Project Buildings

Author

Anthony Pamintuan, California Polytechnic State University, San Luis ObispoFollow

Date

6-2024

Degree Name

MS in Fire Protection Engineering

College

College of Engineering

Advisor

Frederick Mowrer and Christopher Pascual

Abstract

This report analyzes the prescriptive based design of a government-use high-rise building whose primary use is a business office building in California utilizing the California Building Code 2022 Edition. For security purposes, the name of the project will be the “Project Building.” The project site consists of a common podium underground parking garage with two high-rise buildings and an auditorium built on the parking garage. The project buildings that were analyzed consisted of the underground parking garage, the auditorium, and one of the high-rise buildings.

The parking garage is approximately 135,000 square feet consisting of mixed occupancies throughout. The mixed occupancy spaces consist of various areas that act as service spaces for the building such as utilities, storage, in addition to some office spaces for building engineering and break rooms. The parking garage does not have any openings and is accessible via interior exit stairs and elevators through each of the buildings. The project building high-rise is also a mixed-occupancy building. Level 1 and Level 2 were analyzed independently and Level 3 was analyzed as a typical floor plan for Level 3-Level 11. The areas that were reviewed consist of the entry lobby, open office floor plans, conference rooms, offices, and the auditorium. The auditorium, which will be referred to as a Council Chamber, was reviewed during the performance based design. The Council Chamber is a Group A-3 occupancy used for gathering purposes and its connected to the high-rise project building on Level 1.

The building was designed based on the 2013 California Building Code. The goal is to determine if the building will pass today’s building code requirements and identify any deviations from current code. The results conclude that the building passes all of the prescriptive based code analyses and does not have any major variations other than occupant load factors used for business occupancies.

A performance based design analysis was performed on a separate building that is also located on the same project site. The building was selected for its 335 occupant load with a primary occupancy of Group A-3 which is referred to as the Council Chamber. The goal was to determine if the Available Safe Egress Time (ASET) was greater than the Required Safe Egress Time (RSET). The RSET analysis concluded to be 4.4 minutes. The ASET was determined by two analyses: a visibility analysis and a toxic exposure analysis. The ASET required a design fire and a few assumptions. The selected design fire consists of a stack of chairs composed of polyurethane plastics stacked against a wall towards the back of the Council Chamber and is adjacent to the primary entrances. This design fire was chosen because the Council Chamber has many fixed seats and it can be assumed that additional chairs would be made available for additional occupants if all seats were occupied. The selected heat release rate curve for the design fire was based on a stack of 8 chairs of polyurethane. Due to the high-profile government entities that can be present in the space, the fire is assumed to start due to arson attack at the primary entrance to the Chamber.

The results conclude that the visibility analysis failed. The available visibility in the Council Chamber dropped to nearly 3m of available visibility while the required visibility for a light- emitting exit sign was 16 meters. However, it should be noted that the means of egress design resulted in significant exit queuing at a single door which indicates to the occupants that an exit is present and that the occupants did not have to go searching for an exit. It is expected that occupants would follow the crowd until arrival at the exit door. The visibility dropped below 3m in approximately 2 minutes so the ASET for visibility was determined to be 2 minutes. The ASET of 2 minutes is less than the RSET of 4.4 minutes so the visibility analysis failed.

The second analysis, toxic exposure, passed because no occupants were exposed to toxic products of combustion for a duration of time that leads to incapacitation. The occupants were exposed to toxic smoke and gases for about 2.4 minutes. For the toxic exposure analysis to fail, the occupants would have been required to be exposed to toxic gases for a minimum of 5 minutes. Since the occupants do not get exposed to smoke until after 2 minutes, the total ASET for the toxic exposure analysis was about 7 minutes which was greater than the RSET of 4.4 minutes so the toxic exposure analysis passed.

While the performance based design analysis confirms the Council Chamber is designed to code requirements and does not lead to incapacitation of occupants, there are a few recommendations that can be made for future high-occupant load spaces.

A few recommendations can be made for future developments similar to the project building. It is recommended that the Council Chamber exit separation be increased between the primary entrances. Two closely spaced exits can be affected during a fire event and can eliminate exit access through both of the two exits. While a 3rd exit was provided to the north west, the size of the exit is code compliant, however, it is recommended to utilize double doors to reduce exiting and queuing time. If a double door is not feasible, then it is recommended to provide a 4th exit opposite side of the existing 3rd exit. This would also reduce the exiting time in half while also reducing the queuing. Due to the high volume of people expected in this type of space, the space can benefit from a mechanical smoke exhaust system.