What is the formula for taking load from two way slab for beam design?

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How to calculate load from two-way slab on beam?


As per Clause No 24.5 of IS 456: 2000, the loads on beams supporting solid slabs spanning in two directions at right angles and supporting uniformly distributed loads, may be assumed to be in accordance with following Fig.



Let us consider the following example:
ABCD is a two-way slab ( L/B = 1.5<2 )
Assume:
Dead load of slab : 0.125 x 25 = 3.1255 kN/m^2 (100 mm thick slab)
Live load on slab : 3 kN/m^2
Total load = 5.5 kN/m^2
Now for finding force on beam BC the load will come from the triangular hatched part of slab
So we multiply the load by vertical length of triangle to get load on beam per unit length
2∗5.5=11kn/m
fig (b) shows the disribution of load on beam BC ( same will be for beam DC )
(If we convert this load on beam as uniform load we will get maximum bending moment of 11 kN/m but now as we have considered this load in form of triangle so we will get a maximum BM of 14.67 kN/m……Always consider the worst case Mohit Nagpal )
fig (c) load distribution on beam DC


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