Over the past 50 years, fully threaded, high-strength threaded bar and multi-strand anchor systems with corrosion protection have developed into the most accepted and highly reliable ground anchorages available. As the leading steel supplier in the United States’ foundation industry, Nucor Skyline manufactures the most extensive selection of cold and hot rolled, high strength, fully threaded bars; available in both 80 ksi and 150 ksi steel grades.
Nucor Skyline offers the most advanced multi-strand ground anchor technology available in the geotechnical industry in the United States. In addition to traditional multi-strand PTI Class I permanent and Class II temporary strand anchors, we have the world’s most convenient and widely used removable strand anchor system.
Manufactured in the United States with domestic strands, heads, and wedges, we supply the required jacking systems and the technical field support to allow contractors to economically use this technology. Already proven on commercial projects in the United States, a full-scale experimental and theoretical evaluation of the system has been conducted in accordance with US standards by one of the geotechnical industry's most respected independent consulting engineering firms at a location administered by an American university. This information is available to all, along with the technical support required for the use of the system.
Advantages of Ground Anchors
- Highly versatile and well-proven method of transferring tension forces to the ground
- Used in a wide array of installation techniques developed to drive cost-efficient construction in the geotechnical industry
- Tie back installations eliminate internal bracing and rakers which typically congest the excavation. This dramatically increases the efficiency of material removal by the contractor during temporary excavation
- Reliable permanent anchors, with decades of proven performance, allow engineers to confidently design structural and slope stabilization projects
- Tie down applications often replace mass concrete, reducing construction costs
Applications of Ground Anchors
- Retaining Walls: Tie backs are used as either a permanent or temporary anchor system for permanent retaining walls or support of excavation
- Resist Uplift: Used to resist hydrostatic uplift pressures on a slab, structural force, or wind loads on a structure
- Sloped Surface Stabilization
- Landslide Mitigation
- Foundation Stabilization
Tie Back or Tie Down Anchors
Tie backs are fully threaded steel bars that are bored, cast-in-place elements designed to resist tension forces resulting from the support of earth retention systems, such as foundation walls or retaining walls.
Tie backs are commonly used to support temporary walls for excavations in congested urban areas. One type of temporary wall is a beam and lagging wall. The use of tie downs in this application reduces the amount of soil disturbed during excavation and decreases the disturbance on adjacent structures. In this very common application, H-piles are tremie concreted into drilled holes in a vertical orientation, along the perimeter of the intended excavation. Wood lagging is installed horizontally to retain the soil behind and between the piles as the top-down excavation takes place.
Anchor design is based on well-documented and proven principles. Once the structural loading has been identified, the geotechnical information available from the site can be used to determine the appropriate anchor design, as recommended in the PTI Manual “Recommendations of Rock and Soil Anchors”.
The design must take the variability that occurs throughout most sites into consideration. For example, the Great Lakes Region is a region where glaciers traversed the landscape, carving and filling vast areas with sand, clay, gravel, and countless combinations of all soil types. Soils may contain boulders, cobbles, gravel, and other obstructions which make it challenging to drill holes. As a result, soil conditions vary drastically from site to site. For example, in parts of Texas, Oklahoma, and in the upper Missouri Valley, clay soils may be expansive and may dominate the design of ground anchors.
Soil borings and laboratory testing should be used to verify the actual soil conditions in the location of a proposed anchor.