Concrete compressive strength: From material characterization to a structural value

The compressive resistance of concrete in new structures is usually characterized on the basis of tests performed on concrete cylinders or cubes under relatively rapid loading conditions. Although efficient for material characterization, these tests do not acknowledge a number of phenomena potentially influencing the compressive resistance of concrete in actual structures. For this reason, when performing a structural analysis, strength reduction factors are usually considered in codes of practice modifying the uniaxial strength of material tests. In this paper, a detailed investigation of the influence of material brittleness and internal stress redistributions on the structural response of reinforced concrete members is presented. This work is based on a number of theoretical considerations and supported by the experimental results of more than 400 reinforced concrete columns tested with or without eccentricity and gathered from the literature. The results show the pertinence of considering a brittleness factor in the calculation of the structural resistance of reinforced concrete columns and compression zones of beams. The results of this work are eventually formulated in terms of code-like proposals, currently considered in the draft of the new Eurocode 2 (prEN 1992-1-1:2018).