Wind on Ice — ASCE/SEI 7-22

1 · Input data

The wind force on a structure already carrying its ice load, to ASCE/SEI 7-22 Section 10.5. Ice accreted on a structure grows the projected area the wind sees; the structure is then designed for the wind on that enlarged area, acting concurrently with the weight of the ice. The page returns the design ice thickness, the iced projected area, the velocity pressure for the concurrent gust speed, the wind force on the ice-covered members, the Section 29.7 minimum where it applies, and the concurrent ice-plus-wind case with the Section 2.3.3 combinations that carry it named. Three values on this card are INPUTS the standard cannot supply: the concurrent gust speed V_c (Figures 10.5-1 and 10.5-2 are contour maps), the nominal ice thickness t (Figures 10.4-2 through 10.4-5 are maps), and the force coefficient C_f for every type except guys and cables (Figures 29.3-1, 29.4-1, 29.4-2 and 29.4-3 are graphs with no values in the text layer). Read them from the figures or the ASCE 7 Hazard Tool and enter them. A field the engine can do without is optional: leave it blank and the engine either supplies its own default or refuses it by name — the page never invents a value. Press Compute the wind on ice when the card is complete.

The structure and the two inputs the standard cannot supply

Structure type (§10.5.1–10.5.5)

Concurrent gust speed V_c, mi/h — INPUT (Figures 10.5-1, 10.5-2)

Nominal ice thickness t, in. — INPUT (Figures 10.4-2 to 10.4-5)

Height above ground of the design segment, ft

The projected dimensions — enter either a width and a height, or a member diameter and length

Bare projected width w, ft

Bare projected height h, ft

Bare member diameter D, in.

Member length L, ft

The force coefficient and the wind parameters

Force coefficient C_f — INPUT for every type except guys and cables

Exposure category (Table 26.10-1) — or enter K_z below

Velocity pressure exposure coefficient K_z (Table 26.10-1)

Height at which q_z is evaluated, ft (defaults to the design-segment height)

Topographic factor K_zt (defaults to 1.0)

Ground elevation factor K_e (defaults to 1.0)

Wind directionality factor K_d (Table 26.6-1; required for guys and cables)

Gust-effect factor G (26.11.1, defaults to 0.85 for a rigid structure)

The solidity ratio and the weight of the ice — optional

Solidity ratio ε (10.5.3, 10.5.4; based on the iced projected area)

Weight of the ice D_i, lb — INPUT from Section 10.4.1

2 · Solution

No solution yet — complete the card above and press Compute the wind on ice. This card stays empty until a solution is computed, and it is emptied again the moment any input changes, so a displayed solution always belongs to the inputs on screen.