Multiscale Seismic Assessment of Aged and Deteriorated RC Structures in Marine Environment

The assessment of aged and deteriorated RC existing structures is a complex task because the reliability of the entire process relies on the obtainable knowledge level. The effects of aging, especially in marine environment, must be considered in assessing both the static and seismic performances. Structural details and uncertainties on restraint degree in degraded structures present a clear effect. Generalized corrosion of steel reinforcement induced by chlorides attacks from sea water is one of the most evident causes of strength and ductility loss for RC structures over time. The procedure to assess structures in adverse environments is a performance based multi-scale analysis from materials up to structural system. Non-destructive evaluations, destructive tests and structural identification, as well as all possible methods applicable in controlling deterioration are needed to evaluate the actual damage and to predict future service life. The proposed methodology is referred to “Pontile Nord”, a RC pier that in the past served as working pier for the handling of cargos onto and off ships, especially for raw materials for the adjacent former steel industry, Italsider, in the area of Bagnoli, Naples (Italy). Today it has been transformed into a pleasure pier, a seaside promenade and it is one of the most beautiful touristic attractions of the city of Naples. It is about 896 m long and consists of four sections built in different periods (between 1936 and 1968) and according to different structural schemes. The uncertainty on the residual reinforcement ratio led to evaluate both the cracking moment capacity and the flexural/axial capacity of the elements for different reinforcement ratios. In this way it is possible to check if the concrete only (i.e. without any steel reinforcement) is able to carry the loads, or conversely, what reinforcement ratio is needed to satisfy all the capacity checks.