Basic Wind Data (ASCE 7 Wind Wizard)

Once the geometry has been confirmed, (for either method), you are then required to enter the basic wind data. The only difference between the two methods is that the Gust Effect Factor field is only shown for the All Heights Method.


Property	Description
Basic wind speed, V¹	A strictly positive value is required with 90mph being the default.
Occupancy category²	Only displayed when working to ASCE 7-05. Options I to IV with default being II.
Hurricane-prone Region³	Only displayed when working to ASCE 7-05. The default is cleared, i.e. region not prone to hurricanes.
Directionality Factor, K_d⁴	The default is 0.85, range 0.85 to 1.0 inclusive. Note: There is no cross-checking to ensure that the model has met the load combination criteria. If that does not apply, then it is your own responsibility to enter the correct value of 1.0.
Enclosure classification⁵	Options are "Enclosed" and "Partially Enclosed" with default being "Enclosed". Note: "Open" structures are not handled in the current version of the program
Gust effect factor, G⁶	This will only be shown for the All Heights Method. The default value is 0.85.
Tornado Parameters (Only displayed if the Consider Tornado Loads option has been selected when working to ASCE 7-22.)
Tornado speed, V_T	A strictly positive value is required with 90mph being the default.
Calculate...	When pressed, a Calculated Tornado Speed dialog is displayed for calculating V_T (see below for details.)
Tornado directionality factor, K_dT	The default is 0.80, range 0.75 to 1.0
Tornado enclosure classification	Options are "Partially Open", "Partially Enclosed" and "Enclosed" with default being "Enclosed".
Tornado gust effect factor, G_T	The default value is 0.85.
Geodatabase ASCE Hazard Tool - Wind	Click this button to open the ASCE Hazard Tool in a browser window. This tool can be used to look up key design parameters specified in ASCE standards.
Table Parameters
Principal Axes	There are always four directions shown for principal axes, being based on the Orientation of the Longitudinal Direction or Principal Axes depending on the method. You are not able to add, delete or modify any direction.
Exposure Category⁷	Options are "B", "C" or "D" with default being "B".
Topographic Feature⁸	Options are as follows, with the default being "None": "None" - no feature, i.e. K_zt = 1.0. "2D Ridge" "2D Escarp" - 2D Escarpment "3D Hill" - 3D Asymmetrical Hill
Crest Height, H⁹	Height of the hill or escarpment relative to the upwind terrain. The behavior of this field depends on the Feature type as follows: "2D Ridge" - non-zero values allowed, (negative indicates a valley). "2D Escarp" - strictly positive values allowed "3D Hill" - strictly positive values allowed
Crest Length, L_h¹⁰	Distance upwind of crest to where the difference in ground elevation is half the height of the hill or escarpment.
Distance to Crest, x¹¹	Distance upwind or downwind from the crest to the building site. The value may be positive to indicate downwind, or negative to indicate upwind.

Clicking Next takes you to the Results page.

Calculated Tornado Speed dialog


Property	Description
Risk Category	Tornado loads only need to be considered for risk category III and IV.
Effective plan area (building/facility), A_e	This is the effective area of building as previously calculated on the All Heights Building Geometry page. It can't be changed here.
Map Effective Plan Area ≤ A_e, A_esmaller	The default value is the value which is closest but less than or equal to A_e
Map Effective Plan Area ≥ A_e, A_elarger	The default value is the value which is but greater than or equal to A_e
Geodatabase ASCE Hazard Tool - Wind	Click this button to open the ASCE Hazard Tool in a browser window. Specify the location and risk category to determine the relevant V_T values (Map V_Tsmaller and Map V_Tlarger)
Map V_Tsmaller	Wind Speed for smaller area from map.
Map V_Tlarger	Wind Speed for larger area from map.
Calculated Tornado speed, V_T	The value of the Tornado speed is calculated from linear interpolation of tornado speed between maps using the logarithm of the effective plan area size. V_T = V_Tsmaller + (log₁₀(A_e) – log₁₀(A_esmaller )) x (V_Tlarger - V_Tsmaller) / (log₁₀(A_elarger) – log₁₀(A_esmaller ))

Footnotes

¹ ASCE7-10 Clause 26.5.1

² ASCE7-05 Table 1-1

³ ASCE7-05 Clause 6.2

⁴ ASCE7-10 Clause 26.6, and Table 26.6-1

⁵ ASCE7-10 Clause 26.10

⁶ ASCE7-10 Clause 26.9.1

⁷ ASCE7-10 Clause 26.7.3

⁸ ASCE7-10 Clause 26.8 and Figure 26.8-1

⁹ ASCE7-10 Figure 26.8-1

¹⁰ ASCE7-10 Figure 26.8-1

¹¹ ASCE7-10 Figure 26.8-1