A Review of LRFD Bridge Foundation Design and Construction in South Dakota

Load and resistance factor design (LRFD) is a reliability-based limit state design methodology. In this study we investigate the concept, application, and implementation status of LRFD in shallow and deep foundation designs for the South Dakota Department of Transportation. Challenging the use of LRFD in South Dakota and neighboring states are the frequent occurrence of difficult geologic and geotechnical conditions including expansive soil and rock, deep seated landslides, soft and/or highly weathered shales, intermediary geologic materials, highly corrosive soils, and lack of available high-quality engineered fill materials. For deep foundations, pile load testing data are available to evaluate effectiveness of LRFD methodologies in the geologic materials present within the state. However, whereas deep foundation design parameters are relatively well established for LRFD methods, local calibration of shallow foundation design parameters has not yet been performed in most states. This paper examines the current status of LRFD and discusses its implementation for shallow and deep foundation design in South Dakota and provides a set of recommendations that engineers can consider as they pursue implementation of LRFD on construction projects with the ultimate goal of economical designs incorporating quantitative estimations of failure.