Directed Graph Based Risk Analysis of Fire Spread in Buildings in Chinese Traditional Villages

In the development and protection of traditional villages, building renovation and layout change for fire prevention may cause the changes in fire risk. Fire spread simulation is marked by large workloads, high costs and difficulty in acquiring basic data. To cope with these, first, the single building is regarded as the node of the directed graph, and the fire spread relationship between buildings as the edge between nodes. The local spread path around the node is judged through the fire spread simulation, the adjacency matrix of the directed graph is established, the spread range under a specific fire scene is determined by the traversing directed graph algorithm, and the loss expectation for the multiple fire spread scenarios is presented. The adjacency matrix of the directed graph is modified by adding and deleting nodes or edges to reflect the changes of building renovation and addition and trees on the fire spread relationships, and the traversing algorithm of nodes is reused to determine the fire spread risk of the buildings. Finally, a traditional village is used as an example to verify the proposed method. The results show that the proposed method can quickly calculate the fire spread risk of the dynamically changing village buildings and reduces the workload of fire spread re-simulation. In terms of fire spread prevention and control, the maximum loss and loss expectation of fire spread between buildings can be respectively reduced by 61.9% and 52.1% through improving fire preventions of 6 highly-risky nodes. For building planning or management, it is necessary to avoid the case of new buildings, trees and other combustible materials locating in densely built areas or link-nodes connecting multiple densely built areas.