Effect of loading rate on the nonlinear elastic response of concrete

Abstract

Concretes have been observed to exhibit a rate-dependent mechanical behaviour, and the loading rate has important influence on the nonlinear elastic response of concrete under quasi-static condition. As a phenomenological model, the Preisach–Mayergoyz model has been widely used to analyse the elastic hysteresis of consolidated materials and other materials. In this work, by introducing the viscoelastic mesoscopic units (VMUs) possessing time-dependent peculiarity, a modified PM model was obtained to investigate the rate-dependent effects on nonlinear elastic response of concrete. Creep-like test of a concrete sample to obtain deformation–time curve of the VMU was presented, and a reasonable loading speed for configuration of the modified PM space was proposed. With the modified PM model, nonlinear elastic features of concrete especially the rate-dependent effect were studied. The results obtained in this article indicate that, the theoretical model proposed could reflect the feature of the stress–strain curve with different loading rate, as well as non-equilibrium nonlinear during the loading process. Slope of the stress–strain curve of the concrete sample is larger with increase of the loading rate in the loading process. The higher the loading rate is, the longer the time would be taken for the sample to reach equilibrium state.