Stabilisation of continuous Z-purlins by sandwich panels: Full scale experimental approach

The sandwich panel roof supported by continuously connected thin-walled cold-formed Z-purlins with overlapping over intermediate supports is a practical case of very frequent use. Among the two possible directions of investigation mentioned in the code when studying torsional/distortional instability of Z-purlins (i.e. rotational stiffness and linear stiffness) the authors have chosen to look at the notional linear spring placed at the free flange of the purlin. The linear spring is defined by EN 1993-1-3 Annex A5, as an equivalent or alternative to the stabilizing rotational spring generated by the continuous connection of the sandwich panels to purlin upper flange. This type of approach, on authorsʹ opinion, has the advantage to include into the experimental phase, the real imperfections, and support conditions characteristic to such roof systems, having a very important impact on purlin stability behaviour. A description of the proposed full scale arrangement and experimental conditions, plus values of obtained results are given in the paper.