24.02.2017 Views

Structural Concrete - Hassoun

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

950 Chapter 23 Review Problems on <strong>Concrete</strong> Building Components<br />

106″<br />

8′ 8′<br />

5″<br />

10″ 10″ 10″<br />

(a)<br />

15′<br />

106″ 106″<br />

(b)<br />

Figure 23.4<br />

Series of simply supported beams.<br />

Check for the position of the neutral axis:<br />

(<br />

M uf = φA sy f y d − h )<br />

f<br />

, where A<br />

2<br />

sf = 0.85f c ′ h f b<br />

f y<br />

)<br />

M uf = φ0.85f ′ c h f b e<br />

(<br />

d − h f<br />

2<br />

(<br />

= 0.9(0.85)(3)(5)(45) d − 5 )<br />

2<br />

= 8004K ⋅ in. = 667K ⋅ ft > M u = 90 K ⋅ ft<br />

∴ the neutral axislies within the flange, rec tan gular analysis.<br />

Calculate the required A s<br />

a =<br />

A s f y<br />

0.85f c ′ = (1.57)(60) = 0.82 in.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!