3. First step: the mesh#

To perform a calculation on a prestressed reinforced concrete structure, it is necessary to mesh the concrete, the reinforcements and the prestressed cables.

  • The concrete mesh can be created with any solid element in \(\mathrm{3D}\) or \(\mathrm{2D}\). In \(3D\), elements can be linear or quadratic. If shell-type modeling is chosen, the elements will be linear.

  • The frames can be represented:

    • or individually in this case, they will necessarily be meshed with \(\mathit{SEG2}\) (linear elements) whose nodes are common with those of concrete. So you have to think about it when meshing concrete. In addition, care must be taken if the concrete is meshed with quadratic elements in order to properly match all the concrete nodes located along the reinforcement with a steel node: in other words, if the concrete is meshed with quadratic elements, where a reinforcement must pass, 2 \(\mathit{SEG2}\) steel must be defined for a concrete mesh;

    or in a distributed manner in the form of a surface whose nodes are the same as the nodes in the concrete. The cells can be either triangles or quadrangles, linear or quadratic. It will therefore be necessary to take care to identify this surface at the time of the concrete mesh and to duplicate the meshes to define the steel sheet (via*Transformation → Duplication Nodes/Elements*in*salome_meca). If there are several reinforcing bars, these elements must be duplicated as many times as necessary.

  • Prestressing cables must be meshed with one-dimensional elements. If modeling BARRE is used, these elements will be \(\mathit{SEG}2\); if modeling CABLE_GAINE is used, these elements will be \(\mathit{SEG}3\). Whatever the modeling, it is not necessary to make the cable nodes coincide with the concrete nodes: the DEFI_CABLE_BP command makes it possible to create the kinematic links that will link the cable nodes with the concrete nodes of the surrounding mesh. On the other hand, care must be taken to have a similar level of discretization for concrete and steel, so as to have, as far as possible, a steel node in each concrete mesh (so that all the elements see the cable) and to avoid having several steel nodes in a concrete mesh (to avoid adding to the problem with unnecessary Lagrange multipliers).

Since anchor nodes must be defined for each cable, it is necessary to have created node groups for each cable end.