Seismic upgrading of existing reinforced concrete buildings: A state-of-the-art review

•The seismic upgrading of existing RC buildings is progressively receiving more scientific attention.•Local and global retrofitting measures improve the ductility and capacity, respectively.•Traditional and novel techniques are reviewed in terms of their strengths and weaknesses.•Research gaps on seismic upgrading of RC structures with novel techniques are minor.•Integrating seismic with energy upgrading techniques is a promising research area. Collapses or serious damages of existing buildings during strong earthquakes have resulted in significant economic losses, severe injuries and loss of human lives. Given the late introduction of modern seismic standards and the large number of the existing under-designed buildings, the scientific interest has progressively been focusing on developing techniques for the seismic upgrading of existing buildings. The present paper aims at providing a review of the seismic upgrading techniques, which target reinforced concrete (RC) buildings, as such buildings constitute a large portion of the existing building stock. The retrofitting methods are divided into two distinct categories: the local measures, which enhance the behavior of individual elements and the global ones, which operate on the structure as a whole. Both traditional and novel techniques will be discussed, but the latter will be emphasized.