Did you know? In the Design Supports, you can now define fully threaded screws as transversal compression stiffening elements for the "Compression Perpendicular to Grain" design. In this case, the pressing-in and buckling of the bolts is analyzed.
Moreover, the design shear resistance is checked in the plane of the screw tip. The angle of dispersal can be considered as linear under 45° or nonlinear (according to Bejtka, I. (2005). Verstärkung von Bauteilen aus holz mit vollgewindeschrauben. KIT Scientific Publishing.).
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.
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.
Deformation analyses of reinforced concrete surfaces without or with cracks (state II) by applying the approximation method (for example, deformation analysis according to ACI 318-19, 24.3.2.5 or EN 1992‑1‑1, Cl. 7.4.3 )
Tension stiffening of concrete applied between cracks
Optional consideration of creep and shrinkage
Graphical representation of results integrated in RFEM, such as deformation or sag of a flat slab
Clear numerical result display in the detail dialog box
Complete integration of results in the RFEM printout report
Are you looking for a deformation calculation? Check the Serviceability Configuration, where it can be activated. You can also control the consideration of long-term effects (creep and shrinkage) and tension stiffening between cracks in the dialog box above. The creep coefficient and shrinkage strain are calculated using the specified input parameters, or you can define them individually.
Furthermore, you can specify the deformation limit value individually for each structural component. The max. deformation is defined as the allowable limit value. In addition, you have to specify whether you want to use the undeformed or the deformed system for the design check.
Available for cold-formed L, Z, C, channel, top-hat, and CL sections from the cross-section database, as well as for general cold-formed (non-perforated) SHAPE-THIN-9 sections
Determination of the effective cross-section considering the local buckling and the distortional buckling
Cross-section ultimate limit state, stability, and serviceability limit state designs according to EN 1993‑1‑3
Design of local transverse forces for webs without stiffening
Available for all National Annexes included in RF-/STEEL EC3
Module extension RF-/STEEL Warping Torsion (license required) for stability analysis according to second-order analysis as stress analysis including consideration of the 7th degree of freedom (warping)
All roof shapes allow for a free selection of stiffening diagonals. The following types are available:
Falling diagonals
Rising diagonals
Crossing diagonals with verticals
Crossing diagonals without verticals
Crossing diagonals with steel strips (ties)
Consideration of window rows in the ridge by selecting an inner intermediate part.
For design according to EC 5 (EN 1995), the following National Annexes are available:
DIN EN 1995-1-1/NA:2013-08 (Germany)
NBN EN 1995-1-1/ANB:2012-07 (Belgium)
DK EN 1995-1-1/NA:2011-12 (Denmark)
SFS EN 1995-1-1/NA:2007-11 (Finland)
NF EN 1995-1-1/NA:2010-05 (France)
UNI EN 1995-1-1/NA:2010-09 (Italy)
NEN EN 1995-1-1/NB:2007-11 (Netherlands)
ÖNORM B 1995-1-1:2015-06 (Austria)
PN EN 1995-1-1/NA:2010-09 (Poland)
SS EN 1995-1-1 (Sweden)
STN EN 1995-1-1/NA:2008-12 (Slovakia)
SIST EN 1995-1-1/A101:2006-03 (Slovenia)
CSN EN 1995-1-1:2007-09 (Czech Republic)
BS EN 1995-1-1/NA:2009-10 (the United Kingdom)
Simple geometry input with illustrative graphics
Automatic generation of wind loads
Automatic creation of required combinations for the ultimate and serviceability limit states, as well as fire resistance design
Free definition of the load cases to be used
Extensive material library
Optional extension of material library by further materials
Extensive library of permanent loads
Allocation of framework to service classes and specification of service class categories
Determination of design ratios, support forces, and deformations
Info icon indicating successful or failed design
Color reference scales in result tables
Direct data export to MS Excel
DXF interface for preparation production documents in CAD
Program languages: English, German, Czech, Italian, Spanish, French, Portuguese, Polish, Chinese, Dutch, and Russian
Verifiable printout report, including all required designs. Printout report available in many output languages; for example, English, German, French, Italian, Spanish, Russian, Czech, Polish, Portuguese, Chinese, and Dutch.
In the ultimate limit state design, the stiffness of the hinge is divided by the partial safety factor and in the serviceability limit state design calculated using the mean stiffnesses. The limit values for the ultimate and the serviceability limit states can be defined separately.
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 deformation analysis according to the approximation method defined in standards (for example, deformation analysis according to EN 1992‑1‑1, 7.4.3) applies to the calculation of "effective stiffnesses" in the finite elements in accordance with the existing limit state of the concrete with or without cracks. These stiffnesses are used to determine the surface deformation by repeated FEM calculation.
The effective stiffness calculation of finite elements takes into account a reinforced concrete cross-section. Based on the internal forces determined for the serviceability limit state in RFEM, the program classifies the reinforced concrete cross-section as 'cracked' or 'uncracked'. If the tension stiffening at a section should be considered as well, a distribution coefficient (according to EN 1992-1-1, Eq. 7.19, for example) is used. The material behavior for the concrete is assumed to be linear-elastic in the compression and tension zone until the concrete tensile strength is reached. This is reached exactly in the serviceability limit state.
When determining the effective stiffnesses, creep and shrinkage are taken into account at the "cross-section level". The influence of shrinkage and creep in statically indeterminate systems is not taken into account in this approximation method (for example, tensile forces from shrinkage strain in systems restrained on all sides are not determined and must be considered separately). In summary, RF-CONCRETE Deflect calculates deformations in two steps:
Calculation of effective stiffnesses of the reinforced concrete cross-section assuming linear-elastic conditions
Calculation of the deformation using the effective stiffnesses with FEM
The module extension EC2 for RSTAB enables design of reinforced concrete according to EN 1992-1-1 (Eurocode 2) and the following National Annexes:
DIN EN 1992-1-1/NA/A1:2015-12 (Germany)
ÖNORM B 1992-1-1:2018-01 (Austria)
Belgium NBN EN 1992-1-1 ANB:2010 for design at normal temperature, and NBN EN 1992-1-2 ANB:2010 for fire resistance design (Belgium)
BDS EN 1992-1-1:2005/NA:2011 (Bulgaria)
EN 1992-1-1 DK NA:2013 (Denmark)
NF EN 1992-1-1/NA:2016-03 (France)
SFS EN 1992-1-1/NA:2007-10 (Finland)
UNI EN 1992-1-1/NA:2007-07 (Italy)
LVS EN 1992-1-1:2005/NA:2014 (Latvia)
LST EN 1992-1-1:2005/NA:2011 (Lithuania)
MS EN 1992-1-1:2010 (Malaysia)
NEN-EN 1992-1-1+C2:2011/NB:2016 (Netherlands)
NS EN 1992-1 -1:2004-NA:2008 (Norway)
PN EN 1992-1-1/NA:2010 (Poland)
NP EN 1992-1-1/NA:2010-02 (Portugal)
SR EN 1992-1-1:2004/NA:2008 (Romania)
SS EN 1992-1-1/NA:2008 (Sweden)
SS EN 1992-1-1/NA:2008-06 (Singapore)
STN EN 1992-1-1/NA:2008-06 (Slovakia)
SIST EN 1992-1-1:2005/A101:2006 (Slovenia)
UNE EN 1992-1-1/NA:2013 (Spain)
CSN EN 1992-1-1/NA:2016-05 (Czech Republic)
BS EN 1992-1-1:2004/NA:2005 (United Kingdom)
CPM 1992-1-1:2009 (Belarus)
CYS EN 1992-1-1:2004/NA:2009 (Cyprus)
In addition to the National Annexes (NA) listed above, you can also define a specific NA, applying user‑defined limit values and parameters.
Optional presetting of partial safety factors, reduction factors, neutral axis depth limitation, material properties, and concrete cover
Determination of longitudinal, shear, and torsional reinforcement
Design of tapered members
Cross‑section optimization
Representation of minimum and compression reinforcement
Determination of editable reinforcement proposal
Crack width analysis with optional increase of the required reinforcement in order to keep the defined limit values of the crack width analysis
Nonlinear calculation with consideration of cracked cross‑sections (for EN 1992‑1‑1:2004 and DIN 1045‑1:2008)
Considering tension stiffening
Considering creep and shrinkage
Deformations in cracked sections (state II)
Graphical representation of all result diagrams
Fire resistance design according to the simplified method (zone method) according to EN 1992‑1‑2 for rectangular and circular cross‑sections. Thus, fire resistance design of brackets is possible as well.
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.
Optional consideration of stiffening elements for transversal tension
Two design types available for stiffening elements concerning transversal tension:
Constructive if required
Full absorption of tension stresses perpendicular to grain
Calculation of required number of stiffening elements for transversal tension and graphical representation of the arrangement in the beam
Simple geometry input with illustrative graphics
Convenient generation of snow loads according to EN 1991-1-3 or DIN 1055:2005, Part 5
Automatic determination of wind loads according to EN 1991-1-4 or DIN 1055:2005, Part 4
User-defined load cases and load applications
Automatic generation of all possible load combinations
Connection to MS Excel and access via COM interface
Material library for both standards
For design according to EC 5 (EN 1995), the following National Annexes are available:
DIN EN 1995-1-1/NA:2013-08 (Germany)
NBN EN 1995-1-1/ANB:2012-07 (Belgium)
DK EN 1995-1-1/NA:2011-12 (Denmark)
SFS EN 1995-1-1/NA:2007-11 (Finland)
NF EN 1995-1-1/NA:2010-05 (France)
UNI EN 1995-1-1/NA:2010-09 (Italy)
NEN EN 1995-1-1/NB:2007-11 (Netherlands)
ÖNORM B 1995-1-1:2015-06 (Austria)
PN EN 1995-1-1/NA:2010-09 (Poland)
SS EN 1995-1-1 (Sweden)
STN EN 1995-1-1/NA:2008-12 (Slovakia)
SIST EN 1995-1-1/A101:2006-03 (Slovenia)
CSN EN 1995-1-1:2007-09 (Czech Republic)
BS EN 1995-1-1/NA:2009-10 (the United Kingdom)
Extensive library of permanent loads
Allocation of a structure to service class, and specification of service class categories
Determination of design ratios, support forces, and deformations
Info icon indicating successful or failed design
Color reference scales in result tables
Direct data export to MS Excel
DXF interface for preparation production documents in CAD
Program languages: English, German, Czech, Italian, Spanish, French, Portuguese, Polish, Chinese, Dutch, and Russian
Verifiable printout report, including all required designs. Printout report available in many output languages; for example, English, German, French, Italian, Spanish, Russian, Czech, Polish, Portuguese, Chinese, and Dutch.
Design of knee joints, T-joints, cross joints, and continuous column connections with I-shaped sections
Import of geometry and load data from RFEM/RSTAB or manual specification of the connection (for example, for recalculation without an existing RFEM/RSTAB model)
Flush top connections or connections with bolt row in extension
Design of positive and negative frame joint moments
Various inclinations of right and left horizontal beams as well as application to frames of duopitch and monopitch roofs
Consideration of additional flanges in a horizontal beam, for example for tapered sections
Symmetrical and asymmetrical T-joints or cross joints
Two-sided connection with different cross-section depth on the right and left
Automatic preliminary design of bolt layout and required stiffening
Optional design mode with possibility to specify all bolt spacing, welds, and sheet thicknesses
Screwability check with adjustable dimensions of used wrenches
Connection classification by stiffness and calculation of the spring stiffness of connections considered in the internal forces determination
Check up to 45 individual designs (components) of the connection
Automatic determination of governing internal forces for each individual design
Controllable connection graphics in rendering mode with specifications of material, sheet thickness, welds, bolt spacing, and all dimensions for construction
Integrated and flexibly extensible settings of National Annexes according to EN 1993-1-8 standard
Automatic conversion of internal forces from structural analysis into respective sections, also for eccentric member connections
Automatic determination of initial stiffness Sj,ini of the connection
Detailed plausibility check of all dimensions, including specifications of input limits (for example, for edge distances and hole spacing)
Optional application of compression forces to a column through contact
Possibility to update the cross-section depth of horizontal beams in case of tapered connections after connection geometry optimization in RF-/FRAME-JOINT Pro
Comprehensive and easy options in the individual input windows facilitate the representation of the structural system:
Nodal Supports
The support type of each node is editable.
It is possible to define a warp stiffening on each node. The resulting warp spring is determined automatically using the input parameters.
Elastic member foundation
In the case of elastic member foundations, you can manually enter spring constants.
Alternatively, you can use the various options to define the rotational and translational springs from a shear panel.
Member End Springs
RF-/FE-LTB calculates the individual spring constants automatically. You can use the dialog boxes and detailed pictures to represent a translational spring by connecting component, a rotational spring by a connecting column, or a warping stiffener (available types: end plate, channel section, angle, connecting column, cantilevered portion).
Member Hinges
If there are no member hinges defined in RFEM/RSTAB for the set of members, you can define them directly in the RF-/FE-LTB add-on module.
Load Data
The nodal and member loads of the selected load cases and combinations are displayed in separate windows. There you can edit, delete, or add them individually.
Imperfections
RF-/FE-LTB automatically applies the imperfections by scaling the lowest eigenvector.
Determination of longitudinal, shear, and torsional reinforcement
Representation of minimum and compression reinforcement
Determination of neutral axis depth, concrete and steel strains
Design of member sections affected by bending about two axes
Design of tapered members
Determination of deformation in state II, for example according to EN 1992-1-1, 7.4.3
Considering tension stiffening
Considering creep and shrinkage
Precise breakdown of reasons for failed design
Design details of all design locations for better traceability of reinforcement determination
Options to optimize cross‑sections
Visualization of concrete section with reinforcement in 3D rendering
Output of complete steel schedule
Fire resistance design according to the simplified method (zone method) according to EN 1992‑1‑2 for rectangular and circular cross‑sections
Optional extension of the RF‑CONCRETE Members add‑on module with a nonlinear calculation of frameworks for the ultimate and serviceability limit states. The extension enables the design of potentially unstable structural components by means of a nonlinear calculation, or a nonlinear deformation analysis of 3D frameworks. Find more information under the product description of the RF-CONCRETE NL add‑on module.
The nonlinear deformation analysis is performed by an iterative process considering the stiffness in cracked and non-cracked sections. The nonlinear reinforced concrete modeling requires definition of material properties varying across the surface thickness. Therefore, a finite element is divided into a certain number of steel and concrete layers in order to determine the cross-section depth.
The mean steel strengths used in the calculation are based on the 'Probabilistic Model Code' published by the JCSS technical committee. It is up to the user whether the steel strength is applied up to the ultimate tensile strength (increasing branch in the plastic area). Regarding material properties, it is possible to control the stress-strain diagram of the compressive and tensile strength. For the concrete compressive strength, you can select a parabolic or a parabolic-rectangular stress-strain diagram. On the tension side of the concrete, it is possible to deactivate the tensile strength as well as to apply a linear-elastic diagram, a diagram according to the CEB-FIB model code 90:1993, and concrete residual tensile strength considering the tension stiffening between the cracks.
Furthermore, you can specify which result values should be displayed after the nonlinear calculation at the serviceability limit state:
Deformations (global, local based on non-/deformed system)
Crack widths, depths, and spacing of the top and bottom sides in principal directions I and II
Stresses of the concrete (stress and strain in principal direction I and II) and of the reinforcement (strain, area, profile, cover, and direction in each reinforcement direction)
RF-CONCRETE Members:
The nonlinear deformation analysis of beam structures is performed by an iterative process considering the stiffness in cracked and non-cracked sections. The material properties of concrete and reinforcing steel used in the nonlinear calculation are selected according to a limit state. The contribution of the concrete tensile strength between the cracks (tension stiffening) can be applied either by means of a modified stress-strain diagram of the reinforcing steel, or by applying a residual concrete tensile strength.
First, it is necessary to select a tower type and the relevant materials and cross-sections. The tower geometry is defined by individual tower segments. Slopes can be defined via widths or relatively by geometry modification.
After entering the tower legs, you can specify various stiffening of the lattice tower. It is possible to enter detailed specifications of horizontal girts, inner bracing, and vertical bracing of a tower with unequal sides. An extensive library including parametrized bracing types facilitates the input.
In addition, there is an interactive graphic in all input windows.
The Hinged Column Footing category provides four different base plate connections:
Simple column base
Tapered column base
Column base for rectangular hollow sections
Column base for circular hollow sections
The Restraint Column Footing category provides five different joint layouts of I-sections:
Base plate without stiffening
Base plate with stiffeners in center of flanges
Base plate with stiffeners on both sides of column
Base plate with channel sections
Pocket foundation
All connection types include a base plate welded around a steel column. Connections with anchors are set in concrete within the foundation. You can select anchor types M12 – M42 with steel grades of 4.6 – 10.9. The top and bottom sides of the anchors can be provided with round or angled sheets for better load distribution or anchorage. In addition, you can use rectangular or circular anchor heads with threads applied at the member ends.
The material and thickness of the grout layer, as well as the dimensions and material of the footing, can be set freely. Furthermore, you can define edge reinforcement of the footing. For a better transfer of shear forces, it is possible to arrange a shear key (cleat) on the bottom side of the base plate.
Shear forces are transferred by a cleat, anchors, or friction. You can combine the individual components.
The deformation analysis with RF-CONCRETE Deflect can be activated in the settings for the analytical serviceability limit state design in the RF-CONCRETE Surfaces module. Consideration of long-term effects (creep and shrinkage) and tension stiffening between cracks can also be managed in the dialog box above. The creep coefficient and shrinkage strain are calculated using the specified input parameters or defined individually.
You can specify the deformation limit value individually for each surface or for an entire surface group. The max. deformation is defined as the allowable limit value. In addition, you have to specify whether the undeformed or the deformed system is to be used for the design check.
Deformation analyses of reinforced concrete surfaces without or with cracks (state II) by applying the approximation method (for example, deformation analysis according to EN 1992-1-1, Cl. 7.4.3 )
Tension stiffening of concrete applied between cracks
Optional consideration of creep and shrinkage
Graphical representation of results integrated in RFEM; for example, deformation or sag of a flat slab
Numerical results clearly arranged in tables and graphical display of the results in the model
Complete integration of results in the RFEM printout report
Iterative nonlinear calculation of deformations for beam and plate structures consisting of reinforced concrete by determining the respective element stiffness subjected to the defined loads
Deformation analyses of cracked reinforced concrete surfaces (state II)
General nonlinear stability analysis of compression members made of reinforced concrete; for example, according to EN 1992-1-1, 5.8.6
Tension stiffening of concrete applied between cracks
Numerous National Annexes available for the design according to Eurocode 2 (EN 1992-1-1:2004 + A1:2014, see EC2 for RFEM)
Optional consideration of long-term influences such as creep or shrinkage
Nonlinear calculation of stresses in reinforcing steel and concrete
Nonlinear calculation of crack widths
Flexibility due to detailed setting options for basis and extent of calculations
Graphical representation of results integrated in RFEM; for example, deformation or sag of a flat slab made of reinforced concrete
Numerical results clearly arranged in tables and graphical display of the results in the model
Complete integration of results in the RFEM printout report