In this study, seismic retrofitting of undamaged and moderately damaged RC columns with CFRP was investigated. The experimental program was conducted on five RC columns with inadequate tie spacing, 90-degree hooks at tie ends, and plain (undeformed) reinforcing bars. Columns were tested under a constant axial load of 27% of axial capacity and under reversed lateral cyclic loading. The primary objective of this study was to investigate the influence of sustained axial load during repairing, damage, and corner-rounding radius of CFRP wraps on the seismic performance of RC columns. Improved performance in terms of ductility, dissipated energy, and secant-stiffness degradation was observed for the CFRP strengthened columns. Reducing the corner-rounding radius deteriorated the seismic behavior of the columns, while the stiffness degradation response remained unaffected. The sustained axial load during repairing had only minor effect on column behavior. After CFRP repairing, the increase in yield drift ratio and curvature was observed to be in proportion with the corresponding consumed ductility values during damage cycles. A drift-based design equation for FRP repaired columns was proposed that considers the damage amount and axial load level as the major parameters as consistent with the experimental results.

The structural performance of reinforced concrete bridges is crucial regarding the bridge safety. Monitoring the bridge performance under multihazard effects such as scour, and earthquake becomes even more important. Thus, the scour depth along the piers and piles of bridge substructures has to be measured and tracked consistently in order for reliable multi-hazard bridge behaviour predictions. A practical Unmanned Aerial Vehicle based scour measurement method was proposed to increase the measurement accuracy and reduce the implementation costs. This method has been used in shallow and clear-water riverbeds. The Boğaçayı Bridge was selected as the case study located at the Boğaçayı River in Antalya, Turkey, since it was exposed to stream and flood, induced scour in the previous years. In the study region, the amount of scour was determined with considerable accuracy, and the scour measurements were used for generating the Three-Dimensional Finite Element model of the bridge. The multi-hazard performance of the bridge was acquired by implementing nonlinear static analysis using pushover curves corresponding to various scour depths concentrated at some of the bridge piers. Therefore, a continuously updateable multi-hazard bridge assessment system was proposed, which was implemented in bridges under scour and earthquake effects, regarding Unmanned Aerial Vehicle based measurements.