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Base Shear
Importance Factor
Since the building is an office we will be using standard
occupancy for Importance Factor.
I = 1.00
Soil Profile Type
Since soil parameters are unknown, soil profile type D will be
assumed.
SD= 600 ft/sec to 1200 ft/sec
Seismic Zone Factor
Philippines is in seismic Zone 4.
Zone 4 , Z = 0.4
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Seismic source Classification
Since the fault is neither active nor inactive, Type B will be
assumed.
Type B
Near-Source Factor
The location of the building will be at least 15km from
faults.
Na= 1.0 , Nv= 1.0
Ground Response Coefficients
Ground response coefficient for Zone 4 having soil profile type
D will be used for the structure.
Ca = 0.44Na, Cv = 0.64Nv
Since: Na= 1.0 , Nv= 1.0
Therefore: Ca = 0.44 , Cv = 0.64
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Response Modification Factor
Since the structure is composed of Moment resisting frames to
resist lateral loads, response
modification factor for steel or concrete special moment
resisting frames will be used.
R = 8.5
Seismic Dead Load
Total Dead Load for the structure is obtained to be
34648.794KN.
W = 34648.794KN
Fundamental Period of Vibration
Method A
Ct = 0.0731 [for reinforced concrete moment resisting
frames]
Hn= 17.5m
TA= 0.0731 (17.5)3/4
TA= 0.625sec
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Seismic Base Shear
Applicable Coefficient:
I = 1
Z = 0.4
Na= 1
Nv= 1
Ca= 0.44Cv = 0.64
R = 8.5
W = 34648.794KN
T = 0.625sec
The base shear:
V = (0.64) (1) (W)
(8.5)(0.625)
V = 0.1205W
The minimum permitted value:
V = (0.11) (0.44) (1) W
V = 0.0484W
The maximum value:
V = (2.5) (0.44) (1) (W)
8.5
V = 0.129W
BASE SHEAR
Formula Seismic Dead Load (W) Total
Base shear 0.1205W 34648.794KN 4175.18KNMin. Permitted
Value0.0484W 34648.794KN 1677.002KN
Max. Value 0.129W 34648.794KN 4469.694KN
BASE SHEAR = 4175.18KN
