Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Keine Kurzfassung verfügbar.

Stub column compression test of a cold-formed C-shaped steel-section used for the validation of a new design approach which combines the AISI S100-16 Direct Strength Method with EN 1993-1-3. Failure mode of the test specimen: distortional buckling (s. paper: Ungermann, D.; Lemaski, T.; Brune, B., pp. 78-92). Copyright: TU Dortmund Lehrstuhl Stahlbau

This paper reports an experimental investigation on the behaviour and strength of cold-formed high-strength steel (G450-G500) lipped channel beams susceptible to local-distortional interaction. The experimental campaign comprised 36 tests involving simply supported beams bent about the major axis, exhibiting various ratios between their distortional and local critical buckling moments (from 1.09 to 1.46) and acted by either uniform (20 tests) or non-uniform (trapezoidal: 16 tests) bending diagrams. The results presented and discussed consist of equilibrium paths, photos providing the evolution of the beam deformed configurations and failure moments. The paper also includes a few remarks on the design, using the Direct Strength Method, of the beams under consideration.

A Eurocode-compliant design approach was developed for the design of thin-walled cold-formed steel sections which combines the AISI S100-16-Direct Strength Method (DSM) with the design provisions of EN 1993-1-3. The new design approach transfers the cross-sectional resistance determined acc. to DSM based on numerical elastic buckling analyses on the gross cross-section into the global member verification acc. to EN 1993-1-3. Additional factors were introduced to optimize the new approach, e.g., to account for the effects of the nonlinear stress distribution in cross-sections subject to local and/or distortional buckling. Within the framework of the German research project FOSTA P1328/IGF 19964, an extensive series of tests on differently shaped, perforated, and unperforated cold-formed sections in compression and bending were conducted which serve to analyze the buckling phenomena and the load-bearing capacity and to validate the new design approach. In addition, a numerical model was developed, calibrated to the tests, and used for further parametric analyses on the load-bearing capacity of cold-formed sections.

The “General Method” according to chapter 6.3.4 of EN1993-1-1 or 8.3.4 of prEN1993-1-1 deals with the verification of stability problems of frame and beam structures with loadings in-plane. The “General method” according to Eurocode is intended for the general case of a combined moment and normal force. For the choice of the reduction factor &khgr;op, there are two options for applying the reduction curve, either the minimum of lateral torsional buckling (LTB) and flexural buckling (FB) or a weighted combination of both. With the use of analytical derivations, it can be shown that this approach leads to inconsistencies which can possibly lead to incorrect results. In this paper an alternative approach is presented which leads to unification and fully mechanical justification in verification. The approach allows e.g. the verification of stability of an entire frame system directly and without interaction factors (as in the equivalent member method). In addition, the issue of a consistent equivalent imperfection is addressed. With the use of this method, geometrical non-linear analyses of structures showing out-of-plane instability can be omitted; only an in-plane calculation and a determination of a linear buckling analysis is necessary. Finally, examples are presented in this paper that demonstrate the application of the approach shown.

Web holes are commonly seen in cold-formed steel channel sections to accommodate the technical services. The presence of the web holes has resulted in the reduction of the sectional capacities of the cold-formed steel sections and has been considered in the design according to the American Specification AISI S100-16 using a new approach in the design called the Direct Strength Method (DSM). This article, therefore, will use this design method to investigate the sectional capacities of perforated channel sections under compression or bending with the variation of hole sizes in relation to those of gross channel sections. Elastic buckling analysis - a compulsory requirement for application of the DSM - can be conducted using a module CUFSM software program recently developed by the American Iron and Steel Institute. The investigated channel sections are taken from the availably commercial sections. The obtained sectional capacities are seen as the opposite trends for local and distortional buckling modes, although a downtrend of the sectional capacities is found in general with the increase of hole dimensions. It was found that perforated channel sections with smaller hole height and longer hole lengths were recommended to obtain the optimum section capacities in terms of the same web hole area, but the opposite trend was seen for these sections under bending with long hole lengths.