Fire Damage to Concrete Furnace-Supporting Structure and Formulation of Repair Methodology

Abstract

This paper presents the assessment of a fire-damaged reinforced concrete (RC) supporting structure of an arc furnace. The arc furnace rests over a thick RC slab supported by nine RC columns. During the process of operation, the bottom steel plate of the arc furnace was damaged locally. Liquid hot metal at a temperature of approximately 1,4°C came out through a damaged thermocouple hole and spread out over the floor. Visual inspection, rebound hammer (RH) tests, ultrasonic pulse velocity (UPV) tests, and concrete core sampling, etc., are carried out for the assessment of the present condition. Low UPV and low compressive strength are observed from the in situ measurements, which indicate loss of integrity of the fire-affected concrete. A hybrid methodology is adopted wherein in situ material parameters of the fire-damaged structure from the concrete core samples and rebar samples are used in the analysis to check the structural adequacy of the fire-damaged structure. It is observed that the residual strengths of the structural components are found to be adequate for the given loading. Furthermore, necessary repair measures are suggested to improve quality, integrity, and long-term durability of the furnace-supporting structure.