Speed up effects over 3-D complex hills with transmission towers collapsed during typhoon passage

This paper presents topographic effects over 3-D complex hills with transmission towers collapsed during typhoon passage. The meteorological station data were analyzed and wind-tunnel tests were performed to investigate the possible causes of the failure. Topographic factors from the experiment were compared with those from major codes and standards. It was observed that topographic factors from the major codes and standards are hard to apply to the actual complex 3-D hills. Topographic effects are very difficult to be reflected in the codes and standards because actual terrains are so complex. It is understandable that only AIJ recommendations require that topographic effects over 3-D hills be estimated in the wind-tunnel tests.