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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.
Creating a validation example for Computational Fluid Dynamics (CFD) is a critical step in ensuring the accuracy and reliability of simulation results. This process involves comparing the outcomes of CFD simulations with experimental or analytical data from real-world scenarios. The objective is to establish that the CFD model can faithfully replicate the physical phenomena it is intended to simulate. This guide outlines the essential steps in developing a validation example for CFD simulation, from selecting a suitable physical scenario to analyzing and comparing the results. By meticulously following these steps, engineers and researchers can enhance the credibility of their CFD models, paving the way for their effective application in diverse fields such as aerodynamics, aerospace, and environmental studies.
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.
In order to be able to carry out a pushover analysis, it is necessary to transform the determined capacity curve into a simplified form. The N2 method is described in Eurocode EN 1998. This article should help to explain what a bilinearization according to the N2 method involves.
Both the determination of natural vibrations and the response spectrum analysis are always performed on a linear system. If nonlinearities exist in the system, they are linearized and thus not taken into account. They are caused by, for example, tension members, nonlinear supports, or nonlinear hinges. This article shows how you can handle them in a dynamic analysis.
Compliance with building codes, such as Eurocode, is essential to ensure the safety, structural integrity, and sustainability of buildings and structures. Computational Fluid Dynamics (CFD) plays a vital role in this process by simulating fluid behavior, optimizing designs, and helping architects and engineers meet Eurocode requirements related to wind load analysis, natural ventilation, fire safety, and energy efficiency. By integrating CFD into the design process, professionals can create safer, more efficient, and compliant buildings that meet the highest standards of construction and design in Europe.
- 001819
- Design
- Aluminum Design for RFEM 6
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- Aluminum Design for RSTAB 9
- Concrete Design for RFEM 6
- Concrete Design for RSTAB 9
- Steel Design for RFEM 6
- Steel Design for RSTAB 9
- Timber Design for RFEM 6
- Timber Design for RSTAB 9
- Concrete Structures
- Steel Structures
- Timber Structures
- Structural Analysis & Design
- Eurocode 0
- Eurocode 2
- Eurocode 3
- Eurocode 5
- Eurocode 9
- ADM
- ANSI/AISC 360
For the serviceability of a structure, the deformations must not exceed certain limit values. This article describes an example that shows how to analyze the deflection of members using Dlubal's design add-ons.
The size of the computational domain (wind tunnel size) is an important aspect of wind simulation that has a significant impact on the accuracy as well as the cost of CFD simulations.
The dynamic analysis in RFEM 6 and RSTAB 9 is divided into several add-ons. The Modal Analysis add-on is a prerequisite for all other dynamic add-ons, since it performs the natural vibration analysis for member, surface, and solid models.
Modal analysis is the starting point for the dynamic analysis of structural systems. You can use it to determine natural vibration values such as natural frequencies, mode shapes, modal masses, and effective modal mass factors. This outcome can be used for vibration design, and it can be used for further dynamic analyses (for example, loading by a response spectrum).
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.
The new RFEM software generation provides the option to perform stability design of tapered timber members in line with the equivalent member method. According to this method, the design can be performed if the guidelines of DIN 1052, Section E8.4.2 for variable cross-sections are met. In various technical literature, this method is also adopted for Eurocode 5. This article demonstrates how to use the equivalent member method for a tapered roof girder.
In addition to the geometry and shape of a flat roof, you can also take into account the formation of an eaves area when generating the loading.
In the RF-/TIMBER Pro, RF-/TIMBER AWC, and RF-/TIMBER CSA add-on modules, you can consider the resulting deformation of a member or set of members. In addition to the local directions y and z, you have the option "R." This allows you to compare the total deflection of a girder to the limit values given in the standards.
You can make various settings in order to achieve a clearly‑arranged display of the result values. For example, some users may not want the white background in text bubbles. You can adjust the background in "Display Properties" using the Transparent and Background color option.
Besides the standardized gamma method, you can display the semi-rigid composite beams also as a framework model.
The automatic creation of combinations in RFEM and RSTAB with the "EN 1990 + EN 1991‑3; Cranes" option allows you to design crane runway beams as well as support loads on the rest of the structure.
- 000945
- Add-on Modules
- RF-FRAME-JOINT Pro 5
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- JOINTS Steel | Column Base 8
- JOINTS Steel | DSTV 8
- JOINTS Steel | Pinned 8
- JOINTS Steel | Rigid 8
- JOINTS Steel | SIKLA 8
- JOINTS Steel | Tower 8
- JOINTS Timber | Steel to Timber 8
- JOINTS Timber | Timber to Timber 8
- RF-JOINTS Steel | SIKLA 5
- RF-JOINTS Steel | Column Base 5
- RF-JOINTS Steel | DSTV 5
- RF-JOINTS Steel | Pinned 5
- RF-JOINTS Steel | Rigid 5
- RF-JOINTS Steel | Tower 5
- RF-JOINTS Timber | Steel to Timber 5
- RF-JOINTS Timber | Timber to Timber 5
- FRAME-JOINT Pro 8
- Steel Structures
- Timber Structures
- Steel Connections
- Eurocode 3
- Eurocode 5
In addition to the result tables, you can create three-dimensional graphics in RF‑/FRAME‑JOINT Pro and RF‑/JOINTS. This is a realistic representation of a connection to scale.
The joint type "Main member only" in RF‑/JOINTS Timber - Steel to Timber can also be applied for more than one connected member.
For a timber connection as shown in Figure 01, you can take into account the torsional spring rigidity (spring stiffness for rotation) of the connections. You can determine it by means of the slip modulus of the fastener and the polar moment of inertia of the connection.
The RF-/LIMITS add-on module allows you to compare the ultimate limit state of members, member ends, nodes, nodal supports, and surfaces (RFEM only) by means of a defined ultimate load capacity. Furthermore, you can check nodal displacements and cross-section dimensions. In this example, the column bases of a carport are to be compared with the maximum allowable forces specified by the manufacturer.
With the RF-/TIMBER Pro add-on module, you can perform the vibration design known from DIN 1052 for the design according to EN 1995-1-1. In this design, the deflection under permanent and quasi-permanent action at the ideal one‑span beam may not exceed the limit value (6 mm according to DIN 1052). If you consider the relation between the natural frequency and the deflection for a hinged single-span beam subjected to a constant distributed load, the 6 mm limit value results in a minimum natural frequency of about 7.2 Hz.
In RFEM and RSTAB, snow drift is considered according to 5.3.4(3) of DIN EN 1991‑1‑3 for saw-tooth roofs.
In timber design, beams are often built from several timber elements. The individual elements can be connected with glue, nails, bolts, or dowels. A glued connection is to be assumed as rigid. In the case of dowel‑type fasteners, the joint is compliant (slip joint), and the cross‑section properties of the connected elements cannot be fully applied.
For relatively large or relatively small surfaces, it can happen that the automatically created result values do not fit the model: In the case of large surfaces, there can be too many result values; in the case of small surfaces, too few.
The same structures are often needed in several projects, such as the purlin with columns and braces in this example. The dimensions can be changed directly in RFEM or RSTAB by shifting the nodes.
The Eurocode for DIN EN 1991‑1‑4:2010‑12 describes wind loads acting on structural systems.
The RX‑TIMBER stand-alone program offers you the option to optimize the lateral-torsional bracing. With this selection, the program iteratively determines the required minimum length of the lateral-torsional bracing.
RF-/DYNAM Pro - Equivalent Loads allows you to determine the loads due to equivalent seismic loads according to the multi‑modal response spectrum method. In the example shown here, this was done for a multi‑mass oscillator.