Various OBM issues and questions

Hello all,

 

I have a few questions and concerns regarding OpenBridge Designer (version 10.10.00.26) that I hope someone is able to answer. Please find my questions below:

  1. I have a situation where multiple bridges share the same substructure (abutment & piers). Is there a way to define multiple bridges but link them to the same support lines?

  2. Do any of the included OBD programs analyze and/or design post-tensioned reinforced concrete piers?

  3. I have experienced issues where the OBM was sent to LBC only to find that certain items that were modeled did not transfer properly. For instance, items like bearing pad and seat geometry, abutment backwall heights (when told to meet the top of slab), beam end offsets from the backwall, and a few other items did not transfer to LBC appropriately. I then sent the LBC model back to OBM (standalone option) only to find that my model was updated with wrong information, which had to be corrected. I have tried to pick and choose the items I want to transfer back to OBM, but there is not enough independence in the selection options. Though, the additional independence would not be needed if the transferring worked as intended. Is this a common issue and what are the solutions?

  4. I have also had an issue where the LBC models were updated and saved but when I attempted to open the model the next day, the information had not been saved. An image below shows that OBD stated the LBC model was updated at 6:13PM, but the linked file in the folder indicated the last update was at 1:58PM.

 

 5. The saving issue has caused me to not only “Save” but “Save As” the LBC models after updating. When I find that LBC did not save correctly, is it appropriate to delete the previous LBC file and relink the “Save As” file to OBD? Will there be any issues with this process?

 6. I do not understand why the haunch estimation in OBM needs to be so complex. Initially, a haunch is estimated in OBM for the beam placement. Then the model is sent to LBC (Conspan) to be designed. The camber tab in OBM allows the user to import the CONSPAN camber and DL deflection values. However, these values are not automatically sent to the beam definition, where the program updates the haunch. Instead, the user has to manually enter the required start/end haunch or camber for each beam while also verifying adequate beam to slab clearance. However, the haunch process has all the tools necessary to be automated. Another concern is with the option to specify Min. Clearance and Camber. This method does not account for the beam DL deflection at mid-span, which affects the haunch at the center of girder. This is of particular concern since some DOT's have specific ways of calculating haunch at mid-span.

 7. If I decide to use the BIM Workflow option, do I need to re-enter all of the loads in RCPier each time I update the model in OBM? Using the standalone option, changes in the OBM (i.e., horizontal alignment) have to be re-sent to LBC. This results in me losing all of my previous analysis and designs. There must be a better way?

Thank you!

  • For point 2. RM Bridge can do it. 

    RM Bridge is now an integral part of OpenBridge Designer CONNECT Edition as Bentley’s solution for supporting the design and engineering tasks in bridge construction for all types of bridges and construction…

    Ana Carla Peres

    Senior Technical Support Engineer

    Bentley BrIM

  • Thank you for the response. I read that RM Bridge could put tendons in a deck but didn't find information or an example for PT piers. I will search further.

  • Hi William,

    I will try to respond to your questions based on the information that you provided.

    1. Short answer, no. When you place a bridge element, that element is tied to the bridge unit. This means that if a change occurs all elements under that bridge unit will update accordingly. Only one element can adapt to changes from 2 bridge units, and that is a pier (transition pier) that supports girders from 2 adjacent bridge units, in the longitudinal direction.

    2. RM Bridge can be used.

    3. There are known limitations in the transfer process (as stated in the Transfer Report GUI that appears when you send a model to LEAP/RM) but also there are limitations in the LEAP programs. In OpenBridge Modeler you can model the physical model with a high level of detail but LEAP software has its own limitations when it is creating the analytical model. Can you model in LBC the abutment back wall that you have modeled in OBM? If not, then assumptions are made during the transfer.

    4. The LEAP files are by default saved in the obd database and not on external files. If you have exported a LEAP file to a local folder, that model is absolute and it is disconnected from the obd database. More info regarding this you can find in the links below.

    Standalone Workflow for Analysis and Design - LARS | LEAP | OpenBridge | RM Wiki - LARS | LEAP | OpenBridge | RM - Bentley Communities

    BIM Workflow - LARS | LEAP | OpenBridge | RM Wiki - LARS | LEAP | OpenBridge | RM - Bentley Communities

    OpenBridge Designer - New File Format (.obdx) in v10.08.01 - LARS | LEAP | OpenBridge | RM Wiki - LARS | LEAP | OpenBridge | RM - Bentley Communities

    5. Se number 4 answer.

    6. The girders are created in OBM always straight, thus those haunch values coming from LBC can't be used. The haunch values coming from LBC are used in the reports only.

    7. See number 4 answer. The BIM workflow makes a continuous connection between the physical model and the analytical model. If the change in OBM is major, like you are adding an extra column in your pier template, when you open LBC the software will inform you that a major change has been detected and the design results will be reset, but it will try to preserve the loads coming from the superstructure. If your change is minor, say you decrease the distance between girders, in LBC we will inform you that we detected minor changes and we will update the results accordingly, including rebar design if that was done previously.

    Hope this will help you!

    Answer Verified By: William Shekarchi 

  • Vlad,

    Thank you for the response. I have a few follow-up questions and I will continue using the numbering notation as the original post.

    1. A future update to the program should incorporate the ability to have side by side bridges that use the same substructure. We regularly place 1" longitudinal open joints in bridge decks when they exceed a certain width. This means the superstructure is divided but the decks are on the same substructure. We also have situations with direct connectors (or fly overs) that diverge but have 1 or multiple shared abutments or bents.

    3. I understand the limitations during the transfers - especially since OBM is more advanced than LBC. However, it is frustrating as a user to spend the time inputting bearing information only to have it not transfer. Then I have to manually update the same bearing information in LBC to do the analysis. The biggest issue is that I then cannot read the analytics back into OBM without messing up the model. I want to bring in the revised concrete strengths but not the model changes. Please allow the user to select or deselect more options to import. OR fix the importing issues. Otherwise the read from analytics is useless.

    4. I will try again to keep the file in the temp work space. But as I recall, that file also lost my work the next day.

    6. I still don't understand what the limitation is. The girders can remain straight in the model and still have the haunch calculations automated to tell the user what haunch is needed. A program called PGSuper asks the user for an initial guess on the haunch then the user runs the design. The program then tells the user what haunch is needed to satisfy minimum start/end beam haunch and minimum haunch at edge of the beam (due to cross-slope) also called "fillet" based on the design cambers and DL deflections. They also estimate the gap between the cambered beam and deck profile to calculate haunch volume and weight. None of these things require the model to have non-straight girders.

    Thank you.

  • Hi William,

    Just for letting you know that with RM Bridge, you can also do separated decks with common piers. It is possible to model two separated superstructures with a common infrastructure, with just one pier. And at the final, you can send a wireframe model to OBM in *dgn format for drawings production.

     

    In RM Bridge, it is possible to export the wireframe model including all the 3D drawing information viewed in Main View, as prestressing tendons and reinforcements to a *.dgn file format. In Main Window…
     

    If you desire, you can send me a set of drawings of what  your bridge project is and I'll be more than happy in helping you to do it with RM. anacarla.peres@bentley.com

    Ana Carla Peres

    Senior Technical Support Engineer

    Bentley BrIM