Текст A

COLUMNS IN WALLS

A common problem in the design of building foundations is a foundation wall that must share its location with a row of columns. This takes place along the exterior

walls of buildings with frame struc­tures. When loads are transferred to the ground there are various possibilities for the relationships between the columns, the wall, and the foundation elements. The column loads may be light, as in the case of a one-storey building with light construction and short spans or the column loads may be large, as in the case of a multi-storey building.

Type of Foundation. If the foundation consists of deep elements, either piers or groups of piles, the wall is usually designed as a spanning element of one type or another. When the foundation is of the shallow bearing type, there may be several possibilities for the column/wall/footing relationships.

example (see fig. 2)

Allowable soil pressure: 3000 psf (150 kPa).

Concrete design strength: 3000 psi (21 MPa).

Allowable tension on reinforcing: 20.000 psi (140 MPa).

FIGURE 2

Considering the wall by itself and ignoring the columns, the minimum wall footing according to our estimates is 11in. thick, 42in. wide. Thus, if we want to ignore the spanning potential of the wall, this would be the required footing for the wall between the column footings. For the column, if it were freestanding and not in the line of the wall, the required square footing would be 6ft², 16in. thick. However, in this case even if it is decided to use a square footing, it would need to be larger, since it also supports part of the wall. And the larger it is, the more of the wall it supports. If we increase its size to 8ft², the total load on the footing will be the column load of 100 k plus 8ft of the wall load at 10 k/ft, or a total load of 180 k.

Notes:

freestanding adj. свободностоящий

ignore v. не принимать в расчёт