Modeling Moment and Shear Connections

AI Thread Summary
The discussion focuses on modeling moment and shear connections in a 3D structural analysis using S-Frame 11 software. The user encounters an error related to illegal constraints at nodes defined as moment connections, indicating issues with rotation and translation restrictions. It is clarified that a moment connection should be modeled as a rigid joint, which prevents rotation but allows translation along the axes. The user is advised not to modify the degrees of freedom at the joint unless simulating specific fixed conditions. Properly defining moment connections as rigid joints is essential for accurate structural modeling.
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Homework Statement


I am trying to model a structure that has moment connections between some beams and columns, and shear connections between the remaining beam and columns in 3D.

The software I am using (S-Frame 11) gives me an error when running the analysis for the nodes that I have defined as moment connections :
  • No rotation about x,y,z axis
  • No translation about x,y,z axis
The error is : "Illeagel constraint to the support"

Homework Equations


I know that a moment connection prevents rotation and translation about all axis

The Attempt at a Solution



Can some one please provide guidance to how I can define a moment connection or if my understanding of a moment connection is correct?

This figure represents the definition I used for a Moment connection at one of the nodes:
upload_2018-3-21_12-35-7.png


This is my general model of the steel frame building I am going to analyze under gravity and lateral loads. If you can see, I have some nodes as fixed (line with dash underneath - those are the moment connections).

upload_2018-3-21_12-30-37.png
 

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For those who are interested: to model a moment connection, you simply define the joint as a rigid joint.

You do not play around with the degrees of freedom at the joint (only if it is fixed in real conditions, like at the foundation/base). But a moment connection implies that the members are welded together = a rigid joint (that is still able to translate about x,y,z). Also a rigid connection is the default condition set when you model a member connecting into a joint!
 
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