Estudio del comportamiento e inestabilidad del refuerzo longitudinal en estructuras de concreto reforzado sometidas a cargas cíclicas

Abstract

During earthquakes, the detachment of the concrete covering in reinforced concrete structures exposes the steel of the longitudinal reinforcement, which can generate its failure by instability. The present work aims to propose a relation between the critical strain of buckling and the slenderness of longitudinal steel bars of reinforced concrete structures under cyclic loads, generating information for efficient seismic resistant design. As a starting point and based on the study of hysteretic cycles and the revised models, a new hysteretic model of the steel is proposed under cyclic loads of compression-traction before the buckling failure. In the second instance, a model is developed that represents the lateral and turning restrictions provided by the stirrups and the diameter of the longitudinal reinforcement, respectively, through which the critical buckling stress can be obtained, considering the existence of eccentricities and its effect caused. With the proposed models, critical buckling stress vs. slenderness ratio and critical buckling strain vs. slenderness ratio curves are obtained, calibrated and optimized with experimental data obtained from the bibliographic review. We compare the calculated eccentricities and the lateral displacements that could present the concrete in walls and columns of the database, to validate the results. Finally, the buckling critical strain vs. slenderness ratio curve is represented by simple mathematical functions, to facilitate its use.