SEISMIC DESIGN PARAMETERS

SITE-SPECIFIC SEISMIC VALUES UNDER FIVE NATIONAL CODES

The Seismic Design Parameters tool finds site-specific seismic design values for any location and computes the resulting base and story shears.

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Seismic Design Parameters

ASCE/SEI 7-16 & 7-22 site-adjusted values, sourced live from the USGS Seismic Design Web Service.

Street Address

Risk Category

Site Class · 7-16

Site Class · 7-22

Building Period (optional)

Fundamental period, T (seconds)

Structural height, h_n (feet)

Structural System (Table 12.8-2)

Approximate fundamental period per ASCE 7 §12.8.2.1: T_a = C_t · h_n^x

Querying USGS hazard service…

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Site

Coordinates

Reference Standard

ASCE/SEI 7-16

Site D · RC II

Reference Standard

ASCE/SEI 7-22

Site D · RC II

Design Response Spectra

5%-damped horizontal design spectra, S_a(T) — code-edition comparison.

ASCE 7-16 — two-period spectrum

ASCE 7-22 — multi-period spectrum

Base & Story Shear — Equivalent Lateral Force (§12.8)

Computes the ELF base shear and vertical force distribution from the design parameters above.

Compute the design parameters first. Enter a location at the top and click “Compute Parameters.” This section then unlocks and uses those S_DS, S_D1, S₁ and T_L values.

Querying NRCan seismic hazard service…

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Site

Coordinates · Site Designation

Reference Standard

NBCC 2020 · 5%-damped Sa(T,X)

Site C · 2%/50yr

Design Response Spectrum, S(T)

NBCC 2020 §4.1.8.4 — 5%-damped design spectral acceleration for the selected site designation (2%/50-year).

S(T) — NBCC 2020 design spectrum

Base & Story Shear — Equivalent Static Force (§4.1.8.11)

Computes the NBCC 2020 base shear V and vertical force distribution from the design spectrum above. Metric units: heights in metres, seismic weights in kN.

Compute the design parameters first. Enter a Canadian location above and click “Compute Parameters.” This section then unlocks and uses the site-designated S(T) values.

Seismic Force-Resisting System (Table 4.1.8.9)

Importance Category (Table 4.1.8.5 · ULS)

Number of Storeys (1–12)

Higher-mode factor M_v (Table 4.1.8.11)

Base overturning reduction J (Table 4.1.8.11)

Fundamental Period T_a (§4.1.8.11)

Structural height h_n (m)

System (for T_a)

NBCC caps the design period; this tool uses T_a as computed. Verify the upper-limit multiplier per §4.1.8.11.(3)(d).

Fundamental period T_a (s)

Typical storey height (m)

Level	Height h_x above base (m)	Seismic weight W_x (kN)

V = S(T_a)·M_v·I_E·W / (R_d·R_o), bounded per §4.1.8.11.(2). Vertical distribution per §4.1.8.11.(6)–(7) with F_t = 0.07·T_a·V (≤0.25V; 0 if T_a≤0.7s) applied at the roof.

Region

Reference PGA on rock, a_gR (g)

Importance factor γ_I (§4.2.5)

Spectrum Type (§3.2.2.2)

Ground Type (Table 3.1)

Behaviour factor q (design spectrum, §3.2.2.5)

Enter a_gR from your National Annex seismic-zonation map. For Italy, enter the site a_g (2%/50-yr, 475-yr return) from the INGV/NTC hazard grid. The tool applies γ_I and the CEN-recommended soil parameters S, T_B, T_C, T_D; override q per your ductility class and EN 1998-1 §5–§9.

Input Error

Seismic Action

Spectrum · Ground

Reference Standard

EC8 · EN 1998-1:2004 — Spectral Parameters

Type 1 · Ground B

Response Spectra

5%-damped horizontal elastic spectrum S_e(T) and design spectrum S_d(T) (behaviour factor q), per §3.2.2.2 & §3.2.2.5.

S_e(T) — elastic

S_d(T) — design (q)

Base & Storey Shear — Lateral Force Method (§4.3.3.2)

Computes the EC8 base shear F_b = S_d(T₁)·m·λ and vertical force distribution from the design spectrum above. Metric units: heights in metres, seismic masses as weights in kN.

Compute the spectrum first. Enter the seismic action above and click “Compute Spectrum.” This section then unlocks and uses the design spectrum S_d(T).

Hazard factor Z (Table 3.2)

Probability factor k_p (Table 3.1)

Site sub-soil class (§4)

Structural performance factor S_p (Table 6.5)

Structural ductility factor μ (Table 6.5)

Base shear V = [k_p·Z·C_h(T₁)]·(S_p/μ)·W_t (Eq. 6.2(3)). C_h(T) is the spectral shape factor for the sub-soil class (Table 6.4). Read Z and k_p from the AS 1170.4 hazard maps/tables; S_p and μ from Table 6.5 for your framing system.

Input Error

Site Hazard

Sub-soil · Design

Reference Standard

AS 1170.4 — Parameters

Horizontal Design Response Spectrum

C_d(T) = [k_p·Z·C_h(T)]·S_p/μ (§6.4), with the elastic C(T) = k_p·Z·C_h(T) shown for reference.

C(T) — elastic (k_p·Z·C_h)

C_d(T) — design (S_p/μ)

Base & Storey Shear — Equivalent Static (§6.2–6.3)

Computes V = [k_pZ·C_h(T₁)]·(S_p/μ)·W_t and the storey distribution. Metric: heights in metres, weights in kN.

Compute the spectrum first. Enter the hazard inputs above and click “Compute Spectrum” to unlock this section.

Hazard factor Z (Table 3.3)

Return period factor R (Table 3.5)

Site subsoil class (§3.1.3)

Near-fault factor N(T,D) (§3.1.6)

Performance factor S_p (§4.4)

Ductility factor μ (§4.3)

Elastic site spectrum C(T) = C_h(T)·Z·R·N(T,D), capped so Z·R ≤ 0.7 (§3.1.1). Horizontal design action coefficient C_d(T₁) = C(T₁)·S_p/k_μ (§5.2.1.1). Read Z, R from Tables 3.3/3.5; C_h(T) from Table 3.1.

Input Error

Site Hazard

Subsoil · Design

Reference Standard

NZS 1170.5:2004 — Parameters

Class C

Elastic & Design Spectra

Elastic site spectrum C(T) = C_h(T)·Z·R·N and design coefficient C_d(T) = C(T)·S_p/k_μ (§3 & §5).

C(T) — elastic site

C_d(T) — design

Base & Storey Shear — Equivalent Static (§6.2)

Computes V = C_d(T₁)·W_t and the storey distribution (§6.2.1). Metric: heights in metres, weights in kN.

Compute the spectrum first. Enter the hazard inputs above and click “Compute Spectrum” to unlock this section.

Data source: U.S. Geological Survey Seismic Design Web Service (earthquake.usgs.gov/ws/building-codes). Address geocoding by U.S. Census Bureau, with OpenStreetMap Nominatim as fallback. Results are intended as a preliminary reference; values must be verified against the governing code edition and a licensed engineer's site-specific evaluation before use in structural design. Scottsdale Construction Systems assumes no liability for the use of these values.

SEISMIC DESIGN PARAMETERS

SITE-SPECIFIC SEISMIC VALUES UNDER FIVE NATIONAL CODES

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