Development of Design Specifications and Commentary for Horizontally Curved Concrete Box-Girder Bridges (2008) / Chapter Skim
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Chapter 6 - Conclusions
Chapter 6 - Conclusions
Pages 79-83
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From page 79... ...
The first step was to identify a more simplified 3-D analysis approach that would yield results comparable to the more detailed finite element technique. This was accomplished with the grillage analogy approach.
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From page 80... ...
These studies included both grillage analysis and spine beam analysis for which plane frame analysis constituted the case of a bridge with a very large radius. These studies showed that the radius-tospan length ratio as represented by the central angle between two adjacent supports was the dominant parameter that determined the accuracy of the various analysis methods.
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From page 81... ...
When this residual shear flow is combined with the flexural shear in the extreme longitudinal members, the correct demands to be used for web shear design are obtained. The procedures to be used for torsion design for both the spine beam and grillage analogy analysis methods are illustrated in the example problem included in Appendix B
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From page 82... ...
Analytical grillage analogy and finite element studies performed as part of this project demonstrated that interior diaphragms have a minimal effect on the global response of a curved concrete boxgirder bridge with a 400-ft radius and 300-ft span lengths. Therefore, it is proposed that the requirement that interior diaphragms be included in bridges with a radius less than or equal to 800 feet be eliminated.
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From page 83... ...
It is necessary to explicitly consider the difference in tendon length in individual webs and thus prestress tendons should be modeled in their actual transverse location in a 3-D spine beam or grillage analogy analysis. Friction losses should be based on a tendon curved in space when a curved bridge is being designed using 2-D analysis techniques.
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