INVERSE ANALYSIS FOR DETERMINING THE TENSILE PROPERTIES OF UHPC BASED ON BENDING RESPONSE OF NOTCHED BEAMS

In order to efficiently obtain the tensile properties of ultra-high performance concrete (UHPC), a simplified inverse analysis method is proposed based on load-crack mouth open displacement (CMOD) response obtained from the notched bending test. The method consists of a hinge model, which takes into account the influence of the crack localization, and a segmented stress-strain relationship, which is capable of describing the tensile strain softening and strain hardening behaviors. The proposed model can accurately predict the first cracking tensile strength and ultimate tensile strength of strain hardening and strain softening UHPC, as validated by the comparison between the predicted results and uniaxial tensile test results. The predicted results are higher than the test results with the increasing discreteness of the bending response. The model parameter analysis indicated that the predicted tensile properties of strain softening UHPC are slightly affected by the reference length and characteristic point number, while the overestimation of predicted ultimate strength was increased with a larger reference length and fewer characteristic points for strain hardening UHPC. The model can be implemented for inverse analysis of the tensile stress-crack width curve.