SALIENT FEATURES OF IS:13920 - 1993.
CODE OF PRACTICE FOR DUCTILE DETAILING OF RC STRUCTURES
SUBJECTED TO SEISMIC FORCES.
BEAM 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 Minimum longitudinal reinforcement on any face/section shall be :
0.24 * sqrt (fck)/fy
3 The factored axial stress shall not be > 0.1 fck, else the beam should be designed as column.
4 B/D > 0.30 preferably.
5 B should not be < 200 MM.
6 The maximum steel ratio should not be > 2.5 % per face.
7 Beam should not be a DEEP beam.
8 +ve reinforcement should not be < 50 % of -ve steel at that joint.
9 Minimum steel at any section face shall not be < 25 % of maximum -ve steel at any joint.
10 Re-distribution of support moments are not allowed for seismic moments at joints.
11 Development length {Ld} = Ld + 10 x at end joints of column/beam.
12 Top & bottom reinforcements shall be continuous at column joints.
13 All links shall be closed type, having a 135 hook with a 10 extension, but not less than 75 mm at each end.
14 The longitudinal bars shall be spliced, only if links are provided over the entire splice length at spacing not > 150 MM.
15 All splice shall have Ld in tension.
16 Lap splice shall not be at :
Column Joints.
2 x d from column face.
Within 0.25 x span.
17 Not > 50 % of bars shall be spliced at any section.
18 The Minimum link shall be 6 MM for span < 5.0 M.
Use 8 MM links for span > 5.0 M. 
19 The Links shall be designed for :
Factored SF as per Analysis.
SF due to formation of plastic hinges at both ends + gravity loads as per analysis.
20 Spacing of Links within 2 x d from supports shall be minimum of :
d/4
8 x of smallest longitudinal bar.
21 Spacing of links shall not be < 100 MM.
22 1st link shall start 50 mm away from support.
23 Spacing of links away from 2 x d from support shall not be > d 2.
24  Link spacing shall not be > 300 MM. { As per IS-456-2000 }.
25 The top as well as bottom reinforcement shall atleast have 2 bars continuous throughout the whole member.
26 We have restricted the beam section to an Under-Reinforced Section so that they can undergo large rotation before failure. The contribution of concrete towards shear strength is neglected.