1 Introduction
-
PL1 if the temperature is lower than 300°C at 60 min.
-
PL2 if the temperature is lower than 300°C at 45 min and higher than 300°C at 60 min.
-
PL3 if the temperature is higher than 300°C at 45 min.
2 Methods
2.1 Experimental Method
2.1.1 Test Specimens
Name used in the report | Hunton I-joist | Masonite I-joist |
---|---|---|
Produced by | Steico | Masonite beams |
Flange | Laminated veneer lumber—3 mm layer thickness | Solid wood, spruce or pine |
Web | 8 mm hard fibreboards | 10 mm particleboards |
Flange heighta | 39 mm | 47 mm |
Flange width—Small | 45 mm | 47 mm |
Flange width—Medium | 60 mm | 70 mm |
Flange width—Large | 90 mm | 97 mm |
Insulation product name | Type | Density | R-valuea for 200 mm thickness | Material information |
---|---|---|---|---|
CBI isocell evolution | Cellulose fibre, Loose-fill–blown in | ~ 57 kg/m3 | 5.41 m2K/W | 92% mass weight of unused newspapers, 8% mineral salts without Boron |
Hunton Nativo® Wood Fibre | Wood fibre, Loose-fill–manually packed | ~ 40 kg/m3 | 5.26 m2K/W | Natural wood fibre from spruce with addition of the fire-retardant ammonium phosphate |
Hunton Nativo® Wood Fibre | Wood fibre Batt | ~ 51 kg/m3 | 5.26 m2K/W | Natural wood fibre from spruce with addition of the fire-retardant ammonium phosphate |
Kingspan Kooltherm K12 | Thermoset phenolic Batt | ~ 36 kg/m3 | 9.52 m2K/W | Thermoset phenolic foam insulation |
TEST ID | Test no | I-joist | Flange width | Insulation |
---|---|---|---|---|
T1MaSKb | 1 | Masonite (Ma) | S47 mm | Kingspan Kooltherm phenolic foam batt (Kb) |
T1MaMKb | M70 mm | |||
T1MaLKb | L97 mm | |||
T1MaSHb | S47 mm | Hunton Nativo® Wood Fibre Insulation batt (Hb) | ||
T1MaMHb | M70 mm | |||
T1MaLHb | L97 mm | |||
T2HuSClf | 2 | Hunton (Hu) | S45 mm | CBI Isocell Evolution cellulose (Clf) |
T2HuMClf | M60 mm | |||
T2HuLClf | L90 mm | |||
T2MaSClf | Masonite (Ma) | S47 mm | ||
T2MaMClf | M70 mm | |||
T2MaLClf | L97 mm | |||
T3HuSHlf | 3 | Hunton (Hu) | S45 mm | Hunton Nativo® Wood Fibre loose-fill insulation (Hlf) |
T3HuMHlf | M60 mm | |||
T3HuLHlf | L90 mm | |||
T3MaSHlf | Masonite (Ma) | S47 mm | ||
T3MaMHlf | M70 mm | |||
T3MaLHlf | L97 mm | |||
T4HuSHb | 4 | Hunton (Hu) | S45 mm | Hunton Nativo® Wood Fibre Insulation batt (Hb) |
T4HuMHb | M60 mm | |||
T4HuLHb | L90 mm | |||
T4MaSHb | Masonite (Ma) | S47 mm | ||
T4MaMHb | M70 mm | |||
T4MaLHb | L97 mm | |||
T5HuSHb | 5 | Hunton (Hu) | S45 mm | Hunton Nativo® Wood Fibre Insulation batt (Hb) |
T5HuMHb | M60 mm | |||
T5HuLHb | L90 mm | |||
T5HuMHbcc60a | M60 mm | |||
T5HuLHbcc60a | L90 mm |
2.1.2 I-Joist and Insulation Types
2.1.3 Instrumentation
2.1.4 Test Procedure
2.1.5 Determination of Residual Height and Cross-Section
2.2 Determination of Charring Rates
2.2.1 Protected Phase
2.2.2 Post-protected Phase
2.2.3 Lateral Charring
2.3 Method to Compare Charring Rates—Experimental Versus Design Methods
Method | \({\upbeta }_{0}\) | kn | k2 | Flange width | ks | \(\upbeta\) m |
---|---|---|---|---|---|---|
[mm/min] | [–] | [–] | [mm] | [–] | [mm/min] | |
EN 1995-1-2 | 0.65 | 1 | 0.938 | 45 | 1.3 | 0.79 |
47 | 1.3 | 0.67 | ||||
≥ 60 | 1.1 | 0.67 | ||||
prEN 1995-1-2 | 0.72 | 45 | 1.49 | 0.70 | ||
60 | 1.35 | 0.63 | ||||
90 | 1.18 | 0.55 | ||||
47 | 1.47 | 0.69 | ||||
70 | 1.28 | 0.60 | ||||
97 | 1.15 | 0.54 |
2.4 Determination of Insulation Recession Rate
3 Results
3.1 Residual Cross-Section Profiles and Measured Charring Depths
Test ID | Residuala | Test ID | Residuala | ||||
---|---|---|---|---|---|---|---|
Height min/max [mm] | Area min/max [%]b | Cross-section (grey colour) | Height min/max [mm] | Area min/max [%]b | Cross-section (grey colour) | ||
Test 1 | |||||||
T1MaSKb | 0.0 | 0.0 | T1MaSHb | 37.5/38.5 | 68.5/69.2 | ||
T1MaMKb | 24.5/29.0 | 23.8/29.0 | T1MaMHb | 39.0/39.5 | 71.6/72.4 | ||
T1MaLKb | 24.5/25.0 | 25.0/25.0 | T1MaLHb | 41.0/41.0 | 77.0/77.1 | ||
Test 2 | |||||||
T2HuSClf | 0.0 | 0.0 | T2MaSClf | 8.5/10.5 | 6.8/9.2 | ||
T2HuMClf | 0.0 | 0.0 | T2MaMClf | 13.5/15.5 | 14.9/17.6 | ||
T2HuLClf | 8.5/10.5 | 2.3/3.0 | T2MaLClf | 20.0/21.0 | 30.8/32.3 | ||
Test 3 | |||||||
T3HuSHlf | 15.0/16.5 | 13.2/13.4 | T3MaSHlf | 0.0 | 0.0 | ||
T3HuMHlf | 19.0/20.0 | 20.3/22.4 | T3MaMHlf | 22.0/23.5 | 19.2/18.5 | ||
T3HuLHlf | 26.0/27.5 | 39.2/40.1 | T3MaLHlf | 27.5/30.0 | 27.5/32.7 |
Test ID | Residuala | Test ID | Residuala | ||||
---|---|---|---|---|---|---|---|
Height min/max [mm] | Area min/max [%]b | Cross-section (grey colour) | Height min/max [mm] | Area min/max [%]b | Cross-section (grey colour) | ||
Test 4 | |||||||
T4HuSHb | 30.0/30.5 | 54.3/54.6 | T4MaSHb | 32.5/34.0 | 45.4/52.6 | ||
T4HuMHb | 30.0/30.5 | 56.7/58.9 | T4MaMHb | 33.0/34.5 | 50.3/53.1 | ||
T4HuLHb | 32.5/32.5 | 67.8/70.5 | T4MaLHb | 35.5/36.0 | 57.3/57.6 | ||
Test 5 | |||||||
T5HuSHb | 24.5/24.5 | 24.6/28.0 | Not tested | ||||
T5HuMHb | 23.5/24.5 | 29.8/32.7 | T5HuMHbcc60 | 21.0/21.0 | 26.1/26.9 | ||
T5HuLHb | 25.0/25.5 | 41.9/45.1 | T5HuLHbcc60 | 22.5/23.5 | 35.4 38.3 |
3.2 Charring Rates for I-joists
Protected phase | Post-protected phase | ||||||
---|---|---|---|---|---|---|---|
Test ID | tch | Gypsum board fall-off | End of test | Charring rate | Charring rate | ||
a1min | a1max | a2min | a2max | ||||
[min] | [min] | [min] | [mm/min] | [mm/min] | |||
Test 1 | |||||||
T1MaSKb | 23.7 | 22.2 | 45 | – | – | ≥ 2.13a | |
T1MaMKb | 23.9 | – | – | 0.81 | 1.04 | ||
T1MaLKb | 22.5 | – | – | 0.94 | 0.98 | ||
T1MaSHb | 28.5 | 46.5 | 0.49 | 0.56 | – | – | |
T1MaMHb | 28.0 | 0.45 | 0.45 | – | – | ||
T1MaLHb | 31.0 | 0.40 | 0.43 | – | – | ||
Test 2 | |||||||
T2HuSClf | 27.5 | 60.4 | 75 | 0.58 | ≥ 1.55a | ||
T2HuMClf | 28.0 | 0.58 | ≥ 1.59a | ||||
T2HuLClf | 27.9 | 0.61 | 0.67 | 0.87 | |||
T2MaSClf | 27.6 | 65.0 | 0.61 | 1.43 | 1.68 | ||
T2MaMClf | 26.2 | 0.54 | 1.05 | 1.30 | |||
T2MaLClf | 30.7 | 0.52 | 0.82 | 0.97 | |||
Test 3 | |||||||
T3HuSHlf | 29.4 | 62.4 | 62.5 | 0.69 | – | – | |
T3HuMHlf | 29.8 | 0.60 | – | – | |||
T3HuLHlf | 30.7 | 0.40 | – | – | |||
T3MaSHlf | 24.6 | 60.5 | 0.76 | – | – | ||
T3MaMHlf | 25.0 | 0.65 | 0.65 | 1.39 | |||
T3MaLHlf | 27.8 | 0.54 | 0.54 | 1.03 | |||
Test 4 | |||||||
T4HuSHb | 30.2 | 38.3 | 40 | – | – | – | |
T4HuMHb | 30.2 | – | – | – | |||
T4HuLHb | 31.5 | – | – | – | |||
T4MaSHb | 28.4 | 32.4 | – | 1.61 | 1.72 | ||
T4MaMHb | 28.9 | – | 1.64 | 1.71 | |||
T4MaLHb | 29.6 | – | 1.36 | 1.44 | |||
Test 5 | |||||||
T5HuSHb | 30.0 | 36.5 | 45 | – | 1.37 | 1.49 | |
T5HuMHb + T5HuMHbcc60 | 27.1 30.5 | 36.5 33.3 | – | 1.49 | 1.53 | ||
T5HuLHb + T5HuLHbcc60 | 29.5 28.4 | 36.5 33.3 | – | 1.24 | 1.31 |
3.3 Comparison of Charring Rates Against Design Methods
Test ID | Experimental | EN 1995-1-2:2004 | prEN 1995-1-2:2021 | ||
---|---|---|---|---|---|
a1max [mm/min] | βm [mm/min] | βm–a1max [mm/min] | βm [mm/min] | βm–a1max [mm/min] | |
Test 1 | |||||
T1MaSHb | 0.56 | 0.79 | 0.23 | 0.69 | 0.13 |
T1MaMHb | 0.45 | 0.67 | 0.22 | 0.60 | 0.15 |
T1MaLHb | 0.43 | 0.67 | 0.24 | 0.54 | 0.10 |
Test 2 | |||||
T2HuSClf | 0.58 | 0.79 | 0.22 | 0.70 | 0.12 |
T2HuMClf | 0.58 | 0.67 | 0.09 | 0.63 | 0.05 |
T2HuLClf | 0.61 | 0.67 | 0.06 | 0.55 | − 0.06 |
T2MaSClf | 0.61 | 0.79 | 0.18 | 0.69 | 0.08 |
T2MaMClf | 0.54 | 0.67 | 0.13 | 0.60 | 0.05 |
T2MaLClf | 0.52 | 0.67 | 0.15 | 0.54 | 0.02 |
Test 3 | |||||
T3HuSHlf | 0.69 | 0.79 | 0.11 | 0.70 | 0.01 |
T3HuMHlf | 0.60 | 0.67 | 0.07 | 0.63 | 0.03 |
T3HuLHlf | 0.40 | 0.67 | 0.27 | 0.55 | 0.15 |
T3MaSHlf | 0.76 | 0.79 | 0.03 | 0.69 | − 0.08 |
T3MaMHlf | 0.65 | 0.67 | 0.02 | 0.60 | − 0.06 |
T3MaLHlf | 0.54 | 0.67 | 0.13 | 0.54 | 0.00 |
3.4 Recession Rates for Combustible Insulation
Test no | Insulation | Recession rate ± std. deviation [mm/min] | Average time to reach 300°C after start charring | Based on (at depth) | |
---|---|---|---|---|---|
Protected [min] | Post-protected [min] | ||||
1 | Wood fibre batt | 2.7 ± 0.3 | 18 | 0 | 6 corner TCs (47 mm) |
< 4.9a | 21 | 0 | 4 insulation centre TCs (100 mm) | ||
1 | Phenolic foam batt | 5.7 ± 2.3 | 0 | 9 | 6 corner TCs (47 mm) |
6.8 ± 1.2 | 0 | 15 | 4 insulation centre TCs (100 mm) | ||
2 | Cellulose loose-fill | 1.1 ± 0.04 | 39 | 3 | 12 corner TCs (40.5/47 mm) |
≤ 2.2b | 39 | 12 | 8 insulation centre TCs (100 mm) | ||
3 | Wood fibre loose-fill | 2.3 ± 0.5 | 20 | 0 | 12 corner TCs (40.5/47 mm) |
4.1 ± 0.7 | 25 | 0 | 8 insulation centre TCs (100 mm) | ||
4 | Wood fibre batt | 3.6 ± 0.9 | 11 | 2 | 12 corner TCs (40.5/47 mm) |
< 7.0a | 11 | 5 | 8 insulation centre TCs (100 mm) | ||
5 | Wood fibre batt | 3.1 ± 0.4 | 12 | 1 | 10 corner TCs (40.5 mm) |
< 7.9a | 12 | 5 | 7 insulation centre TCs (100 mm) |
4 Discussion
4.1 Charring of I-Joists
4.1.1 Charring Rates on Fire Exposed Side
4.1.1.1 Protected Phase
4.1.1.2 Post-protected Phase
-
Measurement uncertainties, e.g., measured remaining height of the flange, were included in the calculation.
-
The end of the test was defined as when the furnace burners were shut off since the fire exposure would no longer be according to the standard time–temperature curve. However, the pyrolysis process of the I-joists continued for a short period (~ 2 min) between the burner shut-off and extinguishment.
4.1.2 Lateral Charring and Remaining Cross-section Area
4.1.3 Comparison with Calculation Methods
4.2 Recession of Combustible Insulation
4.2.1 Recession Rates
Research | Insulation type | Recession rate | Phase |
---|---|---|---|
Winter et al. [28] | Cellulose, loose-fill | 1–2 mm/min | Protected |
Winter et al. [28] | Cellulose, loose-fill | 2–5 mm/min | Post-protected |
Tiso and Just [23] | Cellulose, batt | 13.4 mm/min | Post-protected |
Winter et al. [28] | Wood fibre, batt | 2–4 mm/min | Protected |
Winter et al. [28] | Wood fibre, batt | 4–16 mm/min | Post-protected |
Manguse [39] | Stone wool, batt | 2.7 mm/min | Mix of protected and post-protected |
Just [14] | Glass wool, batt | 15–28 mm/min | Post-protected |
Manguse [39] | Glass wool, batt | 4.6–11.1 mm/min | Post-protected |
4.2.2 The Effect of Shrinking on the Recession Rate
4.2.3 Insulation Fall-Down
4.2.4 Classification of Insulation Products
-
Rectangular cross-sections instead of I-joists
-
The gypsum board is provoked to fall-off after 45 min by a manual intervention, while in this test series, the fall-off occurred naturally.
-
The test is terminated at 60 min, while in this test series, the tests were terminated based on the charring progression in each test.