Steel Designers Manual - TheBestFriend.org

This material is copyright - all rights reserved. Reproduced under licence from The Steel Construction Institute on 12/2/2007
To buy a hardcopy version of this document call 01344 872775 or go to http://shop.steelbiz.org/
Steel Designers' Manual - 6th Edition (2003)
Practical pile group design
Advice is given in section 2.2 of CIRIA Report 103 14 The design of laterally loaded
piles, which provides a very good description of the design procedure for a pile
group, including a flowchart. It is suggested that the three levels of appraisal detailed
in the CIRIA report should be adopted, i.e.:
(1) Consideration of the ultimate failure mechanism of the foundation and incorporation
of an overall reserve of strength for safety
(2) Computation of the lateral translation and rotation of the foundation at
working loads, and consideration of the effect of this deformation on the whole
structure
(3) Bending resistance of the piles.
29.1.4 Installation
Bearing piles 881
Steel piles can be installed by a variety of methods and equipment. There are three
types of installation equipment, which operate by impact, vibration or by jacking.
Each has particular advantages and disadvantages, and the final choice is, in most
cases, a balance between speed and economy of installation. A further deciding
element is the increasing concern for noise and vibration control to which the industry
has responded with the development of new installation equipment such as
hydraulic hammers.
The installation of steel piles is a specialist activity, calling for considerable knowledge
and experience of handling piles and hammers to achieve an acceptable placement
within specified tolerances of position and level. Guidance on the practical
limits that can be achieved in position and level for driven steel piles is available
from the FPS (Federation of Piling Specialists) 17 and in the TESPA (Technical
European Sheet Piling Association) publication Installation of steel sheet piles
(see also section 29.3.1). 18 Guidance is also included at the back of the new ICE
Specification for Piling and Embedded Retaining Walls 19 and in the Corus Piling
Handbook. 20
The designer should refer to these documents before carrying out a design,
because the advice given will often affect the details at connections to the pile cap
in the structure.
There is much to gain from matching the stiffness of the pile to the hammer and
to the anticipated soil resistance at the site to achieve satisfactory driveability and
to ensure achievement of the required design penetration.
In addition, following research work over the last 30 years, there is a developing
understanding of the benefits of measuring the soil resistance during driving as a
check on the designer’s predicted compressive axial static capacity (see the ICE
Specification for Piling and Embedded Retaining Walls 19 ). Although there are some
caveats to be applied to this practice, it is indisputable that both designer and
installer gain from using dynamic analysis of pile driving and that this is of ultimate