Design of Lateral Support for Non-Integral Wing Walls of Culverts

Abstract

Traditionally, culverts are built with integral wing walls. This style of culvert has shown consistent issues at the joint where the wing wall frames into the culvert bodies due to differential settlement and inadequate reinforcement for the stresses that accumulate at this location. For the purpose of this study, three culverts were constructed utilizing a design in which the wing walls were completely separated from the culvert barrels and laterally supported by a tab that extends from the culvert. During construction, each tab was instrumented with vibrating wire earth pressure cells to monitor the pressure that was induced within the tab. The wing walls were also instrumented to monitor movement relative to the culvert. This data was used to develop an LRFD design procedure that suggests a design load based upon the dimension of the wing wall along with the height and soil properties of the backfill. Based upon their geometry and suspected loading conditions, it was suggested that the tabs extending from the culvert be designed as corbels in the manner laid out in the AASHTO LRFD Bridge Design Specifications. This suggestion was validated following a year of data collection at the three culvert sites. The observations made through this period also allowed for the conclusion that the studied culvert design was effective at mitigating the issues that occur when constructing the wing wall monolithically with the culvert.