Wind Loads

Comprehensive data base from large number of weather stations

For planning the safe operation of buildings and facilities, accurate information about the maximum dynamic wind pressure that can occur is required. By combining measurement data of representative weather stations, wind field simulations and extreme value statistics, we are able to provice precise information on the reference dynamic pressure and gust speeds with different return periods.

The basis of the wind load assessments is reliable wind data over a period of at least 10 years. We host extensive climate databases and thus have access to all relevant data. Each site is evaluated in meteorological terms. Based on the evaluation, a selection of appropriate data sets is applied.

Site-specific spatial extrapolation

The location of a planned installation is typically not within the immediate vicinity of a weather station. For this reason, the measurement data must be transferred from the weather station to the site.

Thanks to our know-how, we are able to assess the spatial distribution of gusts in meteorological terms and then perform this transfer. In complex terrain we recommend a simulation of the wind field with CFD models. These take into account non-linear, three-dimensional phenomena such as reverse flows or vortices.

For more than ten years we have been using the CFD model WindSim, originally developed for wind energy, in complex terrain.

Extreme value statistics for various return periods

In many cases wind gusts need to be calculated with a 50-year period of recovery in order to assess the dynamic pressure. Since hardly any weather station has records going back 50 years, this value must be determined by using extreme value statistics.

We apply various methods for determining the extreme winds with different periods of recovery and the associated confidence intervals. Based on these results and the air density, the dynamic pressure is calculated.

If necessary, other ways of viualisation such as Intensity-Duration-Frequency (IDF) graphs can be considered.

Experienced expertise recognised by the authorities

Our wind load expertise for cableways are based on the SIA 261 standard and recognised by the Swiss Federal Office of Transport. In the field of wind energy, we have conducted extreme wind calculations approved by wind turbine manufacturers for a large number of wind parks. For the Federal Office for the Environment, we have calculated a Swiss storms map for return periods of 30, 50, 100 and 300 years. For the Swiss Federal Office of Energy we elaboratet the Swiss Wind Atlas.

Our assessments are characterised by a transparent and comprehensible presentation of the results and the calculation methods used.