The response spectrum analysis is one of the most frequently used design methods in the case of earthquakes. This method has many advantages. The most important is the simplification: It simplifies the complexity of earthquakes so far that the design can be performed with reasonable effort. The disadvantage of this method is that a lot of information is lost due to this simplification. One way to moderate this disadvantage is to use the equivalent linear combination when combining the modal responses. This article explains this option by describing an example.
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.
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.
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.
Rolled sections, the most common cross‑section type in RFEM and RSTAB, can also have user‑defined parameters. To do this, select the cross‑section to be modified in the cross‑section library and click the [Parametric Input...] button.
In RF-/STEEL EC3, sets of members are calculated according to the General Method (EN 1993-1-1, Cl. 6.3.4) together with the stability analysis. To do this, it is necessary to determine the correct support conditions for the equivalent structure with four degrees of freedom. In most 3D models today, you can quickly lose track of the location of a set of members in the system.
Structure stability is not a new phenomenon when referring to steel design. The Canadian steel design standard CSA S16 and the most recent 2019 release are no exception. Detailed stability requirements can be addressed with either the Simplified Stability Analysis Method in Clause 8.4.3 or, new to the 2019 standard, the Stability Effects in Elastic Analysis method provided in Annex O.
An individual user‑defined workspace can increase your productivity and make your daily work easier. This is why many users take the opportunity to adjust the toolbars in RFEM and RSTAB and to create their own toolbars containing the most frequently used commands.
The most common causes of unstable models are failing member nonlinearities such as tension members. As the simplest example, there is a frame with supports on the column footing and moment hinges on the column head. This unstable system is stabilized by a cross bracing of tension members. In the case of load combinations with horizontal loads, the system remains stable. However, if it is loaded vertically, both tension members fail and the system becomes unstable, which causes a calculation error. You can avoid such an error by selecting the exceptional handling of failing members under "Calculate" → "Calculation Parameters" → "Global Calculation Parameters".
The load generators in RFEM and RSTAB, used to convert area loads to member loads automatically, require cells that are almost even. In the case of arc‑like structures, the cells often cannot be recognized automatically.
A PDF version of the printout report can be created in two ways. The most common way is to use a PDF printer that must be previously installed. The printer will be controlled like a real printer.
To carry out a structural analysis for a structural system according to the current standards, it is necessary not only to deal with the actions and resistances of structural components, but also with the combinations of these actions. Some of the most common actions in structural analysis are, for example, the permanently acting load case of self‑weight and the suddenly acting load cases of wind and snow.
Usually, the lifting forces acting on a structure, which mostly result from wind loads or a dynamic analysis, are transferred into the ground through ties.
To carry out a structural analysis for a structural system according to the current standards, it is necessary not only to deal with the actions and resistances of structural components, but also with the combinations of these actions. Some of the most common actions in structural analysis are, for example, the permanently acting load case of self‑weight and the suddenly acting load cases of wind and snow.
To cover the required transverse reinforcement, RF‑CONCRETE Members and CONCRETE determine the most cost-efficient transverse reinforcement as a reinforcement proposal in accordance with the predefined stirrup diameter.
The most recent standard ACI 318‑19 redefines the long-term relation for the determination of the concrete shear resistance Vc. 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 using an example.
It is necessary to design some structures in different configurations. It may be that an aerial work platform must be analyzed in its position on the ground as well as in the middle and in the extended position. Since such tasks require the creation of several models, which are almost identical, updating all the models with just one mouse click is a considerable relief.
The response spectrum analysis is one of the most frequently used design methods in the case of earthquakes. This method has many advantages. The most important is the simplification: It simplifies the complexity of an earthquake to such an extent that an analysis can be carried out with reasonable effort. The disadvantage of this method is that a lot of information is lost due to this simplification. One way to mitigate this disadvantage is to use the equivalent linear combination when combining the modal responses. This article explains this option by describing an example.
Building Information Modeling is making headlines in building design. While some engineers only use BIM methods for planning, others are dealing with this topic for the first time or rarely have time for it in their daily working routine. However, one topic seems the most important in structural engineering: How can structural engineers benefit from BIM?
Piping systems are exposed to a variety of loads. One of the most decisive is internal pressure. This article will, therefore, deal with the stresses and deformations resulting from a pure internal compression load in the pipe wall or for the pipe.
Shell buckling is considered to be the most recent and least explored stability issue of structural engineering. This is due less to a lack of research activities than to the complexity of the theory. With the introduction and further development of the finite element method in structural engineering practice, some engineers no longer have to deal with the complicated theory of shell buckling. Evidence of the problems and errors to which this gives rise is very well summarized in [1].
This article discusses the most common BIM interfaces. Adjustments are often necessary during the transition to the structural branch-specific model. The tasks that arise and the tools to address them successfully and quickly are presented.
A fillet weld is the most common weld type in steel building construction. According to EN 1993-1-8, 4.3.2.1 (1) [1], fillet welds may be used for connecting structural part where the fusion faces form an angle of between 60° and 120°.
Composite beams in a three-dimensional analysis are usually connected with orthotropic plates. In that case, the longitudinal direction of the plate stiffness is defined by a main beam and the transverse direction by an orthotropic plate. The stiffness of the plate in the longitudinal direction is set almost to zero. This article explains the determination of stiffnesses in the orthotropic plate.
Building Information Modeling describes what is possibly one of the most important current topics in the entire construction software industry. However, the process is not that new, and it is a well-known fact that the total costs of a project can be positively influenced by good planning in the initial stage.
In addition to straight beams, it is sometimes necessary to calculate or design arched or circular beams in RSTAB. For this purpose, there is a special feature under "Tools" → "Generate Model – Members" → "Circle". You can easily use this tool to generate a full or pitch circle. The most important parameter here is the number of new nodes, which affects the accuracy of the results.
In RFEM and RSTAB, several interfaces are available. The DSTV interface (*.stp) is the most convenient for importing beam structures, since supports, hinges, loads, and load combinations are also transferred, in addition to the general topology.