Semester

Spring

Date of Graduation

2004

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

Recent studies have demonstrated that the use of hybrid steel bridge I-shaped girders (specifically sections incorporating Grade 50 webs and High Performance Steel (HPS) 70W flanges) can produce steel weight savings and overall design economy for a wide range of typical steel bridge superstructures. Additionally, recent research at WVU in collaboration with others has led to proposed simplified moment redistribution techniques that have been adopted by AASHTO. These procedures are similar in nature to existing limits that permit up to 10% of the maximum factored negative bending moments to be redistributed to positive bending regions in members comprised of compact sections. However, the more recent procedures may be used for a wider range of sections, including those with non-compact webs, and specifically compute the level of redistribution moment. The primary goal of this study is to assess the suitability of simplified moment redistribution procedures to members fabricated with hybrid configurations.;In this work, refined 3D finite element analysis (FEA) tools are employed to assess the moment rotation characteristics for a wide range of hypothetical hybrid steel I-shaped girder sections. These tools are successfully calibrated against available experimental data and are capable of addressing the influences of both geometric and material non-linearity. Specific ABAQUS subroutines were developed for this effort that are used to introduce specified geometric imperfections and residual stresses in the FEA models.;Results from the parametric studies are used to assess the influence of key design parameters on the inelastic response of hybrid sections and are also used to assess the validity of proposed redistribution procedures for hybrid girders. Lastly, a design example of a two-span hybrid HPS 70W girder bridge is presented to illustrate the successful use of the simplified moment redistribution procedures for these types of members.

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