Flexural buckling analysis is a combination of stability analysis and ultimate limit state design that has been used in steel structures for hundreds of years. The critical buckling load is the starting point here for considering the stability problem, but no design has yet been performed without considering imperfections. How exactly are these imperfections determined?
Every day, thousands of structural engineers design structural components using design check formulas that include the critical buckling load. But where do these old formulas come from, that Leonard Euler established over 200 years ago and that form the basis of all three structural steel design concepts?
When calculating regular structures, data input is often not complicated, but it is time-consuming. Save your valuable time with input automation. The task described in the present article is to consider the stories of a house as single construction stages. Data are entered using a C# program so that the user does not have to enter the elements of the individual floors manually.
When it comes to wind loads on building type structures as per ASCE 7, numerous resources can be found to supplement design standards and aid engineers with this lateral load application. However, engineers may find it more difficult to find similar resources for wind loading on non-building type structures. This article will examine the steps to calculate and apply wind loads as per ASCE 7-22 on a circular reinforced concrete tank with a dome roof.
In many frame and truss structures, it is no longer sufficient to use a simple member. You often have to consider cross-section weakenings or openings in solid beams. In such cases, you can use the "Surface Model" member type. It can be integrated into the model like any other member and offers all the options of a surface model. The present technical article shows the application of such a member in an existing structural system and describes the integration of member openings.
For a stability analysis of members using the equivalent member method, it is necessary to define effective or lateral-torsional buckling lengths in order to determine a critical load for stability failure. In this article an RFEM 6-specific function is presented, by which you can assign an eccentricity to the nodal supports and thus influence the determination of the critical bending moment considered in the stability analysis.
Steel connections in RFEM 6 can be created by simply entering predefined components in the Steel Joints add-on. The collection of these components is constantly being improved to make your work even easier even when modeling steel connections. In this article, the connection plate component is introduced as a component recently added to the add-on's library.
With the most recent ACI 318-19 standard, the long-term relationship to determine the concrete shear resistance, Vc, is redefined. With the new method, the member height, the longitudinal reinforcement ratio, and the normal stress now influence the shear strength, Vc. This article describes the shear design updates, and the application is demonstrated with an example.
Nodal releases are special objects in RFEM 6 that allow structural decoupling of objects connected to a node. The release is controlled by the release type conditions, which may also have nonlinear properties. This article will show the definition of nodal releases in a practical example.
Line releases are special objects in RFEM 6 that allow structural decoupling of objects connected to a line. They are mostly used to decouple two surfaces that are not rigidly connected or transferring only compressive forces at the common boundary line. By defining a line release, a new line is generated at the same place which transfers only the locked degrees of freedom. This article will show the definition of line releases in a practical example.
In RFEM 6 it is possible to define multilayer surface structures with the help of the “Multilayer Surfaces” add-on. Hence, if you have activated the add-on in the model’s Base Data, it is possible to define layer structures of any material model. You can also combine material models of, for example, isotropic and orthotropic materials.
The properties of the connection between a reinforced concrete slab and a masonry wall can be correctly considered in the modeling using a special line hinge that is available in RFEM 6. This article will show you how to define this type of hinge using a practical example.
This article will show you how to properly consider the connection between surfaces that touch each other on one line with the help of line hinges in RFEM 6.
RFEM and RSTAB programs provide parameterized input as an advantageous product feature to create or adjust models by means of variables. This article will show you how to define global parameters and use them in formulas to determine numerical values.
Given that realistic determination of the soil conditions significantly influences the quality of the structural analysis of buildings, the Geotechnical Analysis add-on is offered in RFEM 6 to determine the soil body to be analyzed.
The way to provide data obtained from field tests in the add-on and use the properties from soil samples to determine the soil massifs of interest was discussed in Knowledge Base article “Creating Soil Body from Soil Samples in RFEM 6”. This article, on the other hand, will discuss the procedure to calculate settlements and soil pressures for a reinforced concrete building.
You can model and analyze masonry structures in RFEM 6 with the Masonry Design add-on that employs the finite element method for the design. Complex masonry structures can be modeled, and static and dynamic analysis can be performed, given that a nonlinear material model is implemented in the program to display the load-bearing behavior of masonry and the different failure mechanisms. You can enter and model masonry structures directly in RFEM 6 and combine the masonry material model with all common RFEM add-ons. In other words, you can design entire building models in connection with masonry.
The Construction Stages Analysis (CSA) add-on allows for the design of member, surface, and solid structures in RFEM 6 considering the specific construction stages associated with the construction process. This is important since buildings are not constructed all at once, but by gradually combining individual structural parts. The single steps in which structural elements, as well as loads, are added to the building are called construction stages, whereas the process itself is called a construction process.
You can use the Steel Joints add-on in RFEM 6 to create and analyze steel connections using an FE model. You can control the modeling of the connections via a simple and familiar input of components. Steel joint components can be defined manually, or by using the available templates in the library. The former method is included in a previous Knowledge Base article titled “A Novel Approach to Designing Steel Joints in RFEM 6". This article will focus on the latter method; that is, it will show you how to define steel joint components using the available templates in the program’s library.
RWIND 2 is a program for generating wind loads based on CFD (Computational Fluid Dynamics). The wind flow numerical simulation is generated around any building, including irregular or unique geometry types, to determine the wind loads on surfaces and members. RWIND 2 can be integrated with RFEM/RSTAB for the structural analysis and design or as a stand-alone application.
Structures in RFEM 6 can be saved as blocks and reused in other RFEM files. The advantage of dynamic blocks with respect to non-dynamic blocks is that they allow interactive modifications of the structural parameters as a result of modified input variables. One example is the possibility to add structural elements by changing only the number of bays as an input variable. This article will demonstrate the aforementioned possibility for dynamic blocks that are created by scripting.
In addition to the predefined models available as blocks in Dlubal Center | Blocks, it is possible to create new blocks and save them in the manner discussed in the Knowledge Base article "Saving Models as Blocks in RFEM 6".
In RFEM 6 it is possible to save selected objects (as well as whole structures) as blocks and reuse them in other models. Three types of blocks can be distinguished: non-parameterized, parameterized, and dynamic blocks (via JavaScript). This article will focus on the first block type (non-parameterized).
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 effects due to snow load are described in the American standard ASCE/SEI 7-16 and in Eurocode 1, Parts 1 through 3. These standards are implemented in the new RFEM 6 program and the Snow Load Wizard, which serves to facilitate the application of snow loads. In addition to this, the most recent generation of the program allows the construction site to be specified on a digital map, thus allowing the snow load zone to be imported automatically. These data are, in turn, used by the Load Wizard to simulate the effects due to the snow load.
In this article, the adequacy of a 2x4 dimension lumber subject to combined biaxial bending and axial compression is verified using the RF-/TIMBER AWC add-on module. The beam-column properties and loading are based on example E1.8 of AWC Structural Wood Design Examples 2015/2018.
In RFEM and RSTAB, parametrization provides you with many options, especially for recurring structural elements. Within the parametrization tool, you can access the internal values of a model; for example, the values of a selected cross‑section. The following example shows how this can work.