Hello,
When working with plate stresses, there is a stress type option of 'Global Stress', where the user can choose 'Result Dir.' and' Up'. I can't seem to find a description or derivation for this stress type in the Help. Can I get an explanation / clarification on what this type of stress is defined as?
Thanks!
Plate Moments in STAAD.Pro are reported with respect to the local axis of the plates. However one can also ask the software to plot the moments along the global directions ( Global Moments ) in which case the local axis moments MX, MY and MXY are resolved along a global direction chosen by the user. The stress corresponding to these global moments are global stress. The Result Dir represents the direction along which the Moments are resolved. The Up represents the global direction in which upper surface of the plate ( face in the direction of positive local z ) is assumed to lie for reporting the global moments/stress.
Thanks Sye!
Sye,
Was just reading this post. Thanks for this explanation. It's very helpful.
Does this mean we can use Global moments as design vertical and horizontal moments for plates ?
for example, if I was modelling a concrete rectangular tank, with local Z for all wall plates pointing exterior of tank, can I take vertical design moment as : global moment with result direction along global Y and up direction as global X/Z ? The model is set-up as global Y pointing upwards.
Can you advice on a right approach ?
Thanks Sye
Sye ,
Sorry I missed the last question. So trying to answer both through this response. Global moments can always be used for design of slabs or walls. However it is used mostly in situations where plate local axes are not oriented the same way which typically happens when we use triangular or mixed triangular/quadrilateral type meshing. For meshing which is regular and which has plate local X and Y oriented the same way, you can generally use the plate local moments. These are the moments that STAAD.Pro considers for element design. Also it is important to add here that global moments include contribution from MXY as well. So for situations where you think that twisting of the slab is significant enough and cannot be ignored in the calculcations, you may want to go with the global moments.
Sye, Thank you very much. This was very helpful.