SALIENT FEATURES OF IS:13920 - 1993. CODE OF PRACTICE FOR DUCTILE DETAILING OF RC STRUCTURES SUBJECTED TO SEISMIC FORCES. COLUMN DESIGN: ( Actual program is available in Super Civil CD )
SR	DESCRIPTION
1	Ductile detailing is a must for structures in Zone IV & V. However it should also be followed in zone III, when  Importance factor is > 1.0  OR  Structure is > 5.0 Storey high  OR  the structure is industrial in nature.
2	If the factored axial stress under seismic loads are  < 0.1 fck, than  ductile detailing requirements are not applicable.
3	B/D > 0.40 preferably.
4	Width should not be < 200 MM for span of framing beams up to 5.0 M OR effective height of column up to 4.0 M, else it should be 300 MM.
5	Lap splice shall only be allowed in central half of column length. All splice shall have Ld in tension.
6	Links shall be provided over the entire splice length at spacing not>150 MM.
7	Not more than 50 % of bars to be spliced at one section.
8	Spacing of main longitudinal bars shall not > than 300 MM. Each bar shall have cross tie.
9	All links shall be closed type, having a 135° hook with a 10 Ø extension, but not less than 75 mm at each end.
10	Special confining reinforcement (SCR) requirements  be met with, unless a larger amount of (links) transverse reinforcement is required from shear strength consideration.
11	The length of (SCR) shall not be less than the following. Maximum lateral column dimension. 1 ÷ 6 of clear column span (height). 450 MM.
12	The length of (SCR) shall be at least 300 MM in foundations.
13	When the point of contra-flexure is not within middle half of column than (SCR) shall be provided for full column height.
14	In case of column/shear wall discontinuity (SCR) shall be provided for full height, also it should extend Ld in to the discontinuity.
15	The spacing of (SCR) shall not be more than the following. 1/4 of least column dimension. 100 MM. However it shall not be < 75 MM.
16	Elsewhere the spacing of LINKS shall not < 1/2 of least column dimension.
17	Link spacing shall not be > 300 MM OR 16 Ø. { As per IS-456-2000 }.
18	The minimum area of link bar shall be : ASH = 0.18 * SP*H*FCK/FY {AG/AK -1.0} SP : SPACING OF LINKS. H : MAXIMUM SPACING OF LONGITUDINAL BAR. AG : GROSS AREA. AK = CONCRETE CONFINED CORE AREA.
19	All joints shall have (SCR)  & ASH as mentioned above. However only 50 % of ASH along with (SCR) spacing of 150 MM can be provided in following case. Column having beams from all 4 sides & Beam width > 3/4 Column width.