OasisLMS

The so-called “ bridge bump” , characterized by significant differential settlements between bridge approach/departure slab and bridge abutment, is primarily attributable to the excessive settlement of the embankment that supports bridge approach/departure slabs. There are no widely accepted settlement criteria for the embankment, which make design engineers unable to deliver consistent results. This study reviewed settlement criteria used by other countries and conducted a survey to collect responses from the U.S. state DOTs regarding their criteria of embankment settlement. Australia and Canada have specified their embankment settlement criteria based on the relative distance from the bridge abutment, which varied from 25 mm to 200 mm. Based on the 22 state DOTs that responded to our survey, it can be concluded that even though most of them have set settlement criteria, and these criteria vary significantly and can be divided into four categories: (1) the embankment supporting bridge approach needs to have a settlement nearly the same as the bridge; (2) the embankment supporting bridge approach can settle from 12 mm to 25 mm; (3) the allowable embankment settlement depends on the length of the bridge approach; and (4) the maximum allowable settlement is decided based on each project but definitely cannot be more than 50 mm. Some of the responding state DOTs also suggested that their settlement criteria were advisory rather than mandatory. That meant the engineers can decide whether to use them at their discretion.

Keywords:  settlement, embankment, bridge, bump, dip

J. Huang, A. Anibal Figueroa Cerrato, S. Bin-Shafiue

Journal