# Seismic Anchorage of Structural Walls (ASCE 7)

Calculate the minimum seismic anchorage forces of structural walls as per ASCE 7 cl. 12.11

in
in
psf
g
ft

## Output:

1. Definitions
• Fp = Seismic Anchorage Force
• htrib = Height of wall tributary to support or anchor
• wtrib = Width of wall tributary to support or anchor
• Wunit = Unit weight of wall (psf)
• Wp = Tributary weight of wall (lb)
• SDS = Design spectral acceleration at short periods (0.2sec)
• Ie = Seismic importance factor
• Lf = Span of the flexible diaphragm that provides support for the wall (ft)
• ka = Amplification factor for diaphragm flexibility
2. Determine weight of wall tributary to anchor or support
• Wp = Wunit htrib wtrib = (250)(56)(12)/ (144 in²/ft²) = 1166.7 lb
3. Determine minimum out-of-plane force
• Fpo = 0.4 SDS Ie Wp > 0.1 Wp
• Fpo = 0.4 (0.85) (1) (1166.7) > 0.1 (1166.7)
• Fpo = 396.7 > 116.7
• Fpo = 396.7 lb
4. Determine minimum in-plane force
• ka = 1.0 + Lf/100 < 2.0 = 1.0 + (10)/100 < 2.0 = 1.1
• Fpi = 0.4 SDS ka Ie Wp > 0.2 Wp
• Fpi = 0.4 (0.85) (1.1) (1) (1166.7) > 0.2 (1166.7)
• Fpi = 436.3 > 233.3
• Fpi = 436.3 lb