DEGRADATION OF ELASTIC MODULUS IN CONCRETE DURING CYCLIC COMPRESSION TESTING

Abstract

Concrete is a heterogeneous quasi-brittle material whose response under cyclic compressive loading is characterized by nonlinear stress–strain behavior, residual strain accumulation, and progressive stiffness degradation. Previous studies have shown that repeated compressive loading produces stress–strain hysteresis loops, whose shape reflects the development of irreversible deformation and internal damage in concrete [1–3]. These effects are commonly associated with the initiation and propagation of microcracks in the cement matrix and at the aggregate–cement paste interface.The degradation of stiffness can be interpreted within the framework of damage mechanics, in which the reduction in elastic modulus is related to the evolution of a damage variable [4]. The aim of this paper is to present a brief experimental analysis of the cyclic compressive response of concrete, with particular attention to hysteresis loops, energy dissipation, residual deformation, and stiffness degradation.