Member Type

Glossary Term

The member type controls the stiffnesses and properties of a member which are applied during the structural analysis.

The most commonly used member type is the beam: This rigid member can transfer all internal forces.

Member Types

  • beam
    The beam is a rigid member which is able to transfer all internal forces.
    When two beams are connectedwith each other and no hinge has been defined for the common node, the connection is bending-resistant.
  • rigid member
    The rigid member couples displacements of two nodes by means of a rigid connection. It corresponds basically to a coupling member, but customized hinges can be assigned at the member ends.
    The following stiffnesses are applied during the calculation:
    • longitudinal and torsional stiffness: E ⋅ A = G ⋅ IT = 1013 ⋅ l
    • bending stiffness: E ⋅ I = 1013 ⋅ l3
    • shear stiffness GAy = GAz = 1016 ⋅ l3 where l = member length
  • rib
    Defining a downstand or upstand beam with effective slab widths is possible with the rib. Within the effective slab widths, the slab internal forces are integrated and added to the member internal forces.
  • truss
    The truss is a beam with hinges located at the member ands which do not transfer any moments.
  • truss (only N)
    The truss (only N) has only one longitudinal stiffness E ⋅ A. Moment hinges are arranged at the member ends.
  • tension member/compression member
    A tension member is a truss (only N) with the additional property to only absorb tensile forces. A compression member accordingly transfers only compressive forces.
  • buckling member
    A buckling member is a truss (only N) with the additional property to fail under compressive force which exceeds the buckling force Ncr.
  • Cable
    Cables absorb only tensile forces. They are used to analyze cable chains with longitudinal and
    transversal forces by iterative calculations taking into account the cable theory (large deformation analysis).
  • cable on pulleys
    The cable on pulleys can only absorb tensile forces and only a displacement within the internal nodes in the longitudinal direction ux is possible. This member type is calculated according to the cable theory
    (large deformation analysis) and is appropriate for calculating pulley systems where axial forces are passed on by means of deviating points.
  • result beam
    The result beam has no stiffness and has no influence on the structural analysis. The result beam is a tool to integrate surface, solid or member results in a predefined area  for the subsequent design.
  • definable stiffnesses
    With the stiffness member type, it is possible to assign user-defined stiffnesses to the member for the structural analysis.
  • Coupling
    The coupling member has the stiffness of a rigid member. In addition, when using the coupling member, the degrees of freedom of the start and end nodes are defined depending on the settings. The following coupling members are available:
    • coupling rigid-rigid: rigid coupling with bending-resistant connections at both ends
    • coupling rigid-hinge: bending-resistant connection at member start and hinged connection at member end
    • coupling hinge-hinge:
      hinged connections at both ends of the coupling member
    • coupling hinge-rigid: hinged connection at member start and bending-resistant connection at member end
  • spring
    With the spring, a spring stiffness for a member can be defined.
  • Null
    A dummy member is not considered for the calculation.
    Dummy members are used to analyze, for example, the structural behavior if certain members are not effective.

Keywords

member, member type, bending-resistant, rigid, framework, truss structure, beam structure, spring

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