Example 1: Determining Steel Area When Beam Dimensions Are Predetermined

The dimensions of the beam shown in Figure 1 have been selected for architectural reasons. Determine the reinforcing steel area by each of the methods described in this section. example2b12bpredetermined-5405619

Mu/(Ф*b*d^2) =(1920000)/(0.9*21^2*16)=302.3psi ρ from table A.12
by interpolation  ρ ——–(0.0054-0.0053)/(303.4-298.1)=(0.0054-ρ)/(303.4-302.3) As=ρ*b*d=0.00538*16*21=1.81in2

Use 6 #5 bars (1.84 in.2) a-12-9411786The second method(The use of ρ formula)
untitled-7796858 ρ=(0.85*3000/60000*(1-√(1-(302.3/(0.85*6000))

The third method(Trial and error method) a=(1.78*60000/(0.85*3000*16)) a=(1.81*60000/(0.85*3000*16)) construction management: concrete construction
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