Test on seismic strengthening of RC columns using wire rope and T-plate units

There has been a growing interest in the unbonded-type strengthening technique to enhance the seismic performance of reinforced concrete (RC) columns. The present paper reports the significance and limitation of the strengthening procedure using unbonded wire rope and T-shaped steel plate units, based on flexural tests of RC columns. Five strengthened columns and one unstrengthened column were tested to failure under constant axial load and cyclic lateral loads. The main variables considered were the presence of mortar cover for strengthening steel element and the anchorage method for the T-shaped steel plate. The flexural capacity of the column specimens tested is compared with predictions obtained by using (a) an extended version of the section laminate method and (b) an equivalent stress block specified in ACI 318-05. The displacement ductility ratio of tested columns is also compared with those of conventionally tied columns and of columns strengthened with carbon fibre reinforced polymer (CFRP) sheet...