A unified approach for the local buckling of sandwich panels and trapezoidal sheeting

Failure of thin-walled building components like sandwich panels or trapezoidal sheeting is normally initiated through a local buckling of the plane elements of the cross-section. For trapezoidal sheeting, EN 1993-1-3 gives an equation for the determination of the effective width of these plane elements and thus for the calculation of the load-bearing capacity of these components. The cross-sectional parts of a lightly or strongly profiled facing of a sandwich panel can be regarded as elastically supported plane elements, whereas the elastic support is provided by the core material. For the determination of the load-bearing resistance of sandwich panels with lightly or strongly profiled facings, a calculation procedure to determine the effective width of the elastically supported plane elements is needed. Some approaches for the calculation of the effective width already exist. The papers published so far are using a modified buckling coefficient for the calculation of the buckling strength, following Winters approach such as given in EN 1993-1-3. Because no generally accepted design procedures exist, the load-bearing resistance of sandwich panels is determined experimentally. Based on the basic principles of structural stability, the buckling strength of the elastically supported plane element can be calculated, taking into account the material properties of the core material and the associated buckling wavelength for minimum buckling strength. Then the design procedures of EN 1993-1-3 for thin plate buckling of trapezoidal sheeting can be used, expanded by the procedures of EN 1993-1-5 for taking into account the column type buckling behaviour for buckling wavelengths smaller than the total width of the plane element. Comparison of the test results with different arrangements to the calculated values shows a good consistency. For lightly profiled faces, depending on the depth of the profiling, failure will finally take place through a plate buckling of the plane elements or by a column buckling of the stiffening profiles, whereas the latter failure mode is looking similar as the wrinkling failure of a flat facing. Comparison of the experimental results obtained with different test arrangements to the calculated values show the present limits of the applicability of the proposed design procedure. The differences in failure modes are discussed

Fixings of sandwich panels in building applications

The paper introduces briefly the European Recommendations for Testing and Design of Fastenings of Sandwich Panels, written by the Joint Committee of ECCS TC7.9 and CIB W056. The Recommendations can be seen as an annex to the standard EN 14509 (2006), which concern the factory made sandwich panel products. The paper gives background information about the mechanical behavior and explains the effects of important parameters of a fastening loaded by tensile forces. A design formula is presented, which shows the influence of the essential mechanical parameters in the load-bearing capacity

Tragverhalten dünnwandiger Bauteile aus perforierten Blechen

In dieser Arbeit wird das Tragverhalten dünnwandiger Bauteile aus perforierten Blechen untersucht und daraus ein Bemessungsverfahren für voll- oder teilperforierte Trapez- und Wellprofile entwickelt