When wind-induced surface pressures on a building are available, they can be applied on a structural model in RFEM 6, processed by RWIND 2, and used as wind loads for static analysis in RFEM 6.
RWIND 2 and RFEM 6 can now be used to calculate wind loads from experimentally measured wind pressures on surfaces. Basically, two interpolation methods are available to distribute pressures measured in isolated points across the surfaces. The desired pressure distribution can be achieved using the appropriate method and parameter settings.
To evaluate whether it is also necessary to consider the second-order analysis in a dynamic calculation, the sensitivity coefficient of interstory drift θ is provided in EN 1998‑1, Sections 2.2.2 and 4.4.2.2. It can be calculated and analyzed using RFEM 6 and RSTAB 9.
For the ultimate limit state design, EN 1998‑1, Sections 2.2.2 and 4.4.2.2 require a calculation considering the second‑order theory (P‑Δ effect). This effect may be neglected only if the interstory drift sensitivity coefficient θ is less than 0.1.
Wind direction plays a crucial role in shaping the outcomes of Computational Fluid Dynamics (CFD) simulations and the structural design of buildings and infrastructures. It is a determining factor in assessing how wind forces interact with structures, influencing the distribution of wind pressures, and consequently, the structural responses. Understanding the impact of wind direction is essential for developing designs that can withstand varying wind forces, ensuring the safety and durability of structures. Simplified, the wind direction helps in fine-tuning CFD simulations and guiding structural design principles for optimal performance and resilience against wind-induced effects.
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 “Creation of the 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.
A member's boundary conditions decisively influence the elastic critical moment for lateral-torsional buckling Mcr. The program uses a planar model with four degrees of freedom for its determination. The corresponding coefficients kz and kw can be defined individually for standard-compliant cross-sections. This allows you to describe the degrees of freedom available at both member ends due to the support conditions.
Often in RFEM, only part of a surface must be loaded, not an entire surface. A typical case of this is soil pressure. For this purpose, there is the option of defining free surface loads. They are surface-independent and are displayed in defined coordinate dimensions in the graphic.
A fluid with a constant density in a homogeneous gravity field exerts a hydrostatic pressure on its comprehensive container wall according to Pascal's law.
RF‑/FOUNDATION Pro allows you to check the allowable eccentricity of the soil pressure resultants. According to DIN EN p;1997‑1/NA, this design is to be carried out with characteristic or representative loads.
In addition to the basic combination rules of EN 1990, there are other combination conditions for actions on road bridges specified in EN 1991‑2 that must be taken into account. RFEM and RSTAB provide automatic combinatorics that can be activated in the General Data when selecting the standard EN 1990 + EN 1991‑2. The partial safety factors and combination coefficients depending on the action category are preset when selecting the respective National Annex.
With the RF-STABILITY and RSBUCK add-on modules for RFEM and RSTAB, it is possible to perform eigenvalue analyses for member structures in order to determine the effective length factors. The effective length coefficients can then be used for the stability design.
The following study compares the wind pressure on a tall building obtained by RWIND Simulation with the results published by Dagnew et al. at the 11th Americas Conference on Wind Engineering in June, 2009. In this paper, the Commonwealth Advisory Aeronautical Council (CAARC) building is used as a model, and the results of several different numerical methods are compared with experimental data obtained from wind tunnels.
Performing serviceability limit state design also includes taking into account the allowable deformation. Calculating the deformation of reinforced concrete components depends on whether or not the observed cross-section cracks under the applied loading. The governing control parameter in RF-CONCRETE Deflect is the distribution coefficient ζ.
If the wind load for buildings or structures is to be determined by the simultaneous assumption of aerodynamic pressure and suction coefficients on the windward and leeward sides of the building, the correlation of the wind pressure on zones D and E of the wall surfaces may be taken into account.
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.
Cable and tensile membrane structures are regarded as very slender and aesthetic building structures. The partly very complex double-curved shapes can be found using suitable form-finding algorithms. One possible solution is to search for the form via the equilibrium between the surface stress (provided prestress and an additional load such as self-weight, pressure, and so on) and the given boundary conditions.
Wind is the only climatic load acting on every type of structure in every country in the world, unlike snow. The wind speed depends on the geographic location of the building. Currently, this is one of the main reasons for the necessity of regional division (wind zone) and consideration of the altitude stipulated within the official standards; the variation of the dynamic pressures according to the height above the ground for a "normal" site deprived of masking effect should be taken into account as well.
This article describes the determination of force coefficients using a wind load and the calculation of a stability factor due to lateral-torsional buckling.
In addition to the reinforced concrete design according to EN 1992‑1‑1, RF-/FOUNDATION Pro allows you to perform geotechnical designs according to EN 1997‑1. In RF-/FOUNDATION Pro, the design of the allowable soil pressure is performed as a ground failure resistance design. If you select CEN as National Annex, you have two options for defining the ground failure resistance. First, you can directly specify the allowable characteristic value of the soil pressure σRk. Second, there is also the option to analytically determine the bearing capacity according to [1], Annex D.
RFEM and RSTAB provide the option to create national annexes with user-defined partial safety factors and combination coefficients. They can also be transferred to other computers.
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).
As in RFEM, load combinations can be generated automatically in RF‑PIPING. This feature is activated by default and creates the recommended load and result combinations for piping design. It is necessary to assign the relevant action category to load cases in order to generate the correct combinations. To do this, new action categories have been implemented specifically for loads on piping. Pressure temperature conditions are generated as the sets of the first (second, third, and so on) load case of the "Pressure" category and the first (second, third, and so on) load case of the "Temperature" category. The default setting can be reviewed or adjusted in the "Grouping of Thermal and Internal Pressure Load Cases for Operating Combinations" dialog box. You can access this dialog box by clicking the corresponding button in the "Piping Load Combinations" tab of the "Load Cases and Combinations" dialog box. This dialog box is automatically offered to check your entries in the case of any change of the load case from the "Pressure" or "Temperature" category.
For the ultimate limit state design, EN 1998-1 Section 2.2.2 and 4.4.2.2 [1] requires the calculation considering the second-order theory (P-Δ effect). This effect may be neglected only if the interstory drift sensitivity coefficient θ is less than 0.1.
Due to the structural efficiency and economic benefits, dome-shaped roofs are frequently used for storehouses or stadiums. Even if the dome has the corresponding geometrical shape, it is not easy to estimate wind loads due to the Reynolds number effect. The external pressure coefficients (cpe) depend on the Reynolds numbers and on the slenderness of the structure. EN 1991‑1‑4 [1] can help you to estimate the wind loads on a dome. Based on this, the following article explains how to define a wind load in RFEM. Wind loads of the structure shown in Image 01 can be divided as follows: Wind Load on Wall, Wind Load on Dome.
With RFEM version 5.06, member stiffnesses can be influenced by methods that are aligned with US steel construction standard ANSI/AISC 360-10. According to this standard, reduction factor τb must be considered for the determination of internal forces in all members of which the flexural resistance contributes to the model's stability. This coefficient depends on the axial force in the member: The larger the axial force, the larger τb is.
For the superposition or combination of loads, the German standard DIN 18008 refers to DIN 1055‑100. This also applies for the individual parameters of climatic loads to be transferred. In this case, it is possible to summarize the temperature change and meteorological pressure change in a single load and to define the local altitude change as a permanent load.