Hi guys,
I am modelling a slab supported on piles, the piles are actually tension piles to support upheave beneath the slab. I model the slab using plate elements and use vertical restraint node support at where the piles are located. The issue I am facing here is that, the out-of-plane shear will be very high, especially at those localized area and also closer to the edge of slab. I think that those shear is not realistic. I have read somewhere that, modelling some dummy members might help but I am not sure how to do it or if there is other methods to resolve this issue. There is no beams in the structure, only slab and piles. I have included a few snap shots of the loading conditions and out-of-plane shear results. I am pleased to attach my staad file here too. 1261.Launch chamber.STD
Best regards,
Ze Yang Lee
Check a 2nd point in this Wiki: https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/29385/avoiding-stress-concentrationsAs it suggests, you may connect the support node with adjacent nodes by using the dummy members, which would have a material with high E value and low density. This would spread the stresses and reduce it.
Dear sir,
Yes, I have read about that previously. However, my load is now applied as a plate load instead of a concentrated point load. Do I need to create dummy beams around the perimeter of the slab as my supports are mainly at the 2 sides of the perimeter to help on this situation in this case?
Think about the support nodes as a concentrated load on the mat. You do not need to create dummy members around the perimeter. Instead, create a dummy member between the support node and some nodes around that support node.
Thanks for your suggestion. I have tried to included the dummy members as follows. However, I still facing issue at the left edge of the slab. I am still not sure how to resolve this issue and suspect whether this really manifest in the slab. For your information, this is a slab to resist uplift force and the piles around are actually tension piles.
Do you think we can include the dummy members at the left and right edges too for better load distribution? Really thanks a lot for your reply sir.