Modeling the pin joint between the cross bracing and the trusses

The cross bracing, unlike the internal truss bracing, is bolted to the truss members. You can assume that these bolted connections are unable to transmit rotations or torsion. The duplicate vertices that were defined at these locations are needed to define this constraint. In Abaqus such constraints can be defined using multi-point constraints, constraint equations, or connectors. In this example the last approach is adopted.

Context:

Connectors allow you to model a connection between any two points in a model assembly (or between any single point in the assembly and the ground). A large library of connectors is available in Abaqus. See Connector element library, for a complete list and a description of each connector type.

The JOIN connector will be used to model the bolted connection. The pinned joint created by this connector constrains the displacements to be equal but the rotations (if they exist) remain independent.

In Abaqus/CAE connectors are modeled using connector section assignments. You create an assembly-level wire feature to define the connector geometry and a connector section to define the connection type. You can model connectors at all of the pin joints using one connector section assignment. You create the connector section assignment by selecting multiple wires and specifying a connector section to assign to the selected wires (similar to the association between elements and their section properties). For connections between coincident points, a specialized tool is available to simplify the modeling process. This tool is used here.

  1. From the main menu bar in the Interaction module, select ConnectorCoincident Builder.

  2. Use the Selection toolbar to restrict your selection to Vertices.

  3. In the viewport, drag the cursor around the entire model, then click Done in the prompt area.

    Ten pairs of points should appear in the Coincident Point Builder table. Each corresponds to one of the pin joint locations labeled a–j in Figure 1.

  4. In the Coincident Point Builder dialog box, click to create a section property.

  5. In the Create Connector Section dialog box, select Basic as the Connection Category. From the list of available translational types, select Join. Accept all other defaults, and click Continue.

  6. No additional section specifications are required. Thus, in the connector section editor that appears, click OK.

  7. Click OK in the Coincident Point Builder dialog box to create the connections.