Node-to-node anchors in several elements

Question

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 
 
 Aur&eacute;lien

Dennis Waterman · Answer

Dear Aur&eacute;lien, 
 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