1. Thermal Analysis of a 1 Hour Fire Resistive Joint Design for Architectural Expansion Joints Preliminary Final Report Jason Shaw

2. 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

3. COMSOL Multiphysics is Used to Generate the Thermal Model Concrete Steel Cover Plate Ceramic Fiber Insulation Air Gap Steel “L” Bracket Fire Side Unexposed Side

4. COMSOL Model Parameters Thermal Stress Physics ▫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

5. COMSOL Model Boundary Conditions Convective Cooling ▫Applied to the unexposed side ▫Radiation and convective heat transfer coefficients are manually calculated and applied

6. 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

7. COMSOL Results Initial fire barrier design did not satisfy the temperature rise criteria

8. COMSOL Results

10. Recommendations Increase steel “L” bracket size from 2x1 to 2x2

11. COMSOL Results Configuration Cover Plate Temperature (K) Concrete Temperature (K) MaximumAverageMinimum Original483441407393 Modified417389368393 Increase steel “L” bracket size results in lower temperatures on the unexposed surface of the fire barrier

12. COMSOL Results