Variation of Bilinear Stress-Crack Opening Relation for Tensile Cracking of Concrete at Early Ages

Dept. of Architecturaltural Engineering, Ewha Womans University, Seoul 120-750, KoreaABSTRACT One of the most vulnerable properties in concrete is tensile cracking, which usually happens at early ages due tohydration heat and shrinkage. In order to accurately predict the early age cracking, it needs to find out how stress-crack openingrelation is varying over time. In this study, inverse analyses were performed with the existing experimental data for wedge-splittingtests, and the parameters of the softening curve for the stress-crack opening relation were determined from the best fits of the mea-sured load-CMOD curves. Based on the optimized softening curve, variation of fracture energy over time was first examined, anda model for the stress-crack opening relation at early ages was suggested considering the found feature of the fracture energy. Themodel was verified by comparisons of the peak loads, CMODs at peak loads, and fracture energies obtained from the experimentsand the inverse analysis. Keywords : stress-crack opening relation, softening curve, cracking, ordinary concrete, wedge splitting test, inverse analysis