Engineering and Construction

Universal bearing piles are H-sections produced on a universal hot rolling mill–hence their name.They are essentially the same as universal column sections, except that they have uniform thickness throughout the section. See Fig. 29.1. Universal column H-piles are made in two basic qualities of steel, grade S275 (yield  = 275N/mm2) and grade S355 (yield = 355N/mm2) to BS EN 10025. Typical section sizes are presented in the Appendices.
 
Steel H-piles are very efficient in providing a large surface area for generating shaft friction resistance. In any given foundation plan area, a greater number of  steel H-piles can be used in a group with a standard spacing of 2B (or 2 x dia.) than concrete piles and either the load supported can be greater or the size of the group made smaller.The stiffness of H-piles is different about each orthogonal axis, allowing designers to select the orientation necessary to achieve the most efficient design.

Fig. 29.1 Universal bearing pile

H-piles are used principally for terrestrial structures where the full length of the pile is embedded, e.g. foundations for bridges and buildings, and therefore buckling is not a problem because there is good soil lateral support.They are used very effectively to transfer bearing loads into buried bedrock and to get around buried obstructions. It is sometimes advisable to use special cast steel pile shoes to strengthen the tip and prevent damage or buckling under hard driving conditions into bedrock where very high end bearing pressure can be achieved.

They are generally not the most suitable for conditions where long lengths of the pile shaft protrude above ground level and are unsupported by surrounding soil or through water, because buckling failure about the minor axis can occur at relatively low axial loads. In these cases consider the use of tubular or box piles that have more stiffness.