GRENFELL FIRE RECONSTRUCTION FIRST LESSONS · 2:34:00 North facade Barbara Lane report vol 5. Figure 5.19. –North facade EXAMPLE: NORTH FACADE. ... Numerical study in 4 steps increasing

www.efectis.com 2019

GRENFELL FIRE RECONSTRUCTION

FIRST LESSONS

By Dr. Eric GUILLAUME, General Manager, Efectis France

../../Présentation-ppt/ANIMATIONS/STRUCTURE/Comportement au feu des structures - Parking.mpg

2019www.efectis.com 2February 8th

WARNING PRECAUTION

❑ This reconstruction only uses public data available on Grenfell reports or

published in the scientific litterature

❑ The work has been partially financed by Kingspan

❑ Efectis work condition was a total independence from the results and from

the different players

❑ Results have been reviewed by several international independant experts

❑ All the work will be submitted in peer-reviewed journals in upcoming weeks


PROCEDURE FOR FIRE RECONSTRUCTION

❑ Analysis of Grenfell fire observations

▪ Data collection -> construction of a 3D model of the fire

▪ Vertical and horizontal spread calculations

▪ Hypotheses

❑ Reconstruction

▪ Intermediate scale tests -> Definition of numercial model

▪ DCLG BS8414 tests -> Validation of numerical parameters of the model

▪ Local modelling:

✓ Initial apartment

✓ Singularities: windows, cavity barriers, aluminium profiles, etc

▪ Global modelling. Example of East facade

❑ Test of different hypotheses

▪ Cavity barrier effects

▪ ACM-PE substitution

▪ PIR substitution

❑ Further steps udergoing

▪ Interactions between facade and apartments

▪ Smoke spread internally to the tower


1) ANALYSIS OF GRENFELL FIRE OBSERVATIONS


www.efectis.com 5February 8th 2019

PROCEDURE


2:34:00 North facade

Barbara Lane report vol 5.Figure 5.19. – North facade

EXAMPLE: NORTH FACADE


EAST FACADE – INITIAL VERTICAL SPREAD


1:08:06

EAST FACADE


1:14:53

EAST FACADE


1:15:37

EAST FACADE


1:16:00

EAST FACADE


1:21:37

EAST FACADE


1:22:22

EAST FACADE


1:23:09

EAST FACADE


1:23:36

EAST FACADE


1:24:06

EAST FACADE


1:25:36

EAST FACADE


1:26:37

EAST FACADE


1:29:00

EAST FACADE


HORIZONTAL PROPAGATION



East

1:29:00

North WestSouth

1:29:00



East

1:36:00

North WestSouth

1:36:00



2:10:00

East North

2:23:00

WestSouth



West


East NorthSouth

2:48:00 2:48:00 2:34:00


East NorthSouth

3:11:00 3:11:00

West

3:08:003:11:00



East NorthSouth West

ENDEND 3:20:003:20:00




ENDEND 3:33:003:33:00




ENDEND 3:48:003:48:00




ENDEND 3:53:00END




ENDENDEND 4:09:00




ENDENDEND END

Limit of firefighting

Limit of firefighting



ANALYSIS OF DATA

Vertical propagation on East facade



y = 3E-11x4.0265

R² = 0.9953

y = 0.0596x - 22.971R² = 0.9999

0

5

10

15

20

25

30

35

40

45

50

0 200 400 600 800 1000 1200

Ver

tica

l dis

tan

ce (

m)

Time (s)

Fire spread above flat 16

1:14:53

1:15:37

1:16:00

Phase 1a: vertical propagation above flat 16

Linear spread, supposed to be driven by convection fromplume going out of kitchen fire from appartment 16

VERTICAL PROPAGATION ON EAST FACADE


y = 3E-11x4.0265

R² = 0.9953

y = 0.0596x - 22.971R² = 0.9999

0

5

10

15

20

25

30

35

40

45

50

0 200 400 600 800 1000 1200

Ver

tica

l dis

tan

ce (

m)

Time (s)


Decrease in flame spread rate

Phase 1b: unknown, lack of data from 1:16:00 to 1:21:37



y = 3E-11x4.0265

R² = 0.9953

y = 0.0596x - 22.971R² = 0.9999

0

5

10

15

20

25

30

35

40

45

50

0 200 400 600 800 1000 1200

Ver

tica

l dis

tan

ce (

m)

Time (s)


Phase 2: acceleration of vertical spread

Best regression power 4, supposed to be radiation driven

1:21:37

1:22:22

1:23:09

1:24:06 1:25:36

1:26:37

1:29:00




❑ Observations:

▪ Two phases:

▪ Phase 1: first linear spread from floor 4 to floor 6

▪ Phase 2: rapid growth (power 4) from floor 10 to crown

▪ Lack of data between floor 6 and 10, seems to have a speed down in

propagation

❑ Conclusions – hypotheses

▪ First phase driven by convection from external flame of flat 16, with

contribution of the cladding

▪ Delay phase induced by the time to flashover of flats 26 and 36

▪ Rapid spread after, driven by radiation from the facade flame


ANALYSIS OF DATA

Horizontal propagation at crown



0

10

20

30

40

50

60

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0

Ho

rizo

nta

l fla

me

spre

ad d

ista

nce

(m

)

Time in min (from 1:29:00 when crown is reached)

Horizontal fire spread at crown level

clockwise anticlockwise

N

E

S

W

HORIZONTAL PROPAGATION AT CROWN


HORIZONTAL PROPAGATION AT CROWN

❑ Observations:

▪ Very linear trend

▪ No influence of the direction of spread (clockwise or anti-clockwise)

▪ No step effects (columns, windows, edges not visible)

▪ Horizontal rate: (0,293 ± 0,005) m/min at crown

❑ Conclusions – hypotheses

▪ No influence of external wind

▪ No influence of columns / corners on spread

▪ Linear, driven by conduction on cladding


0

5

10

15

20

25

30

35

40

45

50

0 20 40 60 80 100 120 140 160 180

Ho

rizo

nta

l fla

me

spre

ad (

m)

Time (min)

Horizontal flame spread

Fl 4Fl 10Fl 13Fl 15Fl 18Fl 20Fl 22CrownLinear (Fl 4)Linear (Fl 10)Linear (Fl 13)Linear (Fl 15)Linear (Fl 18)Linear (Fl 20)Linear (Fl 22)Linear (Crown)

HORIZONTAL PROPAGATION AT CROWN FROM SELECTED STOREYS


HORIZONTAL SPREAD RATE VS. HEIGHT

❑ V-shape induced by a reduction

in horizontal rate

❑ Downward propagation

❑ For the first 5 floors plus

crown, excellent linear trend.

Propagation rate decreases

vertically in a regular manner

for the top levels

y = 404.24x - 52.044R² = 0.9998

25

30

35

40

45

50

55

60

65

70

0.1500.1600.1700.1800.1900.2000.2100.2200.2300.2400.2500.2600.2700.2800.2900.3000.310

Hei

ght

(m)

Horizontal propagation speed (m/min)

Horizontal propagation rate vs. height


2) RECONSTRUCTION



OBJECTIVES

❑ To conduct a simulation of the Grenfell Tower fire ▪ For determining the condition of propagation of the toxicity from the façade within the

building

▪ In comparison with the toxicity produced by apartment contents

❑ Numerical study in 4 steps increasing in complexity▪ Step 1

✓ Model validation with a simple façade model

✓ Similar to the one tested according to ISO 13785-1 (ACM PE+PIR test)

✓ Validation based on comparison of experimental and numerical results

▪ Step 2

✓ Global model of a bigger façade element with dimensions of order 8 m x 8 m, or close to BS standard test configuration

▪ Step 3

✓ Global façade fire modelling of the Grenfell tower

✓ To determine behavior at window frames

✓ Including validation according to observations (videos and pictures from the real fire)

▪ Step 4

✓ Impact model, including propagation of fire on the apartments, to assess tenability condition in terms of toxicity in the apartments according to ISO 13571 (2012 and 2018).


METHODOLOGY


EXAMPLE: STEP 1 –

RESULTS FOR THE FLAME PROPAGATION – [ACM-PE + PIR]

RESULTS FOR FLAME PROPAGATION

2m

in

1

min

4 m

in

3

min

RESULTS FOR FLAME PROPAGATION6

min

5 m

in

8 m

in

7

min

RESULTS FOR FLAME PROPAGATION

10

min

9 m

in


RESULTS – HEAT RELEASE RATE

❑ Without burner contribution (100 kW)

❑ Maximum value :

▪ 5 MW during test (10% uncertainty)

▪ 5.3 MW in simulation (17% uncertainty)

❑ Global HRR

▪ The numerical model doesn’t reproduce the small contribution at early time

▪ It predicts longer contribution after the mean peak

▪ Globally within experimental uncertainty

Method Relative difference cosine

Euclidian 10.86% 0.982

Hellinger 5.94% 0.946

Secant 4.65% 0.979

Hybrid 8.33% 0.980

Following ISO 16730-1:2015

method for validation of

calculation:


RESULTS – HEAT FLUX

❑ Uncertainty

▪ 7% during test

▪ 15% in simulation

❑ Experimental results with moving average over 30 seconds

❑ The numerical model is able to reproduce the main experimental phenomenon

▪ Maximum values, global kinetics

Method Relative difference cosine

Euclidian 17.97% 0.918

Hellinger 1.56% 0.660

Secant 3.38% 0.906

Hybrid 11.02% 0.908

Following ISO 16730-1:2015

method for validation of

calculation:


EXAMPLE: STEP 2 –

RESULTS FOR BS 8414-1 DCLG TESTS MODELLING – [ACM-PE + PIR]


RESULTS LEVEL L1 – EXTERNAL BACK WALL

❑ The numerical model is able to reproduce the main experimental phenomenon

▪ Maximum values, global kinetics

▪ Difference due to TC location in air during the fire and particular location (near the junction)

▪ After crib extinguishment during the test: inflammation is missed

▪ Experimental results with moving average over 30 secondsWood crib extinguishment at 395 s


RESULTS – FLAME PROPAGATION

❑ Visualisation at 120 s and every 60s


RESULTS – VIEW OF THE CLADDING COMBUSTION

❑ At wood extinguishment (400 s in simulation)

T [°C]


RESULTS – VIEW OF THE INSULANT COMBUSTION AT BACK WALL

❑ At wood extinguishment (400 s in simulation)T [°C]


RESULTS – VIEW OF THE INSULANT COMBUSTION AT SIDE WALL

❑ At wood extinguishment (400 s in simulation)

T [°C]


IGNITION AND INITIAL FIRE


IMPLEMENTATION OF THE INITIAL FIRE APARTMENT

❑ FDS implementation of the apartment:

▪ Flat 16

▪ 4th floor

▪ East façade


IMPLEMENTATION OF THE APARTMENT

❑ Eastern facade

▪ With insulation and cavity barrier

▪ With external cladding


IMPLEMENTATION OF THE APARTMENT

❑ Northern facade

▪ With insulation and cavity barrier

▪ With external cladding


FIRE DEVELOPMENT IN THE INITIAL APARTMENT

❑ 3 scenarios are investigated:

▪ Scenario 1 a:

✓ Ignition of the mini-fridge with restricted ventilation conditions

✓ To investigate the effects of closed doors in the kitchen (evaluation from

Prof. Torero hypothesis)

▪ Scenario 1 b:

✓ Ignition of the mini-fridge with large ventilation conditions

▪ Scenario 2:

✓ Ignition of the fridge/freezer with large ventilation conditions

✓ To investigate the effects of the fire source location.


SCENARIO EXAMPLE: FIRE DEVELOPMENT IN THE INITIAL APARTMENT

❑ Wall temperature inside the apartment @ 7 min (01h01) and 12 min (01h06)

❑ On window frame : up to 300°C and locally 660°C (top)

▪ Critical temperature for PVC ignition

▪ Critical temperature for aluminium structure

7 min(01h01)

12 min(01h06)


SYNTHESIS FOR THE FIRE SOURCE IN THE INITIAL APARTMENT

❑ For the 3 fire scenarios investigated for the in initial fire development in the kitchen,

whatever the fire location (left or right part of the kitchen, scenario 1B and 2) and the

ventilation condition (scenario 1A and 1B), same conclusion are observed:

▪ Even if the fire source is less than 300 kW, it is enough to ignite the adjacent PVC window

surround early,

▪ The fire propagation leads to the ignition of the fan unit mounting panel and to the appearance

of external flames quickly,

▪ When surroundings elements ignite, the window frame fails in few minutes,

▪ The flash over in the kitchen is not reached in any scenario

✓ But it is not necessary to trigger the external fire

▪ Even if the fire starts being extinguished inside the apartment at 01h20’, the propagation to

the façade has begun

❑ For the 3 scenario investigated, we observe the correlation between the observation

during the real sinister and the numerical prediction

❑ Thus, the global HRR evaluated in this section can be used to investigate the fire

spread to the whole external façade and to the upper apartment


VALIDATION OF SINGLE POINTS EFFECTS


PROPAGATION OF THE FIRE FROM THE FAÇADE TO AN APARTMENT

❑ Evaluation of the windows failure

▪ Fire is coming by the exterior through windows and by the kitchen

▪ Model of the window frame with FEM code (ANSYS)

▪ Evaluation of the thermal loads (temperatures and heat fluxes) on the frame (aluminium and polyamid

bridges)

▪ Boudary conditions from fire simulation (external fire at kitchen)

▪ Thermal analysis in the window frame


Part 7 – temperature at 300s Part 7 – temperature at 600s

Part 8 – temperature at 300s Part 8 – temperature at 600s


❑ External fire sollicitation

▪ Example: Flat 26

outsideinside



❑ Thermomecanical analysis of windows failure

❑ Closed window

▪ Strong deformation of the frame between 3 and 5 minutes of exposure

▪ The window is expected to be partially ruined during this time

Deformation at 316 s: failure of the outer exposed part

Deformation at 750 s: failure of the inner part (fails inside the apartment)



❑ Thermomecanical analysis of windows failure

❑ Tilted window



Deformation at 316 s: failure of the outer exposed part

Deformation at 650 s: failure of the inner part (fails inside the apartment)



❑ Synthesis of the thermomecanical analysis of windows failure



Fire position

Internal fire (Flat 16) External fire

Win

do

w

po

siti

on Closed

Partial ruin: 300 sTotal ruin: 500 s

Partial ruin: 300 sTotal ruin: 750 s

Tilted Not evaluatedPartial ruin: 300 sTotal ruin: 650 s


PROPAGATION OF THE FIRE TO THE FAÇADE

❑ Model of partial façade

▪ Including window infill

✓ Polystyren with 200° temperature ignition

▪ Including gaps filled with insulant beyond PVC

▪ At window frame close to the colomn

✓ Allow ignition of PVC locally

✓ Allow gases to pass from façade to colomn interior PVC between window frame and columnPVC between

window frame and column




▪ Continuity of the aluminium cladding rail along the columns (center and near the window)

Prof. Bisby’s report p45

Prof. Bisby’s report p42




▪ Aluminium cladding rail under window frame

Prof. Bisby’s report p44 and p47


VERTICAL SPREAD MODELLING


PROPAGATION OF THE FIRE TO THE FULL EAST FAÇADE

❑ Full high East façade above 4th floor

▪ Part of the North façade (living)

▪ No local cuts of the cavity barriers

accounted (negligible effects on fire

propagation, mainly driven by the cladding

combustion and the cladding removed)

❑ Implementation of fire contribution from

higher apartments

▪ Kitchen and living

Flat 16 – 4th floorEast façade



❑ Vertical propagation above 4th floor

▪ Fire propagation consistent with observations

1h08’06’’ 1h14’53’’ 1h15’37’’

Observation Model Observation Model Observation Model





1h16’ 1h21’37’’ 1h22’22’’






▪ Differences in horizontal propagation for floors 4 to 8 due to firefighter intervention not simulated

1h23’09’’ 1h23’36’’ 1h24’06’’






▪ Differences in horizontal propagation for floors 4 to 8 due to firefighter intervention not simulated (blue

area)

1h25’36’’ 1h26’37’’ 1h29’





▪ Lack of information between 1h16’ and 1h21’37’’

▪ Details of the propagation

1h16’ 1h17’ 1h18’ 1h19’ 1h20’ 1h21’37’’

Observation Model Observation ModelModel Model Model Model



❑ Horizontal propagation – numerical prediction

1h29’ 1h31’ 1h32’ Grenfell Tower Inquiry – Luke Bisby – Phase 1 expert Report.Figure 93. Page 145.

1h29’


Observation Model

1h36’East North


❑ Horizontal propagation





Model

1h36’View without the burning rate of the

façade: the flame missed at the centre of the façade and are close to the columns




Observation

1h56’

IN PROGRESS

1h40’View without the burning rate of the

façade: the flame missed at the centre of the façade and are close to the columns

Model

Upper level of the tower: global behaviour in agreement with observation, fire development correctly represented

Mid-tower: horizontal propagation enhanced by the non-simulation of the firefighter’s action

Need to modify the model to correctly represent the fire development at the mid-tower level


PROPAGATION OF THE FIRE TO THE FULL NORTH FAÇADE

❑ Horizontal propagation to North façade

Observation Model Model

1h29’ 1h32’ 1h36’



❑ Horizontal propagation from East to North façade

Observation Model

1h29’

1h36’North




❑ Horizontal propagation from East to North façade

Observation Model

2h10’ 1h40’ North1h36’ North


Model Observation



❑ VERTICAL propagation

▪ Black points: from observation

▪ Coloured points: from simulation

▪ 1st phase: linear propagation

▪ 2nd phase: decrease of the propagation velocity – linear propagation

▪ 3rd phase: fast propagation (~ power ^4)

▪ 4th phase: decrease when the top is reached


PROPAGATION OF THE FIRE TO THE FULL FAÇADE

❑ HORIZONTAL propagation at crown

▪ Annoted « NUM »: from simulation

▪ Linear propagation – average: 0.2896 m/min

✓ For clockwise 0.2885 m/min

✓ For anticlockwise 0.2907 m/min



❑ External flames spread rates for past events

▪ From J. Torero’s expert report

From simulation during phase 1





❑ Analysis of windows failure from simulation

▪ Kitchen and living room

▪ East façade above flat 16 (floor 4)

▪ Timescale : 01h14’53’’ = flame out of flat 16 (window failure in the kitchen)

❑ Observation▪ Failure of kitchen windows first (from 1h08 to 1h23)

▪ Failure of the living window begins after and propagates slower (from 1h23 to 1h26)

▪ Then failure of windows from kitchen and living appear at same time (1h26 to 1h29)

▪ Consistent with observations in J. Torero’s report:

✓ Internal fires ignited at 5,12 and 22th floors at 01h18, 01h25 and 01h28 respectively


3) TEST OF DIFFERENT HYPOTHESES



WHAT IF: MINERAL WOOL INSTEAD OF PIR AS INSULANT ?




▪ Same numerical times as for PIR insulant

1h08’06’’ – t0 1h14’53’’ 1h15’37’’






1h16’ 1h21’37’’ 1h22’22’’






1h23’09’’ 1h23’36’’ 1h24’06’’






1h25’36’’ 1h26’37’’ 1h29’

IN PROGRESS

Observation Model Observation Model Observation



❑ Green circles: from PIR simulation

❑ Coloured points: from MW simulation

❑ 1st phase: linear propagation – slower than for PIR

❑ 2nd phase: increase of the propagation velocity – linear propagation – faster than for PIR

❑ 3rd phase: fast propagation (~ power ^4) – faster than for PIR


WHAT IF: ACM A2 INSTEAD OF ACM PE?



❑ Vertical and horizontal propagation above 4th floor

▪ No fire propagation observed

1h08’06’’ – t0 1h29’

Observation Model Observation Model


WHAT IF: NO CAVITY BARRIERS?




▪ Same numerical times as for the initial model

▪ Vertical fire propagation faster without cavity barriers

1h08’06’’ – t0 1h14’53’’ 1h15’37’’

Observation Initial Model No barrier Observation Initial Model No barrierObservation Initial Model No barrier




▪ Vertical fire propagation faster without cavity barriers

1h16’ 1h21’37’’ 1h22’22’’

Observation Initial Model No barrier Observation Initial Model No barrier Observation Initial Model No barrier




▪ Vertical and horizontal fire propagation faster without barriers

1h23’09’’ 1h23’36’’ 1h24’06’’





▪ Vertical and horizontal fire propagation faster without barriers

▪ Fire propagation to the columns without barriers

1h25’36’’ 1h26’37’’ 1h29’




❑ Green circles: from initial simulation

❑ Coloured points: from simulation without cavity barrier

❑ 1st phase: linear propagation – slower than for initial

❑ 2nd phase: increase of the propagation velocity – linear propagation – faster than for initial

❑ 3rd phase: increase of the propagation velocity – linear propagation – faster than for initial

Initial

No cavity barrier



❑ External flames spread rates for past events

▪ From J. Torero’s expert report

▪ [A1], [A2] and [A3]: from simulation with cavity barrier during phase 1, 2 and 3

From simulation without cavity barrier during phase 1



[A2][A1]

[A3]


WHAT IF: JUST PIR, AS AT WORK?




▪ Same numerical times as for the initial model

1h08’06’’ – t0 1h14’53’’ 1h15’37’’





▪ Fire propagation restricted to the insulant between the initial 4th floor and the 5th floor just

above

1h16’ 1h21’37’’ 1h22’22’’





▪ Fire propagation restricted to the insulant between the initial 4th floor and the 5th floor just above

▪ Extinction after 1h24

1h23’09’’ 1h23’36’’

Observation Model Observation Model

1h24’06’’

Observation Model


4) FURTHER STEPS



EVALUATION OF FLOW THROUGH WINDOWS – FLAT 26, 5TH FLOOR

❑ Flat 26, 5th floor, East façade, just above the initial fire

❑ Total window breakage: ▪ After 01h18 in the kitchen (window n°3)

▪ After 01h22 in the living (window n°2)

▪ Coherent with expert reports (1h18)

❑ In the kitchen (window n°3):

▪ Global flow through the window mainly comes from the apartment to the exterior

✓ Especially when the fire ignites in the kitchen

▪ Air entrainment from the vertical façade fire

✓ Plume located mainly between the column and the kitchens

❑ In the living room (windows n°1 and n°2)▪ Global flow through the window mainly comes from the exterior to the apartment (window n°2)

✓ Air entrainment from the kitchen before the window n°2 failure

▪ No breakage of the window n°1

Window: n°3 n°2 n°1


EVALUATION OF FLOW THROUGH WINDOWS – FLAT 26, 5TH FLOOR

n°3 n°2

Flat 26living

Flow comes from the apartment Flow comes from the exterior

Flat 26kitchen

Before kitchen fire After kitchen fire


KITCHEN OF FLAT 26, 5TH FLOOR, EAST FAÇADE

❑ Species concentration in the kitchen of flat 26

▪ Z = 1.5 m high, centre of the kitchen

▪ Under-ventilation in the kitchen after 1h25 (7 min after window failure)


KITCHEN OF FLAT 26, 5TH FLOOR, EAST FAÇADE – EXAMPLE CASE 1

❑ Species concentration in the kitchen of flat 26

▪ Z = 1.5 m high, centre of the kitchen

▪ Case 1: maximum under-ventilation factor for the apartment furniture and the insulant

▪ Total value and detail of release for each burning material involved

✓ CO: mainly from apartment furniture, PIR and TB10

✓ HCN: mainly from PIR (façade insulant)

CASE SPECIES Apartment furniture Insulant

1

Under-ventilated MAX Under-ventilated MAX

CO 13.8 9.2

HCN 2.5 2.5


KITCHEN OF FLAT 26, 5TH FLOOR, EAST FAÇADE – EXAMPLE CASE 1

❑ ISO 13571 FED and FEC evaluation in the kitchen of flat 26 – case 1

▪ Two revisions of the ISO 13571 Standard addressed to evaluate their difference on the model impact results

assessed

✓ 2012 and 2018

▪ Main contribution of apartment furniture

▪ FED = 1

✓ 01h34 for revision 2012

✓ 01h30 for revision 2018

Following revision 2012 Following revision 2018

TO BE CONTINUED…


THANKS FOR ATTENTION


Documents

GRENFELL FIRE RECONSTRUCTION FIRST LESSONS · 2:34:00 North facade Barbara Lane report vol 5. Figure 5.19. –North facade EXAMPLE: NORTH FACADE. ... Numerical study in 4 steps increasing