Author: The Institution of Structural Engineers
1 August 2013
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The Institution of Structural Engineers
The purpose of a pad foundation is to spread a concentrated force into soil. They are one of the most simple and cost effective types of footings for structures. Provided the founding soil is of sufficient strength and is not too deep to reach, pad foundations are the preferred solution for foundations due to the straight forward nature of their design and construction. This Technical Guidance Note covers the design of concrete pad foundations, both mass and reinforced concrete forms. It will not, however, discuss how the bearing capacity of the soil is determined, as that is explained in Technical Guidance Note 19 (Level 1) Soil bearing capacity. It is suggested that you read that text in conjunction with this, in order to gain a more comprehensive understanding of the topic. (This article was updated in October 2016 to reflect errata issued since its original publication.)
The twisting of elements within structures due to eccentric loading is something that is best avoided as far as is possible. Such actions develop torsion forces in elements against which they were not designed to withstand. This Technical Guidance Note concerns this buildability and detailing issue that structural engineers must become familiar with in order to avoid otherwise unforeseen problems that can lead to significant remedial works on site and in some cases failures.
Recently, the technology behind post fix anchors has become increasingly complex. This guidance note has been developed in order to provide some clarity around the multitude of options that can be presented to a designer required to specify anchors.