The First High-Rise, An Inspiring High-Rise
Despite the fact that the great pyramid of Giza is the first high-rise building, yet it reflects innovative features which have been exploited in contemporary high-rise buildings. These innovative features address the building’s form, aerodynamics, earthquake resistance, and construction innovation as well as energy aspects, yet emphasise sustainability. The following part describes that in detail.
Aerodynamics and Building’s Shape and Sustainability
The economics of constructing tall buildings is greatly affected by wind as their height increases. To counteract wind loads and keep buildings’ motions within comfortable limits mainly require robust structural systems, which drive up costs. In fact, both the loads and motions are often subject to dynamic amplification in both the along-wind and cross-wind directions (Irwin et al. 2008). These effects are heavily dependent on shape. Hence, the current trend towards considering the aerodynamics of the shape very early in the design of the very tall towers. Curtain wall loads also tend to increase with height primarily due to the fact that wind speeds in general increase with height, and the winds at ground level and on terraces or balconies are increased. All these effects are familiar to experienced developers and designers of tall towers and can be categorised as potential problems to be solved through the use of wind tunnel testing (Irwin et al. 2008). The pyramid’s shape, which is a tapering one, is unique when dealing with the wind loads, which decreases due to the technique of tapering. Reducing floor areas gradually towards the top is a great approach to improve the lateral performance of a building, meaning that when hitting the building, the vortices will try to shed at different frequencies at different heights, thus resulting in a dramatic reduction of the associated fluctuating forces (Irwin et al. 2008).
Kim and You (2002) and You et al. (2008) investigated the effects of tapering on reducing the wind-induced response of tall buildings of square plan shape through wind tunnel test. This was on the four types of building models (400 mm height) with tapering ratio of 2.5, 5, 7.5, 10, and 15 % and on one square model using high frequency force-balance technique. The results showed that the mean along wind pressure coefficients was reduced by 10-30 % over an extended range of wind direction. Tapering effect for reducing fluctuating across the wind forces appeared evident when wind direction is 0°, meaning normal to windward face. The maximum reduction ratio of fluctuating across-wind forces is about 20 % and about 30 % for suburban terrain and urban terrain, respectively.