Evaluation of residual tensile strength of fire-damaged concrete using a non-linear resonance vibration method

Abstract

The non-linear resonance vibration method is a promising non-linear acoustic technique that has been used to evaluate contact-type defects of concrete induced by exposure to fire. In this work, an experimental study was performed on thin fire-damaged concrete discs to evaluate residual tensile strength using the non-linear resonance vibration method. Using correlation analysis, an experimental relationship is proposed between splitting tensile strength and a hysteretic non-linearity parameter (HNP), as measured from some 350 fire-damaged concrete discs of different mix proportions. In addition, the thermal gradient damage of concrete was examined to verify the efficiency of the proposed equation. It was found that the tensile strength of fire-damaged concrete could be effectively estimated from the measured HNP without consideration of the mix proportion, peak temperature, period after the fire or thermal gradient damage.