Filter
Top Products
STAAD Commands and Input Instructions
Section 5
5-358
General format:
⎧X ⎫ ⎧ ⎫
GRO
UND MOTION ⎨Y ⎬ ⎨ACCEL ⎬ f
3
PHASE f
4
⎩
Z
⎭ ⎩DISP
⎭
Enter the direction of the ground motion, the acceleration and the
phase angle by which the motion in this direction lags (in degrees).
One Ground Motion command can be entered for each global
direction.
f
3
Ground acceleration in g’s or displacement in length units.
f
4
Phase angle in degrees
Next is an optional amplitude versus frequency specification to be
used when the ground motion acceleration is a function of
frequency. For any forcing frequency an amplitude can be
determined, from the data below, which will multiply the
acceleration f
3
entered above. If no amplitude data is entered for a
direction then the acceleration is f
3
for that direction.
AMP
LITUDE ( A a B b C c )
Amplitude = a*ω
2
+ b*ω + c
ω = forcing frequency in rad/sec.
a, b, c = constants entered above. a & b default to zero and c
defaults to 1.0
---------------- or ------------------
AMP
LITUDE
(F1 A1 F2 A2 F3 A3…..)