Recently, corrosion prevention and monitoring of reinforced concrete (RC) structures became an important issue for seismic assessment of such kind of structures. Therefore, it is important to develop adequate models to represent material degradation into seismic behavior simulation of RC structures. Because of its effects, corrosion represents the most important form of degradation for materials and structures, both for wide diffusion and the amount of danger it presents. To understand the corrosion process is critical in order to design RC structures that are able to guarantee the required service life and in order to understand the residual service life and strength of an existing structure. The seismic behavior of a corroded framed RC structure is analyzed by means of push-over analyses, which allow understanding the development of the global behavior of the structure. Three different degrees of corrosion penetration were simulated, by means of the reduction of bars and stirrups’ diameters and concrete cover cracking and spalling, and three different configurations of corrosion, depending on the number of corroded frames and sides of the structural elements.

The beam-column joints are very restricted areas in which the internal forces, generated by boundary elements, act on the concrete core and reinforcing bars with a very high gradient. They are the link between horizontal and vertical structural elements, and therefore, they are directly involved in the transfer of seismic forces. Thus, they are crucial to study the seismic behavior of reinforced concrete (RC) structures. To fully understand the seismic performances and failure modes of beam-column joints in RC buildings, a simplified analytical model of joint behavior is proposed and theoretical simulations are performed. The aim of the model, focusing on internal perimetric joints, is to identify the strength hierarchy in terms of capacity for different failure modes (namely failure of cracked joint, bond failure of passing through bars, flexural/shear failures of columns or beams). It could represent a tool for the designers of new joints to quantify the performance of new structures, but also as a tool for the designers of external strengthening of existing joints in order to calculate the benefits of the retrofit and pushing the initial failure to a more desirable failure mode. Further, some experimental results of tests available in the scientific literature are reported, analyzed and compared.

Worldwide, steel corrosion is one of the greatest deterioration problems for reinforced concrete structures. Comparing some experimental results from literature with a complex FEM model, the present paper points out the principal aspects that characterize the static behavior of reinforced concrete (RC) elements damaged by corrosion. Moreover, the nondimensional abaci defined for some specific case studies finalized to the evaluation of the residual flexural strength of corroded elements highlight the dangerousness of the corrosion degradation if the failure of the element is governed by the steel.