Concrete Slab•Followed ASTM E119 for 2 hours•Gradually reduced air-temperature until 600C
Furnace Specifications
Elin Jensen, Jacob Van Horn, Nabil Grace, and Mena BebawyCollege of Engineering, Civil Engineering Department
New Large-Scale Structural Fire Chamber: Initial Experimental Considerations
Objective: •Define design fires for assessing structural fire performance.•Verify the performance characteristics of the new test facility.
Experimental Considerations:•Furnace specifications•Design fires & furnace response
•Standard air temperature-time curve – ASTM E119•High intensity short duration - Fire A•Progressive burning – Fire B
•Specimen shadow effect •Test repeatability
•Slab•T-beam
Left: Small slab subjected to air temperature – time curve (ASTM).Right: Deflected slab after test
View on left: right front corner of slab & environmental thermocouple in rod
New facility located in the Center for Innovative Materials Research (CIMR) at Lawrence Tech, Southfield, MI
•The internal workload dimensions are 6.0 m x 1.5 m x 1.5 m.
•Max workload equivalent to 5.5 m3 of concrete subjected to ASTM E119 standard temperature-time curve
•Heating capabilities • Nine burners - 555,00 MJ/hour – natural gas• Three control zones • Variable air-gas mixture• Forced air ejector stack
•Mechanical loading of Pmax = 490 kN (compression)
•Controller & Data Acquisition•Closed loop temperature control system•70 set-points available in each temperature-time curve•100 thermo-couple channels
Temperature uniformity in workload area
CharacteristicsMean: 1004CMax: 1016CMin: 983CSt. dev: 6.3CVariation: 0.6 %
Furnace meets the requirements
Standard Fire - ASTM E119: •Standard air temperature-time curve•Allowable deviation from standard curve•Test repeatability
Concrete Test Slab Information:Dimensions: Length (1.82 m)
Width (1.82 m) Thickness (12.5 cm)
Concrete grade: 32 MPaAge: 4 yearsHumidity levels at core: RH 74% - 77% at Tair = 25C
Standard Fire – ASTM E119
Temperature-Time Curve - ASTM E119
0
500
1000
1500
0 2 4 6 8
Test Duration (h)
Air
Tem
pera
ture
(C)
Investigation range for slab testing
Radiation Effect
Shadow Effect During Slab TestingThe furnace roof is covered with white ceramic blanket and the furnace floor is covered with fire brick.
•The fire bricks heat up slower showing an offset between temperature below and above slab.
•Temperature offset decreases from 100C after 6 minutes to 25C after 1 hour.
•Furnace capable of producing Standard Fire - ASTM E119.
•Repeated tests fall within allowable deviation from standard.
Real Fires
Motivation
Design Fires: •A short duration high intensity fire is a result of burning highly combustible materials.•Progressive burning is a result of temporary oxygen depletion in a deep room.
•Capability of Fire Furnace in producing a fire with 1.0 m3 of concrete •Fire A – fire bricks cover the floor•Modified Fire A – ceramic blanket added over fire bricks•Fire B – fire bricks cover the floor
Below and Above Slab Environmental Thermocouples
0
250
500
750
1000
0.0 0.2 0.4 0.6 0.8 1.0
Test Duration (h)
Air-
Tem
pera
ture
(C
)
6 minT(average, below) = 446 CT(average, above) = 555 C
T(average, below) = 800 CT(average, above) = 840 C30 min
60 minT(average, below) = 900 CT(average, above) = 925 C
Design Fires
0
500
1000
1500
0.0 0.5 1.0 1.5 2.0
Duration (h)
Te
mp
era
ture
(C
)
Progressive Burning - Fire B ASTM E119
High Intensity Fire A Modified High Intensity Fire A
Temperature Uniformity
940
960
980
1000
1020
1040
6 min 19 min 34 min 60 min
Tem
pera
ture
(C)
Internal Temperature Profiles
Temperature Development in Slab
0
400
800
1200
0.0 1.0 2.0 3.0 4.0
Duration (h)
Tem
pera
ture
(C
)
Surface TemperatureTemperature at depth: h/4 = 31 mm
Temperature at depth: h/2 = 62.5 mm
•Good agreement between predicted and measuredtemperature development in concrete slab. Variable radiation effect not modeled.
Predicted versus Measured Temperature Development in Slab Subjected to Standard Fire
0
300
600
900
0.0 0.5 1.0 1.5 2.0
Duration (h)
Te
mp
era
ture
(C
)
Depth h/2
Bold line: Predicted - FEAThin line: Measured
Depth h/4
Est thermal conductivity: 0.8 W/mKEst specific heat: 1000 J/kgC
{
Temperature Development at h/2
0
300
600
900
0.0 1.0 2.0 3.0 4.0
Duration (h)
Tem
pera
ture
(C
)
Sensor located over brick support area
Sensor away from brick support
CFRP Prestressed Concrete Beam:Concrete Beam Information:Dimensions: Length (3.99 m)
Cross Section Shown in sketch
Concrete grade: 48 MPaAge: 9 monthsHumidity levels at core: RH 84% - 87% at Tair =
25C
Temperature Development in T-Beam:Development of internal beam temperature in agreement with
expected trends. Post-construction installation of thermocouples is successful.
Acknowledgement:• Center for Innovative Materials Research (CIMR) College of Engineering, Lawrence Tech University, Southfield, MI• National Science Foundation, Award 0747775
• Assistance from: Charles ElderCody TelghederDaniel Ziemba
735°C after 1 hr 20 min
Effect after 5 h
1020°C after 2 hr 19 min
Large Scale Structural Fire-Load Furnace
Thermocouples steel columns
Effect of brick support on temperature development
K-type thermocouples
