Hello,
When attempting to run analysis I receive the following warning message that the bridge is outside the ROA and a "refined method of analysis is required". I then changed the LLDF option to "use the lever rule in those cases where the ROA requirements are exceeded". The analysis and design runs, but when looking at the LLDF Details in the details reports none of the beams show the lever rule being used. The AASHTO equations are used for all beams. I have attached screenshots showing the warning as well as my design file.
Thanks,
Greg Hansen, PE
| Attachment | Size |
|---|---|
 Warning Message | 9.98 KB |
| LLDF Option | 22.08 KB |
 Design File | 201.28 KB |
This appears to be related to the TxDOT method for live load distribution factors. In the Project Criteria, Live Loads tab, the Live Load Distribution Factors are set to "Compute in accordance with TxDOT Bridge Design Manual". Indeed the lever rule is not applied with the ROA requirements are exceeded. However, the lever rule is used if the WSDOT or AASHTO LRFD methods for LLDF are used.
I'm not familiar with the TxDOT BDM enough to say if skipping the lever rule is intentional.
If you need to force LLDF by lever rule, select Loads > Live Load Distribution Factors and select the second option button "Compute all Live Load Distribution Factors using the Lever Rule".