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Interactive Simulator · ASCE 7-22 Chapter 12

Seismic ELF Design Simulator

Step through the ASCE 7-22 Equivalent Lateral Force (ELF) procedure: enter site spectral values, site class, and building system to compute SDS, SD1, Cs, design base shear V, and story force distribution.

📍 Site Parameters

1.00g
0.40g
SITE CLASS
Stiff soil (default if unknown)
RISK CATEGORY

🏗️ Lateral Force-Resisting System

🏢 Story Weights & Heights

Story 1 = roof / top story. Stories listed top → bottom.
Story 5 (Level Roof)
Weight: 800 kips
Height: 14 ft
Story 4 (Level 4)
Weight: 750 kips
Height: 12 ft
Story 3 (Level 3)
Weight: 750 kips
Height: 12 ft
Story 2 (Level 2)
Weight: 700 kips
Height: 12 ft
Story 1 (Level 1)
Weight: 700 kips
Height: 12 ft

📋 ELF Calculation Steps

1
Site Coefficients
Fa = 1.10
Fv = 1.90
2
MCE Spectral Accels.
SMS = Fa×Ss = 1.100g
SM1 = Fv×S1 = 0.760g
3
Design Spectral Accels.
SDS = ⅔SMS = 0.733g
SD1 = ⅔SM1 = 0.507g
4
Seismic Design Category
SDC D
5
Approx. Period Ta
Ta = 0.028 × H^0.8 = 0.76 s
6
Seismic Resp. Coeff. Cs
Cs = 0.0833
R = 8, Ie = 1
7
Seismic Base Shear V
V = Cs × W = 308.2 kips
W = 3700 kips

⚡ Story Force Distribution

V = 308.2 kips total · 5 stories · Special Steel Moment Frame
Roof (h=62ft)
102.2 kCvx=0.332
Story 4 (h=50ft)
80.2 kCvx=0.260
Story 3 (h=38ft)
63.0 kCvx=0.204
Story 2 (h=26ft)
41.0 kCvx=0.133
Story 1 (h=14ft)
21.7 kCvx=0.071
Base Shear V
308.2 k
V / W
8.3%
SDC
Category D
Ω₀ (Overstrength)
3
Cd (Defl. Amplif.)
5.5
Ta (Approx.)
0.76 s
How to use: Enter Ss and S1 from USGS Seismic Design Maps (https://hazards.atcouncil.org) for your project location. Site Class D is the default when a site-specific geotechnical report is not available. The ELF procedure is valid per ASCE 7-22 Section 12.6 when the building meets regularity conditions and SDC is not E or F. Fa/Fv values are interpolated from ASCE 7-22 Tables 11.4-1 and 11.4-2; values shown are approximate for educational use — always reference the published tables for design.