Calibration of the continuous surface cap model for concrete

• MAT145 in LS-Dyna is calibrated for a wide range of concretes.
• Only uniaxial compression strength and the maximum aggregate size are required.
• Other parameters are automatically generated.
• The prediction agrees well with the results of material test and impact test of RC beam.
• A comparison between the MAT 145 and MAT 159 for concrete is provided.

The continuous surface cap (MAT 145) model in LS-DYNA is known by its elegant and robust theoretical basis and can well capture many important mechanical behaviors of concrete. However, it appears to be less popular than many other constitutive models in engineering application due to many material parameters involved in the model formulation which are difficult to calibrate. This study presents an effective calibration method to determine the material parameters for this model as functions of uniaxial compression strength and the maximum aggregate size of concrete according to formulas from CEB-FIP code and concrete test data from other published literatures. The obtained parameters can be conveniently used for occasional users with little or no information on concrete in hand. We further compare the predictions of stress–strain relationship in tension and compression under different confining pressures as well as hydrostatic compression by the model, and validate the model based on impact test of RC beams. Besides, the model is further compared against a similar model-MAT 159 in terms of model performance. The results demonstrate that the model based on the calibrated parameters is capable of offering reasonable and robust predictions.