Semester

Fall

Date of Graduation

2010

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Karl E Barth

Abstract

In lieu of a complex three-dimensional analysis, live load distribution factors (also referred to as girder distribution factors or wheel load distribution factors) are commonly employed by bridge engineers to simplify the analysis of a bridge system. Specifically, instead of looking at the bridge system as a whole, these factors allow for a designer or analyst to consider bridge girders individually by determining the maximum number of wheels (or lanes) that may act on a given girder.;The development of the relatively new distribution factors for beam-and-slab bridges incorporated in the current AASHTO LRFD Specifications are primarily the result of NCHRP Report 12-26. This report, however, does not take into account the different live load responses of interior and exterior girders. Numerous research studies have shown that the distribution of live load in a bridge system differs between interior girders and exterior girders.;The current AASHTO specifications employ three methods to determine the distribution to exterior girders: a statical based procedure called the lever rule, a rigid body rotation procedure called special analysis, and an empirical equation that calculates an adjustment factor that is applied to the interior girder distribution factor. While several studies have shown that for many cases these methods do not accurately predict the load in the exterior girder little work is available to actually evaluate the distribution of live load to exterior girders.;Therefore, the goal of this research is to develop new expressions for the distribution of live load to the exterior girders of steel slab-on-beam bridges. To accomplish this, a commercial finite element software package (Abaqus) is employed. The finite element modeling technique used in this project is first compared with physical data from the August 2002 field test of the Missouri Bridge A6101. Once validated, this modeling technique is then used in a sensitivity study to determine the effect of key parameters on exterior girder live load distribution. Subsequently, a parametric matrix employing these key parameters is developed and analyzed. Data correlation techniques are then used to relate the parameters which were varied throughout the course of this study to develop empirical equations for live load distribution factors.

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