Recently, many long overpasses are being built in urban areas, and various accidents have also occurred in this regard. In particular, as the traffic of special vehicles, such as heavy trucks and tankers, that become a source of flame increases, fire accidents such as overturning and falling of such vehicles have occurred, and the scale of damage is also increasing.
In the event of a fire accident on a steel bridge, an immediate fire impact temperature range estimation method through on-site investigation is necessary in order to quickly determine whether to implement immediate reinforcement such as limiting vehicle traffic or installing temporary bents.
In this study, for 4 types of general heavy-duty coating systems (urethane, ceramic urethane, polysiloxane, fluorocarbon) for domestic steel bridges according to the standard specifications of the Ministry of Land, Infrastructure and Transport (KCS 14 31 40), the fire impact temperature was estimated by evaluating the steel surface coating condition according to the fire occurrence in the steel bridge. In addition, it is intended to evaluate the reusability of damaged coatings through durability performance analysis according to surface conditions.
Using an electric furnace, the prepared specimens of 4 types of general heavy-duty coating systems are used in temperature conditions of 100℃, 150℃, 200℃, 250℃, 300℃, 400℃, 500℃, 600℃, 700℃ and duration time condition of 30, 60, 120 minutes.
For this, a qualitative evaluation was conducted according to the relevant criteria for the appearance conditions such as cracks, swelling, peeling, and discoloration of the surface, and a quantitative evaluation using a color difference meter and a gloss meter.
In addition, adhesion test for durability evaluation of coating, impedance measurement for anticorrosive performance evaluation, FT-IR analysis for organic chemical structure analysis, E-SEM analysis for precise analysis of surface conditions, and TGA, DSC analysis for material property analysis according to heat were performed.
Using these experimental results, in the event of a fire in a steel bridge with a domestic standard of general heavy-duty coating system, it is possible to estimate the fire temperature only by on-site inspection of the coating of the steel surface using simple equipment, and the reusability of damage coating can be determined.