---
title: "Major criteria in foundation design"
subject: "Foundation Engineering"
chapter: 1
key: "semester_5/foundation_engineering:foundation-design-criteria"
source: https://www.bctengineer.com/q/semester_5/foundation_engineering/foundation-design-criteria
site: BCT Engineering
---

# Major criteria in foundation design

Foundation Engineering · Chapter 1: Introduction

- Asked in: 2081 Baisakh, 2 marks; 2076 Asoj, 2 marks; 2072 Chaitra, 2 marks; 2080 Baisakh, 2 marks (asked 4 times)
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/foundation_engineering/foundation-design-criteria
- Whole chapter: https://www.bctengineer.com/md/semester_5/foundation_engineering/chapter-1

## Question

What are the major criteria to be satisfied in the design of a foundation?

## Short answer

A foundation must be placed below frost, scour and seasonal moisture changes; have a factor of safety 2.5-3 against shear failure; limit total and differential settlement to permissible values; be structurally adequate in bending and shear; and be durable and economical.

## Answer

A foundation must carry the structure's load safely and economically. The major criteria are:

1. **Location and depth:** the foundation must be placed below the zone of seasonal moisture change, frost, scour, swelling/shrinkage and made ground, and safe from adjacent excavations.
2. **Safety against shear failure (bearing capacity):** the contact pressure must not exceed the net safe bearing capacity of the soil, i.e. a factor of safety of about 2.5-3 against shear failure.
3. **Tolerable settlement:** total settlement and especially differential settlement must stay within permissible limits so the superstructure is not damaged.
4. **Structural adequacy:** the footing/raft/pile itself must be strong enough in bending, shear and punching.
5. **Durability and economy:** it must resist chemical attack and groundwater, be buildable with local skill and materials, and be the cheapest solution that meets criteria 1-4.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why must a foundation be placed below the zone of seasonal moisture change, frost and scour?
   A. To increase the bearing capacity by making the base wider
   B. To reduce the cost of concrete
   C. So it is not affected by volume change, freezing or erosion of the soil
   D. To avoid the need for any structural design
   Answer: C. Soils near the surface shrink, swell, freeze or wash away, so the base must sit below that zone. (Key point: Depth of foundation)

2. The safety criterion for bearing capacity requires that the contact pressure
   A. not exceed the net safe bearing capacity, with a factor of safety of about 2.5-3
   B. equal the ultimate bearing capacity of the soil
   C. be at least equal to the net safe bearing capacity
   D. exceed the safe bearing capacity by a factor of 2.5-3
   Answer: A. Contact pressure must stay within net safe bearing capacity, which is ultimate capacity divided by FS of about 2.5-3. (Key point: Safety against shear failure)

3. Which settlement is especially important to keep within permissible limits?
   A. Only the elastic settlement of the footing concrete
   B. Only the total settlement, differential does not matter
   C. Settlement of the superstructure materials
   D. Differential settlement, as it damages the superstructure
   Answer: D. Total and especially differential settlement must stay within limits so the superstructure is not damaged. (Key point: Tolerable settlement)

4. The last criterion (durability and economy) requires the foundation to be
   A. the cheapest possible, even if settlement is high
   B. the strongest possible regardless of cost
   C. the cheapest solution that still meets the other criteria
   D. always a raft for uniform behaviour
   Answer: C. Economy means the cheapest option that still satisfies location, safety, settlement and structural criteria. (Key point: Economy)

## Related in Foundation Engineering

- [Define foundation; design criteria](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Adefine-foundation-criteria) — Foundation Engineering, chapter 1, asked 2×
- [Conventional design of mat foundation](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Amat-conventional-design) — Foundation Engineering, chapter 7, asked 3×
- [Why design a mat foundation](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Awhy-design-mat) — Foundation Engineering, chapter 7

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