Reevaluation of the AASHTO effective width equation in concrete slab bridges in Delaware

Shenton, Harry W., IIIIn recent years the need to reevaluate the integrity of Delaware’s concrete slab bridges has become a high priority. The load rating of a bridge is very dependent on the value of the slab effective width. The effective width value is calculated from the American Association of State Highway and Transportation Officials code equation. Research has suggested that the AASHTO code effective width may be conservative. Strain gauge tests were conducted on six concrete slab bridges of varying geometry and design to determine the actual slab effective width. The resulting measured effective widths were compared to the AASHTO code width. For single truck passes, the effective width was up to 125% greater than the code. For multiple truck passes, the measured effective width was up to 39% greater than the code. A new formula was derived based on the measured data, for single and multiple truck passes, which more accurately reflects the true slab effective width.University of Delaware, Department of Civil and Environmental EngineeringM.C.E