Research On Ductility Design For R.C. Special Shaped Column Of Frame

In each of the specifications for RC structures with special shaped columns of local authorities in China, the ductility design of special shaped columns is controlled by the axial force ratio of the columns which is in relation to ratio of stirrup spacing to the diameter of longitudinal reinforcement, and detailing requirements for stirrup or hoop of special shaped columns are in reference to rectangle shaped column's in Code for design concrete structures (GBJ10-89). However, the limited value of axial force ratio in Code for design concrete structures (GB50010-2002) relates to characteristic value for providing stirrup or hoop. In order to accord with the Code and with respect to characteristic for special shaped column, it should be more necessary to research on the limited value of axial force ratio and detailing requirements for stirrup of RC special shaped columns from the point of characteristic value for providing stirrup or hoop.First, the relation of displacement ductility factor and curvature ductility factor of special shaped columns for frame structure should be derived from beam sidesway mechanism. The required curvature ductility factor of special shaped columns respectively in the case of II, III, and IV seismic fortification grade was attained. And the calculated results of curvature ductility factor of special shaped columns accorded with the tested results well in the case of II seismic fortification grade, It was proved that value of the required curvature ductility factor of special shaped columns should be rational.Second, based on nonlinear analysis, ductility of 12960 special shaped columns'section was calculated and analyzed, the limited value of axial force ratio of special shaped columns was obtained in relation with characteristic value for providing stirrup or hoop; Then influence of arrangement of hoop reinforcement on ductility of special shaped columns was discussed from the point of buckling of longitudinal reinforcement and constraint concrete, detailing requirements for stirrup of special shaped columns were obtained.Third, 17778 sets of RC inequiaxial L shaped columns, 18286 sets of RC inequiaxial T shaped columns, 10560 sets of RC inequiaxial十shaped columns were calculated with nonlinear analysis, many relevant factors including the length ratio of the two legs of the inequiaxial special shaped column, direction angle of bending moment,axial force ratio and ratio of spacing of lateral reinforcement and...