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Both the determination of natural vibrations and the response spectrum analysis are always performed on a linear system. If nonlinearities exist in the system, they are linearized and thus not taken into account. They are caused by, for example, tension members, nonlinear supports, or nonlinear hinges. This article shows how you can handle them in a dynamic analysis.
Large-scale models are models which contain multiple dimensional scales and thus are demanding on computational power. This article will show you how to simplify and optimize the calculation of such models with respect to the desired results.
All data in RFEM 6 can be documented in a multilingual printout report. The design of the printout report is modern and has been highly optimized with respect to the previous (RFEM 5) generation of the program. Some of its most significant features are discussed in this article.
The new generation of RFEM software is an intuitive, powerful, and easy-to-handle 3D FEA program that meets all the latest demands in modeling, calculation, and structural design. The modern design concept, as well as the introduction of new features, make the program even more innovative and user-friendly. The main differences between RFEM 6 and its previous version, RFEM 5, are discussed in the following text.
It may become necessary to analyze pipe cross‑sections as surface models in plant engineering in particular, but also when analyzing details of structural systems. For this purpose, RFEM offers the option to create pipe cross‑sections automatically by means of a line.
In the default setting, the cross-section class for each member and load case is determined automatically in the design modules. In the input window of the cross sections, however, the user can also specify the cross-section class manually; for example, if local buckling is excluded by the design.
In EN 1993-1-1, the General Method was introduced as a design format for stability analyses that can be applied to planar systems with arbitrary boundary conditions and variable structural height. The design checks can be performed for loading in the main load-bearing plane and simultaneous compression. The stability cases of lateral-torsional buckling and flexural buckling are analyzed from the main supporting plane; that is, about the weak component axis. Therefore, the issue often arises as to how to design, in this context, flexural buckling in the main load-bearing plane.
For the stability design of members and sets of members with a uniform cross-section, you can use the equivalent member method according to EN 1993-1-1, 6.3.1 to 6.3.3. However, as soon as a tapered cross-section is available, this method can no longer be used, or only used to a limited extent. The RF-/STEEL EC3 add-on module can automatically recognize these cases and switch to the general method.
In RFEM 5 and RSTAB 8, it is possible to assign nonlinearities to member hinges. In addition to the nonlinearities "Fixed if" and "Partial activity", you can select "Diagram". If you select the "Diagram" option, you have to specify the according settings for the activity of the member hinge. For the individual definition points, it is necessary to specify the abscissa and ordinate values (deformations or rotations and the according internal forces) that define the hinge.
The load generator in RFEM and RSTAB provides a powerful tool for determining wind loads.
In the case of open cross-sections, the torsional load is removed mainly via secondary torsion, since the St. Venant torsional stiffness is low compared to the warping stiffness. Therefore, warping stiffeners in the cross-section are particularly interesting for the lateral-torsional buckling analysis, as they can significantly reduce the rotation. For this, end plates or welded stiffeners and sections are suitable.
- 000487
- Modeling | Structure
- RFEM 5
-
- RF-STEEL 5
- RF-STEEL AISC 5
- RF-STEEL AS 5
- RF-STEEL BS 5
- RF-STEEL CSA 5
- RF-STEEL EC3 5
- RF-STEEL GB 5
- RF-STEEL HK 5
- RF-STEEL IS 5
- RF-STEEL NBR 5
- RF-STEEL NTC-DF 5
- RF-STEEL SANS 5
- RF-STEEL SIA 5
- RF-STEEL SP 5
- RF-ALUMINUM 5
- RF-ALUMINUM ADM 5
- RSTAB 8
- STEEL 8
- STEEL AISC 8
- STEEL AS 8
- STEEL BS 8
- STEEL CSA 8
- STEEL EC3 8
- STEEL GB 8
- STEEL HK 8
- STEEL IS 8
- STEEL NBR 8
- STEEL NTC-DF 8
- STEEL SANS 8
- STEEL SIA 8
- STEEL SP 8
- ALUMINUM 8
- ALUMINUM ADM 8
- Steel Structures
- Process Manufacturing Plants
- Stairway Structures
- Structural Analysis & Design
- Eurocode 3
- ANSI/AISC 360
- SIA 263
- IS 800
- BS 5950-1
- GB 50017
- CSA S16
- AS 4100
- SP 16.13330
- SANS 10162-1
- ABNT NBR 800
- ADM
The support conditions of a beam subjected to bending are essential for its resistance to lateral-torsional buckling. If, for example, a single-span beam is held laterally in the middle of the span, the deflection of the compressed flange can be prevented, and a two-wave eigenmode can be enforced. The critical lateral-torsional buckling moment is increased significantly by this additional measure. In the add-on modules for member design, different types of lateral supports on a member can be defined using the "Intermediate supports" input window.
The classification of cross-sections according to EN 1993-1-1 using Table 5.2 is a simple method for designing the local buckling of cross-section parts. For cross-sections of cross-section class 4, it is then necessary to determine the effective cross-section properties according to EN 1993-1-5 in order to consider the influence of local buckling in the ultimate limit state designs.
When connecting tension-loaded components with bolted connections, the cross-section reduction due to the bolt holes must be taken into account in the ultimate limit state design. This article describes how the design of the tension resistance according to DIN EN 1993‑1‑1 can be performed with the net cross-section area of the tension member in the RF‑/STEEL EC3 add-on module.
The classification of cross-sections according to EN 1993‑1‑1 and EN 1993‑1‑5 can be carried out automatically in the RF‑/STEEL EC3 add-on module. The maximum c/t ratios are specified in the standard for straight cross-section parts. There are no normative specifications for curved cross-section parts; therefore, the cross-section classification cannot be performed for these cross-section parts.
The final results of the designs of members and sets of members in the RF‑/STEEL EC3 add-on module can be displayed graphically in the work window of RFEM and RSTAB. By selecting the corresponding design case in the load case menu, the results contained in it are displayed.
This technical article deals with the design of structural components and cross-sections of a welded truss girder in the ultimate limit state. Furthermore, the deformation analysis in the serviceability limit state is described.
RF-MOVE Surfaces facilitates the generation of load cases from different positions of moving loads. Based on the load positions of the moving load, the program generates separate load cases for RFEM 5. Optionally, an enveloping result combination of all load positions is created.
This article describes the basic principles and modeling approaches of pulley systems in RFEM.
This technical article analyzes the effects of the connection stiffness on the determination of internal forces, as well as the design of connections using the example of a two-story, double-spanned steel frame.
Describing the procedure for the serviceability limit state design of a floor slab made of steel fiber reinforced concrete. This article shows how to perform the corresponding design for the SLS by means of the iteratively determined FEA results.
Both the determination of natural vibrations and the response spectrum analysis are always performed on a linear system. If nonlinearities exist in the system, they are linearized and thus not taken into account. Straight tension members are very often used in practice. This article will show how you can display them approximately correctly in a dynamic analysis.
Steel-fiber-reinforced concrete is mainly used nowadays for industrial floors or hall floors, foundation plates with low loads, basement walls, and basement floors. Since the publication in 2010 of the first guideline about steel-fiber-reinforced concrete by the German Committee for Reinforced Concrete (DAfStb), a structural engineer can use standards for the design of the steel fiber-reinforced concrete composite material, which makes the use of fiber-reinforced concrete increasingly popular in construction. This article describes the nonlinear calculation of a foundation plate made of steel fiber-reinforced concrete in the ultimate limit state with the FEA software RFEM.
Determining the Material Properties of Steel-Fiber-Reinforced Concrete and Their Application in RFEM
Steel-fiber-reinforced concrete is mainly used nowadays for industrial floors or hall floors, foundation plates with low loads, basement walls, and basement floors. Since the publication in 2010 of the first guideline about steel-fiber-reinforced concrete by the German Committee for Reinforced Concrete (DAfStb), a structural engineer can use standards for the design of the steel fiber-reinforced concrete composite material, which makes the use of fiber-reinforced concrete increasingly popular in construction. This article explains the individual material parameters of steel-fiber-reinforced concrete and how to deal with these material parameters in the FEM program RFEM.
Daily tasks in reinforced concrete design also include designing compression elements subjected to biaxial bending. The following article describes the different methods according to Chapter 5.8.9, EN 1992-1-1, which can be used to design compression elements with biaxial load eccentricities by means of the nominal curvature method according to 5.8.8.
With RF-FOUNDATION Pro, it is possible to determine the settlements of single foundations and resulting spring stiffnesses of the nodal supports. These spring stiffnesses can be exported into the RFEM model and used for further analyses.
For crane runways with large spans, the horizontal load from skewing is often relevant for the design. This article describes the origin of these forces and the correct input in CRANEWAY. The practical implementation and the theoretical background are discussed.
- 001545
- Modeling | Structure
- RFEM 5
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- RF-FRAME-JOINT Pro 5
- RF-JOINTS Timber | Timber to Timber 5
- RF-JOINTS Timber | Steel to Timber 5
- RF-JOINTS Steel | Rigid 5
- RF-JOINTS Steel | DSTV 5
- RF-JOINTS Steel | Pinned 5
- RF-JOINTS Steel | Tower 5
- RF-JOINTS Steel | SIKLA 5
- RF-JOINTS Steel | Column Base 5
- Steel Structures
- Mechanical Engineering
- Cranes and Craneways
- Towers and Masts
- Process Manufacturing Plants
- Steel Connections
- Finite Element Analysis
- Structural Analysis & Design
- Eurocode 3
- DIN 18800
With RF-/FRAME-JOINT Pro, you can design frame joints according to DIN 18800 or Eurocode 3. When dealing with non-standardized joints or when a deeper insight into the connection and its behavior is required, modeling as a surface model is ideal. This article will show, in principle, how this kind of model is created.
- 001541
- Results
- RFEM 5
-
- RF-DYNAM Pro | Natural Vibrations 5
- RF-DYNAM Pro | Equivalent Loads 5
- RF-DYNAM Pro | Forced Vibrations 5
- RSTAB 8
- DYNAM Pro | Natural Vibrations 8
- DYNAM Pro | Equivalent Loads 8
- Concrete Structures
- Steel Structures
- Timber Structures
- Process Manufacturing Plants
- Power Plants
- Buildings
- Dynamic and Seismic Analysis
- ASCE 7
RFEM offers the option to perform a response spectrum analysis according to ASCE 7-16. This standard describes the determination of seismic loads for the American market. It might happen that the P-Delta effect has to be considered due to the stiffness of the entire structure in order to calculate the internal forces and carry out the design.
Influence lines are less important nowadays due to fast computer systems. However, it might be an advantage to use influence lines in the phase of preliminary design, as well as in the actual creation of the structural designs. With the RF-INFLUENCE add-on module, influence lines and influence surfaces can be generated and evaluated easily due to a fixed internal force. This technical article describes, with a simple example, the basics of determining and evaluating influence lines.