Question 1: Multiuse High Rise Buildings
Multi-use highrise buildings are appearing with increasing frequency and pose interesting decisions for design professionals and regulatory authorities. Assume you are responsible for reviewing the design for such a large building. How would you approach the problem of setting requirements when there are multiple types of occupancies in the same building? The problem is not as simple as requiring fire-rated partitions between the different types of occupancies within the same building. Many of the issues concern human and organizational factors. Especially important is how the occupancies interact regarding exiting requirements. What if a building has an assembly occupancy on it’s second floor. Would you permit the theater patrons to leave using the main building entrance? If you required that most of the patrons leave using exits dedicated to the theater, how would you assure that they would use those exits instead of the main entrance?
Students Answer/
Student 1:
To start, the building will need to be designed with a Fire Alarm System, and program to provide a phased evacuation (Notify floor of origin, the floor above, the floor below); the notification system will need to be voice communication with general selective paging for each floor. Secondly, the fire sprinkler system will need to be designed per the particular occupancy for each floor, with automatic standpipes (Class 1) in the stairwells and an automatic sprinkler on the landings in the stairwell. Third, transitional refuge areas (fire-rated pressurized spaces at various locations in particular for occupancies). Fifth, stairwell pressurization systems. Sixth, the stairwell egress must be wide enough between 66 -72 inches and strong enough to support phased evacuation.
With answering the questions
Yes, I would permit the patrons to leave through the main building entrance, I feel that many people in the theater will begin to backtrack how they entered the building, and we need to make sure we house the egress available for them to do so. However, I would provide alternate route and illuminate those routes when the fire alarm system does alarm as well making sure the staff responds to the alarm and assist with the evacuation.
Student 2:
In a multi occupanci building I think that I need to aprroch the situation in different way for every bilding.I think that more than use the main factor is how much peopl I need to evacuate. If I have a theater, I wuold create special doors for the evacuation just for them. The rapidly increse of people if they are going out for the general evacuation route, willl decrease the walking speed. If they go out out for that special doors, I will mantain the waliking speed in every part of the building. To asure that they will use those door, befero the show start I will put somethin that anounce whete are the emergency exits, I will put them in the side of the stage.
Student 3:
The use of mutli use buildings requires looking at the different occupant loads and hazards of each type of use. There needs to be an examination of how different occupants of each facility are expected to act. There are expected to be occupants in the assembly occupancy which need to be accounted for as oppose to possibly a supply facility with few occupants. For the assembly I would permit patrons to use the main entrance as that may be the safest at the time and its inevitable that some will retrace the route they entered. Each theater will have available exit points from within the theater that should be attempted to be used and I will ensure that they are properly identified and locations announced prior to each presentation.
Student 4:
Performing plan reviews for a large building such as a high rise with multiple uses inside, one must start at the site where this large building will be constructed. Before this construction goes vertical, a lot of requirements must be met on the ground with adequate roadways, access roads, water mains and hydrants. Performance based design options are now used per floor of this high-rise to meet the current codes for egress requirements, number of exits, corridor widths, allowable fire areas through fire-rated partitions, smoke partitions in egress stairwells, fire-rated doors with magnets to close in an emergency to prevent smoke from spreading throughout, emergency lighting and exit signage elements, portable fire extinguishers all of which are code based upon the intended uses on each floor. Let’s not forget the fire sprinkler system required and the addressable fire alarm system too. These are requirements based upon fire codes and NFPA. Depending on the water flow and pressure into the building, a fire pump or pumps will more than likely be required to provide adequate pressure and volume to the upper floors of this high rise. Standpipe systems will also be required in the stairwells for firefighting operations out and to remote areas of the individual floors. If the building has an assembly area on the second floor, then with the designed use of active fire protection for life safety (fire sprinkler system), then allowances are given for corridor lengths are given, but HVAC systems and building ventilation design is required to be tied into the fire alarm which will trigger the building’s ventilation to remove smoke and exchange air to the outside of this high-rise. So, a discussion will ensure with the architect and engineers to determine if the current design warrants the additional capital of additional exits from the second floor or if current exits and egress paths are adequate with the fire protection systems to satisfy the architect’s performance-based design while meeting the code requirements for this design.
Student 5:
The risks associated with residential high rise buildings (buildings over 6 stories) are countless to say the least. Most of these building have very effective fire suppression systems and detection beyond the floor involved. Adding a assembly on the second floor will not only increase the occupant load but require an effective plan for evacuation for all floors above due to convergence with escape routes. This starts the conversation of a phased evacuation where the main fire floor is evacuated and notified first. The stairwells in a mixed use occupancy, will need to be protected with a pressurized stairwell and fire sprinkler suppression systems and wide enough that the convergence of individuals can make egress accessible. In the case of a movie theatre, patrons will be willing to use the entrance as an exit but for this reason an alternate path should be used and staff should coordinate the evacuation plan with well-lit exit signs. A voice notification system should be used to alert all occupants of what floor will be involved.
Student 6:
When a building is of mixed occupancy or used for more than one occupancy, the whole building shall be subject to the most restrictive requirement pertaining to any of the
type of occupancy found therein except in the
following:
When a one-story building houses more than one occupancy, each portion of the building shall conform to the requirement of the particular occupancy housed therein and;
(2) Where minor accessory uses do not occupy more than ten percent of the area of any floor or a building, nor more than ten percent of the basic area permitted in the occupancy requirements, in which case, the major use of the building shall determine the occupancy classification.
Forms Of Occupancy Separation
Occupancy separations shall be vertical or horizontal or both, or when necessary, of such other forms as may be required to afford a complete separation between the various occupancy divisions in the building.
Types of Occupancy Separation
Occupancy separation shall be classified as “One-Hour Fire-Resistive”, “Two-Hour Fire-Resistive”, “Three-Hour Fire-Resistive” and “Four-Hour Fire-Resistive.”
A “One-Hour Fire-Resistive Occupancy Separation” shall be of not less than one-hour fire-resistive construction. All openings in such separation shall be protected by a fire assembly having a one-hour fire-resistive rating
A “Two-Hour Fire-Resistive Occupancy Separation” shall be of not less than two-hour fire-resistive construction. All openings in such separation shall be protected by a fire assembly having a two-hour fire-resistive rating.
A “Three-Hour Fire-Resistive Occupancy Separation” shall be of not less than three-hour fire-resistive construction. All openings in walls forming such separation shall be protected by a fire assembly having
a three-hour fire-resistive rating.
The total width of all openings in any three-hour fire-resistive occupancy separation wall in any
one-story shall not exceed 25 percent of the length of the wall in that story and no single
opening shall have an area greater than 10square meters. All openings in floors forming a “Three-Hour Fire Resistive
Occupancy Separation” shall be protected by vertical enclosures extending above and
below such openings.
The walls of such vertical enclosures shall be of not less than two-hour fire-resistive construction, and all
openings therein shall be protected by a fire assembly having a three-hour fire-resistive
rating.
A “Four-Hour Fire-Resistive Occupancy
Separation” shall have no openings therein and shall be of not less than four-hour fire-
resistive construction.
Fire Rating for Occupancy Separation
Occupancy Separations shall be provided between groups, subgroupings, or divisions of occupancies. The Secretary shall promulgate rules and regulations for appropriate occupancy separations in buildings of mixed occupancy; Provided, that, where any occupancy separation is required, the minimum shall be a “One-Hour Fire-Resistive Occupancy Separation”; and where the occupancy separation is horizontal, structural members supporting the separation shall be protected by an equivalent fire-resistive construction.