Experimental and numerical investigation on the dynamic increase factor of tensile strength in concrete

A unique design for a vertical tension split Hopkinson bar (TSHB) with steel bars 100 mm in diameter and an aluminum hammer is presented. This facility was used to investigate the behavior of concrete under dynamic tension. Experiments conducted with specially shaped concrete samples demonstrate that the testing system is capable of accurately depicting the dynamic tensile strength of concrete. The experimental data were used to calibrate three concrete material models implemented in the numerical code LS-DYNA: (1) The Karagozian & Case (K&C) concrete damage model (*MAT_072R3), (2) the 072-BGU version of the K&C damage model, and (3) the continuous smooth cap model (*MAT_CSCM, *MAT_159). It was found that the automatic generation option included in these models does not provide satisfactory results. However, by readjusting only a few parameters of each of these material models, very good agreement between experimental and numerical results was achieved. This paper outlines the necessary calibration process and its theoretical background.