Reliability Analysis of Anchor Foundations Subject to Vertical Uplift Forces

Abstract

Foundations of transmission towers are subject to uplift forces, and the designs are based on deterministic procedures. Present design guidelines on design of anchor foundations are discussed, and limitations as well as need for incorporation of reliability-based design are brought out. Reliability analysis of anchor foundations subjected to vertical uplift forces using the first-order reliability method is performed. The results of the reliability analysis for different distributions of shear strength parameters of soil and the uplift loads in terms of Hasofer–Lind reliability index have been presented. Load and resistance factors have also been presented to enable reliability-based design. A design example is presented to compare the results obtained from this study. The results show that reliability-based approach can lead to an economic design than the conventional factor of safety approach. It is suggested that codes need to incorporate reliability-based designs in practice.