Analysis Results Comparison (ARC) Tool – New in Release 7.1
August 20, 2021Historically, agencies have had different approaches to testing and upgrading to new versions of AASHTOWare Bridge Design-Rating (BrDR). Some agencies install new software versions immediately after the release with little to no testing, while other agencies perform extensive in-house testing or refrain from adopting the new version until the version has been out for a while and used by other agencies in a production environment. When implementing a new version, the rating results of a bridge or a group of bridges can change due to a variety of factors. These changes – which can lead to either beneficial or unfavorable results – are due to issue fixes or enhancements included in the new version, code changes, the inclusion of additional information to refine the analysis, or issues introduced in the new version. Regardless of the reason, agencies should be aware of the details of how a new version will affect the way they manage their bridge inventory.
To assist the states in assessing the impact that a new version of BrDR will have on the rating of the bridges in their inventory, the Analysis Results Comparison (ARC) tool compares the results between any version of AASHTOWare Bridge Design-Rating beginning with version 7.0 (i.e. all modernized versions of BrDR). For example, the ARC tool can be used to evaluate the rating results from BrDR version 7.1 – which has an anticipated release date of August 2021 – with the rating results from BrDR 7.0. Using this tool, agencies can compare the rating factors for a representative sample or all of the bridges in their inventory. The tool has three levels of comparison, with each increasing level providing more in-depth analysis. The three levels include Level 1 – Overall Controlling Bridge rating; Level 2 – Member Alternative rating; and Level 3 – Point of Interest analysis. The three levels are described in more detail later in this article.
When launched, the ARC tool opens the main Dataset Explorer window. This window allows the user to create, manage, and compare datasets. It also allows the user to run a scan for the versions of BrDR supported by the ARC tool.
Figure 1: Analysis Results Comparison Tool main screen
The Create Dataset window is used to set the version to be used, define the analysis setting, and provide the location where the dataset will be stored. The window also has a checkbox to allow Level 3 analysis. The Level 3 analysis will provide much more detail for comparing each version; however, it produces much larger data files. To limit dataset file size, creating Level 3 datasets for a select group of bridges needing additional analysis is preferred. All bridges could be analyzed for both Level 1 and Level 2 analysis. Note that if/when an error is encountered when analyzing a bridge, the ARC tool closes the bridge with the error and continues to analyze the remaining structures. The bridge with the error will still be included in the list of bridges in the Level Comparison windows; however, the results for that structure will be blank.
Figure 2: Create dataset window
Through the ARC tool main Dataset Explorer window, two datasets can be selected for comparison. Clicking on the Compare button opens the Dataset Comparison Setting window. This window is used to specify a percent difference at which the ARC tool will flag the results. The tolerance for Rating Factor or Design Ratio (RF or DR) is used for flagging Level 1 and Level 2 analysis results. Capacity, Dead Load, and Live Load tolerances are used for Level 3 analysis.
Figure 3: Dataset Comparison Settings window
The Level 1 Comparison window displays a comparison of the controlling load-rating factor for each dataset at the overall bridge level. The ‘Location same’ and ‘Limit state same’ column values will be shown in red if either of those respective values are different between the two datasets. Percentages changes are displayed in red if the value is greater than the specified tolerance.
Figure 4: Level 1 Comparison window
The Level 2 Comparison window displays a comparison of the controlling load-rating factor for each dataset at the member level. Similar to Level 1, the ‘Location same’ and ‘Limit state same’ column values will be shown in red if either of those respective values are different between the two datasets. Percentages change are displayed in red if the value is greater than the specified tolerance.
Figure 5: Level 2 Comparison window.
Level 3 analysis is an in-depth comparison of the results. This comparison shows differences in dead load, live load, and capacity at all points of interest set under the control options. This window can be used to pinpoint where the differences are in a model to assist in understanding why the rating factor or design ratio is different. The Level 3 analysis produces large files; therefore, it is recommended to perform the Level 3 analysis only on select bridges that require further analysis.
Figure 6: Level 3 Comparison window.
The ARC tool assists in testing new BrDR releases to provide comparison information that will provide agencies with the confidence they need to upgrade to the most current release of the software. The results can be retained and new versions can be compared to multiple past versions. For all comparison levels, the results can be exported to a CSV file that can then be saved in Microsoft Excel format to assist in managing the comparisons.
The ARC tool included in the BrDR version 7.1 release is the first generation of the tool. As agencies take advantage of this new tool, the Task Force welcomes input on features and/or recommended enhancements that could be included in the tool to support easier version comparison testing going forward.