Compliance Monitoring of Crack Growth in Concrete

The method of compliance measurement is sometimes used to determine the length of cracks in fatigued metal specimens. This paper considers an application of this method to plain, concrete beams subjected to sinusoidal loading in three point bending. Three beams, prenotched by cutting with a concrete saw, were used to determine a compliance calibration curve. This curve was then used to determine the extent of cracking in eight beams that were fatigue loaded. Of the beams precracked by fatigue loading, six were subsequently statically loaded to failure. A method for estimating the effective fracture toughness based on a test procedure for metal specimens was used to obtain experimental data as input to a finite element model. Results, including fracture surface appearance, indicate that the compliance method is a convenient and suitable testing technique for monitoring crack growth in concrete beams due to fatigue.