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.
To be able to evaluate the influence of local stability phenomena of slender structural components, RFEM 6 and RSTAB 9 provide you with the option of performing a linear critical load analysis on the cross-section level. The following article explains the basics of the calculation and the result interpretation.
The design of cold-formed steel members according to the AISI S100-16 is now available in RFEM 6. Design can be accessed by selecting “AISC 360” as the standard in the Steel Design add-on. “AISI S100” is then automatically selected for the cold-formed design (Image 01).
This technical article presents some basics for using the Torsional Warping add-on (7 DOF). It is fully integrated into the main program and allows you to consider the cross-section warping when calculating member elements. In combination with the Stability Analysis and Steel Design add-ons, it is possible to perform the lateral-torsional buckling design with internal forces according to the second-order analysis, taking imperfections into account.
Very small torsional moments in the members to be designed often prevent certain design formats. In order to neglect them and still perform the designs, you can define a limit value in RF‑/STEEL EC3 from which torsional shear stresses are taken into account.
This technical article deals with the stability analysis of a roof purlin, which is connected without stiffeners by means of a bolt connection on the lower flange to have a minimum manufacturing effort.
The critical factor for lateral-torsional buckling or the critical buckling moment of a single-span beam will be compared according to different stability analysis methods.
The RF‑/STEEL Warping Torsion module extension of the RF‑/STEEL EC3 add‑on module allows you to design members with asymmetric cross‑sections. The new option is fully integrated in the design module and can be activated for sets of members.