The mechanical properties of concrete materials vary with the loading rate underdynamic conditions, which can influence the dynamic fracture behavior of structures. The ratedependency is reported as due to the microscopic mechanisms, such as a material inertia effectand the Stefan effect. In this study, the rigid-body-spring network (RBSN) is employed forthe fracture analysis, and the visco-plastic damage model is implemented to represent the rateeffect in this macroscopic simulation framework. The parameters in the Perzyna type visco-plastic formulation are adjusted through the direct tensile test with various loading rates asa preliminary calibration. As the loading rate increases, the strength increase is presented interms of the dynamic increase factor (DIF), and compared with the experimental and empiricalresults. Next, the flexural beam test is conducted for plain and reinforced concrete beams underslow and impact rates of loading. At the failure stage, different crack patterns are observeddepending on the loading rate. The impact loading induces the failure to be more localizedon the compressive zone of the beam, which is due to rather the rate dependent materialfeatures. In structural aspects, the reinforcement exerts stronger effects on reducing crack widthand improving ductility at the slow loading rate. The ductility is also evaluated through thecomparison of load-deformation curves until the final rupture of the beams. This study canprovide understandings of the structural rate dependent behavior and the reinforcing effectunder dynamic loadings.
New methodology for calculating damage variables evolution in Plastic Damage Model for RC structures
