Deformation Capacity of FRP-Strengthened RC Columns with Lap Splices

Deficient lap splices in the plastic hinge regions of RC columns are common in older, seismically vulnerable buildings. Over the last two decades, numerous studies have investigated retrofit strategies for such columns, with fiber-reinforced polymer (FRP) jacketing being one of the most widely adopted. This technical note compiles an experimental database of 75 FRP-jacketed RC columns with insufficient lap splices tested under reversed cyclic loading to assess parameters that impact their deformation capacity. The database is further used to evaluate current American Concrete Institute standard provisions for lap-spliced RC columns. An updated design equation, consistent with the current American Concrete Institute standard, is proposed for determining the minimum FRP thickness to prevent lap splice failure. Alternatively, a minimum clamping coefficient is recommended to calculate the required FRP thickness.