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

# Define foundation; design criteria

Foundation Engineering · Chapter 1: Introduction

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

## Question

Define foundation. Enlist the major criteria to be satisfied in the design of foundation. Mention two important things considered during foundation design.

## Short answer

A foundation is the lowest part of a structure that safely transmits loads to the ground. Major criteria: depth below frost and weak soil, safety against shear failure with proper factor of safety, total and differential settlement within limits, structural strength, durability and economy. Two key considerations are bearing capacity and settlement.

## Answer

#### Definition
A **foundation** is the lowest part of a structure, in direct contact with the ground, that transmits the load of the superstructure (and its own weight) safely to the soil or rock below.

#### Major design criteria
- The foundation depth must be adequate (below frost, scour, weak soil and swelling soil).
- It must be safe against shear failure (bearing capacity with a proper factor of safety).
- Total and differential settlement must stay within permissible limits.
- It must be structurally strong, durable and economical.

#### Two important things considered
1. **Bearing capacity:** the soil must not fail in shear under the foundation pressure.
2. **Settlement:** the soil must not settle more than the tolerable total and differential limits. For example, for isolated footings IS 1904 permits about 50 mm in sand and hard clay and about 75 mm in plastic clay.

## Check yourself

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

1. A foundation is best defined as
   A. the lowest part of a structure, in contact with the ground, transmitting loads safely to soil or rock
   B. the whole superstructure above ground
   C. the soil layer below the structure
   D. the plinth beam above ground level
   Answer: A. It is the structural element that transfers superstructure load and its own weight to the ground. (Key point: Definition)

2. The bearing capacity consideration ensures that
   A. the soil does not settle more than 25 mm
   B. the soil does not fail in shear under the foundation pressure
   C. the footing concrete does not crack
   D. the footing is cheap
   Answer: B. Bearing capacity concerns shear failure of soil; settlement is a separate consideration. (Key point: Bearing capacity consideration)

## Related in Foundation Engineering

- [Major criteria in foundation design](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Afoundation-design-criteria) — Foundation Engineering, chapter 1, asked 4×

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