1 The trend for international standards is to adopt and adapt the ASCE-7 approach for primary systems.

2 NotationFactor What does it mean? Directionality Takes into account the probability that the maximum wind has the same direction as that of the maximum pressure Importance I Converts a 50-year return period into a 100-year return period recommended for hospitals Exposure Represents the wind velocity at a ‘z’ height above the ground Topography Takes into account the fact that the structure may be located on top of a hill or on an escarpment, increasing the wind velocity Meaning of factors in ASCE-7

3 NotationFactor What does it mean? 3-sec gust G Represents the turbulence-structure interaction and the dynamic amplification of the wind External pressure coefficient Estimates the wind pressure on the building, external walls Internal pressure coefficient Reflects the internal pressure due to wall opening quantity and sizes Design pressure pRepresents the design pressure Design force F Represents the net force on open structures Meaning of factors in ASCE-7

4 Effects of terrain roughness and height on wind speeds

5 Effects of exposure and altitude

Case 1Case 2 Case 1 and 2 Case 1Case 2 Case 1 and 2 ≤ Height Z (m) B C BC Exposure Exposure Coefficients K z K h Exposure type B C NOTE: 1.Case 1 shall be used for all primary systems in buildings with height ‘h’ less than 18 m and for secondary systems of any type of structure 2.Case 2 shall be used for all primary systems of any other structure not indicated in case 1 3.For values of Z not shown, linear interpolation shall be permitted

7 Topographic effect showing wind velocity increase

8 Sketch showing effects of topography on wind velocity on a hilly island

9 Different ways of measuring wind velocity Average time Wind velocity 1 Hour minutes Fastest mile second gust

10 N knots mph kph m/s Storm Category N 89.5 W 23 N 59 W Wind velocities in the Caribbean for a return period of 100 years

11 Modified basic pressure- ASCE-7 Modified basic pressure in ASCE-7 to accommodate local parameters

12 A high percentage of wall openings are dangerous for a health facility

13 Different types of forces acting on structural elements

14 Wind can induce torsional effects on structural steel

15 Design pressure on primary systems (structural) Rigid primary systems Flexible primary systems p = q GC p - q h (GC pi ) p = qG f C p - q h (GC pi )

16 Pressure coefficients on high- rise buildings

17 Design pressure diagram on gabled roof building

18 Total destruction of Princess Margaret Hospital in Jamaica

19 Absence of an appropriate anchorage led to the overturning of a clinic

20 Failure of steel beams support