Transcript Final Report Powerpoint.pptx

Thermal Analysis of a 1 Hour Fire
Resistive Joint Design for
Architectural Expansion Joints
Preliminary Final Report
Jason Shaw
Architectural Expansion Joints are Openings
Between Concrete Slabs in a Building
• Engineered into a building to permit movement
▫ Thermal loading (i.e., change of season)
▫ Wind loading
▫ Seismic activity
• Building codes often require fire resistive
systems be installed in these joints to restrict the
passage of smoke, heat, and flames
• Fire barriers are tested to UL 2079
▫ Acceptance criteria: Temperature rise ≤139 K
COMSOL Multiphysics is Used to
Generate the Thermal Model
Unexposed Side
Concrete
Steel Cover Plate
Steel “L” Bracket
Air Gap
Ceramic Fiber Insulation
Fire Side
COMSOL Model Parameters
• Thermal Stress Physics
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▫
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Isotropic, linear elastic material
Quasi-static structural transient behavior
Surface to surface radiation
Radiation in participating media
Time dependent – 0 to 3,600 seconds (1 hour) in
100 second time steps
COMSOL Model Boundary Conditions
• Convective Cooling
▫ Applied to the unexposed side
▫ Radiation and convective heat transfer coefficients
are manually calculated and applied
COMSOL Model Boundary Conditions
• Heat Flux
▫ Applied to the fire side boundary
▫ Fire temperature in accordance with ASTM E119,
approximated by the following equation
• Heat transfer in fluids
▫ Applied to the air gap
COMSOL Results
• Initial fire barrier design did not satisfy the
temperature rise criteria
COMSOL Results
COMSOL Results
Recommendations
• Increase steel “L” bracket size from 2x1 to 2x2
COMSOL Results
• Increase steel “L” bracket size results in lower
temperatures on the unexposed surface of the
fire barrier
Cover Plate Temperature (K)
Configuration
Concrete
Temperature
Maximum
Average
Minimum
Original
483
441
407
393
Modified
417
389
368
393
(K)
COMSOL Results