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Difference between FIXED and PINNED Supports

What is the main difference between  FIXED and PINNED Supports.

I know Fixed will have moment.And in pinned there won't be moment.

But How it will be in practical Scenario. If i have Steel Bridge, The column support will be bolted. So in STAAD it should be Fixed Support.

Some people are using Pinned Support. Which one is correct. What is the main difference between  FIXED and PINNED Supports in real time.

Can some one clarify.



3 Replies (Most Recent Reply)

  • Fixed base is a base which resists Moments along with Tension and shear whereas Pinned base resists  tension and shear.

    In reality the action is always between the two i.e niether does a FIXED BASE nor PINNED BASE exists in reality.

    Coming to your situation, the way you design & detail your baseplate and foundation will define whether you should use a fixed base or pinned base.

    If you design the moment to be transfered through your baseplate to the fundation then it is a fixed base and if you only take tension and shear transfered to the foundation it would be a pinned base.

    Hope that clarifies you doubt.


  • In reply to syedmuzaffer:

    Dear Muzaffer,

    Have you worked on steel structures? Recently for three months I had the opportunity to work. It is not the base plate which was deciding factor for fixed support or pinned support. Base plate was in all the cases. The position of anchor bolt was a deciding factor. When I questioned, I was told that this is the practice in the company. Before that I could learn much about it, I left the company for personal reasons. I expect some detailed reply from the colleagues or Muzaffer may post a detailed reply.

  • In reply to sureshprsharma:

    Dear Suresh

    I do work for a Structural Steel Contractor. Thankyou very much.

    Yes the Base plate is there for all the cases whether it is Fixed or Pinned. Its only the design and detailing which changes.for example you would not need baseplate extension beyond the column face if its assumed as pinned base.

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