Ongoing Issues with Generating Sections for Resultant Forces & MCT Command for Their Definition

Question:

To whom it may concern,

I am writing with regards to definition/generation of “Sections for Resultant Forces” for composite steel girders bridges.
I have been working with Midas Civil since “Sections for Resultant Forces” facility was first implemented. Since then, I constantly had issues with quick and automatic generation of the “virtual beams”.

The attached Midas Civil example is another case where I had to manually define in excess of 400 virtual beams or “Sections for Resultant Forces”. Note that the resultant forces have been defined at every division points per span in order to produce the complete bending moment and shear force diagrams on the steel-composite tapered girders.

Whilst working to define these virtual beams, I noticed the following issues:

1. Although, I have defined relevant Structure Groups for all the main girders in each of the 3no. main spans, using the following automatic virtual beam definition mode does not seem to work no matter what:
   
   • Mode: Structure Groups
     
   • No. of Division: say 12no. divisions for “NEW G2_1” (or any other end span Structure Group)
     
   • Direction vector: 1, 0, 0
     
2. When instead using the very tedious and time consuming (Mode: Elements Select combined with No. of Division: 1no.), I am also finding that the defined virtual beams don’t always consider the original manual elements selection. See below, and also you can try to replicate it using the attached file.
   

Manually selected elements for definition of virtual beam Virtual beam as defined by Midas (as if my selection was not understood!)
=>

1. we are increasingly starting to use the MCT Command Shell functions to speed up the definition and assignment process of the various FEA parameters.
   
   • Can you please confirm if there is an MCT Command for definition and modification of the Virtual Beams/ Sections for Resultant Forces in order to significantly improve the control and speed up the process for their definition
     

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Answer: Hello User,


Thanks for writing to us.

1) I was able to generate the virtual sections using "Structure Group method" in your model with an ease. We need to select the direction vector by clicking on the corresponding node points of the structure group. kindly checkout this FAQ: https://midassupport.jitbit.com/helpdesk/KB/View/10923481-boundary--how-to-use-section-for-resultant-forces and also checkout this interesting video which show the procedure in detail : https://mega.nz/#!opRSiaTR!MHH74LcKrwl14cvmZoHBHMsTgzo4HPWhJ8OZJwv87lw







2) Checkout the video for use of different modes to create section for resultant forces.

3) *VIRTUAL_SECT is for Virtual Section Definition.
*VIRTUAL_BEAM is for Virtual Beam Definition.

See below for command description.


*VIRTUAL_SECT ; Virtual Section
; iVSEC, NAME, CENT_CALC_TYPE, CEN_PT_X, CEN_PT_Y, CEN_PT_Z, NORMAL_X, NORMAL_Y, NORMAL_Z ; line 1
; NODE LIST ; line 2
; ELEM LIST



*VIRTUAL_BEAM ; Virtual Beam
; iVBEAM, iVSEC1, iVSEC2





kindly reply back if you have any further issues.
Regards,
Suman Dhara
Technical Support, MIDAS