Proposal for the approach of torsional restraint by sandwich panels under uplifting loads

Sandwich panels are able to support their substructure against failure resulting from stability loss. Especially for the thin‐walled cross‐sections, practical spans can often only be realized by taking the stabilization into account. In mechanics, this stabilization can be described as a combination of shear field and torsional restraint. However, for the load combination of self‐weight and wind suction, the shear field is usually applied to the flange in tension, which means that only slight stabilization effects can be added to the system. In addition, there is no standardisation for the approach of a torsional restraint under uplifting loads. Recent investigations showed on the one hand that the reduction of the torsional restraint under uplifting loads given in the literature is correct, but on the other hand, they offer a specific quantification of the reduction. Thus, a qualified estimation of the applicable torsional restraint under uplifting loads, based on tests and calculations using the finite element method, is made possible on the basis of a well‐founded mechanical model. The scientific background to this as well as the mechanical model and a proposal for its application in construction practice are described below.