What should I do if the program indicates that the girders are failing in negative flexure near the contraflexure points after running the design check on a curved composite steel plate girder? The span check table and design results diagram show a very high negative moment in this region, however, a results table for the maximum negative moment for that same load case indicate the opposite. Is it possible for the girders to fail in this region?


Answer:

The software performs the check for the sections based on the moments between the bracings, in the model, sent the bracing definition is not provided hence the design was performed the maximum negative moment in the bridge rather than design for a moment near contra flexure points. Thus we need to assign the transverse elements intersecting the girders at the brace locations as "brace " member type along with the "composite span information" which would enable the software to understand the bracing location and perform design checks for moments between the bracings as per AASHTO 6.10.1.6.



The modify member type option is as shown below:



In the case where there are no transverse elements intersecting the girder at the brace location, kindly create a dummy brace section and create at the brace location as shown below:


Kindly make sure these transverse dummy brace members are activated in the final construction stage.

 The modified model is attached and the design guide for your reference. (Kindly refer Pg.24).


Creation date: 3/3/2020 5:37 AM      Updated: 5/10/2023 2:02 PM
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