Study On The Ductility Performance Of Special-shaped Reinforced Concrete Column

Special-shaped columns are RC columns with T-shaped section, L-shaped section, +-shaped section and Z-shaped section. The ratio of height to width of the section is not greater than 4. The buildings with Special-shaped columns are applied in many cities in our country with the advantage of not appearing column edges indoors, being easy to arrange furniture, extending service areas. Based on the past research findings, the ductility capability of the RC columns with T-shaped section are studied in this paper. The chief research results are summarized as follows:First, the calculating formulas of yield curvature and ultimate curvature for T-shaped columns are derived when web and flange are pressed respectively, which are divided into two groups as the big axial compression ratio and the small axial compression ratio. The calculating formulas of the curvature ductility are given when web and flange are pressed respectively.Second, the boundary value of the axial compression ratio for T-shaped column is derived and the influencing factors of the boundary Value of the axial load ratio are studied when web and flange are pressed respectively. At last, the approximate calculating formulas of the boundary value are given in these two cases.Third, the influencing factors of the yield curvature for T-shaped columns, including the ratio of height to width of the column limb h/b , the ratio of axial compression ηk, the ratio of reinforcement of the longitudinal reinforcement ρs, and the ratio of the strength of the reinforcement to the concrete nf etc. are studied when web and flange are pressed respectively, which are also divided into two groups as the big and the small axial load ratio. And therelations between the yield curvature and each influencing factor are deduced. At last, the simplified calculating formulas of the yield curvature are given by fitting a large group of data in each case.Fourth, the calculating formulas of the ultimate curvature and the curvature ductility factor for T-shaped column are decuced respectively when web and flange are pressed. And the calculating formulas for the ultimate curvature and the curvature ductile factor are given. Each influencing factor on curvature ductility factor is studied, including the ratio of height to width of the column limb h / b, the ratio of axial compression rjk, the ratio of reinforcement of the longitudinal reinforcement ps, and the ratio of the strength of reinforcement to concrete nf, the diameter of stirrup d and the spacing of stirrup sp etc. The main influencing factors are found and the practical formulas are given which can be referred to in design.Finally, to compare with the experiment which was carried out by Professor Cao Wanlin who performed it in Beijing University of Technology on the capability of the RC T-shaped columns which was endured by the plane periodic load exerted from different direction repeatedly, we find that the gap between them is small. So the calculating formulas of the curvature ductile factor which is derived in this paper can be used in design. But it should be proved further.