Concept: The effective length of compression flange for a cantilever beam as per IS 800:2007, Clause No. 8.3.2, and Table No. 16:
Restraint Condition
Loading Condition
At Support
At Top
Normal
Destabilizing
a) Continuous, with lateral restraint to the top flange
i) Free
3.0L
7.5L
ii) Lateral restraint to the top flange
2.7L
7.5L
iii) Torsional restraint
2.7L
4.5L
iv) Lateral and torsional restraint
2.1L
3.6L
b) Continuous, with partial torsional restraint
i) Free
2.0L
5.0L
ii) Lateral restraint to the top flange
1.8L
5.0L
iii) Torsional restraint
1.6L
3.0L
iv) Lateral and torsional restraint
1.4L
2.4L
c) Continuous, with lateral and torsional restraint
i) Free
1.0L
2.5L
ii) Lateral restraint to the top flange
0.9L
2.5L
iii) Torsional restraint
0.8L
1.5L
iv) Lateral and torsional restraint
0.7L
1.2L
d) Restrained laterally, torsionally, and against rotation on plan
i) Free
0.8L
1.4L
ii) Lateral restraint to the top flange
0.7L
1.4L
iii) Torsional restraint
0.6L
0.6L
iv) Lateral and torsional restraint
0.5L
0.5L
So, A cantilever beam of span L is built-in at the support. It is restrained against lateral deflection and torsion at the free end. The effective length of compression flange for the beam as per IS 800 ∶ 2007 is "0.5L"