FOUNDATIONS

FOUNDATIONS 11.1 GENERAL CONSIDERATIONS Foundations transfer loads from the building or individual columns to the earth. Types of foundations commonly used are:

 Isolated bases for individual columns  Combined bases for several columns  Rafts for whole buildings which may incorporate basements

All the above types of foundations may bear directly on the ground or be supported on piles. Only isolated and combined bases are considered in this chapter. The type of foundation to be used depends on a number of factors such as

 Soil properties and conditions  Type of structure and loading  Permissible amount of differential settlement

The design of any foundation consists of two parts

 Geotechnical design to determine the safe bearing strength of the soil  Structural design of the foundation using reinforced concrete

The Eurocode governing the geotechnical aspects of foundation design is BS EN 1997-1:2004: Eurocode 7: Geotechnical Design —Part 1: General Rules. Spread foundations are covered in section 6 and in Appendix D. Pile foundations are covered in section 7 of the code. A very useful reference on Eurocode 7 is Bond and Harris (2008). The Eurocode governing the structural aspects of foundation design is BS EN 1992-1-1:2004: Eurocode 2: Design of Concrete Structures Part 1: General Rules and Rules for Buildings. For the vast majority of simple foundations, the two aspects can be treated separately. However for some types of foundations, for example raft foundations, the interaction between the structure and foundation might need to be taken into account. 11.2 GEOTECHNICAL DESIGN The following is a brief description of the important aspects of geotechnical design as given in Eurocode 7.