Influence of Material Variation and Corrosion Deterioration on Seismic Vulnerability Assessment of RC Buildings in North Cyprus

During the last few years there have been a growing interest in studies on corrosion related deterioration, parallel to the increase in the expected service life of buildings. The existing literature reveals that corroded reinforced concrete elements results in a brittle global structural behaviour. Due to the late adaptation of proper construction material standards and seismic design provisions in the Mediterranean region, the current building stock faces significant variation in seismic resistance. Likewise the humid environment and the use of chloride contaminated concrete aggregates resulted in a further deficiency, leading to deterioration of the reinforced concrete elements. In this study, the local concrete material as well as naturally corroded local reinforcing steel from North Cyprus was tested. The provided empirical steel material deterioration relationships were then considered in developing fragility curves for the building stock in North Cyprus. Furthermore, the unique character of the local design practice was simulated on scaled columns. The static cyclic tests were performed to assess the ductility degradation phenomena of the lightly reinforced columns with inappropriate stirrup settings. Based on the local design information, deterministic frame models were generated in the second part of the thesis. The parametrically assessed concrete strength, allows identifying the corrosion related reduction in seismic resistance of the “seismic” and “pre-seismic” reinforced concrete buildings (i.e. the pre-1999 reinforced concrete structures designed according to modern seismic design provisions and those belonging to a previous era, respectively). The presented fragility functions, highlight the significance of considering the combined corrosion effects, such as reinforcement buckling phenomena, type specific bond and deterioration models, time period specific material strength, and the corresponding effects in seismic resistance. The corresponding dependence of modelling parameters on seismic performance of seismic and pre-seismic reinforced concrete buildings are then discussed in detail. The results revealed that, considering the combined effects of corrosion resulted in a further 37% reduction in seismic capacity of the pre-seismic models in comparison to seismic models when subjected to the same corrosion level. Finally, the vulnerability curves are presented based on the effect of concrete strength on both building groups. Keywords: Corrosion, aging effects, seismic fragility, concrete strength, Cyprus