Research on Dynamic Evacuation Simulations in large-scale shopping centers
Abstract
This study chose a large-scale shopping center housed in a typical warehouse-style commercial building as an example to review its fire accident history and to conduct an on-site questionnaire survey to determine the features and conditions of the fire and smoke hazards when this type of building is on fire. The features of the distribution of people and the characteristics of their behavior and responses from the literature were quantified into parameters and inputted into the evacuation model. The FDS+Evac computer simulation software of the performance-based analysis was used to dynamically simulate the amount of time required for evacuation. The present study chose two fire scenarios and, depending on the activation of the fire safety equipment, each scenario was further divided into four more scenarios for discussing their impacts on evacuation. Hazardous impacts from the height of the smoke layer, fire temperature, CO concentration, visibility, and radiation intensity on people during evacuation were simulated and analyzed. The present study further verified and validated the hazardous conditions for the shoppers using the FED value and explored the approach for helping people who need assistance during shopping center evacuation at the time of occurrence. The results show that when fire equipment (smoke exhausts and automatic fire sprinklers) is activated, the majority of people can be evacuated safely. If only one of the equipment is activated, then the activation of the smoke exhaust would work better than the automatic fire sprinklers in protecting people’s lives. For warehouse store fire safety, it is critical to plan the evacuation routes according to the local conditions and enhance guidance for people who need assistance in an emergency evacuation.
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Introduction
In recent years, there have been frequent fire accidents worldwide. Aside from the heavy casualties due to terror attacks, the most serious accidents, in terms of human injuries, deaths and financial losses, often happened at crowded, large-scale shopping centers. For example, the Ycuá Bolaños supermarket fire in Asunción, Paraguay on August 1, 2004 was the most detrimental one; 509 people were killed and 144 injured. Due to industrialization and commercialization, large-scale shopping centers featuring large shopping areas, extensive product lines, and convenient parking have been built in cities to accommodate the needs of consumers. These large-scale shopping centers are filled with not only all sorts of shoppers and but also a lot of combustible goods. Moreover, the many product display racks arranged in the shopping center may block safety routes and sight; not to mention that shoppers can be easily trapped due to the maze-like floor plan inside the large building and the hidden exits and exit indicators. In addition, fire and electricity are frequently used in shopping centers, and when fire happens, they can speed up fire propagation, resulting in not only serious financial losses but also the deaths and injuries of people who fail to find their way out. Therefore, evacuation safety is a critical issue for these types of buildings.
Many evacuation studies such as Shields (1), Ding (2), Cheng (3), Tsai (4), Fang (5), and Hsu (5) are focused on fire prevention strategies, evacuation routes, the analysis of the distribution of people and dynamic flow of people, and evacuation time estimation. Few studies have explored evacuation behavior during fire accidents. Chen and Lin (7) examined the evacuation time required by people in buildings in countries worldwide but they did not take into account the possibility of prolonged evacuation time due to obstructions caused by fire. Neither did these authors assess the evacuation behavior or capability of people.
Conclusion
To create a safe shopping environment, the present study established effective evacuation safety guidelines for warehouse stores that business owners and architects can refer to in building fire prevention design and fire evacuation safety drill planning. Here are the major conclusions based on the findings of the present study.
1. It is important to pay attention to the regional tumble phenomenon and to control combustible items at each area. It is especially critical to avoid putting too many combustible items at fire prevention zones or placing combustible items near these zones in order to prevent the flashover phenomenon, which may push burning to its peak state.
2. At the beginning of a fire accident, it is more important to activate the smoke exhaust equipment, instead of the automatic fire sprinkler equipment as early as possible to better protect people’s lives. As for the automatic fire sprinkler equipment, it is more effective in slowing down fire propagation and fire extinguishment. Because of the competing conditions between the smoke exhaust equipment and the automatic fire sprinkler equipment, it is important to have professionals conduct routine maintenance to make sure that the equipment functions effectively during fire accidents.
3. During a fire evacuation, women, children, elderly people, and other people who need assistance are more likely to be trapped in the fire. They need special guidance during evacuation. For self-protection fire prevention training, evacuation drills should be a focus.
4. During the design stage, the accuracy of the fire safety and fire evacuation equipment safety inspection and performance assessment results should be improved.
The conventional performance-based design is composed of two parts: fire development and evacuation of people. Nonetheless, fire accidents may block evacuation, forcing some people to change their evacuation routes. Furthermore, fire may also prolong the evacuation time because it may reduce the use rate of certain exits, causing other exits to be congested by crowds trying to escape. This study took the distribution characteristics of evacuation pre-movement time into consideration and combined route selection and fire accident together in performance-based evaluation for building fires. This approach is different from the conventional approach, which only uses the height of the smoke layer, visibility, and temperature in the evaluation. The present study also combined evacuation and fractional effective dose (FED) for the performance-based evaluation for building fires. It is a new attempt and has eliminated the shortcomings of the conventional performance design, which only uses the time of the occurrence of untenable conditions to determine the hazardous condition. In contrast, the new approach developed by this study has quantified the performance-based design, thereby making the approach more scientific. Through the evacuation safety performance design, alternative design plans can be adopted to make the evacuation safety design of large-scale commercial buildings more flexible and reasonable. The information here can be used to improve the evacuation safety criteria in the performance-based design. For a good building design project, the performance-based concept and approach should be adopted at the design stage, and computer simulation software, such as the evacuation software, the structure computation software, day light analysis software, and energysavings software, can be employed to inspect or correct those natural shortcomings of the design project to ensure safe building evacuation and to prevent serious injuries and causalities in an emergency situation. The above ideas are especially crucial and urgent for the initial building permit validation of large-scale public buildings or places in lots of people gather.A conclusion section must be included and should indicate clearly the advantages, limitations, and possible applications of the paper. Although a conclusion may review the main points of the paper, do not replicate the abstract as the conclusion. A conclusion might elaborate on the importance of the work or suggest applications and extensions.