Identification of Dynamic Behavior Models of Concrete B22.5

Area of Science:

• Materials Science
• Civil Engineering
• Computational Mechanics

Background:

• Dynamic loading poses significant challenges for concrete structures.
• Understanding concrete's behavior under high strain rates is crucial for safety and design.
• Existing models often lack accuracy in predicting failure under dynamic conditions.

Purpose of the Study:

• To experimentally determine the dynamic mechanical properties of fine-grained concrete B22.5.
• To calibrate and validate computational models (*MAT_CONCRETE_DAMAGE and *MAT_CSCM in LS-DYNA) using experimental data.
• To enhance the predictive accuracy of concrete's deformation and destruction under dynamic loads.

Main Methods:

• Experimental testing using the Kolsky (split-Hopkinson pressure bar) method at strain rates from 400 to 2000 s^-1.
• Numerical simulations using LS-DYNA with *MAT_CONCRETE_DAMAGE and *MAT_CSCM models.
• Comparative analysis of model predictions against experimental results through single-element modeling.

Main Results:

• Obtained rate-dependent ultimate stresses and fracture energies in tension and compression.
• Identified model parameters significantly improved predictive capabilities compared to default settings.
• The *MAT_CSCM model, incorporating fracture energy rate dependence, showed more realistic post-ultimate stress behavior.

Conclusions:

• Experimental data on strain rate dependence of fracture characteristics substantially enhances concrete material model accuracy.
• Calibrated LS-DYNA models provide improved simulation of concrete's dynamic response.
• The *MAT_CSCM model's fracture energy rate dependence is key for realistic simulation beyond ultimate stress.