Helical piers (also known as helical piles) are used to repair an existing structure and also for new construction in place of micropiles, caissons, geopiers or other deep foundation systems. They can also be used instead of an over- excavation. The helical pier can be both time and cost effective.
When helical piers are used to repair an existing structure, they are “screwed” into the soil until a pre-determined torque is reached. A bracket is then placed on the steel shaft and positioned under the footing of the structure, transferring the load of the structure to the helical piers. The structure can then be stabilized or lifted back level.
Helical Piers have been in use for almost 200 years, and more recently have become more popular with engineers and contractors and used often in place of more costly alternatives
Products
Round Shaft
Round shafts are 2 7/8″ diameter, 3.5 inch diameter and 4.5 inch diameter. The Round Shaft lead sections utilize 1, 2 or 3 helix flights which are 8″, 10″, 12″ and 14″ in diameter.
Square Shaft
Square Shafts are 1.5, 1.75 and 2.25 inch Round Corner Square (RCS). Square Shaft lead sections utilize 1, 2 or 3 helix flights which are 8″, 10″, 12″ and 14″ in diameter.
New Construction Bracket
Standard Bracket
Heavy Duty Bracket
Flat Bracket
WalkWay Support Bracket
Post Bracket
Extensions
Round Shaft and Square Shaft Extensions have lengths of 3, 5 and 7 foot sections.
Advantages
- Lead sections and extensions can be configured to achieve design depth and capacity
- Lead sections available in 2, 5 and 7-foot lengths
- Extensions available in 3, 5 and 7-foot lengths
- Extensions utilize rigid, three-bolt couplings
- Helical piers available with single, double and triple helix lead sections
- Helix blade diameters of 8, 10, 12 and 14 inches
- Available with hot-dipped galvanized coating for added corrosion resistance
Retrofit
- Lead sections of pier can be configured to achieve design depths and capacities
- Minimal excavation required around foundation area
- Installs quickly with small or handheld equipment
- Vibration-free installation (unlike traditional driven piles)
- No wait ? piers installed year-round
- Installs in areas with limited or tight access without generating spoils
- Pier system installed below grade ? not visible once installation is complete
- Cost-effective ? gets a structure back on solid ground
- Permanent solution ? prevents further vertical movement
New Construction
- All-weather installation
- Can be installed with either handheld or small equipment
- Can be installed in areas of limited or tight access
- Foundation concrete can be poured immediately following installation
- Lead sections can be configured to achieve design depth and capacity
- Cost-competitive versus other deep foundation alternatives
- Vibration-free installation (unlike traditional driven piles)
- Installs quickly without generating spoils
Specifications
Helical Pier/Anchor Tube
- 2.875-inch Outside Diameter (O.D.) x 0.262-inch wall tube steel, ultimate tensile strength = 58,000 psi (min.), yield tensile strength = 50,000 psi (min.)
- Torque Strength Rating = 9,000 ft.-lb.
- Torque Correlation Factor (Kt) = 9 ft-1
- Connecting Bolts
0.75-inch diameter Heavy Hex Machine Bolt (SAE J429 ? Grade 8) - Weld
E70 ? minimum tensile strength = 70,000 psi - Ultimate axial capacity based upon installation torque = 100 kips (tension/compression)
- Allowable axial capacity based upon installation torque = 50 kips (FOS = 2)
- Allowable capacity with retrofit foundation bracket = 40 kips
New Construction Bracket
- 3.5-inch O.D. x 0.300-inch wall (ASTM A500, Grade C)
- 4.0 inches x 8 inches x 1-inch thick plate steel (ASTM A-36)
- Connecting Bolts
0.75-inch diameter Heavy Hex Machine Bolt (SAE J429 ? Grade 8) - Weld
E70 ? minimum tensile strength = 70,000 psi - Allowable axial capacity = 50 kips (compression), 44 kips (tension)
Retrofit Foundation Bracket
- Bracket Tube
3.875-inch O.D. x 3.125-inch Inside Diameter (I.D.) x 10-inch long DOM mechanical steel tubing conforming to ASTM 513 ? Type 5 / Grade 1026. Ultimate tensile strength = 100,000 psi (min.), yield tensile strength = 90,000 psi (min.) - Angle Bracket
0.5-inch thick flat plate conforming to ASTM A-36 hot rolled steel bent to form a 90 degree angle with equal sides of approximately 8 inches. Ultimate tensile strength = 58,000 psi (min.), yield tensile strength = 36,000 psi (min.) - Bracket Support Strap
0.375-inch thick x 3 inches wide x 21.25 inches flat bar conforming to ASTM A-36 hot rolled steel which is bent into a “horseshoe” shape around the bracket tube. Ultimate tensile strength = 58,000 psi (min.), yield tensile strength = 36,000 psi (min. - Top Plate
0.75-inch thick x 5.5 inches wide x 9.5 inches long conforming to ASTM A-36 hot rolled steel. Ultimate tensile strength = 58,000 psi (min.), yield tensile strength = 36,000 psi (min.) - Cap Plate
1.0-inch thick x 4.0 inches wide x 8.5 inches long conforming to ASTM A-36 hot rolled steel. Ultimate tensile strength = 58,000 psi (min.), yield tensile strength = 36,000 psi (min.) - Weld
E71T1, minimum tensile strength = 71,000 psi ? peformed by AWS certified welder - Threaded Rod
0.75-inch diameter x 12 inches long ASTM A311 ? Class B / Grade 8 Zinc Plated. Ultimate tensile strength = 150,000 psi, yield tensile strength = 130,000 psi