pylon and other area connectivity is poor , -ve stiffness happen because of no proper connection
Assuming your question is related to STAAD.Pro, here is a forum post that deals with connectivity issues between solids and beam elements
https://communities.bentley.com/products/ram-staad/f/ram-staad-forum/168263/instability-in-staad/482280#482280
can i share my staad file here kindly help me out where i made a mistake
ok please upload the model and one of us will take a look.
4527.design towers.STD
sir i attach my file here kindly hav a look