Modeling Moment and Shear Connections

In summary, the conversation is about a person trying to model a structure with moment connections between some beams and columns and shear connections between the remaining beam and columns in 3D using S-Frame 11 software. However, when running the analysis, an error is encountered regarding illegal constraints to the support. The person is seeking guidance on how to properly define a moment connection and clarifies that a moment connection prevents rotation and translation about all axis. The person also provides a figure and explains the general model of the steel frame building. They mention that to model a moment connection, the joint is defined as a rigid joint and the degrees of freedom are not adjusted unless it is fixed in real conditions. They also clarify that a moment connection implies that the
  • #1
CivilSigma
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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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  • #2
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!
 

1. What is the purpose of modeling moment and shear connections?

The purpose of modeling moment and shear connections is to accurately predict the behavior and strength of structural connections, which are critical components in any building or structure. This allows engineers and designers to ensure the structural integrity and safety of the overall structure.

2. What factors are considered when modeling moment and shear connections?

Several factors are taken into account when modeling moment and shear connections, including the type and size of the members being connected, the loads and forces acting on the structure, and the materials and methods used for the connection.

3. What are the common methods used for modeling moment and shear connections?

The most commonly used methods for modeling moment and shear connections include the rigid body assumption method, the elastic analysis method, and the plastic analysis method. Each method has its own advantages and limitations, and the choice depends on the specific needs and requirements of the project.

4. How do you ensure the accuracy and reliability of modeled moment and shear connections?

To ensure the accuracy and reliability of modeled moment and shear connections, it is important to use appropriate structural analysis software, verify the input data and assumptions, and validate the results through physical testing or comparison with established design standards and guidelines.

5. What are some challenges in modeling moment and shear connections?

Modeling moment and shear connections can be challenging due to the complex nature of structural connections and the various factors that can influence their behavior. Some common challenges include accurately representing the connection details, accounting for different loading conditions, and considering the effects of geometric imperfections and material nonlinearity.

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