Structural Concrete - Hassoun

418 Chapter 11 Members in Compression and Bending
11.8 (Design of rectangular column sections) For each assigned problem in Table 11.4, design a rectangular
column section to support the factored load and moment shown. Determine A s , A ′ s ,andh if not given;
then choose adequate bars considering that A s = A ′ s . The final total steel ratio, ρ g , should be close to
the given values where applicable. Check the load capacity, φP n , of the final section using statics and
equilibrium equations. One solution for each problem is given in Table 11.4.
11.9 (ACI charts) Repeat Problems 11.2b, 11.2d, 11.2f, 11.8a, 11.8c, and 11.8e using the ACI charts.
11.10 (Circular columns: balanced condition) Determine the balanced load capacity, φP b , the balanced
moment, φM b , and the balanced eccentricity, e b , for the circular tied sections shown in Fig. 11.36. Use
f c ′ = 4ksiandf y = 60 ksi.
11.11 Repeat Problem 11.10 for Fig. 11.37.
Table 11.4 Problem 11.8
One Solution
Number f ′ c (ksi) P u (K) M u (K ⋅ ft) b (in.) h (in.) ρ g % h (in.) A s − A′ s
a 4 530 353 16 — 4.0 20 5 no. 10
b 4 410 205 14 18 — 18 5 no. 8
c 4 480 640 18 — 3.5 24 6 no. 10
d 4 440 440 20 20 — 20 6 no. 9
e 4 1125 375 20 24 — 24 6 no. 10
f 4 710 473 18 — 3.0 24 5 no. 10
g 5 300 300 14 — 2.0 20 3 no. 9
h 5 1000 665 20 26 — 26 6 no. 10
i 6 590 197 14 — 2.0 18 2 no. 10
j 6 664 332 16 20 — 20 4 no. 9
6 no. 9 bars
Figure 11.36 Problem 11.10.
8 no. 10 bars
Figure 11.37 Problem 11.11.