Eccentric Loading of Helical Piers\u3csup\u3eTM\u3c/sup\u3e for Underpinning

Over the last six years, Helical Piers have been utilized as compression members in the remedial repair of residential and light commercial structures. Current installation techniques create a small offset between the pier shaft and the grade beam or footing being underpinned. The purpose of this study was to examine the effects of the eccentric load that is applied to the top of the shaft on the Helical Pier. Three different sizes of piers were installed at a building site where the soil is predominantly clay. Compressive loads were applied, and data was recorded from which bending moments versus depth, stress distributions, and angular deflections at the top of the shaft were developed. Results show Helical Pier behavior compares with piles under lateral loading conditions. The specific loads required will determine which pier type to use