Equivalent Frame Method

Assumptions 

The bending moments and shear forces may be determined by an analysis of the structure as a continuous frame and the following assumptions may be made: 

a) The structure shall be considered to be made up of equivalent frames on column lines taken longitudinally and transversely through the building. Each frame consists of a row of equivalent columns or supports, bounded laterally by the centre-line of the panel on each side of the centre-line of the columns or supports. Framesadjacent'and parallel to an edge shall be bounded by the edge and the centre line of the adjacent panel.

b) Each such frame may be analyzed in its entirety, or, for vertical loading, each floor thereof and the roof may be analyzed separately with its columns being assumed fixed at their remote ends. Where slabs are thus analyzed separately, it may be assumed in determining the bending moment at a given support thattheslabisfixed at any support two panels distant therefrom provided the slap continues beyond the point. 

c) Forthe purpose of determining relative stiffness of members. the moment of inertia of any slab or column may be assumed to be that of the gross cross-section of the concrete alone. 

d) Variations of moment of inertia along the axis of the slab on account of provision of drops shall be taken into account. In the case of recessed or coffered slab which is made solid in the region of thecolumns. the stiffening effect may be ignored provided the solid part of the slab does not extend more than 0.15'eI' into the span measured from the centre-line of the columns. The Stiffening effect of flared column heads may be ignored.