Helical Pile Acceptance Criteria, Design Guidelines, and Load Test Verification

Abstract

Lack of standard helical design, installation and load test verification criteria has previously limited the use helical foundations. In 2007, the International Code Council adopted AC358 Acceptance Criteria for Helical Pile Foundations Systems. The establishment of the AC358 acceptance criteria quickly led to the inclusion of helical piles in the 2009 International Building Code®. Based upon AC358 and 2009 IBC, the development of a draft NYC Helical Pile Building Code has been completed and is currently under final review. This paper presents the recommended AC358 and 2009 IBC guidelines for the design, installation, and verification of the ultimate helical pile capacity. An overview of the various helical pile configurations in use today is presented along with an evaluation of some 75 North American helical pile load tests. A recommended helical load test acceptance criteria based upon total and differential settlement is also presented for small, medium, and large displacement helical screw piles. Load test data from several helical pile projects is also presented.