The International Information Center for Structural Engineers

Steel Bridge Design Handbook Design Example 5: Three-Span Continuous Horizontally Curved Composite Steel Tub-Girder Bridge

Authors
B. Chavel,J. Rivera.
Year
2012
Series
FHWA-IF-12-052
Volume
24
Description
Tub girders, as closed-section structures, provide a more efficient cross section for resisting torsion than I-girders, which is especially important in horizontally curved highway bridges. The increased torsional resistance of a closed composite steel tub girder also results in an improved lateral distribution of live loads. For curved bridges, warping, or flange lateral bending, stresses are lower in tub girders, when compared to I-girders, since tub girder carry torsion primarily by means of St. Venant torsional shear flow around the perimeter of their closed sections, whereas I-girders have very low St. Venant torsional stiffness and carry torsion primarily by means of warping. This design example illustrates the design calculations for a curved steel tub girder bridge, considering the Strength, Service, fatigue and Constructibility Limits States in accordance with the AASHTO LRFD Bridge Designs specifications. Calculations are provided for design checks at particular girder locations, a bolted field splice design, an internal pier diaphragm design, and a top flange lateral bracing member design.
Tags
Steel Tub Girder Bridge,Steel Box Girder Bridge,LRFD,Bolted Field Splice,Box Girder Distortional Stresses

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