Investigation of damage in concrete columns under variable loading

Abstract

Accumulation of the global and the local damage under combined loading consisting of constant longitudinal and transverse cyclic loads in reinforced high-strength concrete columns is experimentally investigated. Two identical column specimens with annular cross-section and spiral reinforcement were designed and two tests, up to failure, were carried out at the LNEC shaking table facility. The specimens were designed and reinforced in such a way that the accumulation of damage was predicted by dominating deformations (cracking and crushing of the concrete) while the increasing of the loading values was a dominating factor of damage. Sine type signals, controlled in amplitude, frequency and time duration were used for these experiments. Accumulation the global and the local damage based on concept of the stiffness degradation is considered in detail and illustrated by experimental results.