Abstract: This paper attempts to evaluate the effect of fire
damage on concrete by using nonlinear resonance vibration method,
one of the nonlinear nondestructive method. Concrete exhibits not
only nonlinear stress-strain relation but also hysteresis and discrete
memory effect which are contained in consolidated materials.
Hysteretic materials typically show the linear resonance frequency
shift. Also, the shift of resonance frequency is changed according to
the degree of micro damage. The degree of the shift can be obtained
through nonlinear resonance vibration method. Five exposure
scenarios were considered in order to make different internal micro
damage. Also, the effect of post-fire-curing on fire-damaged concrete
was taken into account to conform the change in internal damage.
Hysteretic nonlinearity parameter was obtained by amplitudedependent
resonance frequency shift after specific curing periods. In
addition, splitting tensile strength was measured on each sample to
characterize the variation of residual strength. Then, a correlation
between the hysteretic nonlinearity parameter and residual strength
was proposed from each test result.