In any rapidly-changing technology, there are sometimes branches off the main stream that are critically important, highly developed, and short-lived. People work very hard to perfect something that they need, only to have it replaced by something better a few years later. Structural engineering is not now changing rapidly, but 125 years ago it was. Grillage foundations were part of the change to steel-frame technology in the 1890s and remained in use into the twentieth century, but are now so rare that the majority of engineers have never analyzed one.
The idea behind grillages was simple: there was little guidance available for analyzing reinforced concrete, so concrete was used mostly as a mass unreinforced material, effectively as geometrically flexible masonry. Steel was well understood and strong, but vulnerable to rusting. Given those materials, how do you design a spread footing, where a concentrated load from a column, pier, or wall had to be distributed over a large area to get the pressure low enough that the soil could resist it? The answer was a grillage, with two or more layers of steel beams at right angles to spread the load. The beams were either sitting on top of a layer of unreinforced concrete or embedded in a concrete footing. When the beams are embedded in concrete, it's easy to mistake for a reinforced-concrete footing, but the structural action is different: in a grillage the beams are doing all the work rather than working compositely with the concrete, as in a modern reinforced-concrete footing. Improvements in reinforced-concrete analysis and materials are what eventually killed off grillages.
Steel Utility Foundation Grillages are 100% completely bespoke and customized to support Monopole, H-section Frame or Lattice power transmission structures. They can be engineered to withstand axial, shear and moment combinations of even the largest dead-ends. They eliminate the need for concrete and curing time. These foundations are ready immediately after installation. All components are available fully galvanized. The grillage foundation helps connect the entire base into a unity structure and uniformly distribute the building and transmission tower load.
Grillages are used to attach helical piles to structure bases or tower legs. Grillages can be designed to fit various possible combinations of piles and structure designs. Please contact us for additional information about specific projects.
Notes:
• Grillage assembly depicted accomodates 4-6 helical piles. Four
radially spaced and an optional sixth helical pile.
• Grillage assembly is welded steel plate and hollow structural steel.
• Steel plate per ASTM A572 Grade 50. Hollow structural steel per
ASTM A500 Grade B.
• Hot dip galvanized per ASTM A123 and ASTM A153.
• Manufaturer to have in effect industry recognized written quality
control for all materials and manufacturing processes.
• Crimp system bolts are 1 inch per SAE J429 Grade 8, Zinc plated
per ASTM B633. Installation torque of bolt is 450 ft-lb.
• Non-shrink grout to fill void between helical pile and grillage
hollow structural steel.
Advantages of Steel Grillage Foundation
Its installation process is easy and fast.
The steel used in steel grillage foundations can be reused recyclable, making it environmentally friendly.
The engineering design and applied material in the steel grillage installation and fabrication are simple and efficient, making it affordable.
You can customize the steel grillage as per the project requirements, making it bespoke for different transmission steel tower foundations or other construction buildings.
Suitable for low bearing capacity soil. You can save up to 30% on foundation construction.
Grillages are used to attach helical piles to structure bases or tower legs. Grillages can be designed to fit various possible combinations of piles and structure designs. Please contact factory for additional information about specific projects.
- Pre-engineered, power-installed
- Lower project costs
- No advance site preparation, excavation or concrete required
- Install and set tower in all types of weather
- Removes the need to excavate the soil
- Eliminates the need for expensive casings used with drilled shafts
- Grillage assembly available for 3-12 helical piles
- Non-shrink grout to fill void between helical pile and grillage hollow structural steel
- Grillage intended to be used with 3.5" and 4.5" diameter helical pipe piles
- Galvanized
- Contact factory for additional information about specific projects.
- Hardware to connect to piles sold separately.
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