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