Travel to exits – occupant movement simulation
Computer simulation is the tool in design of life safety in means of egress and it performs with adequate capacity and protection to provide occupants adequate time to reach a place of safety without being unreasonably exposed to untenable conditions. In a sense, performance-based analysis and design is in computer simulation of fire engineering, a solution to meet specific levels of performance, where performance may be stated in terms of qualitative or quantitative objectives, criteria, or limiting states of damage or injury. Evacuation - Calculations are countable in a priority and becoming a part of performance-based analyses to assess the level of life safety considered in buildings. The occupants are assumed to be standing / moving at the exits-doorway on each floor as soon as the evacuation begins. Evacuation simulation and calculation focuses mainly on points of narrowing throughout the building exits and the time for the occupants to flow past that point, and to the outside of building. Evacuation planning should anticipate the obstruction of primary means of egress and plan for use of secondary means of egress. Evacuation modeling in life safety design, has become important in recent season(s) to be in performance based design and also participates in prescriptive design of means of egress. The evacuation time for an individual is the entire span of time that elapses from the ignition of the fire until the occupant emerges from the building or arrives at a location of safety. It consists of four components, all of which must be taken into consideration. (a) Time to notification (b) Reaction time (c) Pre-evacuation activity time (d) Travel or movement time. The first three components are often grouped together and referred to as “delay time” or pre-movement time. Evacuation time (1) = (delay time + travel time) = (time to notification + reaction time + pre evacuation time) + travel time It is very important that, not underestimate the contribution that delay time can make to total evacuation time. Studies of evacuation drills, have shown that, on average, travel time makes up less than 25 percent of the average total time to evacuate. In office evacuations, however, delay times can be extremely short, and the largest proportion of total evacuation time is accounted for by travel time. Therefore the selection, estimation, or calculation of pre movement times s extremely important to obtain valid results. Building codes such as NFPA – 101 (Life Safety Code), International Building Code (IBC), established the minimum requirements for the safe design of a building. Nevertheless, additional life safety measures are often necessary to mitigate the risks that arise from the complexity of these types of buildings and the possible difficulties in firefighting and rescue operations.