Hello, as you can see in the attached image, I have to dig an excavation with a strut type shoring system. The problem is that the butons are bi-pods. I tried to use a central beam connected to two node-to-node to attach a sheet pile curtain to the plate. The calculation fails. Do you have a technique for modeling these shoring in several elements?
Best regards
Aurélien
Dear Aurélien,
You mention that your calculation fails, but you share no more details. Is the failure related to the modelling or other reasons, e.g. soil failure?
Just to understand, do you intend to create a connection between the single horizontal node-to-node anchor with the bi-pods on each end, also modelled as node-to-node anchors? Or is one of them a beam element?
Dear Stefanos,
The calculation said "slow convergence".
The bi-pods are node-to-node anchor beacause i need a preload. The single element between the two bipods is a beam (circular strut). I think the problem comes from joining the nodes.
Is it possible to create a node/node connection? I know that we can create a connection plate/plate or beam/plate. My goal is that there is only the normal effort passing through this strut. Do you have any advice on how best to model my scenario?
Thanks a lot for your help
Node-to-node anchors always are connected through a hinge, because this is the only way to assure they only have axial force and no shear force or bending moments. Hence, the bi-pods are hinged to the wall, to each other and to the single element. I can imagine that makes the construction kinematically undetermined.
Maybe it's worth a try to use beams for the bi-pods and a node to node anchor for the single element. Then apply the prestress to the single element rather than to the bipods. If you know what prestress force you need in the bi-pods and you know the angle under which they're connected to the single element, one can calculate the necessary prestress in the single element.
With kind regards,
Dennis Waterman
Dear Dennis,
Thank you for your feedback.
So I will try to reverse the elements using the bipods in beam and the single central element in node-to-node.
Is it a problem to have node-to-node not connected to a plate but just to a node?
I don't know .... I have never tried. That's why I said "it maybe worth a try" because I have never tried myself. I would suggest to make a separate very small model to check rather then changing your large model....in case it doesn't work either.
With kind regards.