This paper describes an experimental research program on the use of rectang
ular steel jackets for seismic retrofit of nonductile reinforced concrete f
rame columns with inadequate shear strength. Eleven large-scale columns wer
e tested to examine the effectiveness of various types of steel jackets for
improving the ductility and strength of columns with inadequate shear resi
stance. Response of the columns before and after being strengthened with st
eel jackets was examined. Several types of steel jackets were investigated
including rectangular solid steel jackets and partial steel jackets. The te
st results indicate that a thin rectangular steel jacket can be a highly ef
fective retrofit measure for reinforced concrete columns with inadequate sh
ear resistance.