Which type of footing is not recommended for an array of columns?

• A. Isolated footing
• B. Strip footing
• C. Raft footing
• D. Pile footing

Answer: (B)

The type of footing that is typically not recommended for an array of columns is strip footing. Strip footings are continuous foundations that are used to support walls or rows of columns rather than individual columns. They work by spreading the load over a long, narrow strip, which can be effective for supporting linear structures or multiple closely spaced columns.

In cases where there is an array of columns, isolated footings, raft footings, or pile footings are generally more suitable. Isolated footings can effectively support individual columns by distributing the load in a way that prevents excessive settlement. Raft footings provide a broad base that can support multiple columns over a large area, which is beneficial in cases of poor soil conditions or heavy loads. Pile footings are installed deep into the ground and can transfer loads to stronger soil layers, making them ideal for structures where surface soil conditions are inadequate.

Selecting a footing system is based on the load distribution, the type of structure, and the site conditions. Therefore, among the choices provided, strip footings are less appropriate for an array of columns, which often requires more robust solutions to manage structural loads effectively.