The events of recent years remind us of the importance of earthquake engineering in seismic regions. For you as an engineer, the design of structures in earthquake-prone areas is a constant trade-off between economic efficiency – the financial possibilities – and structural safety. If a collapse is inevitable, engineers must estimate how it will affect the structure. This article aims to provide you with an option on how to perform this estimation.
Cross-section properties in RFEM and RSTAB include different types of shear areas. This technical article explains the calculation and meaning of various values.
With the SHAPE‑THIN cross‑section properties software, you can create any thin‑walled cross‑section and use it in RFEM or RSTAB as a member cross‑section. SHAPE‑THIN can give all relevant cross‑section values of any cross‑section for a design and stress analysis.
Concrete on its own is characterized by its compressive strength. An important part of reinforced concrete is reinforcing steel, which contributes to both the compressive and the tension resistance of the concrete. Welded wire fabric is generally located in the tension areas of the beams or surface elements (hollow core ceiling, wall, shell) to transfer the tensile forces induced by external loading.
According to Book 631 of the DAfStb (German Committee for Structural Concrete), Chapter 2.4, the structural behavior of ceilings changes if their continuous support by walls is interrupted in areas of openings. Depending on the length of the opening area and the plate thickness, measures are necessary regarding the analysis of the ceiling in the area of the opening.
Buildings are structures surrounded by wind. The flow around them creates specific loads on the surfaces, which are to be used for the design in structural analysis.
DIN EN 1998-1 with the National Annex DIN EN 1998-1/NA specifies how to determine seismic loads. The standard applies to structural engineering in seismic areas.
This article describes how a flat slab is generated as a 2D model in RFEM and the loading is applied according to Eurocode 1. The load cases are combined according to Eurocode 0 and calculated linearly. In the RF-CONCRETE Surfaces add-on module, the bending design of the slab is performed while taking into account the standard requirements of Eurocode 2. The reinforcement is complemented by a rebar reinforcement for areas that are not covered by the mesh basic reinforcement.
A previous article presented different variants of surface elastic foundations in addition to the traditional subgrade reaction modulus method. The following article describes another method for surface foundation. This method considers the adjacent ground areas by means of a foundation overlap. In this case, foundation parameters refer to the continuing works by Pasternak and Barwaschow.
SHAPE‑THIN cross‑section properties software provides the option to combine cross‑section parts in a "section" and display the cross‑section properties. Thus, you can determine the values of the individual components in a composite cross‑section.
The RF‑STABILITY and RSBUCK add‑on modules for RFEM and RSTAB allow you to perform eigenvalue analysis for frame structures in order to determine critical load factors, including the buckling modes. Several buckling modes can be determined. They provide information about the model areas bearing stability risks.
With the SHAPE-THIN cross-section program, you can model the corner areas of cross-sections in detail: The "Smooth Corner" function fills the corner with an element and automatically connects it with a null element. For this, simply click the corner. Use the "Create Round or Angled Corner" function to round or angle the corner. To do this, specify the fillet radius and click both elements.
As an alternative to the conventional automatic arrangement of surface reinforcement in RF-CONCRETE Surfaces, it is also possible to set it according to the individual requirements. For example, this can be useful when creating of reinforcement drawings as the reinforcement areas are clearly defined and also include dimensions.
The transparency of the glass material should not be missing in any building. In addition to the typical application areas such as windows, this building material is increasingly being used for facades, canopies, or even as bracing of stairways. Of course, the planning architects often set a very high standard of transparency on fixation of the glass panes. This requires special glass fittings that couple the glass panes.
As of program version RFEM 5.06, you can not only perform the automatic arrangement of an additional reinforcement, but also define the surface reinforcement manually. In addition to the uniformly distributed basic reinforcement, you can define various surface reinforcements (per surface; rectangular, circular, or polygonal).
In RFEM, areas can be defined where the internal forces in surfaces are not displayed with the real distribution from FE calculation, but as mean values. You can use various settings for averaging the internal forces. There are three possible application areas of the "Average Region" function.
Users of RFEM and RSTAB already know the advantages of various visibilities that can be used to create user‑defined areas of the structure for further editing.
If you select the combinatorics according to EN 1990 + EN 1991‑2 and define a load case in action category gr1a, gr2, or gr5, you have to additionally define in the program which load model should be taken as a basis for the load case. This information is crucial for defining combination rules for automatic combinations according EN 1990 + EN 1991-2. In the gr1a category, you can select TS (LM1), UDL (LM1), or pedestrian and cycle track, for example. TS (LM1) is preset by default. In the gr2 category, you can select breaking and acceleration forces or centrifugal forces as a specification.
In RF-CONCRETE Surfaces, the reinforcement areas of the mesh reinforcement for basic and additional reinforcement are not entered manually, but you can select them in the library. Therefore, various product ranges are available (for example, from Germany, Austria, and the United States).
In RFEM and RSTAB, there are several ways to select a part of the structural model for further processing. The most frequently used selection option is definitely "selection using window". Depending on the size of the structure, the simultaneous selection of several areas of the structure using this option may be time-consuming, since the unwanted model parts are selected as well.
Sometimes, a detailed examination is needed of problematic areas of a joint or the stiffness of a frame joint. The following tips can help you with this. As an example, a frame joint was modeled using RF‑FRAME‑JOINT Pro and members, and used as a basis.