A Steel grillage is a foundation technique that is often used to support towers, gantries, signs, overhead line electrification (OLE) masts and similar structures. Depending on the size and weight of the structure being supported, a traditional foundation of this type (sometimes called a floating foundation) is a large box-like structure, not unlike the mesh cages used to reinforce concrete structures.
A steel grillage is placed on several screwpiles – typically between four and eight depending on the overlying structure. Using this system, construction time has been reduced by over half the time; with one lighting column being able to be installed in under an hour. It is fast to install and is a foundation formed with better technology and innovative designs. This technology can be applied to many structures that have a high turning moment and that need to been installed quickly and cost-effectively.
How Grillages work
Where reinforcement is usually created by surrounding the structure with a concrete base, here, a steel grillage (which is a rigid construction that’s placed at sufficient depth below ground that the weight of soil removed to input the grillage equals it in weight) can be used in replacement.
Increasingly, for structures such as road signs or railway gantries, grillages have been designed to consist of one or more steel beams (an interface) mounted on underlying helical piles to give extra support. The fast installation and the fact that the grillage is fabricated off-site make this a very suitable yet versatile foundation solution.
Advantages and benefits
Steel grillages have many benefits to contractors, some of these include –
- Speed of installation – using a grillage often permits valuable time savings.
- Convenience – avoidance of poured concrete saves time and simplifies installation.
- Reduced costs – through minimal disruption of transport infrastructure.
- Versatility – the technology suits many different applications.