In computational fluid dynamics (CFD), complex surfaces that are not completely solid can be modeled using porous or permeability media. In the actual world, examples of such things include windbreak fabric structures, wire meshes, perforated facades and claddings, louvers, tube banks (stacks of horizontal cylinders), and so on.
For a frame trussed from below, compression members are to be modelled perpendicular to the inclined beam. The member length and the intersection with the horizontal beam are defined.
General thin-walled cross-sections often have asymmetrical geometries. The principal axes of such sections are then not parallel to the horizontally and vertically aligned axes Y and Z. When determining the cross-section properties, the angle α between the center-of-gravity axis y and the principal axis u is determined in addition to the principal axis-related moments of inertia.
In the case of horizontal beam-like supporting structures, the favorable and unfavorable load components of the permanent actions should be considered separately. In RFEM and RSTAB, you can do this as follows.
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".
To control the lateral displacements of a model, you can use the RF-/LIMITS add‑on module. This add‑on module allows you to, for example, run a serviceability limit state analysis to find horizontal nodal deformations and to set it against a limit value.
Model and load objects can be defined graphically or in tables, or they can be created using parameters (see the manual). With this parameterized input, you can also access the cells of certain tables of the program. In this way, it is possible to link a load parameter with a model data parameter, for example. The reference is created by the $ sign.
In RF‑/FOUNDATION Pro, the reinforcement to be placed in the foundation slab and, if necessary, the bucket links, is displayed in a 3D rendering and in the reinforcement drawings.
The network-capable Project Manager controls the projects of all Dlubal Software applications in one central location. The projects are linked to the folders on the hard disk.
When introducing and transferring horizontal loads such as wind or seismic loads, increasing difficulties arise in 3D models. To avoid such issues, some standards (for example, ASCE 7, NBC) require the simplification of the model using diaphragms that distribute the horizontal loads to structural components transferring loads, but cannot transfer bending themselves (called "Diaphragm").
The Project Manager is installed by default when installing RFEM and RSTAB and it manages all projects and calculation files. In the Project Manager, you can link different projects to have a clear overview of the program files.
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.
The story drift of a building provides valuable information about its structural behavior under seismic loads. These could cause large horizontal deformations and even instabilities. Some standards, therefore, call for a check of the story drift in its center of gravity. It indicates, for example, if a second-order analysis (P-Δ effect) is necessary.
Sections 4.1 and 4.2 of this article series describe the optimization of a frame using the RF‑/STEEL EC3 add-on module. The fifth section explains how to link the module and get the relevant members. The elements already explained in the previous sections will not be described again.
Buildings must be designed and dimensioned in the way that both vertical and horizontal loads are conducted safely and without large deformations in the building. Examples of horizontal loads are wind, unintentional inclination, earthquake, and a blast.
If nodal supports should have an effect in certain directions only, you can define failure. Here is an example of a single‑span beam, of which the right support can only absorb positive vertical loads. The load comprise vertical suction load and horizontal load. However, there are 2 failure options: 1) Failure if negative PZ' 2) Failure all if negative PZ' The difference is illustrated in the graphic.
Some compound beam structures, such as stacked containers or retracted telescopic bars, transfer the forces in the connection between the components by friction. The load-bearing capacity of such a connection depends on the effective axial force perpendicular to the friction plane and on the friction coefficients between both friction surfaces. For example, the more the friction surfaces are compressed, the more horizontal shear force can be transferred by the friction surfaces (static friction).
When using the wind load generator for vertical walls with a roof, it may be necessary to load the edge members on eaves or on a gable only with the wind loads of the roof. For structural reasons, the horizontal wind loads should apply to the vertical walls by the facade. In previous versions, it was necessary to apply the wind loads separately to the walls and the roof with the corresponding generators and exclude the unwanted members.
The integrated project manager helps you to organize design files of Dlubal Software programs. For this, a link is created between an existing project folder on the hard drive and the Project Manager. If you want to delete a project created in the Project Manager, there are two methods.