MODELING FRACTURE OF REINFORCED CONCRETE STRUCTURES UNDER IMPACT

Introduction : The papers presents results of an integrated experimental and numerical study on behavior of reinforced-concrete beams under impulse loading. The beams under study had three layers. The upper and lower layers were of fiber-reinforced concrete with a carbon fiber volume fraction of 0.2%. The middle layer was of concrete with metal reinforcement. Methods : Experimental studies were performed using a pile driver. A falling weight of 450 kg was dropped on a beam from a height of 0.7 m. The authors performed numerical studies based on the finite element method in a full dynamic 3D setting, using the proprietary EFES software suite considering structure fragmentation, formation of contact and free surfaces. Results : In numerical modeling, the reinforcement mesh was clearly defined. The authors studied changes over time in the stress-strain state, and fracture of reinforced-concrete beams under short-term impact loading. They developed a calculation algorithm and procedure that made it possible to analyze and predict behavior of actual structures in a full dynamic 3D setting. They also proposed a model of concrete and fiber-reinforced concrete behavior, considering anisotropy, bimodularity with regard to strength characteristics, plastic properties, and relations between strength and strain rate / pressure. Fracture dynamics in concrete beams reinforced with metal bars was studied. Good agreement of the results with the experimental data was observed.