Defining beam section properties

Since the material behavior in this simulation is assumed to be linear elastic, it is more efficient from a computational point of view to precompute the beam section properties. Assume the trusses and bracing are made of a mild strength steel with E = 200.0 × 109 Pa, ν = 0.25, and G = 80.0 × 109 Pa. All the beams in this structure have a box-shaped cross-section.

Context:

A box-section is shown in Figure 1. The dimensions shown in Figure 1 are for the main members of the two trusses in the crane. The dimensions of the beam sections for the bracing members are shown in Figure 2.

Figure 1. Cross-section geometry and dimensions (in m) of the main members.

Figure 2. Cross-section geometry and dimensions (in m) of the internal and cross bracing members.

  1. In the Model Tree, double-click the Profiles container to create a box profile for the main members of the truss structures; then, create a second profile for the internal and cross bracing. Name the profiles MainBoxProfile and BraceBoxProfile, respectively. Use the dimensions shown in Figure 1 and Figure 2 to complete the profile definitions.
  2. Create one Beam section for the main members of the truss structures and one for the internal and cross bracing. Name the sections MainMemberSection and BracingSection, respectively.
    1. For both section definitions, specify that section integration will be performed before the analysis. When this type of section integration is chosen, material properties are defined as part of the section definition rather than in a separate material definition.
    2. Choose MainBoxProfile for the main members' section definition, and BraceBoxProfile for the bracing section definition.
    3. Click the Basic tab, and enter the Young's and shear moduli noted earlier in the appropriate fields of the data table.
    4. Enter the Section Poisson's ratio in the appropriate text field of the Edit Beam Section dialog box.
  3. Assign MainMemberSection to the geometry regions representing the main members of the trusses and BracingSection to the regions representing the internal and cross bracing members. Use the Part list located in the context bar to retrieve each part. You can ignore the Truss-all part since it is no longer needed.