Distortional Analysis of Steel Box Girders

다국어 초록 (Multilingual Abstract)

Box girders are susceptible to cross sectional distortion under eccentric loading condition. Distortional warping and transverse bending stresses should be appropriately limited to a specific level to prevent premature severe distortion of cross section, which is generally achieved by installing intermediate diaphragms. In most design practicing procedure, provision of intermediate diaphragms based on design specifications suffices the consideration of distortion and hence the distortional stresses are not computed. Presented in this study is a box girder element, which is extremely effective in computing accurate stresses of the cross section. Two additional degrees of freedom were included to take the distortional warping and the transverse bending of the cross section into account. An extensive comparative study showed strong validity of the presented element. Considering the exhaustive input preparation task and the vast amount of output analysis procedure in a box girder modeled using a shell element, superiority of the presented element over shell elements becomes apparent. The basic principles of distortional design included in various current design specifications were revisited. In this study, a series of example analyses based on the various ratio of the distortional warping normal stress to the bending normal stress, which related determination of the spacing of intermediate diaphragms, was performed. From the results of analyses, it has demonstrated that the spacing of intermediate diaphragms should be changed. This strongly indicates a need for improvement in design of distortion.

목차 (Table of Contents)

• 1. Introduction
• 2. Box Girder Element Formulation
• 2.1 Distortion of box girder
• 2.2 Governing differential equation
• 2.3 Stiffness matrix
• 3. Numerical Verification
• 3.1 Box girder without intermediate diaphragms
• 3.2 Box girder with intermediate diaphragms
• 4. Review of Specification provisions for Spacing of Diaphragm
• 4.1 Hanshin expressway public corporation of Japan
• 4.2 AASHTO
• 5. Parametric Study
• 6. Concluding Remarks
• References