MS in Fire Protection Engineering
College of Engineering
Frederick Mowrer and Christopher Pascual
Sacramento State Union is a centrally located building with a large occupant load during the school year. This building is a 239,000-square-foot three-story structure built originally back in 1975. This original building was constructed using waffle slab construction. Additions in 1996 and 2016 were built using steel beam and girder construction to meet the total square footage we have today. This mixed-use occupancy is not only a congregation point, but many events are held in this building as well.
In this analysis of the building, fire life safety systems are reviewed and determined if they not only meet the minimum requirements set forth by the code but also do they allow for appropriate egress from design fires. The Structural fire protection was reviewed for appropriate rating on structural system like walls and ceilings as well as for the structural members. Fire Sprinkler and Fire Alarm systems were reviewed for appropriate space and calculations set forth by NFPA 13 and NFPA 72. Finally, the Egress was analyzed for occupant load and exit load on the floors, exit path and common path of travel. The analysis of all the prescriptive fire life safety systems proved to meet all code requirements.
Performance-based analysis was also done to review the required egress time for occupants to exit the building versus the allowed time determined from the design fires. The first design fire is located on the first floor in the dining center. This fire was selected due to its proximity to a major egress path that feeds both the first and second floor. The second design fire catches a wooden desk on fire in a small retail space, the fire then spreads to some surrounding clothing racks. Similar to the first, this design fires were selected due to its exposure to an egress path. The third design fire looked at how a large occupancy event could be impacted by a fire event. An electrical fire started a fire during a career fair event in the large multi-purpose room. This fire was analyzed as it travels down the room and spreads to more fuel load. The heat on the structure was also reviewed to see if any damage would occur. In all three design fires sprinkler activation was calculated using plume temperature calculations to operate at 100 seconds, 130 seconds, and 110 seconds using plume calculations and temperature of the upper plume. Through basic modeling using CFAST updated activation times were seen at 140 seconds and 50 seconds, no modeling was completed for the third design fire due to complexity. Two of the three scenarios showed a quicker activation of sprinklers than what was calculated by hand. The required egress time that was calculated was 144 seconds for the first floor. All fires had activation times prior to egress times. The tenability was also measured at activation and all design fires had Carbon Monoxide levels under the 1400 ppm requirement and temperatures under 60°C. The actual calculated RSET or required egress time for the design fires was 3 minutes and 24 seconds. With all three design fires having activation of sprinklers, it is assumed tenability would maintain and or increase as time increased, thus allowing for acceptable egress times. CFAST results show that for design fire 1 untenable conditions would not be reached until over 8 minutes after ignition. Design fire 2 results showed after 4 minutes conditions we exceed tenability requirements. Design fire three did not have CFAST results, but with limited fuel load and large open space an assumption can be made that tenability would remain high past RSET time. The results from this analysis of the building and its fire life safety systems show that all systems meet the minimum code requirements for the prescriptive designed system, as well as provide appropriate means of safety to adequately allow for egress according to the design fires that were presented. The only recommendation I would make to further help with fire life safety features is to install a smoke evacuation system at the skylight located in the center of the building. This would help to limit smoke exposure due to the open atrium between the first and second floor.