Lateral Support Condition
If the compression flange is adequately supported in the lateral direction throughout its length as in the case of encased flange (Figure (a)), no reduction in σbc is required. If local support through a cross-beam is provided as shown in Figure (b), the effective length is reduced accordingly.
However the slabs in Figures (c) and (d) are not supposed to provide adequate lateral support to the flange hence the σbc value is to be modified.
Figure
Checking for Maximum Deflection
The maximum permissible deflection in the beam depends upon the user conditions, vibrational effects due to moving loads, etc. The exact calculations for deflections are a bit cumbersome; however the limiting values of δ/L are prescribed for same specific condition as given in Table 2. Here δ is the deflection and L is the span of the beam.