Influence of Facing on the Construction and Structural Performance of GRS Bridge Abutments

Abstract

Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) technology has been developed significantly over the last decade through extensive support and promotion by the Federal Highway Administration (FHWA). It is considered as a viable and cost-effective bridge construction alternative to the conventional, deep-foundation bridge abutment systems for local and county roads across the U.S. In this study, large concrete blocks (2 ft. high × 2 ft. deep × 4 ft. wide) were used as facing to construct full-scale (8 ft. high) model GRS bridge abutments to investigate their possible structural contribution to the load-bearing capacity and performance of the abutments, and their potential to further reduce the construction time and labor requirements for GRS-IBS, leading to further cost savings. Three instrumented model GRS abutment models were constructed in an outdoor test station to compare the construction speed and structural performance of models with larger blocks relative to those with standard CMU block facing. Numerical modeling was performed to compare with the results from the full-scale surcharge load testing of all three GRS abutment models. Results of the study showed that large concrete block facing GRS abutment models were constructed in shorter period of time and showed greater load-bearing capacity and smaller deformations relative to the nominally identical models with CMU facing alternative. Nevertheless, all GRS bridge abutment models showed significantly larger load-bearing capacity relative to the requirements stipulated in current design guidelines.