Reference no: EM132647773

300717 Egress and Risk - Western Sydney University

Question - Occupant Evacuation

Introduction

A hotel building has 10 levels, consisting of reception, the lobby and a restaurant on Ground floor, three (3) function rooms on Level 1 and hotel rooms on Levels 2-9. Ground floor and Level 1 are connected through an open stair of 1.8m width.

The building has a smoke detection and alarm system throughout except the kitchen where heat detectors are installed. The alarm will sound in the whole building once a fire is detected, regardless of the location of the fire. The detection and alarm system is connected to the fire brigades.

Exit provisions include the front entrance (2m) and a rear exit door (1m) on the Ground floor and two fire isolated stairs serving the upper levels that discharge to the street. Each stair has a 1m clear width fire door at entrance and exit. Each function room has one exit door into Level 1 foyer.

Occupant numbers and characteristics in the function rooms are summarised in the following table.

Average travel speeds are assumed as follows:

Male able adult: 1.2m/s Female able adult: 1m/s Persons with limited mobility: 0.6m/s

For a fire in the kitchen of the restaurant,

1. Identify the mostly likely means of detection for occupants in the restaurant, the function rooms and the hotel rooms. For each occupant group you are expected to
a) consider three most likely cues.

b) estimate cue occurrence times for each cue and explain the assumptions you've adopted in the quantification. Also identify what methods and tools would be used to quantify them in a real fire safety engineering assessment.
2. Develop behavioural models for restaurant staff, restaurant guests and patrons in the function rooms and estimate the overall pre-movement (response and delay causing behaviour) times for each of these three occupant groups. Briefly justify your assumptions when allocating time values.
The models must identify the 5 most likely actions to be adopted by each occupant group. The actions listed in Bickman's model may be used for guidance but action types should be enhanced taking into consideration the nature of the occupancy. The actions must be listed in the order of likely occurrence. The following table may be adopted; you may also choose your own format of display.

3. Assume 1/3 of all occupants in the function rooms use each of the two fire stairs (1.1m wide; maximum specific flow Fsm = 1 person/s/m; constant k in Eq. (5) or (7) = 1.08) and the open stair (1.8m wide; maximum specific flow Fsm = 1.2 person/s/m; constant k in Eq.
(5) or (7) = 1.3) for emergency evacuation. Assume that the floor-to-floor distance through the fire stairs or the open stair is 12m. Maximum travel distance on Level 1 is 40m from the door of each function room to the nearest exit. The effective boundary layer width

when the occupants move to the nearest exit on Level 1 is assumed to be 4m. Assume 1/2 of the occupants on the ground floor (occupants who used the open stair) use each of the front entrance and the rear exit door. Maximum travel distance on the ground floor is 20m. The effective boundary layer width when the occupants move to the nearest exit on the ground floor is assumed to be 2m. Use the second-order hydraulic models in SFPE handbook Section 59 (or the method in Appendix A of Module 9~10), to:
a) calculate the movement time of all the occupants in the function rooms required to evacuate the building.
b) calculate RSET (detection time + pre-movement time + movement time) for occupants in the function rooms.
Note: If you need any further assumptions, clearly state them.

Question 3 - Toxicity and Tenability

Concentrations of three narcotic gases (CO, CO2 and HCN) in the smoke layer of the Ground level during the first 9 minutes of a fire starting in the restaurant seating area are given in Table 3-1. The occupants are in the 25L/min RMV, light activity mode. The height of smoke layer interface on the Ground floor is given in Table 3-2. It is assumed that occupants are not affected by the gases while smoke layer is above 2m. Impact of oxygen is ignored for the purpose of this exercise.

Table 3-1 Concentration of CO and HCN in smoke layer of Ground level

Table 3-2 Height of smoke layer interface

1. Calculate the fraction of incapacitating dose for each individual gas and show the time of incapacitation.

2. Calculate the combined fraction of incapacitating dose for all gases and show the time of incapacitation.
3. Assume:

• 150 people are in the restaurant;
• 1 occupant exits the restaurant in each second after a combined cue and pre- movement time of 240s has elapsed.
Estimate the number of occupants that would become incapacitated or trapped in the event of a fire in the restaurant (i.e. number of occupants still in the restaurant when the time of incapacitation is reached for each gas and all gases combined).