Dear all, Currently i am modelling tunnel lining for a project in Staad Pro. This requires the application of compression springs both on sides as well as invert. i have doubts regarding direction of radial and tangential stiffness to be applied in the model. 1.As far as i understand, the KFX, KFY and KFZ values are to be specified along the current global axis of the model or is it a convention that radial stiffness always has to be specified as KFX irrespective of the global axis? 2. Directions of radial stiffness shall be different for the invert (Global vertical) and side walls (Global horizontal). Do we have to consider different directions( KFX(radial for side walls) and KFY(radial for invert)) while specifying stiffness or they shall remain same (e.g. as KFX(radial for sidewalls as well as invert)) throughout the model? Regards
Supports ( including springs ) are defined with respect to the global axis system. The only exception is when you are defining inclined supports which has it’s own axis system that can be defined by the user. So when your walls and slabs are planar and lie in one of the global planes ( XY, YZ, XZ ) you need to define supports along the global directions. For example if your side wall is in the global YZ plane and you want to define soil support normal to it, you would use KFX. Similarly if your base slab is in the XZ plane, you would use KFY.
If you have a circular cross section and need to define inclined supports, the following forum thread may of use
https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/140157/support-reaction-other-than-global-direction/424626#424626
Thank you very much Sye for clearing my doubt. I have some more issues:
1. In order to define the compression spring i have chosen a reference joint opposite to the plate where the spring is to be attached.Is this the correct way of doing it?
2.I have a number of nodes along each sidewall of the structure. Do i have to define reference points for each horizontal line of nodes and refer them with a node at opposite end? Is it not possible to select all the nodes lying on a sidewall at once and simultaneously refer them to some node at opposite wall. i tried using both the approaches and got different results
3.Also , in the invert, i have chosen the 'Ref' option in the inclined reference point menu? Is it the right way of defining reference points of invert slab or is there any other way
Thanks and Regards
For the records, this is being discussed further at
https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/147015/compression-springs-staad-pro/447123#447123