Concrete Column Base Plate Design

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Concrete Column Base Plate Design

Civil Engineering & Design

Base plates are usually used to distribute column loads over a large enough area of supporting concrete construction that the design bearing strength of the concrete is not exceeded.

The factored load, Pu, is considered to be uniformly distributed under a base plate.

The nominal bearing strength fp kip/in2 or ksi (MPa) of the concrete is given by:

In most cases, the bearing strength, fp is 0.85Fc when the concrete support is slightly larger than the base plate or , 1.7Fc when the support is a spread footing, pile cap, or mat foundation. Therefore, the required area of a base plate for a factored load Pu is:

where

is the strength reduction factor 0.6. For a wide flange column, A1 should not be less than bf d, where bf is the flange width, in (mm), and d is the depth of column, in (mm).

The length N, in (mm), of a rectangular base plate for a wide-flange column may be taken in the direction of d as:

The width B, in (mm), parallel to the flanges, then, is:

The thickness of the base plate tp, in (mm), is the largest of the values given by the equations that follow:

Where:

m projection of base plate beyond the flange and parallel to the web, in (mm)
(N = 0.95d)/2