Preliminary design of beam before going to give properties to the structure in the staad pro preliminary design have to be done to find out the dimensions of beam

1. DESIGN OF T-BEAM
DESIGN OF BEAM
Taking both ends are simply supported
Span le = 6.1 m
Width bw = 0.30 m
Depth of web Dw = 0.45 m
Thickness of flange Df= 120 mm
fck = 20 N/mm²
fy = 415 N/mm²
STEP 1:- DIMENSIONS
Total Load = 6 kN/ m2.
Load transferred from slab = (2 x 6.1+6.1 x 1.5) x 6= 128.1kN..
Self weight = 0.3 x 0.45x 25 x 6.1 = 20.58 kN.
Wall load = 0.3x3.5x20x6.1 = 128.1 kN.
Total load=276.78 kN.
Factored load Wu = 276.78×1.5/6.1 = 68KN/m
Bending moment Mu = Wu l²/8
= 68 x6.1²/8
= 316.28KN/m
Width of flange, bf = lo/6 + bw + 6df
= 3.5/6 + 0.3 +( 6x0.12)
= 1603.3 mm.
Assume effective cover, d’ = 20 mm
Effective depth, d = 0.57-0.02 = 0.550mm
STEP 2:- DEPTH OF NEUTRAL AXIS
Assume neutral axis lies at the junction of the flange and web-
MU lim = 0.36 x fck x Xu x bf [d-0.42x Xu]
= 0.36 x 20 x 1603.3 x 120 [550-0.42x120]
= 692KN-m
Thus, Mu< Mu limit
Hence, neutral axis lies within the flange.
Mu lim = 0.138 x Fck x bf x d2
d = 395 mm<450mm

2. SPAN OF THE BEAM(m) PRELIMINARY BEAM
DIMENSIONS(mm x mm)
6.1 300x450
6.1 300x450
3.6 300x450
3.6 300x450
3.6 300x450
2 230x300
2 230x300
2 230x300