Experimental tests were conducted on seven 1/3-scale column specimens to evaluate the vulnerabilities of existing cruciform-shaped columns and to develop appropriate retrofit measures that address the identified vulnerabilities. The specimens represented both solid and split columns in the Aurora Avenue Bridge in Seattle, Washington. The as-built specimens failed at low ductility levels due to shear distress. Fiber reinforced polymer (FRP) jackets with FRP inserts to anchor the jackets in the column reentrant corners along with steel confinement collars to provide confinement in the hinging regions were used to retrofit the column specimens. The retrofitted specimens developed plastic hinging in the column, with enhanced strength, energy and ductility capacities. Guidelines were presented for designing the various components of the retrofit measures.