Error w/ Distribution Factors and Bearing Loads?

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William Shekarchi
Error w/ Distribution Factors and Bearing Loads?
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Looking at the detailed report, I have concerns about how the distribution factors are being calculated based on the DF equations and the lever rule. Specifically, the multiple presence factor is not being applied to the lever rule. Is there somewhere else the MPF is being applied when the lever rule is used? The equations already have the MPF built in so it seems odd that the MPF is always 1 when the lever rule is used. I don't recall having TxDOT criteria saying the lever rule should use a MPF of 1.

I also found that the distribution factor is not being applied to the live load bearing design parameters, which leads to large bearing loads per girder.

Attached are examples of these issues.

thanks,
Will

Pickings
Will,

Will,
The bearing design issue is a known bug that will be fixed in the 5.0 release that is due to be deployed next month. In the meantime, you will need to enter distribution factors manually, or you can try the 5.0 Beta version available at WSDOT's download site.

Richard Pickings, P.E.
BridgeSight Inc.

William Shekarchi
Thank you. Was it determined

Thank you. Was it determined that the loads used for the analysis did use the distribution factors? I am wondering if the moment and shear demands are too high the my current version.

Is there any insight into the question regarding the multiple presence factors being applied to the lever rule?

William Shekarchi, Ph.D., P.E.

Pickings
I don't see where the lever

I don't see where the lever rule is used in your example all factors are computed using the equations which have the MPF built-in.

Yes, the MPF should be applied if the lever rule is used per TxDOT's BDM. If you feel that there is a bug, please send additional questions to TxDOT's support line at BRG_TxDOT_PGSuperHelp@txdot.gov

Richard Pickings, P.E.
BridgeSight Inc.

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