Stiffness Analysis

The result tables of the Stiffness Analysis category display the stiffnesses of the analyzed joints, including the classification.

Stiffness Analysis

The "Stiffness Analysis" table lists the joint stiffnesses by joints.

Result Tables "Stiffness Analysis" for Steel Joint Design

The green check mark indicates that the calculation of the steel joint model was successful.

Status

The "Status" column lists the members connected to the node, including their descriptions (see Chapter Main). This covers all members with the same properties and location. The joint stiffnesses are displayed for each of these groupings that you have selected for the stiffness analysis (see Chapter Members).

Axial Stiffness S_N+ / S_N-

Both columns include the stiffnesses that the joint represents for the positive axial forces (tension) and for the negative axial forces (compression). The +∞ entry means infinitely high axial stiffness and thus a fixed connection.

Rotational Stiffness S_My+ / S_My- / S_Mz+ / S_Mz-

This column displays the constants of rotational springs that result from the boundary conditions of the joint. The rotation capacity is analyzed if the moment M_y or M_z was considered for a connected member (see the image Internal Forces for Stiffness Analysis ). The signs of the internal forces correspond to the conventions shown in the image Sign Rules for Member Internal Forces .

Classification

The "Classification" table shows the classification limits and the arrangement of the analyzed nodes.

Classification of Nodes

Node

The results are displayed for each node of a joint.

Status

The "Status" column lists the members connected to the node selected for the stiffness analysis (see Chapter Members), including their descriptions.

Stiffness Analysis

The "Type" column lists the types of internal forces analyzed in the rotation capacity analysis. Usually, these are the bending moments M_y and M_z in the connected member (see the image Internal Forces for Stiffness Analysis ). The analysis is performed for both positive and negative moment loading. The initial stiffness "S_j,ini" of the joint is given as the result respectively.

Member Length

The unsupported member length affects the joint stiffness.

Classification Boundaries

The joint classification limits are determined from the boundary conditions of the joint. If the joint stiffness for a moment loading is greater than or equal to the value specified in the column S_j,rig, there is a rigid connection. In case of the stiffness lower than or equal to the value specified in the S_j,pin column, the connection is a pinned joint. The stiffnesses between these limit criteria indicate a semi-rigid or non-rigid joint.

The limit criteria for the classification according to the stiffness are described in EN 1993‑1‑8, 5.2.2.5, for example.

Classification

Depending on the rotation capacity, the connection is classified as "rigid", "semi-rigid", or "pinned". This allows you to determine how internal forces are transmitted.