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Structural Concrete - Hassoun

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11.1 Introduction 357<br />

B<br />

C<br />

H A<br />

A<br />

D<br />

V A V D<br />

H D<br />

Figure 11.1<br />

tension side.<br />

Two-hinged portal frame with bending moment diagram drawn on the<br />

Example 11.1<br />

Determine the plastic centroid of the section shown in Fig. 11.2. Given: f c ′ = 4ksiandf y = 60 ksi.<br />

4 no. 9 2 no. 9<br />

F S1<br />

F C<br />

F S2<br />

Solution<br />

Figure 11.2<br />

Example 11.1: Plastic centroid (PC) of section.<br />

1. It is assumed that the concrete is stressed in compression to 0.85 f c ′:<br />

F c = force in concrete =(0.85f c ′)A g<br />

=(0.85 × 4)×14 × 20 = 952 K<br />

Force F c is located at the centroid of the concrete section (at 10 in. from axis A–A).

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