An analytical model for predicting load–deformation behavior of the FHWA GRS-IBS performance test

Abstract

The Federal Highway Administration (FHWA) has recently developed a new bridge abutment system, known as Geosynthetic-Reinforced Soil-Integrated Bridge System (GRS-IBS). The term “GRS” refers to a soil mass that is reinforced internally by closely spaced (reinforcement spacing not more than 0·3 m) horizontal layers of geosynthetic sheets. The design protocol of GRS-IBS recommends a “performance test” be conducted to estimate the load–deformation behavior of a GRS-IBS system. The performance test involves a cuboidal block-faced GRS mass that is subjected to increasing axial loads. More than 100 GRS-IBS have been constructed in the US since its introduction in 2011. In light of the rapid development of the new bridge abutment system, an analytical model is developed for predicting the load–deformation behavior of the performance test up to the ultimate load-carrying capacity that is determined from the “W-equation.” This paper presents the analytical model and validation of the analytical model. Validation of the model was accomplished by comparing the analytical results with measured data of four sets of performance tests. The paper also presents a new interpretation of the W-equation, an equation that has been shown to be capable of predicting the ultimate load-carrying capacity of a GRS mass with very good accuracy. The analytical model is seen to give very good predictions of the load–deformation behavior of the performance tests up to the ultimate load-carrying capacity; hence may be used to supplement or replace the FHWA performance test that is rather laborious and time-consuming to conduct.