Question

When the allowable soil is low or the building loads are heavy, the footing used is ___________

(a) Raft footing

(b) Strap footing

(c) Trapezoidal combined footing

(d) Rectangular combined footing

This question was posed to me in an interview for job.

The origin of the question is Shallow Foundations in division Shallow Foundations of Geotechnical Engineering II

Answer 1

The correct option is (a) Raft footing

For explanation I would say: When the allowable soil pressure is low, or the building loads are heavy, the use of spread footings would cover more than one-half of the area and it may prove more economical to use mat or raft foundation.