Tension elements cannot be linked to the master object

Hello, for the attached model I would like to model prestressing strands with variable profiles. Ideally, I want to model 32 of them in the end, if it works computationally. Initially, I had the middle one of the 3 prestressing strands as a polyline and that worked; it was somehow automatically already connected with the master object Beam 1. However, I used very many nodes there, so that the file basically only lagged and crashed. I then decided to use fewer nodes and tried it with a spline. I wonder why I cannot connect them with the master object Beam 1 in the properties of the prestressing strands? Beam 1 is actually a bridge cross-section as a plate girder, inserted via Rsection. Could you help me with this? Many thanks in advance. Feel free to call me if you have any questions! It should actually be possible to apply a prestressing force and have everything calculated. Either it did not work with the master object or there were problems with error 191 internal calculation error.

I would appreciate your support.

Löbtauer Brücke A-E.rf6 (1.7 MB)

Hello @ErikBau, welcome to the Dlubal Community! :waving_hand:,

The problem lies in the spline geometry. A spline is a polynomial curve that passes through all defined nodes. The more nodes a single spline has, the higher the polynomial degree and the more numerically unstable the curve becomes. At 125 m with many nodes in a single spline, RFEM can no longer accurately assign the path to the member, which is why the master object is not recognized.

The solution: divide the tension member into several short spline sections. I recommend a maximum of 4 nodes per spline. This keeps each section geometrically stable, the master object is reliably recognized, and the model runs much faster.

Please also ensure that the tension member lies completely within the cross-section of the member. Even if a very small section of the tension member is outside the cross-section, RFEM will no longer recognize the master object.

Best regards
Hedi Boukraa