Patch + Member Offset behaviour [Multiframe]

Hi,

I am modeling a stiffened steel plate (horizontal flat steel plate, with attached bulb profile stiffeners for example)... Is it correct to model the patches (plates) and elements connected in their N.A as default? (see picture 1). Or should I be "aligning and offsetting member to patch" as per the "Frame" menu in Multiframe? (see picture 2)

Pic 1:

Pic 2:

It seems logical and correct to align the members as in picture 2... but once Multiframe introduces the rigid "offsets" the bending moment diagram shows big serrated jumps for continuous members (uniform continuous load and geometry)... As seen here:

Does anyone have any idea of why is this happening? Is this correct?

Sorry for my ignorance, and thank you for your time!

Carlos

  • Hi Carlos, thanks for your requests. Both ways of modeling patch and members are valid. If adding member offsets, Multiframe would automatically add offsets effects into Multiframe server.

    As to jumps shown on bending moment diagrams due to different offset at the same joint, it is a correct behavior.  If you replace the rigid links with very stiff members, you would also see the similar results.  Please see picture below.

    Regards,

    Jason