Seismic collapse assessment of non-seismically designed circular RC bridge piers retrofitted with FRP composites

The seismic vulnerability of a bridge pier is generally expressed in terms of fragility curves, which reveal the conditional probability of exceeding a predefined performance damage state at different levels of earthquake intensities. This research presents the results of fragility curves of typical single circular reinforced concrete (RC) bridge piers. The different parameters considered in the analysis include: the strength of concrete, yield strength and amount of longitudinal steel rebar, level of axial load, shear span-depth ratio, and carbon fiber reinforced polymer confinement layer. Nonlinear static pushover analysis (NSPA) is conducted along with incremental dynamic analysis using suits of earthquake ground motions with scaled peak ground acceleration (PGA) to investigate the nonlinear dynamic behavior of the retrofitted piers. The impact of various parameters is evaluated under probability point of view in terms of its influence on the bridge pier fragility curve. Considering collapse drift as demand parameters, fragility curves were generated with different parameters of non-seismically designed RC circular bridge piers. It was observed that the amount of reinforcement, shear span-depth ratio, and level of the axial load could significantly affect the collapse fragility curve of the retrofitted bridge piers.