A rectangular reinforced concrete beam 325 x 550 mm (b x d) is provided with 3H25 bar (As = 1473 mm2) as compression steel. Determine the area of tension steel needed for the beam to attain its full moment capacity. Calculate the corresponding ultimate moment of resistance. Assume fck = 30 N/mm2and fyk = 500 N/mm2and d’ = 55mm.
A rectangular reinforced concrete beam 325 x 550 mm (b x d) is provided with 3H25 bar (As = 1473 mm2) as compression steel. Determine the area of tension steel needed for the beam to attain its full moment capacity. Calculate the corresponding ultimate moment of resistance.
Assume fck = 30 N/mm2and fyk = 500 N/mm2and d’ = 55mm.
Take until 2 decimal point for each calculation.
Notes :
Internal forces
Fcc = 0.567fck(b x 0.8x) = 0.454 fck bx
Fst = 0.87 fyk As
Moment of resistance with respect to steel,
M = Fcc.z
Moment of resistance with respect to concrete,
M = Fst.z
Mbal = Kbal fck bd2 where Kbal = 0.167
As ‘ = (M-Mbal) / 0.87 fyk (d-d’)
As = Mbal / 0.87 fyk zbal + As’
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