Efeitos da velocidade de endurecimento do cimento nas deformações por fluência do concreto

Abstract

A concrete member, kept under sustained loads, presents progressive deformations over time, associated to creep. Such kind of deformations can develop for a period up to five years, although in your advanced stage, evolve under smallest rates. In reinforced concrete structural members, the creep strains cause the mass of concrete compressive stresses reduction and reinforcement bars stresses increase and may induce its steel to experience the yielding phenomenon. The pioneering formulations describing the phenomenon, were developed on the base of creep coefficient concept and are applicable, especially, when the magnitude of the stresses remains constant. Its application to reinforced concrete members, which exhibits change in the stress magnitude over the highlighted phenomenon development course, requires simplifications of which result the memory models, which have the disadvantage of requiring the storage of the stress history. The state models provides such robustness of storage, that’s why, they are improved from the integrating scheme changing. The aim of this work is the numerical simulation of the mechanical performance of structural members considering the creep of concrete, carried out on the base of a state model, fixing the values of its relevant parameters from NBR 6118/2014 proceedings, paying attention, over all, to the temperature effects. The obtained results show that the temperature accelerates the deformational process associated to creep anticipating the asymptotic level of the stresses in the reinforcement steel bars.