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.
The advantage of the RFEM 6 Steel Joints add-on is that you can analyze steel connections using an FE model for which the modeling runs fully automatically in the background. The input of the steel joint components that control the modeling can be done by defining the components manually, or by using the available templates in the library. The latter method is included in a previous Knowledge Base article titled “Defining Steel Joint Components Using the Library". The definition of parameters for the design of steel joints is the topic of the Knowledge Base article “Designing Steel Joints in RFEM 6".
To perform deflection analysis in the right manner, it is important to “inform” the program about the exact support conditions of the element of interest. The definition of design supports in RFEM 6 will be shown for a reinforced concrete member set.
In RF-/FOUNDATION Pro, the foundation design requires the definition of the corresponding loading (load cases, load combinations, or result combinations) for different design situations (STR, GEO, UPL, or EQU).
Supports contributing to a load reduction only under compression or tension can be defined as nonlinear supports in RFEM and RSTAB. It is not always easy for the user to select the correct nonlinearity for "failure under tension" or "failure under compression".
The additional loads from self‑weight are usually composed of several layers; for example, classic floor and ceiling layers in buildings, or road coatings for bridge constructions. When defining load definitions in RFEM and RSTAB, you can use the multi-layer load to define the individual layers with thickness and specific weight.
In the RF-GLASS add-on module, 3D rendering is implemented to facilitate the definition of the support conditions. This interactive graphical visualization facilitates the input and control of line and nodal supports. However, the schematic display can also be selected, if necessary.
You can use the "Free Circular Load" option in RFEM to apply a partial uplift force to a cone‑shaped floor slab. It can be defined as linearly variable. The definition of center C and the outer boundary R can be specified easily, using the select function.
In RFEM, surfaces are automatically connected if they have common boundary lines. If the definition line of a surface is lying in another surface, the line is automatically integrated into the surface, provided that it is a planar surface. For quadrangle surfaces, however, automatic object detection would be relatively time-consuming. For this reason, the corresponding function is deactivated. The integrated objects must be specified manually.
When using the RF‑GLASS add‑on module, you can define just the geometry in the main program, as well as the load situation of the structural component to be designed. The respective support conditions and all further design-relevant definitions (for example, the layer structure and support conditions), can be further specified in RF‑GLASS.
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.
When defining the effective slab width of T-beams, RFEM provides the predefined widths that are determined as 1/6 and 1/8 of the member length. A more detailed explanation on these two factors is given below.
This example describes a definition of a planar surface by four nodes that have been imported and seem to lie in a common plane. In reality, they are not exactly in one plane due to (for example) a previous modeling error of a few millimeters. When trying to create a planar surface, the error message "Error in the surface definition! The nodes do not lie in a common plane." appears.
The definition of the non-linear contact problem plays an important role for more detailed investigations of shear/hole bearing connections or their immediate environment. This article uses a solid model to search for comparable and simplified surface models.
The time-dependent stress losses from creeping, shrinkage, and relaxation have to be considered when designing prestressed concrete components. The consideration of relaxation losses when designing prestressed concrete in RF-TENDON and RF-TENDON Design is discussed in detail in the following text.
With RF-PUNCH Pro, the punching shear design can be performed according to 6.4, EN 1992-1-1. In the following example, the design according to DIN EN 1992-1-1 will be presented first with automatic design of the inner and outer perimeters and then on the basis of the inner perimeters defined by the user on a simple example.
RFEM and RSTAB provide numerous options for nonlinear definitions of nodal supports. With regard to an earlier article, further possibilities of the nonlinear support design for a movable support are shown in a simple example in this article. For a better understanding, the result is always compared to a linearly defined support.
In the case of plate structures, it is always necessary to consider realistic definition support conditions. Depending on the way of defining the flexibility of the supports, clear differences may occur in the results.
The boundary conditions of a plate support can be entered quickly as singular and line supports in the FEA software. However, if the flexibility of the supports is not considered when modeling the structure, it is often necessary to take a closer look at the support definitions during the design using stresses or the determination of the required reinforcement, at the latest.
My previous article Result Combinations 1 explained the basic principles of result combinations on simple examples. This article describes a further application case that combines the definition options of Examples 1 and 2. Likewise, the effort should be compared to a combination by means of load combinations.
At first glance, the material list for masonry seems empty. The reason for this is that bricks and mortar can be used in many combinations, which would lead to a very long and unclear list. Therefore, it is necessary first to create a new material for masonry in order to consider these possible combinations in the calculation.
The insulating glass pane design places a special requirement on the load application point of the loading. For example, wind loads and loads due to fall protection may appear. For this, the wind load should be applied on the external glass side and the handrail load should act on the internal glass pane.
In his bachelor's thesis, Jonas Mösch analyzes the open and closed interfaces in BIM-based structural design. The theoretical section covers the definition of the term "Building Information Modeling".
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).
Generally, RFEM automatically detects all objects lying on a surface that are not used for surface definition. Objects integrated into surfaces can be selected using the "Select Integrated Objects" option in the shortcut menu of the relevant surface in Project Navigator. This way, you can easily find in the graphics which objects have already been integrated into a surface, for example.
Input data and results can be clearly arranged in a printout report. The contents are listed in compliance with the program-specific definition. If the order of the contents does not correspond to your requirements, you can move the individual parts anywhere in the printout report.