Corrections
On p. 40 the return periods for basic design wind speeds in Singapore should have been given as 50-year and 100-year, not 50-year and 1000-year. The article was updated on 3 March 2017.
On p. 27 there are errors in Equations 16 and 18. In Equation 16 the answer should be multiplied by a factor of 0.6. In the second part of Equation 18,
Nc should not be multiplied by a factor of 1.5.