Open structure wind (AS/NZS 1170.2 Appendix B)

Tools ▸ Open structure wind (1170.2 App B)… runs the second wind engine: the structures the enclosed-building wizard (Wind loads) cannot see. It covers, from AS/NZS 1170.2:2021:

Structure	Where in the standard	What comes back
Hoarding / freestanding wall	Appendix B.2, Tables B.2(A) to B.2(D), Equation B.1, Table B.3	net pressure coefficient per band from the windward free end, the porosity factor, the resultant force with its height and eccentricity, frictional drag for parallel wind
Free roof (monoslope, pitched, troughed)	Appendix B.3, Tables B.4(A), B.4(B), B.5, B.6, with Clause 5.4.2 Ka and the Table B.1 local factor	Cp,n for the windward and leeward halves (or the three zones of a low monoslope roof), every alternative the table prints as a design case, Cshp = Cp,n Ka Kl and the pressure
Attached canopy, awning, carport	Appendix B.4, Tables B.9 and B.10	the downward and upward cases at the building's average roof height
Local factor Kl for cladding on an enclosed building	Clause 5.4.4, Table 5.6, Figure 5.3, Table 5.7	Kl for the case (WA1, RC1, RC2, RA1 to RA4, SA1 to SA5), the dimension a, the area the case applies to, the parapet reduction, and Kl Cp with the −3.0 floor

Every cell was read from the standard's text and is held against the compiled engine by a ledger check (docs/reference/wind_validation.md, "Appendix B and Clause 5.4.4"). The dialog names the tables each result stands on.

Using it

1. Set the project's Design criteria (region, terrain, importance level); the dialog reads them as defaults. The item is greyed on a project whose wind standard is not AS/NZS 1170.2: ASCE 7 Chapter 27 open buildings and EN 1991-1-4 7.3 canopy roofs are different tables the engine does not carry.
2. Pick the structure with the segmented control and enter its geometry. For a hoarding, c is the panel height and h the height of its top (a wall on the ground has c = h). For a free roof, h is the average roof height and d the along-wind depth: 0.25 < h/d < 1 for the main tables, 0.05 to 0.25 routes a monoslope roof to Table B.4(B)'s zones.
3. Blockage under a free roof runs from 0 (empty under, less than 50 % of the cross-section blocked) to 100 (blocked under, more than 75 %); between, the two columns are interpolated as Clause B.3.1 allows, only between values of the same sign.
4. A pitch above a table's last row, a hoarding with b/c below 0.5, a canopy steeper than 10°: the engine refuses by name rather than clamping.
5. Add to report leaves one card per structure kind under Design calculations.

Positive is net downward on a roof and in the wind direction on a hoarding (the standard's own convention). The velocity pressure is taken at the top of a hoarding (Clause B.2.1 Note 2) and at the average roof height of a roof or the host building (Clause B.4.1).

From a script

// A 12 m x 3 m solid hoarding with its top 4 m above ground, wind normal
CivilKit.openStructureWind({ kind: 'hoarding', b: 12, c: 3, h: 4, solidity: 1, wind: 'normal' });
// A 15° monoslope free roof, 5 m high over a 10 m span, empty under, wind up the slope
CivilKit.openStructureWind({ kind: 'free_roof', roof: 'mono', alpha_deg: 15, h: 5, d: 10, b: 20, blockage: 0, wind: '0' });
// Table 5.6 RC1 on a 20 x 40 x 6 m building whose roof corner has Cp,e = -1.3
CivilKit.openStructureWind({ kind: 'local_pressure', case: 'RC1', b: 20, d: 40, h: 6, cp_e: -1.3 });

The site defaults come from the project's criteria; every field is overridable. The result carries q_pa, the coefficients, steps (the clause-by-clause working), warnings and tables.

Not carried

Hyperbolic paraboloid roofs (Table B.7), conical canopies (Table B.8), isolated cantilever roofs (Table B.11), solar panels (Appendix B.6) and the exposed members and lattice towers of Appendix C. The engine says so in its warnings.