In RFEM 6, seismic analysis can be done by using the Modal Analysis and the Response Spectrum Analysis add-ons. Once the spectral analysis has been performed, it is possible to use the Building Model add-on to display story actions, interstory drifts, and forces in shear walls.
The Steel Joist Institute (SJI) previously developed Virtual Joist tables to estimate the section properties for Open Web Steel Joists. These Virtual Joist sections are characterized as equivalent wide-flange beams which closely approximate the joist chord area, effective moment of inertia, and weight. Virtual Joists are also available in the RFEM and RSTAB cross-section database.
The design of cross-sections according to Eurocode 3 is based on the classification of the cross-section to be designed in terms of classes determined by the standard. The classification of cross-sections is important, since it determines the limits of resistance and rotation capacity due to local buckling of cross-section parts.
Plate girder is an economical choice for long spans construction. I-section steel plate girder typically has a deep web to maximize its shear capacity and flange separation, yet thin web to minimize the self-weight. Due to its large height-to-thickness (h/tw) ratio, transverse stiffeners may be required to stiffen the slender web.
The National Building Code of Canada (NBC) 2020 Article 4.1.8.7 provides a clear procedure for earthquake methods of analysis. The more advanced method, the Dynamic Analysis Procedure in Article 4.1.8.12, should be used for all structure types except those that meet the criteria set forth in 4.1.8.7. The more simplistic method, the Equivalent Static Force Procedure (ESFP) in Article 4.1.8.11, can be used for all other structures.
In this article, a lap joint of a ZL purlin on a monopitch roof is modeled and designed using the Steel Joints add-on, and compared with the load-bearing capacity table of the manufacturer.
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.
This example is described in technical literature [1] as Example 9.5 and in [2] as Example 8.5. A lateral-torsional buckling analysis must be performed for a principal beam. This beam is a uniform structural member. Therefore, the stability analysis can be carried out according to Clause 6.3.3 of DIN EN 1993‑1‑1. Due to the uniaxial bending, it would also be possible to perform the design using the General Method according to Clause 6.3.4. Additionally, the determination of the critical load factor is validated with an idealized member model in line with the method mentioned above, using an FEM model.
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.
Building Model is one of the special solution add-ons in RFEM 6. It is an advantageous tool for modeling, with which building stories can be created and manipulated easily. Building Model can be activated at the beginning of the modeling process and afterwards.