Car (category 3)

02468

101214161820

0 10 20 30 40 50 60 70 80

Tempo [min]

RHR [kW]

Time (min)

RHR [MW]

VAN

02468

101214161820

0 10 20 30 40 50 60 70 80

Tempo [min]

RHR [kW]

Time (min)

RHR [MW]

Location and number of cars involved in fire

Case Study: Fire Scenarios - Open Car Parks


Closed Car ParksCEC Agreement 7215 - PP/025:

Results“pre-flashover” fire and post-flashover“ fire;

fire propagation times by a car to adjacent oneis about 6 min

Full-scale tests

Case Study: Fire Scenarios - Closed Car Parks


Localised Fire Scenarios - Pre-flashover according to INERIS Guideline.

Propagation time 12min.

SCENARIO L1: 7 vehicles, of which 1 central VAN and 6 cars, that burn with a fire propagation time from car to adjacent one equals to 12 min from the VAN.SCENARIO L2: 4 vehicles, of which 1 central VAN and 3 cars surrounding a column, that burn with a fire propagation time from car to adjacent one equals to 12 min from the VAN.

0 m

in

12 m

in

12 m

in

24 m

in

36 m

in

24 m

in

36 m

in

0 min

12 m

in

24 m

in

12 min

Generalized Fire Scenario- Post-flashover

SCENARIO D1: 34 vehicles, of which 2 central VAN and 32 cars, that burn with a fire propagation time from car to adjacent one equals to 6 min from the VAN

Propagation time 6 min.

Case Study: Design Fire Scenarios


Hasemi’s Method[Annex C, EN1991-1-2]]

Qmp

H

ZS

ZP

0

Strato inf.

Strato sup.

mOUT,U

mOUT,LmOUT,L

mIN,L

QC

QR

mU , TU, VU, EU, U

mL , TL, VL, EL, L

p

Z

RHR curves Heat Fluxes on structural members

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Flusso termico [kW/m^2]

Tempo [min]

SCENARIO L2

SCENARIO L1

One-Zone Model[Annex D, EN1991-1-2]

Case Study: Fire models

Generalized Fire Scenario

Localised Fire Scenarios 0

200

400

600

800

1000

0 30 60 90 120 150 180

V1V2V4V3V5V6V7

Temperatura [°C] Scenario D1

Tempo [min]Time (min)

Temperature (°C)



Protection










ments

Or


YES

NO

END

YES

NO


Global Structural Analyses

Detailed 3D Structural Analyses


Global Analyses

In order to limit the analysis time without compromising the accuracy of the results, thethermo-mechanical analyses, for each fire scenario, have been conducted with thereference to a significant substructure.

SAFIR 2007(University of Liege, Belgium)

Material Finite Element Section Thickness (mm)

Columns Steel S355 BEAM Circular Hollow

Dext = 800mm 15

Slab Concrete C30/37 SHELL Solid 500

Case Study: Thermo-Mechanical Structural Analyses


Detailed 3D Analysesin order to calculate more accurately thethermal field and stresses distribution in thecapitals above the columns and to assessthe possible local buckling.

ABAQUS

Finite Element Properties of finite element

Thermal Analyses ABAQUS element DC3D4 4-node linear heat transfer tetrahedron

Mechanical Analyses ABAQUS element C3D10 10-node quadratic tetrahedron

For each fire scenario, the axial load at the top of column, corresponds to the axial load obtained by the global structural analyses.

Analyses have been conducted with reference to the more stressed and heated column



Thermal Analysis

0

200

400

600

800

1000

1200

0 300 600 900 1200Temperatura acciaio [°C]

c a[J

/kgK

]

0

10

20

30

40

50

60


a[W

/mK]

Specific heat Thermal conductivity

Localized fire Boundary conditons: Heat flux

Generalized fire Boundary conditons: Temperature vs time curve

Thermal properties of Steel (EN1993-1-2)


Steel temperature Steel temperature


Thermal expansion Strain-Stess Relationship

Boundary conditions: Thermal field obtained from Thermal Analysis

Mechanical properties of Steel (EN1993-1-2)

02468

101214161820


( L/

L)×1

03Case Study: Thermo-Mechanical Structural Analyses

Mechanical AnalysisLocalized fire

Generalized fire

Steel temperature


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 300 600 900 1200 1500Temperatura acciaio [°C]

Fatto

re d

i rid

uzio

ne

,,

aE

a

Ek

E

,,

app

ay

fk

f

,,

auu

ay

fk

f

,,

ayy

ay

fk

f

0255075

100125150175200225250275300325350375

0 0.025 0.05 0.075 0.1 0.125 0.15 0.175 0.2 0.225

20 °C100 °C200 °C300 °C400 °C500 °C600 °C700 °C800 °C900 °C1000 °C1100 °C

nom-nom

nom

[N

/mm

2 ]

nom

Strain-Stess Relationship



Thermal expansion Strain-Stess Relationship

Boundary conditions: Thermal field obtained from Thermal Analysis

Mechanical properties of Steel (EN1993-1-2)

02468

101214161820


( L/

L)×1

03Case Study: Thermo-Mechanical Structural Analyses

Mechanical AnalysisLocalized fire

Generalized fire

Steel temperature

0255075

100125150175200225250275300325350375

0 0.025 0.05 0.075 0.1 0.125 0.15 0.175 0.2 0.225

20 °C100 °C200 °C300 °C400 °C500 °C600 °C700 °C800 °C900 °C1000 °C1100 °C

nom-nom

nom

[N

/mm

2 ]

nom



Protection










ments

Or


YES

NO

END

YES

NO



Fire scenario L2 – Global AnalysisTemperatures vs time

0

100

200

300

400

500

600

700

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

BEAM 10 BEAM 20 BEAM 30 BEAM 40 BEAM 50BEAM 60 BEAM 70 BEAM 80 BEAM 90 BEAM 100BEAM 110 BEAM 120 BEAM 130 BEAM 140 BEAM 150BEAM 160 BEAM 170 BEAM 180 BEAM 190 BEAM 200

Temperature [°C]

Tempo [min]Time (min)800

1200

1600

2000

2400

2800

3200

3600

4000

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

Beam 10 Beam 20 Beam 30 Beam 40 Beam 50Beam 60 Beam 70 Beam 80 Beam 90 Beam 100Beam 110 Beam 120 Beam 130 Beam 140 Beam 150Beam 160 Beam 170 Beam 180 Beam 190 Beam 200

Sforzo Normale [kN]


Axial load (kN)

-4

-2

0

2

4

6

8

10

12

14

16

18

20

22

24

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340


Spostamento verticale [mm]


Vertical displacement (mm)

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

Sforzo Normale [kN]

Tempo [min]

Riserva di resistenza t = 20min

Tmax = 587°C

Resistenza

Sollecitazione

Axial load (kN)

Time (min)Axial load effect

Axial loadresistance

Displacements vs time

Axial loads vs time

Axial load resistance vs time

Case Study: Global Analyses Results

There is not structural collapse


Fire scenario L2 – Global analysisTemperatures vs time

0

100

200

300

400

500

600

700

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

BEAM 10 BEAM 20 BEAM 30 BEAM 40 BEAM 50BEAM 60 BEAM 70 BEAM 80 BEAM 90 BEAM 100BEAM 110 BEAM 120 BEAM 130 BEAM 140 BEAM 150BEAM 160 BEAM 170 BEAM 180 BEAM 190 BEAM 200

Temperature [°C]

Tempo [min]Time (min)800

1200

1600

2000

2400

2800

3200

3600

4000

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340


Sforzo Normale [kN]


Axial load (kN)

Axial loads vs time


The maximum temperatures reached in the columns do not exceed 600°C

Because of the thermal curvature of the slabthe axial load of these columns increase

The axial load is further amplified from the differential thermal elongation of columns, exposed to different thermal conditions, which is constrained from slab shear stiffness

The columns displacement reflects, in general, the temperatures trend.

Displacements vs time

-4

-2

0

2

4

6

8

10

12

14

16

18

20

22

24

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340






-4

-2

0

2

4

6

8

10

12

14

16

18

20

22

24

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340





Columns Displacements

The maximum differential displacement, during the fire exposure, is about 16mm (between the column 120 and column 130) and this value corresponds to 2.6 ‰ below the limit value of 5.0 ‰.



Axial load resistance vs time

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

Sforzo Normale [kN]

Tempo [min]

Riserva di resistenza t = 20min

Tmax = 587°C

Resistenza

Sollecitazione

Axial load (kN)

Time (min)Axial load effect

Axial loadresistance

The axial load resistance of the column, evaluated according to EN1993-1-2, was compared with the axial load during the fire exposure.

Reserves of resistance


The more loaded column, even when the maximum temperature is reached, still has a significant reserves of resistance.


Fire scenario L2 – Detailed analysis

Residual Plastic strain

The displacement at the top of column is very similar to those obtained in the global structural analyses. The final displacement is about 5mm in the central area of capital and about 2mm in the tube head: this is due to the plastic strain.

The 3D Thermal Analyses allowed to calculate more accurately the thermal field and stresses distribution in the capitals above the columns.

Case Study: Detailed Analyses Results


Conclusions

The FSE application to car parks is facilitated by the information about thepossible fire scenarios provided by the European Research Project CECagreement 7215-PP/025 (2001) and from INERIS (2001) guideline.

The substructure extension has allowed assessing in an appropriate way boththe thermal field and the hyperstatic effects induced by different thermalexpansions of steel columns and bending of the concrete reinforced slab.

In addition to the global analysis, for each fire scenario, in order to calculatemore accurately the thermal field and stresses distribution in the capitalsabove the columns and to assess the possible local buckling, detailed 3Dthermo-mechanical analyses have been conducted with reference to themore stressed and heated column.

The thermo-mechanical analyses in fire situations for the described case studyshowed that the structures, and in particular the steel columns, consideredunprotected, satisfy the performance level set to the design fire scenarios, alsothanks to an overstrength in normal condition design.


Future developments

The fire development and its effects on the structure will be evaluated bysoftware FDS in order to take into account the distribution of heat flux bothalong and around the columns.

How to link CFD fire model and structural model?

Through Adiabatic Surface Temperature?

Which value of coefficient of heat transfer byconvection should be assumed?

Which value of emissivity should be assumed?

Questions

Thank you for your attention

Thanks to:Prof. E. Nigro

Prof. E. CosenzaProf. G. Manfredi

Eng. A. Ferraro

Documents

Fire Safety Engineering for open and closed car parks: C.A ...fire.fsv.cvut.cz/ifer/2012-Training_school/Student-presentations/... · Fire Safety Engineering for open and closed car