An evacuation model: the SGEM package

The United Kingdom, New Zealand, Australia, Sweden, Hong Kong and many other developed countries are moving away from the prescriptive-based building/fire codes and towards performance-based approaches. Designers adopt a fire safety engineering approach to provide rational design on the basis of performance criteria. One of the major issues in fire safety engineering design refers to the design of the escape system. It can be regarded as the skeleton of many fire safety engineering designs, in particular for the evaluation of life safety of occupants. In view of the complexity of modern buildings, it is difficult to model the escape pattern of the occupants by simple calculations. With the advancement of digital computers, many researchers have recently developed computer-based evacuation models. For modern complex buildings, it may be time-consuming to develop the input for simulation. This article describes an evacuation model-spatial-grid evacuation model (SGEM), which includes a pre-processing engine to assist in the transformation of the spatial information from computer-aided design (CAD) based architectural plans and perform a simulation to generate the escape patterns in many complex buildings. This model resolves the setting of a building into a network with a series of nodes. Each node consists of a loop (an open-loop) representing enclosed spaces with at least one opening that serves as an arc of the network, and other close-loops, which represent obstacles, can exist in the open-loop. The geometrical and spatial information captured from CAD plans will be integrated with the simulator, and the movement of evacuees is solved by a series of difference equations, within a finite grid that is generated within a node. The trajectory of each individual is recorded and the evacuation pattern will be visualized under the AutoCAD environment. In addition, a crowd flow function which has been generated by a gas-lattice model is adopted in the model. (C) 2003 Elsevier Ltd. All rights reserved.