Buffeting analysis: a numerical study on the extraction of equivalent static wind loads

The characterization of the structural response to the wind action is usually obtained by means of dynamic analyses based on the unsteady pressure distributions recorded in wind tunnel tests. In order to simplify the design operations, equivalent static wind loads (ESWLs) can be extracted so allowing to reproduce the extreme effects recorded in a series of dynamic analyses by enveloping a few, statically applied, load conditions. Recently, a new efficient technique for the extraction of ESWLs has been proposed, where the sharp maximum/minimum operator, typical of envelope evaluation procedures, has been smoothed, so allowing to adopt efficient gradient-based optimization techniques in order to individuate the ESWLs. In the present paper, such technique is analyzed from a numerical perspective highlighting the fundamental role played by the applied smoothing operation in the correct individuation of the optimal load conditions. Similarities between the proposed technique for the extraction of ESWLs and well known procedures used in linear classification are highlighted and the proposed smoothing operation is framed in the context of graduated optimization techniques. Numerical results confirm the soundness of the proposed approach.