Fire Risk Assessment for Highway Bridges in South Korea

The study presented in this paper developed a sequential and universal bridge fire risk assessment procedure for constructed bridges, as well as countermeasures to reduce the risk level. Of interest were concrete and steel bridges on highways, except for certain special types of bridges. The fire risk assessment procedure consisted of three steps: ( a) preliminary risk analysis (PRA), which was a screening step to determine the likelihood of bridge fire events; ( b) simplified risk analysis (SRA), which was performed with the use of bridge inventory databases and checklists; and ( c) detailed risk analysis (DRA), which made use of computer simulation and collected data. A PRA determines whether a bridge requires an SRA on the basis of bridge clearance height and roadway conditions under the bridge. An SRA has three parts: analysis of fire occurrence, vulnerability to fire, and bridge importance. Itemized details were developed to evaluate the three parts and determine risk scoring. The SRA procedure identified which parts contributed to the resultant risk level. Reliability indexes concurrent with the latest ISO DP 10252 design code were used to determine the score of a given bridge and to perform an analysis to determine the risk level of 8,267 bridges in South Korea. The DRA was the final step, a detailed analysis of occurrence and vulnerability of a bridge mainly on the basis of computer simulation. This study provided guidelines to determine the DRA levels. Countermeasures also were developed for each of three risk levels (i.e., occurrence, vulnerability, and importance); the application of the countermeasures depended on the factors causing the risk.