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Using the Timber Design add-on, timber column design is possible according to the 2018 NDS standard ASD method. Accurately calculating timber member compressive capacity and adjustment factors is important for safety considerations and design. The following article will verify the maximum critical buckling strength calculated by the Timber Design add-on using step-by-step analytical equations as per the NDS 2018 standard including the compressive adjustment factors, adjusted compressive design value, and final design ratio.
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.
The modal relevance factor is a result of the linear stability analysis and qualitatively describes the degree of participation of individual members in a specific mode shape.
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.
The “Modal Analysis” add-on in RFEM 6 allows you to perform modal analysis of structural systems, thus determining natural vibration values such as natural frequencies, mode shapes, modal masses, and effective modal mass factors. These results can be used for vibration design, as well as for further dynamic analyses (for example, loading by a response spectrum).
This article will show you a practical example of how to determine critical load factors and corresponding mode shapes in RFEM 6.
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).
Using the Concrete Design add-on, concrete column design is possible according to ACI 318-19. The following article will confirm the reinforcement design of the Concrete Design add-on using step-by-step analytical equations as per the ACI 318-19 standard, including the required longitudinal steel reinforcement, gross cross-sectional area, and tie size/spacing.
In accordance with Sect. 6.6.3.1.1 and Clause 10.14.1.2 of ACI 318-19 and CSA A23.3-19, respectively, RFEM effectively takes into consideration concrete member and surface stiffness reduction for various element types. Available selection types include cracked and uncracked walls, flat plates and slabs, beams, and columns. The multiplier factors available within the program are taken directly from Table 6.6.3.1.1(a) and Table 10.14.1.2.
The stability checks for the equivalent member design according to EN 1993-1-1, AISC 360, CSA S16, and other international standards require consideration of the design length (that is, the effective length of the members). In RFEM 6, it is possible to determine the effective length manually by assigning nodal supports and effective length factors or, on the other hand, by importing it from the stability analysis. Both options will be demonstrated in this article by determining the effective length of the framed column in Image 1.
RFEM and RSTAB can calculate the critical load factor for each load case (LC) and each load combination (CO) in the case of a geometrically nonlinear calculation (second-order analysis and following).
The RF-STABILITY add-on module determines any critical load factors, effective lengths, and eigenvectors of RFEM models. Stability analyses can be carried out by various eigenvalue methods, the advantages of which depend on the structural system as well as computer configurations.
In RF‑TENDON and RF‑TENDON Design, you can review and adjust the code‑dependent factors, calculation parameters, and calculation methods using the "Code" button. You can display the settings and adjustment options according to a chapter of a code, selecting the "Grouping" option in the dialog box.
In the case of using slow‑curing concrete (usually for thick components), you can reduce the calculated minimum reinforcement by a factor of 0.85 to apply the load due to restraint, according to EN 1992‑1‑1, Section 7.3.2. However, a precondition for reduction is that the characteristic value of the strength development r = fcm2 / fcm28 does not exceed 0.3. Other key requirements for the application of this reinforcement reduction are specified explicitly in the final planning documents.
In RF-/FOUNDATION Pro, the user can freely select the proportion of the relieving soil pressure by means of the factor kred.
In the "Edit Load Cases and Combinations" dialog box, you can combine different load cases in one load combination under the "Load Combinations" tab.
In RF‑/CONCRETE Columns, different methods are available for defining the minimum longitudinal reinforcement. The minimum reinforcement can be selected according to the design standard used and/or specified by the user.
In PLATE‑BUCKLING 8, two options in the detail settings can be used to calculate the reduction factors of plate buckling.
The Aluminum Design Manual (ADM) 2020 was released in February 2020. The ADM 2020 gives guidance for both the allowable strength design (ASD) and load and resistance factor design (LRFD) for aluminum members to ensure reliability and safety for all aluminum structures. This latest standard was integrated in the RFEM/RSTAB add-on module RF-/ALUMINUM ADM. The text below will highlight the applicable updates relevant to the Dlubal programs.
The function, which is also known as shifting, allows you to calculate critical load factors beyond a user‑defined initial value. Determination of the critical load factors is usually done from the smallest to the greatest critical load factor.
The shear force resistance VRd,c without computational shear force reinforcement according to 6.2.2 of EN 1992-1-1 [1] or 10.3.3 of DIN 1045-1 [2] is calculated depending on the longitudinal reinforcement ratio. If the required longitudinal reinforcement from the bending design is used for the calculation of VRd,c, this leads to an underestimation of the shear force resistance without shear reinforcement in the vicinity of the hinged end supports. In contrast to the shear force, the required bending reinforcement decreases in the direction of the support. Furthermore, the actually inserted longitudinal reinforcement usually deviates significantly from the required bending reinforcement in the end support area (for example, in the case of non-staggered beam reinforcement).
In this article, we will look at the design of shear connectors of cross‑laminated timber structures that transfer the longitudinal forces of the shear wall to the soil.
In Part 1, the selection of the design criteria for dimensioning the reinforcement for the serviceability limit state design in RF‑CONCRETE Members and CONCRETE was explained. Now, we go into detail for the function "Find economical reinforcement for crack width design".
The RF-CONCRETE Members and CONCRETE add-on modules provide the option for "Dimensioning of Longitudinal Reinforcement for Serviceability Limit State". You can select the design criteria for the calculation of the longitudinal reinforcement.
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.
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.
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.
Using the RF-TIMBER CSA module, timber column design is possible according to the CSA O86-19 standard. Accurately calculating timber member compressive resistance and adjustment factors is important for safety considerations and design. The following article will verify the factored compressive resistance in the RFEM add-on module RF-TIMBER CSA, using step-by-step analytical equations as per the CSA O86-19 standard including the column modification factors, factored compressive resistance, and final design ratio.
Using the RF-TIMBER AWC module, timber column design is possible according to the 2018 NDS standard ASD method. Accurately calculating timber member compressive capacity and adjustment factors is important for safety considerations and design. The following article will verify the maximum critical buckling in RF-TIMBER AWC using step-by-step analytical equations as per the NDS 2018 standard including the compressive adjustment factors, adjusted compressive design value, and final design ratio.
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.