Inverse analyses of bending tests for determining the properties of strain hardening cement-based materials

A procedure for determining the mechanical material properties of strain hardening cement-based materials is proposed. It is based on the inverse analysis of bending tests. The experimental results obtained under four-point bending of unnotched specimens allow the determination of the strain hardening curve up to the localization point. A load-crack opening relationship describing the behavior after the localization point is determined on the basis of bending tests at notched specimens. For the numerical simulation of the experiments, a hardening/softening behavior under tension and a non-linear stress-strain curve under compression have been adopted. The optimization required in the inverse analyses is performed by using an evolutionary algorithm which proved be an appropriate as well as efficient numerical tool for the problem to be solved here. The results obtained by inverse analyses of bending tests are compared with those obtained in direct tension tests.