Assumptions and Limitations When Exporting to LEAP Bridge Steel

Please be aware of the following assumptions and limitations when transferring the physical model from OpenBridge Modeler to an analytical model in LEAP Bridge Steel and bringing selected changes back to OpenBridge Modeler.

1. Data Transfer: In version 10.11, the data transfer is bi-directional, i.e., from OpenBridge Modeler to LEAP Bridge Steel, and back from LEAP Bridge Steel to OpenBridge Modeler, for selected changes in superstructure and substructure. While the entire model is transferred from OpenBridge Modeler to LEAP Bridge Steel, on the way back only selected superstructure (beams and beam layout) and all substructure information is transferred. In LEAP Bridge Steel, use the OpenBridge Modeler > Save to OBM option to write information back to OpenBridge Modeler via an XML file. In OpenBridge Modeler on the Utilities tab of the ribbon toolbar, select LBS > Update from Analytics to select the same transfer XML file, and start the process of updating the OpenBridge Modeler model with LEAP Bridge Steel data changes if any. You will be prompted with a dialog showing what information has changed, along with options to bring in select information into OpenBridge Modeler. In this release, stiffeners and cross-frames are written from OpenBridge Modeler to LEAP Bridge Steel, but any changes made in LEAP Bridge Steel, cannot be sent back to OpenBridge Modeler.
2. Stiffeners and Cross Frames defined in OpenBridge Modeler can now be transferred to LEAP Bridge Steel along with all other bridge elements defined. At this time, the transfer is only one way from OpenBridge Modeler to LEAP Bridge Steel.
3. Model: Model must be completed in OpenBridge Modeler, with all super and substructure including bearings defined, before transferring to LEAP Bridge Steel.
4. Deck Slab Thickness: For a bridge model with varying deck thickness in spans, or across the cross-section in a single span, OpenBridge Modeler will transfer the minimum thickness of the slab across all cross-sections and all spans to LEAP Bridge Steel. The deck thickness is not transferred back from LEAP Bridge Steel to OpenBridge Modeler.
5. Haunch Thickness: In both OpenBridge Modeler and in LEAP Bridge Steel, haunch thickness is measured from the bottom of the top flange to bottom of deck. OpenBridge Modeler will conservatively transfer the maximum thickness from among all beams in all spans to LEAP Bridge Steel.
6. Beam Layout: To cover a wide variety of possible scenarios, LEAP Bridge Steel will always bring in beam paths from OpenBridge Modeler as custom beam paths. While the user can modify these beam paths in LEAP Bridge Steel and send the information back to OpenBridge Modeler, deleting and adding entirely new beam layouts and attempting to transfer this information back to OpenBridge Modeler is not supported.
7. Beam Cross-sections: When using Rolled Beam Shapes, OpenBridge Modeler transfers the appropriate name to LEAP Bridge Steel, and a corresponding section is picked from the Standard Sections list in LEAP Bridge Steel. For Built-up shapes, all transfers are by plate dimensions, a much simpler transfer. Steel Tubs are currently not transferred from OpenBridge Modeler to LEAP Bridge Steel or vice-versa.
8. Bearings: LEAP Bridge Steel can currently only handle rectangular shape bearings. Any other shape of bearing coming from OpenBridge Modeler is converted to equivalent rectangular bearing during transfer. Grout pads on top of the bearings in OpenBridge Modeler are not transferred to LEAP Bridge Steel, but the thickness at the center is added to the bearing seat thickness to compensate.
9. Substructure:
   1. Pier Location offset is measured in OpenBridge Modeler, along the SupportLine, whereas in LEAP Bridge Steel it is measured perpendicular to the alignment. The conversion is done on the fly when data is transferred from OpenBridge Modeler to LEAP Bridge Steel.
   2. Since LEAP Bridge Steel does not support inclined/sloped pier cap, when such a cap is transferred from OpenBridge Modeler, it is treated as a straight/level cap and the bearing seats adjusted to fill in the gap under bearings/beams.
   3. For Abutments, to accommodate various agency practices, OpenBridge Modeler allows users to set three different locations (front face of backwall, centerline of abutment cap, back of abutment) as the reference line for placing abutments. Since LEAP Bridge Steel only allows one reference line at center of abutment, OpenBridge Modeler on data transfer will maintain the accurate lengths of the girders and adjust the position of abutment for an additional offset distance.
   4. LEAP Bridge Steel can have round, rectangular and rectangular-variable column shapes. OpenBridge Modeler supports the following additional shapes: rectangular-chamfered, rectangular-filleted, rectangular-beveled and oval. All are transferred from OpenBridge Modeler as standard rectangular columns in LEAP Bridge Steel. When transferring template-based column cross-sections from OpenBridge Modeler, columns come in with a cross-section represented by a bounding rectangle around the shape. Variable pier caps with parabolic or circular variations are approximated by linear variations.
   5. Integral substructures in LEAP Bridge Steel will not transfer to OpenBridge Modeler in this release of OpenBridge Modeler.
   6. LEAP Bridge Steel does not support Struts between columns or wingwalls. So transfer from/to OpenBridge Modeler is not yet supported for these elements.
   7. If you have modified the column length in LEAP and you want to update the column length in OpenBridge Modeler, please be sure to have the footings elevation constraints unchecked in order to see the updated model.
   8. For Variable Columns, defined using Templates, transfer to LEAP Bridge Steel is not possible at this time.
   9. User defined templates for footings and abutments are transferred as equivalent rectangles.
10. Auxiliary/Barrier: In this release OpenBridge Modeler will transfer Barriers from OpenBridge Modeler to LEAP Bridge Steel as equivalent loads. User should verify and adjust these elements in LEAP Bridge Steel as needed.
11. File Name: When attempting to transfer data from OpenBridge Modeler to LEAP Bridge Steel, user can provide a file name and path for the LEAP Bridge Steel data file. If such a file already exists, OpenBridge Modeler will replace only the geometry and material data and retain all loads and other design parameter information.
12. Steel member definition in LEAP Bridge Steel is per span and in OpenBridge Modeler could be defined from support to support as continuous. Therefore, after transfer from OpenBridge Modeler to LEAP, user may find multiple pieces of the same member defined from support to support. In recent updates in LEAP Bridge Steel, it is now possible to define beam overhangs and also when data is sent back to OpenBridge Modeler, the beams are no longer broken down at supports.
13. For offset (from alignment) bridges, OBM and LBS support line stationing could be different due to differences in assumptions on layout in these two products. While the conversion is done on the fly and the bridge will be located geometrically accurate, future versions will address this issue.
14. Field Splices and Shear Studs defined in OpenBridge Modeler can be transferred to LEAP Bridge Steel. At this time, the transfer is only one way from OpenBridge Modeler to LEAP Bridge Steel
15. While Steel Tubs (box girders) can be modeled in OpenBridge Modeler, they cannot yet be transferred to LEAP Bridge Steel or to RM Bridge.