Beam Type: Standard
In the Define Beam Properties dialog, if you choose Beam Type = Standard, then you can define the properties of beam support elements that can resist axial, flexural and shear loading. For information about the numerical implementation of beam support in RS3 see the Beams and Plates document in the RS3 Theory section.
The following properties are used to define Standard Beam support.
Elastic Properties
For a Standard Beam, you must define the following Elastic Properties:
- Young's Modulus
- Poisson's Ratio
Strength Parameters
For a Standard Beam the following Strength Parameter options are available:
MATERIAL TYPE: ELASTIC
If the beam Material Type = Elastic, then strength parameters are not considered. The beam will only respond elastically to loading, and there will be no upper limit to the loading that can be sustained by a beam.
MATERIAL TYPE: PLASTIC
If the beam Material Type = Plastic, then you may enter the beam shear strength, and peak and residual compressive and tensile strength parameters, which will be used in the analysis. Beams defined as Plastic will yield if the peak strength is reached. The plasticity calculation uses the "layering" method presented in Owen and Hinton (1986), in which the cross-section of the beam is partitioned into layers. If the stress in a given layer exceeds the peak strength (compressive or tensile), the layer yields.
Stage Beam Properties
The properties of a Standard Beam can be modified at different stages of a multi-stage model, by using the Stage Beam Properties option in the Define Beam Properties dialog. This could be used, for example, to model an increase or decrease in strength or stiffness of a concrete beam with time.
Most of the parameters entered in the Define Beam Properties dialog can be increased or decreased by user-defined factors at different stages. For details about staging beam properties, see the Stage Material Properties topic, as the general procedure for staging properties is the same.
Geometry
The beam cross-section is defined by entering the Area and moment of inertia values I-min and I-max.
Include Weight in Analysis
By default the forces due to the weight of a beam are not included in the finite element analysis (i.e. beams have zero weight).
If you wish to account for the beam weight in the stress analysis, select the Include Weight in Analysis checkbox, and enter the Unit Weight of the beam material.
RS3 will then use the beam cross-sectional Area and Unit Weight to determine the weight of each beam element and include the resulting forces in the finite element analysis.
Pre-Tensioning
The Pre-Tensioning option allows you to model a support element that is pre-tensioned.
To define a Pre-Tensioning force for a Standard Beam, select the Pre-Tensioning checkbox and enter a value of Pre-Tensioning Force.
Mesh Conforming
If the Mesh Conforming checkbox is selected, then the finite element mesh will conform to the locations of the beam elements (i.e. the edges of the tetrahedral elements will align with the beam element locations). If the Mesh Conforming checkbox is not selected (i.e. turned off), then the finite element mesh will be generated independently of the beam element locations (i.e. edges of the tetrahedral elements may cross the beam elements).
Beam Element Formulation
For a Standard Beam you may select one of two different Beam Element Formulations:
BERNOULLI
This is the classical Euler-Bernoulli beam formulation, which does not account for transverse shear deformation.
TIMOSHENKO
The Timoshenko beam formulation accounts for transverse shear deformation effects.
The Timoshenko Beam Formulation is recommended if you are using higher order tetrahedral elements (i.e. 10-noded tetrahedrons), since in this case RS3 will automatically use 3-noded Timoshenko beam elements, resulting in displacement compatibility between the finite elements and the beam elements. Bernoulli beam elements are always 2-noded, and give less accurate results when used with higher order tetrahedrons.