Residual crack opening in fiber-reinforced structural elements subjected to cyclic loading

In the present work, the fracturing process in fiber-reinforced concrete beams subjected to seismic or generally repeated loadings is discussed, focusing on local phenomena related to the cracked cross-section. In particular, the residual crack opening in structural elements under cyclic loading is investigated. In this context, the Bridged Crack Model can take into account the concrete fracturing mechanism, as well as slippage and yielding of fiber reinforcement. A rigid-plastic constitutive law will be assumed for fibers, whereas for the matrix a linear elastic law, coupled with a fracturing condition according to Linear Elastic Fracture Mechanics will be utilized. In fact, a realistic fiber-reinforced concrete model should simulate an elasto-softening behaviour with the possibility of crack formation and propagation. The Bridged Crack Model is able to predict with accuracy the order of magnitude of some interesting quantities, such as the crack opening and closure in a beam cross-section, the residual crack opening, and the dissipated energy in the loading cycles.