NBC 105:2020 — Seismic Coefficient Calculator

Computes Ch(T), C(T), Cdu, Cds, Cv, Cs, and spectrum exponent k using your Excel-matched logic.

Inputs

Choose a Nepal location to auto-fill Z, or select Custom Z for manual entry.
kt (from structure type)
Used in T1 = 1.25·kt·h^0.75
Period, T1 (s)
T1 = 1.25·kt·h^0.75
Ru, Ωu, Ωs
From building system dropdown.
Spectrum Region
Based on Ta, Tc and T1.
Response spectrum shape (Ch vs T, 0–6s). Dot shows your T1.
Ta/Tc/α/K from soil & method, then Ch(T), then C(T)=Ch·Z·I, then Cdu/Cds.

Results

Rounding matches the sheet: C(T) to 3 decimals, Cdu/Cds to 4 decimals.
Parameter Value
Ta
Tc
α (peak spectral factor)
K (descending branch factor)
Ch(T1)
C(T) = Ch·Z·I
Cv = 2/3·Z
Cs = 0.2·C(T)
Cdu = C(T)/(Ru·Ωu)
Cds = Cs/Ωs
k (period exponent)