Dynamic fracture of concrete – compact tension specimen

• Published in: International journal of solids and structures Vol. 48; no. 10; pp. 1534 - 1543
• Main Authors: Ožbolt, Joško, Sharma, Akanshu, Reinhardt, Hans-Wolf
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.05.2011; Elsevier
• Subjects: Applied sciences; Building structure; Buildings. Public works; Compact tension; Compact tension specimen; Concrete; Concrete structure; Concrete structures; Concretes; Construction (buildings and works); Crack branching; Crack propagation; Dynamic fracture; Dynamics; Exact sciences and technology; Finite element analysis; Finite element method; Fracture mechanics; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Loading rate; Mathematical analysis; Measurements. Technique of testing; Microplane model; Physics; Rate sensitivity; Solid mechanics; Structural and continuum mechanics; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...); Crack branching; Microplane model; Compact tension specimen; Rate sensitivity; Concrete; Dynamic fracture; Finite element analysis; Constitutive equation; Mode coupling; Propagation velocity; Ductility; Tension compression fatigue test; Modeling; Static load; Crack propagation; Finite element method; Compact tension test; Strain strength; Damaging; Strain rate; Rupture; Cracking; Quasi static theory; Critical speed; Experimental study; Failure rate; Phenomenological model; Concrete construction; Inertia; Fracture mode; Dynamic load; Mechanical shock; Crack
• ISSN: 0020-7683; 1879-2146
• DOI: 10.1016/j.ijsolstr.2011.01.033

The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, and ductility, and, second, there are inertia forces activated. Both influences are clearly demonstrated in experiments. Moreover, for concrete structures, which exhibit damage and fracture phenomena, the failure mode and cracking pattern depend on loading rate. In general, there is a tendency that with the increase of loading rate the failure mode changes from mode-I to mixed mode. Furthermore, theoretical and experimental investigations indicate that after the crack reaches critical speed of propagation there is crack branching. The present paper focuses on 3D finite-element study of the crack propagation of the concrete compact tension specimen. The rate sensitive microplane model is used as a constitutive law for concrete. The strain-rate influence is captured by the activation energy theory. Inertia forces are implicitly accounted for through dynamic finite element analysis. The results of the study show that the fracture of the specimen strongly depends on the loading rate. For relatively low loading rates there is a single crack due to the mode-I fracture. However, with the increase of loading rate crack branching is observed. Up to certain threshold (critical) loading rate the maximal crack velocity increases with increase of loading rate, however, for higher loading rates maximal velocity of the crack propagation becomes independent of the loading rate. The critical crack velocity at the onset of crack branching is found to be approximately 500 m/s.