Building Construction Handbook, Sixth Edition

Part 4: Substructure

Foundations Function, Materials and Sizing

Foundations Functions

Foundations ~ the function of any foundation is to safely sustain and transmit to the ground on which it rests the combined dead, imposed and wind loads in such a manner as not to cause any settlement or other movement which would impair the stability or cause damage to any part of the building.

Example ~

Subsoil beneath foundation is compressed and reacts by exerting an upward pressure to resist foundation loading. If foundation load exceeds maximum passive pressure of ground (i.e. bearing capacity) a downward movement of the foundation could occur. Remedy is to increase plan size of foundation to reduce the load per unit area or alternatively reduce the loadings being carried by the foundations.

Foundations Subsoil Movements

Subsoil Movements ~ these are due primarily to changes in volume when the subsoil becomes wet or dry and occurs near the upper surface of the soil. Compact granular soils such as gravel suffer very little movement whereas cohesive soils such as clay do suffer volume changes near the upper surface. Similar volume changes can occur due to water held in the subsoil freezing and expanding this is called Frost Heave.

Typical Example ~

Trees ~ damage to foundations. Substructural damage to buildings can occur with direct physical contact by tree roots. More common is the indirect effect of moisture shrinkage or heave, particularly apparent in clay subsoils.

Shrinkage is most evident in long periods of dry weather, compounded by moisture abstraction from vegetation. Notably...

UNLIMITED FREE ACCESS TO THE WORLD'S BEST IDEAS

close
Already an Engineering360 user? Log in.

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.

Customize Your Engineering360 Experience

close
Category: Waterproofing Membranes
Privacy Policy

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.