We devised three types of postearthquake modifications for exposed steel column bases which resisted bending moment and shear force, and investigated the effects of the modifications experimentally. For column bases damaged by shear force, the following two modifications were planned; 1) a modification using shear-resisting plates welded under a steel base plate, and 2) a modification of cladding a column base with a reinforced concrete stub. For a column base damaged by bending moment, a modification of cladding the column base with a concrete stub and fixing steel plates to the outside of the concrete stub was adopted. The effects of these modifications on the strength, deformation capacity and stiffness of the column bases were discussed using the results of premodification and postmodification tests.
