State of practice in seismic rehabilitation of buildings and fragility analysis of RC columns retrofitted with FRP

Minor Garcia, Oscar
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The first part of this thesis is a report intended to document the type of works for seismic building retrofits that are taking place in the state of California, where the legislation mandates retrofits of existing infrastructure so that minimum levels of safety are met. These retrofits are mainly on hospitals, but other type of structures such as non-ductile concrete buildings are also included. Five case studies are presented along with the description of the structure, the retrofit techniques, and illustrations to visualize where and how the works have been implemented. Regulations include not only structural but also non-structural elements; therefore, these kinds of works are similarly described. The second part of this thesis concentrates on the determination of the lateral deformation capacity and damage fragility of circular reinforced concrete columns retrofitted with FRP jackets. A database of 56 tests found in the literature is compiled, and it is used to assess the accuracy of two different methods proposed in the literature to estimate the lateral deformation capacity of FRP-jacketed columns. New analytical expressions are developed to compute the ultimate curvature and the plastic hinge length. These equations are used to compute the lateral deformation capacity of the columns in the database, obtaining good estimations. Finally, fragility curves are proposed based the results of tests included in the database. Three damage states are defined: longitudinal reinforcing yielding, discoloration in the FRP wrap and failure of the FRP. Two groups of fragility curves are proposed: group A utilizes story-drift ratio as a demand parameter, and Group B uses story-drift ratio normalized to the theoretical ultimate story-drift ratio. The fragility curves can be utilized in the performance-based evaluation of circular columns retrofitted with FRP.