Design of Horizontally Curved Steel Bridge Girders with Tubular Flanges

Abstract

This study presents a practical approach for the design of horizontally curved steel I-shaped bridge girders with tubes as flanges [i.e., tubular flange girders (TFGs)]. Previous research has shown that the large torsional stiffness of a TFG, compared with a conventional steel I-shaped plate girder (IG), leads to improved behavior and potential for simpler curved bridge erection. The study shows that existing design criteria for curved IGs in the current design specifications can be adopted for curved TFG design. A few modifications to the existing design criteria, developed for TFGs, are presented. Simplified finite-element (FE) models for use in the design of curved TFG bridges are summarized. The simplified FE models are used to determine the design load effects for various limit states, and these limit states are then checked using the design criteria. Detailed FE models are also summarized, and these models are used to evaluate the limit state responses of several curved TFG bridges designed using the approach presented in the study. The results show that the design criteria used for curved IGs, with a few modifications, can be used to safely design curved TFGs for highway bridges. Additionally, the behavior of curved TFG bridges with different types of TFGs are compared.