Analytical and Experimental Investigation of Shear Distribution Factors

摘要

This paper investigates the bearing forces and shears for typical Illinois bridges, using both field testing and analysis. Based on a survey of the literature, as well as information presented at Illinois Department of Transportation (IDOT) seminars on Load and Resistance Factor Design (LRFD), using the LRFD Specification for bridges in Illinois can result in bearing shears of up to 40% greater than those calculated using Load Factor Design (LFD). Two factors in the LRFD Specification contribute most strongly to this increase: rn•The requirement that the lane loading be considered simultaneously with the truck loading, designated as HL-93, and rn•The effect of the revised girder shear distribution factors rnThis paper will examine the suitability of the revised LRFD shear distribution factors. Twelve bridges along the Interstate 55 (I-55) and Interstate 270/70 (I-270/70) corridors have been selected and monitored. The candidate structures were chosen to vary as many parameters as possible. Factors such as skew angle, beam material, bearing material, beam spacing, design methodology, age, traffic factors, and environments are some of the factors that were considered when selecting the candidate structures. These structures were instrumented with strain gages and monitored for six months during two different time intervals. Data were collected and analyzed to determine if the LRFD design factors are realistic in terms of actual Illinois loading conditions.