A module of wind functions for AFE

Wind.txt

Get_C_prob = LAMBDA(return_period, [n], [K],
    LET(
        p, return_period,
        n, IF(ISOMITTED(n), 0.5, n),
        K, IF(ISOMITTED(K), 0.2, K),
        ((1 - K * LN(-LN(1 - 1 / p))) / (1 - K * LN(-LN(0.98)))) ^ n
    )
);

Get_C_alt = LAMBDA(altitude, [reference_height],
    LET(
        A, altitude,
        z, IF(ISOMITTED(reference_height), 10, reference_height),
        1 + 0.001 * A * IF(z <= 10, 1, (10 / z) ^ 0.2)
    )
);

Get_Fundamental_Basic_Wind_Velocity_Altitude_Corrected = LAMBDA(
    fundamental_basic_wind_velocity,
    altitude_factor,
    LET(V_b_map, fundamental_basic_wind_velocity, C_alt, altitude_factor, C_alt * V_b_map)
);

Get_Basic_Mean_Wind_Velocity = LAMBDA(
    fundamental_basic_wind_velocity_altitude_corrected,
    [probability_factor],
    [direction_factor],
    [season_factor],
    LET(
        V_b_0, fundamental_basic_wind_velocity_altitude_corrected,
        C_prob, IF(ISOMITTED(probability_factor), 1, probability_factor),
        C_dir, IF(ISOMITTED(direction_factor), 1, direction_factor),
        C_season, IF(ISOMITTED(season_factor), 1, season_factor),
        V_b_0 * C_prob * C_dir * C_season
    )
);

Get_Basic_Wind_Velocity_Pressure = LAMBDA(basic_mean_wind_velocity, [air_density],
    LET(
        V_b_mean, basic_mean_wind_velocity,
        ρ, IF(ISOMITTED(air_density), 1.226, air_density),
        ρ * V_b_mean ^ 2 / 1000 / 2
    )
);

Get_Peak_Wind_Velocity_Pressure = LAMBDA(
    basic_mean_wind_velocity_pressure,
    exposure_factor,
    terrain,
    [town_factor],
    LET(
        q_b, basic_mean_wind_velocity_pressure,
        C_e, exposure_factor,
        T, terrain,
        C_T, IF(OR(ISOMITTED(town_factor), T <> "Town"), 1, town_factor),
        C_e * C_T * q_b
    )
);

Get_Characteristic_Wind_Pressure = LAMBDA(peak_velocity_wind_pressure, net_pressure_coefficient,
    LET(qp, peak_velocity_wind_pressure, C_p_net, net_pressure_coefficient, qp * C_p_net)
);

Get_Design_Wind_Pressure = LAMBDA(characteristic_wind_pressure, [variable_load_factor],
    LET(
        q_k, characteristic_wind_pressure,
        γ_q, IF(ISOMITTED(variable_load_factor), 1.5, variable_load_factor),
        γ_q * q_k
    )
);

Get_C_season = LAMBDA([duration_in_months], [starting_month],
    LET(
        months, IF(ISOMITTED(duration_in_months), 12, duration_in_months),
        duration_index, IFS(
            months <= 1,
            1,
            months <= 2,
            2,
            months <= 4,
            3,
            months <= 6,
            4,
            months > 6,
            5
        ),
        month_index, MONTH(starting_month & 1),
        duration_coeff, {
            0.98, 0.83, 0.82, 0.75, 0.69, 0.66, 0.62, 0.71, 0.82, 0.82, 0.88, 0.94;
            0.98, 0.86, 0.83, 0.75, 0.71, 0.67, 0.71, 0.82, 0.85, 0.89, 0.95, 1;
            0.98, 0.87, 0.83, 0.76, 0.73, 0.83, 0.86, 0.9, 0.96, 1, 1, 1;
            1, 1, 1, 0.84, 0.84, 0.84, 0.84, 0.84, 0.84, 1, 1, 1;
            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
        },
        INDEX(duration_coeff, duration_index, month_index)
    )
);

Get_C_dir = LAMBDA([angle_of_wind_clockwise_from_north], [segment_angle],
    LET(
        seg_angle, IF(ISOMITTED(segment_angle), 0, segment_angle),
        dir, IF(
            ISOMITTED(angle_of_wind_clockwise_from_north),
            240,
            angle_of_wind_clockwise_from_north
        ),
        interval, IF(dir < 0, -10, 10),
        angle, MOD(MROUND(dir, interval), 360),
        angle_index, (angle / 10) + 1,
        dir_coeffs, {
            0.78,
            0.77,
            0.75,
            0.73,
            0.73,
            0.73,
            0.73,
            0.73,
            0.74,
            0.74,
            0.74,
            0.73,
            0.73,
            0.75,
            0.78,
            0.8,
            0.82,
            0.84,
            0.85,
            0.88,
            0.91,
            0.93,
            0.96,
            0.98,
            1,
            1,
            1,
            0.99,
            0.97,
            0.94,
            0.91,
            0.88,
            0.85,
            0.82,
            0.81,
            0.8,
            0.78
        },
        INDEX(dir_coeffs, angle_index)
    )
);