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MCER / Design elastic spectrum for a Vs30/Vref slice (ASCE 7-22 shape)

designUHS.Rd

Builds the two-period design/MCER spectrum shape of ASCE 7-22 Sec. 11.4.5.2 (Eqs. 11.4-3/-4/-5, DESIGN = 2/3 x MCER), with the spectral parameters derived from the input site-specific spectrum per ASCE 7-22 Sec. 21.4: at MCER level, SMS = 0.9 x max SaM(T) over T from 0.2 to 5 s, and SM1 = max(0.9 x max of T x SaM(T), SaM(1 s)) over T from 1 to 2 s when vs30 > 442 m/s, else 1 to 5 s (the 1.5 and 2/3 factors of Eqs. 21.4/11.4-1/-2 cancel at MCER level). Evaluation windows are clamped to the period range of the input. The Sec. 21.2.3 80-percent floor and the Sec. 21.2.2 deterministic cap are NOT applied (both require mapped/deterministic inputs this function does not receive). See NEWS.md for the audit summary.

Usage

designUHS(UHS, TL = 8, spectrum = c("MCER", "DESIGN"), vs30 = NULL)

Arguments

UHS

data.table slice from UHSTable (single TR, p == "mean").

TL

numeric, long-period transition (seconds). Default 8.

spectrum

character, "MCER" (default) or "DESIGN" (2/3 * MCER).

vs30

numeric scalar or NULL. Site Vs30 (m/s) selecting the Sec. 21.4 SD1 window: 1 to 2 s when vs30 > 442 m/s, else 1 to 5 s. NULL (default) uses the conservative 1 to 5 s window.

Value

data.table with columns Tn, SaF.

Details

The input UHS slice must contain at least Tn and SaF. Typical usage passes a single TR and p == "mean".

Examples

uhs <- data.table::data.table(Tn = c(0, 0.2, 0.5, 1, 2), SaF = c(0.4, 1.0, 0.9, 0.6, 0.3))
designUHS(uhs)
#>             Tn        SaF
#>          <num>      <num>
#>  1:  0.0000000 0.36000400
#>  2:  0.1350000 0.90000000
#>  3:  0.6749999 0.90000000
#>  4:  0.7688095 0.79018256
#>  5:  0.8756566 0.69376498
#>  6:  0.9973530 0.60911221
#>  7:  1.1359624 0.53478872
#>  8:  1.2938354 0.46953413
#>  9:  1.4736491 0.41224187
#> 10:  1.6784529 0.36194037
#> 11:  1.9117198 0.31777663
#> 12:  2.1774054 0.27900173
#> 13:  2.4800154 0.24495811
#> 14:  2.8246812 0.21506848
#> 15:  3.2172478 0.18882595
#> 16:  3.6643722 0.16578553
#> 17:  4.1736367 0.14555648
#> 18:  4.7536775 0.12779577
#> 19:  5.4143307 0.11220221
#> 20:  6.1667998 0.09851137
#> 21:  7.0238450 0.08649107
#> 22:  8.0000000 0.07593748
#> 23:  8.0000000 0.07593748
#> 24:  8.2972404 0.07059417
#> 25:  8.6055247 0.06562684
#> 26:  8.9252633 0.06100903
#> 27:  9.2568819 0.05671615
#> 28:  9.6008218 0.05272534
#> 29:  9.9575407 0.04901534
#> 30: 10.3275136 0.04556639
#> 31: 10.7112328 0.04236013
#> 32: 11.1092091 0.03937947
#> 33: 11.5219723 0.03660855
#> 34: 11.9500717 0.03403260
#> 35: 12.3940771 0.03163791
#> 36: 12.8545796 0.02941172
#> 37: 13.3321921 0.02734217
#> 38: 13.8275503 0.02541825
#> 39: 14.3413135 0.02362971
#> 40: 14.8741657 0.02196701
#> 41: 15.4268160 0.02042131
#> 42: 16.0000000 0.01898437
#>             Tn        SaF
#>          <num>      <num>