AN EXPERIMENTAL STUDY ON SEISMIC RETROFITTING METHODS FOR EXISTING REINFORCED CONCRETE COLUMNS WITH EXTERNAL LATERAL REINFORCEMENT ANCHORED AT FOUR CORNERS OF COLUMNS

Since the Hyogo-Ken Nanbu earthquake in 1995, seismic retrofitting of existing RC columns has been carried out. Steel jacket methods are the most commonly adopted, but these methods are not available in the case of RC viaducts whose columns are in contact with or used by shops, store, and houses. A new seismic retrofitting method which can be easily applied in these cases was developed. External lateral reinforcement is arranged around an existing RC column and anchored at the four corners of the column with l-shaped steels. Cyclic loading tests of columns retrofitted with this method confirmed that ductility is much improved.