Support Configuration for Vertical Uplift Release 1

[drahmatxvx]

I have some problem for Boundary condition. I need to design support for Inplace condition, The support need to be release in uplift direction and restrain in compression. I have try to modeling the support configuration use Compression Only. But its will ask to put spring definition. And when I check the reaction, there is still have tension force. Can some one help me to solve this issue. I attach sample for Staad Pro Modeling.

 

[SethGuthrie]

You are on the right track, but you need to assign some KFY spring stiffness (it can be a large number). When nothing is entered, then a rigid bi-directional condition is used (only springs can be compression only). Review the Technical Reference section 5.27.5 Spring Tension/Compression Specification in the Help for details.

 

[drahmatxvx]

Hi SethGuthrie Thanks alots for your guidance.

 

[drahmatxvx]

Hi SethGuthrie, Now after we set to compression only support and put define spring, I need to add Support Displcaement on the Joint. When I read the Staad Technical Reference, we cannot combine spring support with Support displacement. I try use another methode to combine support displacement and vertical uplift release by selection compression member only at the column. But the result is not correct. all member ratio more than 100 and there is Warning Shown in the result. do you have any methode to combine between uplift release and vertical support displacement.

 

[SethGuthrie]

That does create a bit of a dilemma. I guess I tend to go with the most direct approach which would be to apply a point load, identify the deflection, then factor the point load to yield the desired support displacement (downward I assume, though I’m not exactly sure how that’s possible in the real world) and then combine that loading with all the other loads in a model with compression only springs.

 

[drahmatxvx]

For this case I use Temperature Load (Strain and Elongation) to replace Support Displacement. And I modeling dummy member and applied compression only. The Support condition I use restrain in vertical direction. When I running, there is lot of warning due to zero stiff, but its still work.