AASHTOWare Bridge Rating – Curved Girder Module
Vanessa Storlie, E.I.T.Chad Clancy, P.E.
Presentation Organization
• Background Info• Modeling • Analysis• Results• Conclusions
Background Info
• Performed Beta Testing of Curved Girder Module in BrR 6.5 – Needed to use a bridge where design force
effects and resistances were available– Bridge had to be curved but with a small enough
radius where the curvature would have an effect– Selected a four-span continuous unit with a radius
of 1145.92 feet; four girders in cross-section spaced at 10’-4”; bridge was designed by MM
Modeling – General Information
• Appurtenances (medians, parapets, railings, etc.) do not have to be input as “generic” as shown in example.
• Define different diaphragm/cross-frame types using “Diaphragm Definitions”
Modeling – Superstructure Definition – Definition Tab
Modeling – Superstructure Definition – Analysis Tab
Modeling – Structure Framing Plan Details
Modeling – Structure Framing Plan - Diaphragms
Modeling – Structure Framing Plan Schematic
Modeling – Diaphragm Loading Selection
• Check the boxes for which you want force effects to be calculated
• Adds a significant amount of time to the analysis.
Modeling – Member Alternatives
• Curved girders input the same way as straight girders.
• Girder web does not have to be defined with separate sections for each different cross-section
• For bearings aligned along a chord line, angles should be closer to zero than to 90.
• Local z-axis is transverse and y-axis is vertical
Modeling – Visual Verification of Input
• Traditional framing plan, cross-section, and girder schematics are still available.
• 3D schematics showing elements are available when using 3D FEA analysis
Analysis – Analysis Settings
Results
• Dead load and live load moments and shears can be obtained from “View Analysis Report”; element level forces/stresses can be found in xml files by using “View analysis output”
• Report tools function but it appears as though there are small bugs in populating the reports for both LFR and LRFR.
Results
• Compared BrR moments and shears to BSDI values used for design. Generally very similar for interior girders, some differences for exterior girders that with additional effort could be eliminated.
Conclusions
• BrR provides moments and shears similar to those from BSDI analysis used for design.
• Some significant differences in positive moments – reason yet to be identified
• Need to look at cross frames• More comparisons planned as part of
rating 5-span units on the Huey P. Long bridge in New Orleans