Gust factors for locations downstream of steep mountain ridges

Motivated by observed severe damage to building structures in complex terrain, the main focus of this paper is on the problem of establishing a relative gust factor concept for geographic locations on the lee side of steep mountain ridges exposed to winds making an angle with the main horizontal axis of the ridge. Two specific locations of this type will be considered here. They are situated some distance away from a reference station for which estimates of e.g. 50 yr values for both gust wind and 10 min mean wind speeds can be obtained. Relative to the dominant wind speed direction, both locations are situated on the leeward side of steep terrain, which is a typical location for the observed damage. Simultaneous wind speed and meteorological data have been recorded for the two locations and the reference station for the duration of one winter season.