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Structural Concrete - Hassoun

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828 Chapter 20 Seismic Design of Reinforced <strong>Concrete</strong> Structures<br />

Table 20.10<br />

Calculated Member Forces<br />

Location Bending Moment (kip ⋅ ft) Shear (Kip)<br />

Load cases<br />

D Support −95 24<br />

Midspan 65<br />

L Support −22 11<br />

Midspan 15<br />

Q E Support ±290<br />

Midspan 0 ±25<br />

Load combinations<br />

1.4 D Support −133 33.6<br />

Midspan 91<br />

1.2D + 1.6L Support −149 46.4<br />

Midspan 102<br />

1.4D + 0.5L + Q E Support −434/146 a 64.1<br />

Midspan 98.5<br />

D + 0.5L + Q E Support −396/184 a 54.5<br />

Midspan<br />

−473<br />

1.1D + Q E Support −395/186 a 51.4<br />

Midspan −471.5<br />

0.7D + Q E Support −357/224 a 41.8<br />

Midspan 45.5<br />

a Q E<br />

has negative and positive value.<br />

Table 20.11<br />

Calculation of Longitudinal Reinforcement<br />

Location M u<br />

(kip ⋅ ft) A s<br />

(in. 2 ) Reinforcement φM n<br />

(kip ⋅ ft)<br />

Support (top) –434 5.20 7 no. 8 (A s = 5.53 in. 2 ) –474<br />

Support (bottom) 224 3.00 6 no. 7 (A s = 3.6 in. 2 ) 323<br />

Midspan 102 1.20 2 no. 7 (A s = 1.2 in. 2 ) 113<br />

Table 20.12<br />

Summary of Reinforcement<br />

Reinforcement Provided<br />

Location Top Bottom<br />

Support 7 no. 8 (5.53 in. 2 ) 6 no. 7 (3.6 in. 2 )<br />

Midspan 2 no. 8 a (1.58 in. 2 ) 2 no. 7 (1.2 in. 2 )<br />

a Two no. 8 bars are extended from seven no. 8 support bars into the negative moment zone at midspan.

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