Date
6-2021
Degree Name
MS in Fire Protection Engineering
College
College of Engineering
Advisor
Frederick Mowrer and Christopher Pascual
Abstract
This project report is a component of the culminating project required by the California Polytechnic State University, Master of Science, Fire Protection Engineering program. The purpose is to demonstrate the student’s comprehensive knowledge, skill, and ability to evaluate fire and life safety engineering principles utilizing both prescriptive and performance- based design as applied to the built environment. The student project building is a two-story, 78-bed, federally funded, government owned, skilled nursing facility with 90% of the occupants being mobility impaired.
The project building was designed and constructed using prescriptive codes. Fire and life safety structural components, means of egress, fire alarm system, suppression systems, and smoke control systems were evaluated. The analysis revealed three conflicting fire protection elements to the prescriptive codes. The first being the new building roof deck was not constructed using a 1-hour fire resistance rated material; the second being the window openings in the rated exterior walls between the new and existing buildings (East and West sides) exceeded allowable area limits for unprotected openings in a rated exterior wall; the third being the magnetic door hold open devices were not provided in the fire alarm system sequence of operations matrix.
The roof deficiency resulted in the brand-new building sitting vacant for several months until an equal or greater level of protection was agreed upon, installed, and passed final inspection. In the available construction drawings analyzed, the percentage of allowable area for unprotected openings permitted in an exterior wall based on separation distance was contradictive to prescriptive code requirements. As-built suppression system drawings revealed there were no water curtains installed to protect any exterior wall openings in the new building. The unprotected openings were not field verified that standard windows were installed as plans specified. The fire alarm system sequence of operations matrix update to include the magnetic hold-open devices is inconsequential in comparison to the other two structural fire protection elements noted.
The performance-based analysis included rescue procedures of staff, occupant characteristics, flammability assessment, tenability, and a zone-model design fire simulation.
The goal sought after is preserving life safety and to provide insight to increase the survivability of mobility impaired occupants during a fire. The objectives being pursued to accomplish this the goal were to evaluate rescue and evacuation practices of the staff evacuating mobility impaired occupants and the effectiveness of fire and smoke containment measures integrated into the building.
The design fire scenario was simulated to be on a 2nd-floor resident room, near an egress stairwell. Resident bed capacity of the chosen smoke compartment is 20 residents. The size of the chosen smoke compartment is 11,390 ft2. The design fire ignition source chosen was a faulty wall TV. The wall TV was impregnated with fire retardant resulting in slow burning to start. The peak heat release rate of the wall TV was 5 kW at 420 seconds. At 150 seconds, the wall TV pooled on top of the combustible pine wood dresser below the wall TV, which subsequently ignites the wood dresser. The peak heat release rate of the wood dresser was 1,800 kW at 420 seconds. No additional fuel sources contributed to fuel load in the project design fire. Calculated estimates of the HRR needed to cause flashover ranged between 1,151 kW and 2,630 kW. Flashover was not evidenced in the design fire simulation. Room #2 maximum upper layer temperature observed during the FDS simulation was 854 °C at 423 seconds.
20 total occupants are assumed to be in the smoke compartment during the simulated design fire. Two of the total occupants were staff, the remainder were resident occupants. The facility reported 90% of the occupants required staff assistance to aid in evacuation. The occupants requiring staff assistance were assumed to be in their room, alert, dressed, and in their wheelchairs ready and waiting for evacuation assistance from staff.
The second-floor smoke compartment containing the design fire has a total of two exits. The West exit door is approximately 11-feet Southwest of room #2 and was assumed not utilized as a means of egress, considered impassable due to the fire location. The second exit is located on the East side of the smoke compartment and passage provides a safe place for occupants.
The Available Safe Egress Time (ASET) is the time to critical conditions. For this project, the Fractional Effective Dose (FED) and visibility obscuration at the East Exit were two criteria of
critical conditions selected. A FED value of 0.5 for incapacitation criteria and a FED value of 1.0 for lethality criteria was recognized. A visibility obscuration of 2 meters (6.6 feet) above the floor was selected due to staff familiarity of the facility. The FDS design fire simulation revealed a maximum FED value of 0.04 and a maximum visibility obscuration of 2.06 meter (6.8 feet) above the floor at the East exit at 1000 seconds (16.7 minutes), the conclusion of the simulation. Room #2 tenable conditions deteriorated quickly, resulting in FED value greater than 0.5 suggesting the resident had met FED incapacitated criteria upon arrival of rescue staff.
The Required Safe Egress Time (RSET) is the time it takes to evacuate to a safe place. Calculations revealed 677.4 seconds (11.3 minutes) was necessary to evacuate the occupants through the East exit of the affected smoke compartment into the adjoining smoke compartment designated as the safe place.
The results of the performance-based design fire simulation in comparison with the tenability criteria revealed the RSET was greater than ASET in room #2 implying the occupants would not make it to the safe place unaffected by fire conditions. Several assumptions were made in this design fire, such as the sprinkler system being down for maintenance and non- functional, only two staff members performed the entire smoke compartment evacuation and were unaffected by the products of combustion, the West exit was not used; room #2 door was left open after rescue; or the 5 kW HRR of the ignition source did not activate the fire alarm prior to the wood dresser fire. These and other assumptions made may or may not be pertinent during a real fire event and would certainly impact safe egress times for the better or worse.
Recommendations based on the design fire simulation supported the significance of frequently inspecting, testing, and maintaining the detection, suppression, and containment systems to ensure operational readiness, and where deficiencies exist, provide prompt corrective action. The simulation supported isolating a fire to the room of origin whenever possible, being essential to slow the spread of products of combustion. Lastly, the simulation supported tenable conditions can change rapidly and is essential to have additional rescue staff available to respond promptly to assist in the timely evacuation of occupants.
https://digitalcommons.calpoly.edu/fpe_rpt/147
Final Presentation