A 30-storey residential building (importance level 3) with a 4-storey basement is about to be built in Sydney CBD

A 30-storey residential building (importance level 3) with a 4-storey basement is about to be built in Sydney CBD. The floor height in the lobby (ground floor) is 4.5 metres, while the height of the remaining floors is 3.2 metres. The site is surrounded by existing buildings on three sides, most notably a 150-year-old heritage cathedral on its east side, and a fairly busy street on the south. Soil investigation reveals that the soil condition is mainly sandstone, and the ground water level is high.

The building is located on a 32-metre hill, 20 metres from the crest with a terrain category 4. The slope of the hill is 8%. Determine design wind speed from the east at 90 metres of building height. (15%)