Occupant evacuation and casualty estimation in a building under earthquake using cellular automata

• We model the emergency evacuation in a building using cellular automata method.
• Evacuation and building collapse simulations are coupled for casualty estimation.
• Casualty estimation is analytical rather than experiential or statistical.
• Occupant distribution, gathering, stranding, locations of casualties are calculated.
• Fragility of casualty and death induced economic loss are calculated.

Knowledge of occupant evacuation process in a building presents engineers with an efficient way of testing the rationality of the building design before construction. Meanwhile, it benefits to the occupant casualty estimation in the building under earthquakes, which has been an essential problem in the performance-based earthquake engineering methodology. The cellular automata model is adopted to simulate the occupant movements in the building. The factors including the behaviors of directional moving to exits, directional moving with crowds, and the competitive phenomenon to a position are included in the model. Evacuation processes at different regions of the building containing room, corridor and staircase are considered and effects of model parameters, competition, exit width, and occupant density are studied. The building collapse under earthquakes is simulated by explicit finite element method. The occupant casualties in an earthquake are evaluated by coupling the building collapse simulation and evacuation process simulation with time and space synchronization. A casualty occurrence criterion is defined using relative displacement. Comparing with existing methods, the presented method can provide estimations on occupant evacuation process and occupant casualties in a more accurate way and provide after-earthquake occupant casualty distributions in the building. Fragility functions of casualty and death caused economic loss are also provided.