Member Type

The most common member type is a beam: This bending-resistant member can transfer all internal forces.

Member Types

Beam

A beam is a bending-resistant member that can transfer all internal forces. If there are two beams connected to each other and no release has been defined for the common node, the connection is bending-resistant.

Rigid member

A rigid member couples the displacements of two nodes by means of a rigid connection. In principle, it corresponds to a coupling member, but its hinges can be assigned individually at the member ends.
The following stiffnesses are used in the calculation:

• Longitudinal and torsional stiffness: E ⋅ A = G ⋅ I_T = 10¹³ ⋅ l
• Flexural resistance: E ⋅ I = 1,013 ⋅ l³
• Shear stiffness: G_Ay = G_Az = 10¹⁶ ⋅ l³, where l is the member length

Rib

A rib allows you to define a downstand or an upstand beam with effective slab widths. Within the effective slab widths, the slab internal forces are integrated and added to the member internal forces.

Truss

A truss member is a beam member with hinges arranged at the member ends that transfer no moments.

Truss (only N)

A truss member (only N) has only one longitudinal stiffness E ⋅ A. Moment hinges are arranged at the member ends.

Tension / Compression

A tension member is a truss member (only N) with the additional property of absorbing tensile forces only. Accordingly, a compression member only transfers compressive forces.

Buckling

A buckling member is a truss member (only N) with the additional property of the failure when the compression force exceeds the buckling force N_cr.

Cable

Cables only absorb tension forces. They allow to create cable chains with longitudinal and transversal forces by using an iterative calculation and by considering the cable theory (a large deformation analysis).

Cable on Pulleys

A cable on pulleys can only absorb tensile forces and has only one possible displacement of the inner nodes in the longitudinal direction u_x. This type of member is calculated by considering the cable theory (a large deformation analysis) and is used for the calculation of pulley systems, where longitudinal forces are transferred by a pulley wheel.

Result Beam

A result beam has no stiffness and has no influence on the structural analysis. The result beam is a tool for integrating surface, solid, or member results in a predefined area for the subsequent design.

Definable Stiffness

The member type of definable stiffness allows for specifying user-defined stiffnesses for a structural analysis.

Coupling

A coupling member has the stiffness of a rigid member. Furthermore, the degrees of freedom of the start and end nodes are defined for the coupling member, depending on the specification. The following coupling members are available:

• Coupling Rigid-Rigid: a rigid connection of the coupling member on both sides
• Coupling Rigid-Hinge: A rigid connection at the start, a hinged connection at the end of the member
• Coupling Hinge-Hinge: a hinged connection of the coupling member on both sides
• Coupling Hinge-Rigid: a hinged connection at the start, a rigid connection at the end of the member

Spring

A spring allows you to specify a spring stiffness for a member.

Dashpot

This member type is relevant for a time history analysis in the dynamics add-on modules RF‑/DYNAM Pro - Forced Vibrations and RF‑/DYNAM Pro - Nonlinear Time History. The member properties can be specified in the dialog box that you can access by clicking the [Edit] button in the dialog box or in the table.

Null

A null member is not taken into account in the calculation. For example, you can use null members to analyze the structural behavior if certain members are not effective.