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A R.C beam 300×450mm (effective) is subjected to an ultimate moment of resistance of 240kNm. Determine steel required if σcu=20N/mm2 and σsy=420N/mm2. Use ULM.

Mumbai University > CIVIL > Sem 7 > Limit State Method

Marks: 10 M

Year: May 2013

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Given: b=300mm

d = 450mm.

σcu=fck=20N/mm2σsy=fy=420N/mm2Mu=240kNm

To find = Ast = ?

Mumax=0.25fckbd2=0.25×20×300×4502=303.75kNm

Mu<Mumax Singly reinforced section

Mu=Cu×la=23×fckb×a×(da2)240×106=23×20×300×a×(450a2)

a = 162.77mm

Mu=Tu×la=fy×Ast×(da2)224×106=420×Ast×(450162.772)Astr=1550.2mm2

$Provide \ 5-20 \ mm∅ \\ …

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