Frame release concept clarification

[nanmi]

Hello,

I am new grad and want to understand better about frame releases.

Can you please confirm if the partial releases are correct:

1. Beam as rigid to the wall – no release in rigid connections

2. pinned connection of beam to the column - release moment in major and minor (M2, M3).

What could be examples where we intend/not intend to frame release.

Thanks

 

[KootK]

I don't believe that enough information has been provided for either of your cases to all us to make a determination. You haven't even told us what materials you're considering such that we might be able to tell you what is most typical.

No connection is perfectly rigid and very few are perfectly flexible. Most are something in between. Deciding how to model such connections must, invariably, consider the following:

1) What you as the designer need the connection to do and;

2) How you can reasonably expect the connection to behave given material characteristics, connection configuration, and the nature of the loading. Much depends on the relative stiffness of the components involved.

Engineering judgment is required in virtually all cases. Ideally, this should come from a mentor who is a real life colleague of yours. We can also help with this aspect but would require more information. If you want to take the latter route, I'd recommend posting some sketches of situations that pique your interest and we can weigh in on them on a case by case basis.

 

[Ron247]

Frame releases occur in the structural analysis phase of a project design. The structure you are attempting to "create the model" for is dependent on your unique project requirements. So I do not have a set of guidelines I could spell out as to when you do or do not use releases. I can make very general statements but no hard rules.

1. The less X-bracing or K-bracing your unique project allows, the more you will tend to have fully fixed connections or shearwalls.
2. The more redundancy you want in your structure, the more you will tend to have fixed connections or shearwalls.

Remember how designs occur in the first place. "Design Loads--Structural Analysis--Material Checks"

a) Someone needs a structure of some kind to provide an environment to conduct business.
b) The design team comes up with a preliminary layout that offers the floor space, headroom, clearances and appearance needed to satisfy business needs and wants. You take this preliminary building and review the design loads.
c) You attempt to combine structural components in "some fashion" to support this unique building and loading. This is the first part of you deciding on fixed versus pinned connections.
d) You create your structural model and apply the design loads from the building code to your model. This is the 2nd part of the fixed versus pinned debate.
e) You perform the structural analysis of the components and then you check each component against its material code (steel, concrete, wood etc). The results of the analysis is based on the components and how they are connected. Change the connectivity and the results change. In the structural analysis phase ALL materials can do ANYTHING. Nothing ever breaks in the structural analysis portion. You can fixed connect nasal hair to beads of sweat in the structural analysis phase but in the material check, you find out it is not so easy to do. The material check is where you find out "a beam made of wood cannot hold this up" or that you cannot actually connect hair to sweat.

These are some of the reasons you see us comment on what material you are using or we want more specifics about your actual structure.

KootK's comment on including your Mentor in this conversation is great advice. First, you do need a Mentor to properly progress in this field. Second, If I was mentoring someone and I found out they were consulting everyone but me, it would bother me a lot. A LOT.