DUCTILITY OF REINFORCED CONCRETE COLUMN SECTIONS IN SEISMIC DESIGN

THE DUCTILITY REQUIRED OF ECCENTRICALLY LOADED REINFORCED CONCRETE COLUMN SECTIONS IN SEISMIC DESIGN IS DISCUSSED. A METHOD FOR THE DETERMINATION OF THE AMOUNT OF SPECIAL TRANSVERSE STEEL REQUIRED FOR DUCTILITY IS SUGGESTED. THE METHOD IS BASED ON A THEORETICAL STUDY USING STRESS-STRAIN CURVES FOR CONCRETE CONFINED BY RECTANGULAR HOOPS AND FOR STEEL INCLUDING STRAIN HARDENING. THE METHOD TAKES INTO ACCOUNT THE REQUIRED ULTIMATE CURVATURE, THE LEVEL OF AXIAL LOAD, THE LONGITUDINAL STEEL CONTENT, AND THE MATERIAL STRENGTHS. IT IS FOUND THAT PRESENT CODE RECOMMENDATIONS FOR TRANSVERSE STEEL MAY BE LESS THAN APPROPRIATE IN SOME CASES OF HIGH AXIAL LOAD AND LOW LONGITUDINAL STEEL CONTENT, AND COULD BE RELAXED IN SOME OTHER CASES.