Reference no: EM132631145

Question 1. Discuss the difference between the event tree analysis and the fault tree analysis.

Question 2. Find the minimal cut set of the fault tree below. Clearly show the calculation steps and details.

Question 3. An existing shopping centre has two retail levels that are connected by an atrium. The building is equipped with:
• a smoke detection system with smoke detectors located in accordance with AS1668.1 that will
initiate occupant warning and the smoke exhaust system;
• an automatic sprinkler system throughout (sprinklers also to activate the smoke exhaust system),
• a smoke exhaust system in the atrium, extracting at the top of the atrium, and
• an occupant waming system.

Tasks: Assume the probability of a fire in a shopping centre is 0.01. For a fire on the Ground floor, you are required to:

1. Develop an event tree that includes the fire detection system, sprinkler operation. smoke exhaust and occupant warning systems.
2. Use probability values below to calculate probability of each final event.
3. Conditions are acceptable for occupant safety IF at least TWO of the above mentioned fire safety systems work properly. Calculate the probability that the conditions are NOT acceptable for occupant safety
4. What is the change in probability that conditions WILL be acceptable if the existing sprinkler system is upgraded to a new system?
Assumed Probabilities for Question 3
Detection system 95%
Mechanical smoke exhaust system 85%
Occupant warning system 98%
Existing sprinkler system 90%
New sprinkler system 95%

Question 4. A night club building has a smoke detection system and an occupant warning system with tone signal only. Both systems are in good working condition. For an upgrade a perfonnance based fire engineering approach is to be adopted.

You are required to evaluate a number of fire safety systems to be used to upgrade the night club and to recommend the option with lowest risk value. Consider 4 design options each having a combination of any 3 of the following 4 systems:
• Sprinklers
• Mechanical smoke extraction
• Upgrade warning system to a pre-recorded automatic voice alarm system.
• Additional exits

Task:
1. Develop risk assessment event trees which can he used for design validation of the 4 design options.
2. Use system performance consequences in the table below to estimate C_i; (consequence or number of persons exposed) for each final event on your trees.
3. Calculate ΣPi - C_i for each of your designs and compare the design options.

To estimate the Ci values:
• Assume a total building occupant number of 300.
• It was estimated that in the event of a fire in the existing club (with no upgrade) 60 persons would perish whether the existing systems are working or not. The introduction of various systems would reduce the casualties as follows: