WIND ENGINEERING

WIND ENGINEERING

1. 1. DEAD LOAD

   • acting permanently on structure
   • made up of self-weight of permanently-applied building fixture, main structural element, fitting
   • the superimposed dead load will account for permanent texture

2. 2. IMPOSED LOAD

   • define as a uniformly distributed gravity load
   • usually, only consider general area live loads

3. 3. LOAD COMBINATION

   • subjected to gravity loads acting downward
   • lateral load acting on different horizontal direction
   • critical combination depends on building frame and balancing characteristic
   • design of rc element based on ULS combination

4. 4. CONSTRUCTION LOAD

   • consideration of construction load in early stage is important
   • const. load greater than load applied to the building
   • (i) incorporating const. load in design plans
   • (ii) load impact from the temporary tower crane
     • effect on the design of various building elements is the placement of temporary tower crane
     • crane usually seated on piled, RC bases cast integrally with the basement work

5. 5. ACCIDENTAL LOAD & DISPROPORTIONATE COLLAPSE

   • tall building should be design to avoid disproportionate impact from accident action

6. 6. TEMPERATURE LOAD

   • importance to consider to element of the structural frame outside the cladding line : cooled/heated
   • can result in the worst case moments & forces of some elements
   • different from imposed gravity @ wind loads, as they are self-straining loads
   • in the case of temp. reduction, stress develops due to restrained condition with resultant tensile stress

7. Definition: rational treatment of interaction between wind in the atmospheric boundry layer & man & his works on the surface earth

8. Influences a number of tall-building design aspect including:

   • in the design of its foundations & later-stability system
   • controlling its global deflection & inter-storey drift
   • dictating the level of comfort
   • key role in design of glazing/building envelope & facade system
   • changing both global & local wind flow pattern

9. 1. WIND CLIMATE

   • synoptic winds (latitudes 40-60)
   • tropical storms (latitudes 10-30)

10. 2. WIND LOADING FOR STRENGTH & SERVICEABILITY DESIGN

    • vortex-shedding
      • interaction between wind & structure
      • happens at any wind speed for any plan form
      • typically enhanced by low levels of wind turbulance
    • serviceability
      • human response to building motion - a complex phenomenon involving many physiological & psychological
    • mitigation of wind loading
      • increasing the stiffness of structure
      • increasing mass at the top of building
      • increasing structural damping
      • using a passive tuned-mass damper
      • using other viscoelastic
      • changing aerodyamic
    • code of practice
      • Australian code
      • Canadian Code
      • Eurocode
      • Japanese code

11. 3. WIND-TUNNEL TESTING & TECHNIQUES

    • high frequency force balance (HFFB)
    • simultaneous pressure integration (SPI)

12. 4. PROCURING WIND ENGINEERING CONSULTANT

    • atmospheric boundary-layer profile simulation
      • refers to lowest portion of troposphere
      • showing the mean wind speed/turbulence intensity & turbulence scale
    • wind-tunnel models
      • electronic information necessary to construct surround models includes:
        • survey maps
        • building height
        • photos from site survey
        • site plan drawing

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