October, 1962 303 Some Recent Developments in the Design of High Buildings in Hong Kong* by K. T. Philcox, A..M.I.Struct.E. Synopsis As buildings in Hong Kong have increased in height withoutnecessarilyincreasing in width, so the effect of " Typhoon " wind pressures onstructural design has become increasingly important. Many buildings are now stiffened against the effects of wind by in-situ concrete shear walls, which, as vertical cantilevers, normally follow therequirements of CP 114-1957 in respect of height width ratios in an effort to limit horizontal deflexions. Buildings with height width ratios of less than 2 which were designed without wind prior to 1958 (which year saw the introduction of the requirement that allbuildings in Hong Kong should be designed against the effect of wind, irrespective of height width ratio), have in a recent typhoon exhibited the tendency to vibrate to an uncomfortable degree, withhoweverno signs of structural failure. A shear wall stiffened building has on the other hand been reported to be almost free from vibration at the height of the typhoon. Typhoon design wind pressures on tall narrow buildings have led to the introduction of " belled out " caissons bearing on very dense granular material, known in Hong Kong as decomposed granite. The col- lated results of routine plate loading tests show a rela- tionship between settlement and N values. Collated results of routine pile loading tests show that different sizes and differentlengths of piles, when driven to a Hiley set in granular soils and test loaded to twice the working load, yield totalsettlementsthatare com- parable, within narrow limits, and which normally should not exceed Q in. Friction in the granular soils of Hong Kong is shown to be low, whereas bearing is shown to be high. The effect of overburden is discussed with respect to its moderating effect on the settlement of a pile under test load. The effect of driven piles on the density of granular soils is discussed and information from split-spoon tests before and after driving presented. Lastly, a limiting settlement approach to the design of founda- tions in granularsoils, based on A' values, is presented, and discussed. * Paper to be read before the lnstitutiolt of StructuralEngirzeers, at 11, Up$er Belgrave Streef, Lolldon, S. W.I., on Thrtrsday, 1 Ith, October, 1962, at 6 p.m. Introduction Hong Kong occupies only a small area, but with a population of more than three millions, it is literally ' bursting at the seams,'withdensities of more than 2,000 persons per acre. Much of the island of Hong Kong and the mainland of Kowloon and the New Ttrritories is mountainous, hencc building land is r L Fig. l-Map of Kowloon and Hong Kong showing extent of reclamation. scarce and therefore expensive, indeed much of the building land has been reclaimed from the sea, as shown in Fig. 1. The high cost of land, plus the press of people, have forced development upwards. The Buildings Ordinance was completely revised in 1955 to
