Global 3D calculation of the global model, where the slabs are modeled as a rigid plane (diaphragm) or as a bending plate
Local 2D calculation of the individual floors
After the calculation, the results of the columns and walls from the 3D calculation and the results of the slabs from the 2D calculation are combined in a single model. This means that there is no need to switch between the 3D model and the individual 2D models of the slabs. The user only works with one model, saves valuable time, and avoids possible errors in the manual data exchange between the 3D model and the individual 2D ceiling models.
The vertical surfaces in the model can be divided into shear walls and opening lintels. The program automatically generates internal result members from these wall objects, so they can be designed as members according to any standard in the Concrete Design add-on.
You have the option to perform the fire resistance design of surfaces using the reduced cross-section method. The reduction is applied over the surface thickness. It is possible to perform the design checks for all timber materials allowed for the design.
For cross-laminated timber, depending on the type of adhesive, you can select whether it is possible for individual carbonized layer parts to fall off, and whether you can expect increased charring in certain layer areas.
With the Concrete Design add-on, you can perform the fatigue design of members and surfaces according to EN 1992‑1‑1, Chapter 6.8.
For the fatigue design, you can optionally select two methods or design levels in the design configurations:
Design Level 1: Simplified design according to 6.8.6 and 6.8.7(2): The simplified design is performed for frequent action combinations according to EN 1992‑1‑1, Chapter 6.8.6 (2), and EN 1990, Eq. (6.15b) with the traffic loads relevant in the serviceability state. A maximum stress range according to 6.8.6 is designed for the reinforcing steel. The concrete compressive stress is determined by means of the upper and lower allowable stress according to 6.8.7(2).
Design Level 2: Design of damage equivalent stress acc. to 6.8.5 and 6.8.7(1) (simplified fatigue design): The design using damage equivalent stress ranges is performed for the fatigue combination according to EN 1992‑1‑1, Chapter 6.8.3, Eq. (6.69) with the specifically defined cyclic action Qfat.
The Ponding load type allows you to simulate rain actions on multi-curved surfaces, taking into account the displacements according to the large deformation analysis.
This numerical rainfall process examines the assigned surface geometry and determines which rainfall portions drain away and which rainfall portions accumulate in puddles (water pockets) on the surface. The puddle size then results in a corresponding vertical load for the structural analysis.
For example, you can use this feature in the analysis of approximately horizontal membrane roof geometries subjected to rain loading.
For the meshing of solids, you have the option of arranging a layered FE mesh. This option allows you to perform a defined division of the solid with finite elements between two parallel surfaces.
You can graphically evaluate result sections for the timber surface design. This can be done in the RFEM graphic as well as in the result history window. The sections can be placed at any location in order to evaluate the design results in detail.
For timber surfaces with the "Constant" thickness type, the crack factor kcr and thus the negative influence of cracks on the shear capacity is taken into account.
Here, the weld design becomes child's play. Using the specially developed material model "Orthotropic | Plastic | Weld (Surfaces)", you can calculate all stress components plastically. The stress τperpendicular is also considered plastically.
Using this material model you can design welds closer to reality and more efficiently.
In the Timber Design add-on for RFEM, you can design members as well as surfaces according to Eurocode 5, SIA 265 (Swiss standard), CSA O86 (Canadian standard), or ANSI/AWC NDS (American standard); for example, cross-laminated timber, glued-laminated timber, softwood, mass timber, and so on.
Curved elements are available only in RFEM. It's possible to intersect curved surfaces and solids.
When doing this, the program generates surfaces with the "Trimmed" surface type. With this technology, you can create very complex geometries, such as pipe intersections or curved openings, with a single click.
The intersection of solids is carried out adaptively using the new solid types "Hole" and "Intersection", according to the set theory. Use this method to create new, complex solid geometries similar to the manufacturing process (drilling, milling, turning, etc.). Therefore, it is possible to create complex curved surface or perforated solid elements. It's a simple process!
Use RWIND 2 Pro to easily apply a permeability to a surface. All you need is the definition of
the Darcy coefficient D,
the inertial coefficient I, and
the length of the porous medium in the direction of flow L,
to define a pressure boundary condition between the front and back of a porous zone. Due to this setting, you obtain the flow through this zone with a two-part result display on both sides of the zone area.
But that's not all. Furthermore, the generation of a simplified model recognizes permeable zones and takes into account the corresponding openings in the model coating. Can you waive an elaborate geometric modeling of the porous element? Understandable – we have good news for you then! With a pure definition of the permeability parameters, you can avoid complex geometric modeling of the porous element. Use this feature to simulate permeable scaffolding, dust curtains, mesh structures, and so on.
You probably already know that node, line, and surface releases are used to define transfer conditions between objects. For example, you can release members, surfaces, and solids from a line. It is also easily possible for the releases to have nonlinear properties, such as "Fixed if positive n", "Fixed if negative n", and so on.
Do you want to generate surfaces from members? Nothing is easier than that. You can find the right solution under Transverse Stiffeners Options when processing the members. In this case, you can adjust the transverse stiffeners according to the type and position.
Did you know that you can extrude surfaces into members? In this case, the program assigns a desired member property to the lines generated by the extrusion. A few clicks later, you are already at the desired result.
Extruding surfaces into a casing is also possible without any problems. Place the desired surface properties between the boundary lines of the surface and the copied lines. The program does the rest for you.
Converting members to surface models works without any major problems. Easily generate member local section reductions using the Generate Surfaces from Members function. Thus, you can convert the members into surface models.
Did you know? You can easily define structural modifications in load cases of the Modal Analysis type. This allows you, for example, to individually adjust the stiffnesses of materials, cross-sections, members, surfaces, hinges, and supports. You can also modify stiffnesses for some design add-ons. Once you select the objects, their stiffness properties are adapted to the object type. In this way, you can define them in separate tabs.
Do you want to analyze the failure of an object (for example, a column) in the modal analysis? This is also possible without any problems. Simply switch to the Structure Modification window and deactivate the relevant objects.
RFEM/RSTAB also provides a range of functions for the case of a fire. The program allows for the automatic generation of load and result combinations for the accidental design situation of fire design. The members to be designed with the corresponding internal forces are imported directly from RFEM/RSTAB. Also, all information about the material and cross-section is stored. You don't need to do anything else.
You only define the parameters relevant for the fire resistance design by assigning a fire resistance configuration to the members and surfaces to be designed. Moreover, you can also make further detailed settings, such as the definition of the fire exposure on one side up to all sides.
Are you familiar with the Tsai-Wu material model? It combines plastic and orthotropic properties, which allows for special modeling of materials with anisotropic characteristics, such as fiber-reinforced plastics or timber.
If the material is plastified, the stresses remain constant. The redistribution is carried out according to the stiffnesses available in the individual directions. The elastic area corresponds to the Orthotropic | Linear Elastic (Solids) material model. For the plastic area, the yielding according to Tsai-Wu applies:
All strengths are defined positively. You can imagine the stress criterion as an elliptical surface within a six-dimensional space of stresses. If one of the three stress components is applied as a constant value, the surface can be projected onto a three-dimensional stress space.
If the value for fy(σ), according to the Tsai-Wu equation, plane stress condition, is smaller than 1, the stresses are in the elastic zone. The plastic area is reached as soon as fy (σ) = 1; values greater than 1 are not allowed. The model behavior is ideal-plastic, which means there is no stiffening.
Did you know? In contrast to other material models, the stress-strain diagram for this material model is not antimetric to the origin. You can use this material model to simulate the behavior of steel fiber-reinforced concrete, for example. Find detailed information about modeling steel fiber-reinforced concrete in the technical article about Determining the material properties of steel-fiber-reinforced concrete.
In this material model, the isotropic stiffness is reduced with a scalar damage parameter. This damage parameter is determined from the stress curve defined in the Diagram. The direction of the principal stresses is not taken into account. Rather, the damage occurs in the direction of the equivalent strain, which also covers the third direction perpendicular to the plane. The tension and compression area of the stress tensor is treated separately. In this case, different damage parameters apply.
The "Reference element size" controls how the strain in the crack area is scaled to the length of the element. With the default value zero, no scaling is performed. Thus, the material behavior of the steel fiber concrete is modeled realistically.
Find more information about the theoretical background of the "Isotropic Damage" material model in the technical article describing the Nonlinear Material Model Damage.
You determine the deformation for members and surfaces, taking into account the cracked (state II) or non-cracked (state I) reinforced concrete cross-section. When determining the stiffness, you can consider "tension stiffening" between the cracks according to the design standard used.
The following new features are available for your work with surfaces: When creating surface intersections, independent surface components are now created for you instead of surface components.
If you want to describe surface thicknesses, you can now use a new thickness object. It can be used for several surfaces. If you modify the thickness of this object, all assigned surface thicknesses are adjusted accordingly in one step.
Another useful features in the Load Wiyard is the determination of member loads from area loads by defining surfaces (using corner nodes) and cells in a definition.
The aim of this feature is to make your design more efficient. In addition to member sets, you can also combine lines, surfaces, and solids into sets. For example, you can consider them as uniform elements in the design.
RFEM is entering a new phase with RFEM 6! The new generation of the 3D FEA software is also used for the structural analysis of members, surfaces, and solids. Many of the tried and tested features remain, but we have improved them and added new features to make your work with RFEM even easier.
What particularly distinguishes RFEM 6 is the modern design concept, with the add-ons integrated directly into the program. Curious to learn more?