Effective Span and Length:

Effective Span of Beams

It shall be taken as the length among the centre of the supports.

Effective Length of Compression Flanges

For simply supported beams where no lateral restraint of the compression flanges is given, but while each end of the beam is restrained against torsion, the effective length 'l' of the compression flange shall be taken as follows. For the ends of the compression flanges:

(i)        Unrestrained against lateral bending (i.e. free to rotate in plan at the bearings) l = span.

(ii)       Partially restrained              l = 0.85 × span

(iii)      Fully restrained against lateral bending (i.e. not free to rotate in plan at the bearing) l = 0.7 × span.

[Note: Restraint against torsion could be provided through]

(i)        Web or flange cleats;

(ii)       Bearing stiffeners acting within conjunction along with the beam bearing;

(iii)      Lateral end frames or other external support to the ends of the compression flange; and

(iv)      Their being built into walls.