Title: An Experimental Study for the Fatigue Crack Growth Behavior of Concrete

Author(s): Jin Keun Kim and Yun-Yong Kim

Publication: Symposium Paper

Volume: 172

Issue:

Appears on pages(s): 413-426

Keywords: Calibrating; cracking (fracturing); fracture properties; strength; stresses; tests

DOI: 10.14359/6144

Date: 12/1/1999

Abstract:
In this study, the wedge splitting test(WST) was carried out for the fatigue crack growth behavior of concrete. Selected test variables were concrete compressive strength of 28, 60 and 118 MPa, and stress ratio with 2 levels (6, 13 %). In order to make the designed stress ratio, the maximum and the minimum fatigue loading were 75-85 % and 5~10 % of ultimate static load, respectively. Fatigue testing was preceded by crack mouth opening displacement(CMOD) compliance calibration and fracture energy test, and then the fatigue crack growth was computed by crack length vs. CMOD compliance relations acquisited by the CMOD compliance calibration technique. In fatigue test, the frequency of loading cycle was 1 Hz, and the initial notch length(%) was 30 % of specimen height. To evaluate the validity of CMOD compliance calibration technique, the crack length measured by the method suggested in this study was compared with that predicted by linear elastic fracture mechanics(LEFM). On the basis of the experimental results, a LEFM-based empirical model for fatigue crack growth rate(da/dN-AKi relationships) considering the effects of concrete strength was presented. The fatigue crack growth rate increased with the strength of concrete. It appears that the da/dN-AK1 relationships was influenced by stress ratio, however, the effect is diminished with an increase of strength. In addition, the effect of initial notch length on the fracture energy were shown, and the comparisons between CMOD compliance calibration technique and LEFM gave the validity of CMOD compliance calibration technique for the WST.