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Structural Concrete - Hassoun

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Problems 487<br />

Section 13.5<br />

Plain concrete may be used to support walls. The maximum flexural stress in tension should be<br />

calculated and must be less than the allowable stress of 5φ √ f ′ c.<br />

Section 13.6<br />

A combined footing is used when a column is located near a property line. Design of such footings<br />

is explained in Example 13.7.<br />

Sections 13.7–13.9<br />

Footings under eccentric column loads are explained in Example 13.8.<br />

REFERENCES<br />

1. R. W. Furlong. “Design Aids for Square Footings.” ACI Journal 62 (March 1965): 363–372.<br />

2. R. Peck, W. Hanson, and T. Thornburn. Foundation Engineering, 2nd ed. Wiley, New York, 1974.<br />

3. ACI Committee 436. “Suggested Design Procedures for Combined Footings and Mats.” ACI Journal 63<br />

(October 1966): 1041–1058.<br />

4. F. Kramrisch and P. Rogers. “Simplified Design of Combined Footings.” Journal of Soil Mechanics and<br />

Foundation Division, ASCE 85 (October 1961).<br />

5. L. S. Blake (ed.). Civil Engineer’s Reference Book, 3rd ed. Butterworths, London, 1975.<br />

6. American <strong>Concrete</strong> Institute (ACI). Building Code Requirements for <strong>Structural</strong> <strong>Concrete</strong>. ACI Code<br />

318–14. ACI Detroit, MI, 2014.<br />

PROBLEMS<br />

For all problems in this chapter, use the following:<br />

H a = distance from bottom of footing to final grade<br />

h = depth of concrete footing<br />

q a = allowable soil pressure in ksf<br />

Assume the weight of the soil is 100 pcf and f y = 60 ksi.<br />

13.1 For each problem in Table 13.1, design a wall footing to support the given reinforced concrete wall<br />

loads. Design for shear and moment; check the development length requirements. Also, determine the<br />

footing bars and their distribution. (Assume d = h − 3.5 in.)<br />

13.2 For each problem in Table 13.2, design a square single footing to support the given square and round<br />

column loads. Design for moments, shear, load transfer, dowel length, and development lengths for<br />

footing main bars. Choose adequate bars and spacings. (Assume d = h − 4.5 in. for all problems.)<br />

13.3 Repeat Problem 13.2a–h using rectangular footings with widths of 6, 6, 8, 8, 7, 8, 6, and 9 ft, respectively.<br />

13.4 Repeat Problem 13.2a–d using rectangular columns of 14 × 20 in., 16 × 20 in., 16 × 24 in., and<br />

12 × 18 in., respectively, and rectangular footings with the length equal to about 1.5 times the width.<br />

13.5 Repeat Problem 13.1a–d using plain concrete wall footings and one-half the applied dead and<br />

live loads.

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