In the Construction Stages Analysis (CSA) add-on, you can use built-up cross-sections by means of what are known as phase sections. This allows you to activate and deactivate the parts of the "Parametric - Massive II" section type throughout the construction stages.
Design of five types of seismic force-resisting systems (SFRS) includes Special Moment Frame (SMF), Intermediate Moment Frame (IMF), Ordinary Moment Frame (OMF), Ordinary Concentrically Braced Frame (OCBF), and Special Concentrically Braced Frame (SCBF)
Ductility check of the width-to thickness ratios for webs and flanges
Calculation of the required strength and stiffness for stability bracing of beams
Calculation of the maximum spacing for stability bracing of beams
Calculation of the required strength at hinge locations for stability bracing of beams
Calculation of the column required strength with the option to neglect all bending moments, shear, and torsion for overstrength limit state
Design check of column and brace slenderness ratios
The seismic design result is categorized into two sections: member requirements and connection requirements.
The "Seismic Requirements" include the Required Flexural Strength and the Required Shear Strength of the beam-to-column connection for moment frames. They are listed in the ‘Moment Frame Connection by Member’ tab. For braced frames, the Required Connection Tensile Strength and the Required Connection Compressive Strength of the brace are listed in the ‘Brace Connection by Member’ tab.
The program provides the performed design checks in tables. The design check details clearly display the formulas and references to the standard.
In the Geotechnical Analysis add-on, the Hoek-Brown material model is available. The model shows linear-elastic ideal-plastic material behavior. Its nonlinear strength criterion is the most common failure criterion for stone and rocks.
You can enter the material parameters using
Rock parameters directly, or alternatively via
GSI classification.
Detailed information about this material model and the definition of the input in RFEM can be found in the respective chapter Hoek-Brown Model of the online manual for the Geotechnical Analysis add-on.
Using the "Damper" member type, you can define a damping coefficient, a spring constant, and a mass. This member type extends the possibilities within the Time History Analysis.
With regard to viscoelasticity, the "Damper" member type is similar to the Kelvin-Voigt model, which consists of the damping element and an elastic spring (both connected in parallel).
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.
For calculation diagrams, you can use the "2D | Hinge" diagram type. These hinge diagrams show the hinge response of load situations for nonlinear hinges.
For calculations with several load situations, such as the case with the pushover analysis and time history analysis, you can evaluate the hinge condition in each load step.
If you have experimentally determined surface pressures available for a model, you can apply them to a structural model in RFEM 6, process them in RWIND 2, and use them as wind loads in the structural analysis of RFEM 6.
You can find out how to apply the experimentally determined values in this technical article.
In the Modal Analysis add-on, you have the option to automatically increase the sought eigenvalues until reaching a defined effective modal mass factor. All translational directions activated as masses for the modal analysis are taken into account.
Thus, it is possible to easily calculate the required 90% of the effective modal mass for the response spectrum method.
The Time History Analysis add-on provides you with accelerograms for the calculation. This extension allows for dynamic structural analysis of the acceleration-time diagrams.
There is an extensive library of earthquake records available for you, but you can also enter or import your own diagrams. The time history analysis is performed using the modal analysis or the linear implicit Newmark analysis.
The modal relevance factor (MRF) can help you to assess to which extent specific elements participate in a specific mode shape. The calculation is based on the relative elastic deformation energy of each individual member.
The MRF can be used to distinguish between local and global mode shapes. If multiple individual members show significant MRF (for example, > 20%), the instability of the entire structure or a substructure is very likely. On the other hand, if the sum of all MRFs for an eigenmode is around 100%, a local stability phenomenon (for example, buckling of a single bar) can be expected.
Furthermore, the MRF can be used to determine critical loads and equivalent buckling lengths of certain members (for example, for stability design). Mode shapes for which a specific member has small MRF values (for example, < 20%) can be neglected in this context.
The MRF is displayed by mode shape in the result table under Stability Analysis → Results by Members → Effective Lengths and Critical Loads.
The combination wizard provides you with the option to consider more than one initial state. RFEM and RSTAB allow you to specify different initial states (prestress, form-finding, strain, and so on) for the target combinations in the combinatorics.
You can thus, for example, generate load states on the basis of a form-finding analysis with varying imperfections.
Within the "Plastic capacity design | Simplex Method" in RSECTION, the simultaneous variation of shear stresses over the cross-sectional area is performed in addition to the variation of axial stresses. This extended form of analysis allows you to use redistribution reserves, especially for the cross-sections subjected to shear loading, thus loading the cross-sections even more efficiently.
It is necessary to enter the required force-time diagrams. They can be combined in load cases or load combinations of the type Time History Analysis | Time Diagrams with the loading in order to define where and in which direction the force-time diagrams act.
The second option is to enter acceleration-time diagrams, which can be used in the load cases of the Time History Analysis | Accelerogram type.
All calculation parameters are specified in the time history analysis settings. These include, for example, the type of analysis method and the maximum calculation time.
The time history analysis is performed with the modal analysis or the linear implicit Newmark analysis. The time history analysis in this add-on is limited to linear structural systems. Although the modal analysis represents a fast algorithm, it is necessary to use a certain number of eigenvalues to ensure the required accuracy of results.
The implicit Newmark analysis is a very precise method, independent of the number of eigenvalues used, but requires sufficient small time steps for the calculation.
As soon as the program has completed the calculation, the summary of the results is listed. All result windows are integrated in the main program RFEM/RSTAB. You will find all the results arranged in tables; they can be displayed for each individual time step or as an envelope, and you also have the option of displaying the results graphically as well as animating them.
The results from the time history analysis can be displayed in the calculation diagrams. All the results are shown as a function of time. You can export the numeric values to MS Excel.
All result tables and graphics are part of the RFEM/RSTAB printout report. In this way, you can ensure clearly arranged documentation. You can also export the tables to MS Excel.
The Concrete Design add-on allows you to perform the seismic design of reinforced concrete members according to EC 8. This includes, among other things, the following functionalities:
Seismic design configurations
Differentiation of the ductility classes DCL, DCM, DCH
Option to transfer the behavior factor from a dynamic analysis
Check of the limit value for the behavior factor
Capacity design checks of "Strong column - weak beam"
Detailing and particular rules for curvature ductility factor
Detailing and particular rules for local ductility
In the Steel Design add-on, you can apply a value for cold-formed sections according to EN 1993‑1‑3, which performs the stability analysis and cross-section design according to Sections 6.1.2 - 6.1.5 and 6.1.8 - 6.1.10.
In the "Steel Joints" add-on, you can consider preloaded bolts in all components during the calculation. You can easily activate the preloading using the check box in the bolt parameters, and it has an impact on the stress-strain analysis as well as the stiffness analysis.
Preloaded bolts are special bolts used in steel structures to generate a high clamping force between the connected structural components. This clamping force causes friction between the structural components, which allows for the transfer of forces.
Functionality Preloaded bolts are tightened with a certain torque, causing them to stretch and generate a tensile force. This tensile force is transferred to the connected components and leads to a high clamping force. The clamping force prevents the connection from loosening and ensures safe force transmission.
Advantages
High load-bearing capacity: Preloaded bolts can transfer large forces.
Low deformation: They minimize the deformation of the connection.
Fatigue strength: They are resistant to fatigue.
Easy assembly: They are relatively easy to assemble and disassemble.
Analysis and Design The calculation of preloaded bolts is performed in RFEM using the FE analysis model generated by the "Steel Joints" add-on. It takes into account the clamping force, friction between structural components, shear strength of bolts, and load-bearing capacity of the structural components. The design is carried out according to DIN EN 1993‑1‑8 (Eurocode 3) or the US standard ANSI/AISC 360‑16. You can save the created analysis model, including the results, and use it as an independent RFEM model.
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.
You can display the RWIND results directly in the main program. In the Navigator - Results, select the Wind Simulation Analysis result type from the list above.
Currently, the following results are available, which refer to the RWIND computational mesh:
The initial stiffness Sj,ini is a crucial parameter for evaluating whether a connection can be characterized as rigid, semi-rigid, or pinned.
In the "Steel Joints" add-on, you can calculate the initial stiffness Sj,ini according to Eurocode (EN 1993‑1‑8, Section 5.2.2) and AISC (AISC 360-16, Cl. E3.4) with regard to the internal forces N, My, and/or Mz.
The optional automatic transfer of initial stiffnesses allows for a directly transfer as member hinge stiffnesses in RFEM. The entire structure is then recalculated and the resulting internal forces are automatically adopted as loads in the analysis and design of the connection models.
This automated iteration process eliminates the need for manual export and import of data, reducing the amount of work and minimizing potential sources of error.
The pushover analysis is managed by a newly introduced analysis type in the load combinations. Here, you have access to the selection of the horizontal load distribution and direction, the selection of a constant load, the selection of the desired response spectrum for the determination of the target displacement, and the pushover analysis settings tailored to the pushover analysis.
In the pushover analysis settings, you can modify the increment of the increasing horizontal load and specify the stopping condition for the analysis. Furthermore, it is possible to easily adjust the precision for the iterative determination of the target displacement.
Consideration of nonlinear component behavior using plastic standard hinges for steel (FEMA 356, EN 1998‑3) and nonlinear material behavior (masonry, steel - bilinear, user-defined working curves)
Direct import of masses from load cases or combinations for the application of constant vertical loads
User-defined specifications for the consideration of horizontal loads (standardized to a mode shape or uniformly distributed over the height of the masses)
Determination of a pushover curve with selectable limit criterion of the calculation (a collapse or limit deformation)
Transformation of the pushover curve into the capacity spectrum (ADRS format, single degree of freedom system)
Bilinearization of the capacity spectrum according to EN 1998‑1:2010 + A1:2013
Transformation of the applied response spectrum into the required spectrum (ADRS format)
Determination of target displacement according to EC 8 (the N2 method according to Fajfar 2000)
Graphical comparison of the capacity and required spectrum
Graphical evaluation of the acceptance criteria of predefined plastic hinges
Result display of the values used in the iterative calculation of the target displacement
Access to all results of the structural analysis in the individual load levels
During the calculation, the selected horizontal load is increased in load steps. A static nonlinear analysis is carried out for each load step until reaching the specified limit condition.
The results of the pushover analysis are extensive. On one hand, the structure is analyzed for its deformation behavior. This can be represented by a force-deformation line of the system (a capacity curve). On the other hand, the response spectrum effect can be displayed in the ADRS display (Acceleration-Displacement Response Spectrum). The target displacement is automatically determined in the program based on these two results. The process can be evaluated graphically and in tables.
The individual acceptance criteria can then be graphically evaluated and assessed (for the next load step of the target displacement, but also for all other load steps). The results of the static analysis are also available for the individual load steps.
Would you like to perform cross-section design checks for cold-formed steel members according to EN 1993‑1‑3? No matter if you design the cold-formed sections from the cross-section library or the general cold-formed (non-perforated) sections from RSECTION – your structural analysis program helps you to determine the effective cross-section, taking into account the local buckling and instability. You can also perform a cross-section check according to EN 1993‑1‑3, 6.1.6. In this case, the internal forces from the calculation using Torsional Warping (7 DOF) are taken into account by means of the equivalent stress check