Confined high-strength concrete under dynamic compressive loading

High- and very high-strength concretes (HSC and VHSC) are often used for building columns. However, closely spaced hoops are necessary to improve the ductility of such relatively brittle concrete. Such a measure of providing closely spaced transverse reinforcement results in difficulties in concrete placement. This can also present major drawbacks, both regarding assembly control and increased cost associated with required specialized labor. By confining HSC inside a steel circular tube, steel congestion can be avoided while improving concrete behavior and providing more competitive construction cost. The behavior of concrete columns confined inside a steel circular tube has been evaluated when subjected to rapid cycles of compressive loading. Results are compared with those obtained with similar elements subjected to monotonic static loading. Tbe dynamic behavior of confined HSC columns is similar to that of an elastoplastic material where the unloading-reloading branches remain linear and parallel, and the degradation is manifested only through plastic strain. The confined columns are found to be highly capable of absorbing and dissipating energy while featuring a high level of residual strength.