Design of shallow foundations
Sivakugan, Nagaratnam, and Pacheco, Marcus (2011) Design of shallow foundations. In: Das, Braja M., (ed.) Geotechnical Engineering Handbook. J. Ross Publishing, Fort Lauderdale, FL, USA, pp. 3-1.
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[Extract] A foundation is a structural element that is expected to transfer a load from a structure to the ground safely. The two major classes of foundations are shallow foundations and deep foundations. A shallow foundation transfers the entire load at a relatively shallow depth. A common understanding is that the depth of a shallow foundation (Df ) must be less than the breadth (B). Breadth is the shorter of the two plan dimensions. Shallow foundations include pad footings, strip (or wall) footings, combined footings, and mat foundations, shown in Figure 3.1. Deep foundations have a greater depth than breadth and include piles, pile groups, and piers, which are discussed in Chapter 4. A typical building can apply 10–15 kPa per floor, depending on the column spacing, type of structure, and number of floors.
Shallow foundations generally are designed to satisfy two criteria: bearing capacity and settlement. The bearing capacity criterion ensures that there is adequate safety against possible bearing capacity failure within the underlying soil. This is done through provision of an adequate factor of safety of about 3. In other words, shallow foundations are designed to carry a working load of one-third of the failure load. For raft foundations, a safety factor of 1.7–2.5 is recommended (Bowles 1996). The settlement criterion ensures that settlement is within acceptable limits. For example, pad and strip footings in granular soils generally are designed to settle less than 25 mm.
|Item Type:||Book Chapter (Research - B1)|
|Date Deposited:||06 Dec 2010 04:41|
|FoR Codes:||09 ENGINEERING > 0905 Civil Engineering > 090501 Civil Geotechnical Engineering @ 100%|
|SEO Codes:||87 CONSTRUCTION > 8702 Construction Design > 870201 Civil Construction Design @ 100%|
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