WIND CLASSIFICATION TO AS4055-2012BY ANDREW MACKENZIE – MARCH 2018

AS4055 – THE W’S

• AS4055 “Wind Loads for housing” and is a simplified version of AS1170.2.

• Engineers, designers, builders, architects and manufacturers in the Residential sector.

• Used to classify sites into 1 of 10 bracketed wind speed categories.

• Speed Pressures Forces Design of bracing, members and connections.

• Faster, reasonably accurate method.

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SCOPE AND LIMITATIONS

HOW CLASSIFICATION PROCESS WORKS

• Need to determine 4 site specific conditions and refer to Table 2.2

• Wind Region – Choice of 4

• Terrain Category – Choice of 5

• Shielding Class – Choice of 3

• Topographic Class – Choice of 5

WIND REGION

TERRAIN CATEGORY

TOPOGRAPHIC CLASSIFICATION

SHIELDING CLASS

• Full, Partial and No shielding

• Full = 2 rows of houses surrounding site considered (can include large trees in Region A & B)

• Partial = 1 row of houses surrounding site

• No Shielding = 0

FINAL WIND CLASSIFICATION

ADDITIONAL INFORMATION

• Further detail, explanation and commentary provided in clauses and Appendix of AS4055

• If classification is not possible – Refer to AS1170.2

EXAMPLE 1–10 TAABINGA STREET, WAVELL HEIGHTS

• Region B

• TC3

• T1 – Top third of a10m Hill @ 5°

• FS

• N2

EXAMPLE 2 – 773 STOCKROUTE ROAD, PALMYRA

• Region C

• TC2

• T2 – Top third of a <30m Hill @ 9.5°

• NS

• C3

COMPARISON TO AS1170.2

• Same site to AS1170.2

• Wind Speed to AS4055