pinned vs fixed what is the difference?

[Anonymous]

what is the difference?

Which to use in reinforced concrete construction

[mustafahesenow]

1

[Anonymous]

Hi @Anonymous

The difference between a pinned  connection and a fixed (moment) connection is the rotation constrain. We assume that a pin connection will not restrain any rotation thus there is no end moment while a moment(fixed connection) is able to restrain rotation and taking a end moment.

However, in reality, for the structure we constructed in real world, no matter what you designed for, the connection it will more or less restrain a rotation of connected member. If the connection is technically be defined as a fixed or a simple connection is depending on how much moment it is able to transferred. (Say fixed end moment 100kNm, your connection is able to transfer 98kNm moment, we consider it as a fixed connection, if only 2kNm moment get transferred, we ignore the end moment and assume it is a pin connection.)

You can use Mustafas solution for RC design.

[mustafahesenow]

Hi @Anonymous

In addition to above see this link :Release

[Anonymous]

which one should ultimately be used

[mustafahesenow]

Hi @Anonymous

What do you mean ?

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

Assuming that your concern is about the stiffness of the connection you may think in another way. If you e.g. want to say that instead of 100% of the bending the connection will transfer only 60% distributing 40 % to span moment you can use partial releases:

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous · Accepted solution]

It is your job as the engineer to decide such things @Anonymous (sadly you'll hear this a lot) what type of connection you want to design for sometimes pinned, sometimes fixed sometimes partially fixed. Through experience and reading you will come to know which connection you are designing for and it will always be dependent on the overall structure so such a question as 'what ultimately should be used' is not a worth while question 

[mustafahesenow · Accepted solution]

1

[Anonymous]

I understand

thanks for everything

[Anonymous]

thanks i learned something new 🙂

[mustafahesenow]

Hi @Anonymous

You are welcome thats good keep going.

[Anonymous]

I am working on PEB since 2008, I found something new, when you design fixed type connection for PEB (Pre Engineered Building) you consider all load to be shifted to civil foundation, ultimately you put the building load on minimum side and weight of building would be on lower side, while, when you choose pin (hinge) type connection you put the load of building on higher side and minimize the moment and forces on civil foundation that result in increase in PEB weight and cost. Tentatively, approx. 20% to 25% increase in PEB weight will be there when you switch fixed connection to pin type connection from the foundation plate.

It is recommended to use fixed type of connection for crane building otherwise weight of building will increase ultimate cost increases.