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.
Several modeling tools are available for elements in building models:
Vertical line
Column
Wall
Beam
Rectangular floor
Polygonal floor
Rectangular floor opening
Polygonal floor opening
This feature allows you to define the element on the ground plane (for example, with a background layer) with the associated multiple element creation in space.
Lines can be imported into RFEM either as lines or members. The names of layers are adopted as the cross-section names, and the first material from the predefined materials is assigned. However, if the section of the Dlubal cross-section library and the material are recognized from the layer name, they are adopted as well.
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.
A library for cross-laminated timber panels is implemented in RFEM, from which you can import the manufacturer's layer structures (for example, Binderholz, KLH, Piveteaubois, Södra, Züblin Timber, Schilliger, Stora Enso). In addition to the layer thicknesses and materials, there is also the information about stiffness reductions and the narrow side bonding.
Did you know? You can enter the soil layers that you have obtained from the subsoil expertises done in the locations into the program in the form of soil samples. Assign the explored soil materials, including their material properties, to the layers.
For the definition of the samples, you can enter the data in tables as well as in the respective editing dialog box. Furthermore, you can also specify the groundwater level in the soil samples.
The soil solids that you want to analyze are summarized in soil massifs.
Use the soil samples as a basis for a definition of the respective soil massif. This way, the program allows for user-friendly generation of the massif, including the automatic determination of the layer interfaces from the sample data, as well as the groundwater level and the boundary surface supports.
Soil massifs provide you with the option to specify a target FE mesh size independently of the global setting for the rest of the structure. You can thus consider the various requirements of the building and soil in the entire model.
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.
Do you work with steel connections? The Steel Joints add-on for RFEM supports you when analyzing steel connections by using an FE model. In this case, the modeling runs fully automatically in the background. Nevertheless, you can control this process via the simple and familiar input of components. You can then use the loads determined on the FE model for your design of the components according to EN 1993‑1‑8 (including National Annexes).
Calculation of stationary incompressible turbulent wind flow using the SimpleFOAM solver from the OpenFOAM® software package
Numerical scheme according to the first and second order
Turbulence models RAS k-ω and RAS k-ε
Consideration of surface roughness depending on model zones
Model design via VTP, STL, OBJ, and IFC files
Operation via bidirectional interface of RFEM or RSTAB for importing model geometries with standard-based wind loads and exporting wind load cases with probe-based printout report tables
Intuitive model changes via drag & drop and graphical adjustment assistance
Generation of a shrink-wrap mesh envelope around the model geometry
Consideration of environmental objects (buildings, terrain, and so on)
Height-dependent description of the wind load (wind speed and turbulence intensity)
Automatic meshing depending on a selected depth of detail
Consideration of layer meshes near the model surfaces
Parallelized calculation with optimal utilization of all processor cores of a computer
Graphical output of the surface results on the model surfaces (surface pressure, Cp coefficients)
Graphical output of the flow field and vector results (pressure field, velocity field, turbulence – k-ω field, and turbulence – k-ε field, velocity vectors) on Clipper/Slicer planes
Display of 3D wind flow via animated streamline graphics
Definition of point and line probes
Multilingual user interface (German, English, Czech, Spanish, French, Italian, Polish, Portuguese, Russian, and Chinese)
Calculations of several models in one batch process
Generator for creating rotated models to simulate different wind directions
Optional interruption and continuation of the calculation
Individual color panel per result graphic
Display of diagrams with separate output of results on both sides of a surface
Output of the dimensionless wall distance y+ in the mesh inspector details for the simplified model mesh
Determination of the shear stress on the model surface from the flow around the model
Calculation with an alternative convergence criterion (you can select between the residual types pressure or flow resistance in the simulation parameters)
Entering soil layers for soil samples is performed in a clearly arranged dialog box. A corresponding graphical representation supports clarity and makes checking the input user-friendly.
An extensible database facilitates the selection of soil material properties. The Mohr-Coulomb model as well as a nonlinear model with stress and strain dependent stiffness are available for a realistic modeling of the soil material behavior.
You can define any number of soil samples and layers. The soil is generated from all entered samples using 3D solids. Assignment to the structure is carried out using coordinates.
The soil body is calculated according to the nonlinear iterative method. The calculated stresses and settlements are displayed graphically and in tables.
If you release a structural component with a nonlinear elastic material again, the strain goes back on the same path. In contrast to the Isotropic|Plastic material model, there is no strain left when completely unloaded.
You can select three different definition types:
Standard (definition of the equivalent stress under which the material plastifies)
Bilinear (definition of the equivalent stress and strain hardening modulus)
The meshing algorithm of RWIND Simulation uses the boundary layer option to mesh the area near the model surface with a voluminous layer mesh. The number of layers is controlled by a user-defined parameter.
This fine mesh in the area of the model surface helps to represent the wind velocity close to the surface.
The stiffness of gas given by the ideal gas law pV = nRT can be considered in the nonlinear dynamic analysis.
The calculation of gas is available for accelerograms and time diagrams for both the explicit analysis and the nonlinear implicit Newmark analysis. To determine the gas behavior correctly, at least two FE layers for gas solids should be defined.
After opening the module, the materials and surface thicknesses defined in RFEM are preset. The nodes to be designed are automatically recognized but can also be modified by the user.
It is possible to consider openings in the area with risk of punching shear. The openings can be transferred from RFEM or specified only in RF‑PUNCH Pro so they do not effect the stiffnesses of the RFEM model.
The parameters of the longitudinal reinforcement are the number and direction of the layers and the concrete cover, specified separately for the top and bottom of the slab on a surface-by-surface basis. The next input window allows you to define all additional details for nodes of punching shear. The module recognizes the position of the punching node and automatically sets, whether the node is located in the center of the slab, on the slab edge or in the slab corner.
In addition, it is possible to set punching load, load increment factor β, and the existing longitudinal reinforcement. Optionally, the minimum moments can be activated for determining the required longitudinal reinforcement and enlarged column head.
To facilitate orientation, a slab is always displayed with the corresponding node of punching shear. You can also open the design program by HALFEN, a German producer of shear rails. All RFEM data can be imported to this program for further easy and effective processing.
The nonlinear calculation is activated by selecting the design method of the serviceability limit state. You can individually select the analyses to be performed as well as the stress-strain diagrams for concrete and reinforcing steel. The iteration process can be influenced by these control parameters: convergence accuracy, maximum number of iterations, arrangement of layers over cross-section depth, and damping factor.
You can set the limit values in the serviceability limit state individually for each surface or surface group. Allowable limit values are defined by the maximum deformation, the maximum stresses, or the maximum crack widths. The definition of the maximum deformation requires additional specification as to whether the non-deformed or the deformed system should be used for the design.
RF-CONCRETE Members
The nonlinear calculation can be applied to the ultimate and the serviceability limit state designs. In addition, you can specify the concrete tensile strength or the tension stiffening between the cracks. The iteration process can be influenced by these control parameters: convergence accuracy, maximum number of iterations, and damping factor.
The geometry is entered by means of templates, as in all other programs of the RX‑TIMBER family. By selecting the roof structure, you define the base geometry, which can be adjusted by user-defined settings. The relevant timber grade of the material can be selected from the material library. All material grades for glulam, hardwood, poplar and softwood timber specified in EN 1995-1-1 are available. Furthermore, it is possible to generate a strength class with user-defined material properties in order to extend the library.
Since the stiffening bracing includes the steel cross-sections, current steel grades are integrated in the library as well. Therefore, rolled and welded cross-sections are also available. Stiffening of coupling elements can be considered in Table 1.5 Connections as translational and rotational spring stiffnesses. The program handles these stiffnesses with a stiffness divided by the partial safety factor for the design of the bearing capacity and with the mean values of the stiffness for the serviceability limit state design. The loading can be entered directly as a lateral load (equivalent lateral load) resulting from a truss girder design.
The wind load is applied automatically to all four sides of the structure. Additionally, you can specify user-defined loads; for example, concentrated loads from columns (buckling load). According to the generated loads, the program automatically creates combinations for the ultimate and serviceability limit states as well as for fire resistance design in the background. The generated combinations can be considered or adjusted by user-defined specifications.
Graphical and numerical results of stresses and stress ratios fully integrated in RFEM
Flexible design with different layer compositions
High efficiency due to few entries required
Flexibility due to detailed setting options for basis and extent of calculations
A local overall stiffness matrix of the surface in RFEM is generated on the basis of the selected material model and the layers contained. The following material models are available:
Orthotropic
Isotropic
User-defined
Hybrid (for combinations of material models)
Option to save frequently used layer structures in a database
Determination of basic, shear, and equivalent stresses
In addition to the basic stresses, the required stresses according to DIN EN 1995-1-1 and the interaction of those stresses are available as results.
Stress analysis for structural surfaces including simple or complex shapes
Equivalent stresses calculated according to different approaches:
Shape modification hypothesis (von Mises)
Shear stress hypothesis (Tresca)
Normal stress hypothesis (Rankine)
Principal strain hypothesis (Bach)
Calculation of transversal shear stresses according to Mindlin or Kirchhoff, or user-defined specifications
Serviceability limit state design by checking surface displacements
User-defined specifications of limit deflections
Possibility to consider layer coupling
Detailed results of individual stress components and ratios in tables and graphics
Results of stresses for each layer in the model
Parts list of designed surfaces
Possible coupling of layers entirely without shear
After opening the program, you can define the standard and method according to which the design is performed. The ultimate and serviceability limit states can be designed according to the linear and nonlinear calculation methods. Load cases, load combinations or result combinations are then assigned to different calculation types. In other input windows, you can define materials and cross‑sections. In addition, it is possible to assign parameters for creep and shrinkage. Creep and shrinkage coefficients are directly adjusted, depending on the age of the concrete.
Support geometry is determined by means of design‑relevant data such as support widths and types (direct, monolithic, end, or intermediate support) and redistribution of moments as well as shear force and moment reduction. CONCRETE recognizes the support types from the RSTAB model automatically.
A segmented window includes the specific reinforcement data such as diameters, the concrete cover and curtailment type of reinforcements, number of layers, cutting ability of links, and the anchorage type. In the case of the fire resistance design, it is necessary to define the fire resistance class, the fire‑related material properties, and the cross-section side exposed to fire. Members and sets of members can be summarized in special 'reinforcement groups', each with different design parameters.
You can adjust the limit value of the maximum crack width in the case of crack width analysis. The geometry of tapers is to be determined additionally for the reinforcement.
Various buttons allow you to directly change the perspective and work plane. By zooming, rotating, and shifting the structure you can quickly adjust the appropriate view. Partial views represent specific structural parts clearly. Inactive objects can be displayed transparently in the background. By selecting structural elements according to special criteria, it is possible to group objects in a simple way.
There are various tools such as the object snap, user‑defined input grids, and guidelines, that facilitate the graphical input of structural data. DXF files can be imported as line models or used as a layer in the background in order to use specific snap points.
There are various tools such as the object snap, user‑defined input grids, and guidelines, that facilitate the graphical input of structural data. DXF files can be imported as line models or used as a layer in the background in order to use specific snap points.