Seismic Bracing — CableTrayRoute

Preliminary screening only. The force equation is the ASCE 7-16 method. ASCE 7-22 component-force provisions are not implemented, and the 12 ft / 40 ft spacing values are NEMA VE 2 installation guidance rather than literal ASCE 7 limits.

Method & Assumptions

Seismic brace forces are computed per ASCE 7-16 §13.3.1 (Nonstructural Component Seismic Force). The displayed 12 ft lateral and 40 ft longitudinal spacing values are screening guidance from NEMA VE 2.

Edition notice: This calculator implements the ASCE 7-16 component-force equation. The revised ASCE 7-22 seismic equation is not implemented; do not use this output as an ASCE 7-22 seismic design.

Design seismic force:

Fp = (0.4 × ap × SDS × Wp) / (Rp / Ip) × (1 + 2z/h)

Subject to:

Fp_min = 0.3 × SDS × Ip × Wp
Fp_max = 1.6 × SDS × Ip × Wp

Cable tray component factors from ASCE 7-16 Table 13.6-1:

ap = 1.0 — component amplification factor
Rp = 2.5 — component response modification factor

Brace force components:

Lateral (transverse): Fp × Wp
Longitudinal: 0.4 × Fp × Wp (ASCE 7 §13.5.6.1)
Vertical: ±0.2 × SDS × Wp (I_p does not multiply E_v)

Maximum brace spacing (SDC C–F): lateral ≤ 12 ft, longitudinal ≤ 40 ft. No bracing required for SDC A and B.

Citations: ASCE 7-16 §13.3.1 and §13.5.6, IBC 2021 §1613, NEMA VE 2-2006.

Site Seismic Parameters

S_DS — Design spectral acceleration, short period (g)

Obtain from ASCE 7 ground motion maps or USGS Seismic Design Maps tool (mapped value S_S × F_a). Typical range: 0.1–2.5 g.

S_D1 — Design spectral acceleration, 1-second period (g)

Mapped value S₁ × F_v. Used to determine the Seismic Design Category.

Risk Category (Occupancy Category)

Per IBC 2021 Table 1604.5. Affects the Importance Factor (Ip) and SDC thresholds.

I_p — Component Importance Factor

Use 1.5 for components required for continued operation of Risk Category IV facilities, or when component failure could pose a life-safety hazard (ASCE 7-16 §13.1.3).

Installation Parameters

z — Tray attachment height above base (ft)

Height of the tray support attachment to the structure above the building base (grade for ground-floor, top of foundation for elevated structures).

h — Average roof height above base (ft)

Average height of the roof or highest supported floor above the building base. Must be ≥ tray attachment height.

W_p — Tray + cable operating weight per linear foot (lbs/ft)

Sum of tray self-weight and total cable weight per foot of tray. Use the Support Span Calculator to determine cable weight per foot from the cable schedule. Typical empty ladder tray: 2–6 lbs/ft. Full tray: 10–30 lbs/ft.

Evaluation Mode Single tray — enter weight directly above From Project — evaluate all trays in the Raceway Schedule