Design of Ribbed Concrete Approach Slab Based on Interaction with the Embankment

Abstract

To alleviate the “bump” problem at bridge ends, a ribbed concrete approach slab (similar to slab-on-beam bridge decks) was proposed in place of the pile–column-supported approach span or flat slab system. The effect of given embankment settlement on the structural performance of a ribbed concrete approach slab with a span length of 60 ft and a width of 40 ft was investigated. The approach slab was modeled as a ribbed slab with a beam spacing of 32, 16, and 12 ft. A three-dimensional finite element analysis was conducted to model the interaction between the approach slab and the embankment soil. Finite element modeling techniques that simulate the separation of the slab and soil provide information on the effect of the embankment settlement on structural performance and beam design. The predicted internal forces provide design engineers with a scientific basis to design the approach slab properly, considering different levels of embankment settlements. Current AASHTO code specifications do not provide guidelines to design approach slabs considering the embankment settlement.