It is well known that seismic isolation is based on the increasing of the fundamental period of vibration
of the building, which corresponds to a terrific reduction of the seismic actions that affect the structure.
From Figure 11, it is observed that the period of vibration
with restraining moments is shorter than that without the restraining moments.
Lying prone on a massage table with arms extended (180[degrees]) LV arm was exposed to a 10-min recovery period of vibration
, while PAS arm remained passive.
where: [S.sub.d] ([T.sub.1]) is the ordinate of the design spectrum at period [T.sub.1]; [T.sub.1] is the fundamental period of vibration
of the building for lateral motion in the direction considered; W is the total weight of the building, above the foundation level; g is the gravity acceleration; [lambda] is the effective modal mass correction factor, the value of which is equal to: [lambda] = 0.85 for T [less than or equal to] 2 [T.sub.C], and n > 2 stories, where n number of stories; [T.sub.c] is the upper limit of the period of the constant spectral acceleration branch as shown in Figure 1.
This indicates that the 10-min period of vibration
did not bring about a state of relaxation in the subjects.
Due to vibrator limitations associated with fast frequency changes observed in pretests, only one period of vibration
could be delivered by each vibrator within each cycle of stimulation.
In this table, [T.sub.1] denotes fundamental period of vibration
, [C.sub.y] denotes seismic coefficient at yield, and [D.sub.y] denotes roof displacement at yield.
The results of phase -I revealed that seismic isolation of a fix base building reduces the floor accelerations and base shear by lengthening the natural period of vibration
of the structure.
Figures 5(a)-5(d) also indicate that the maximum interstory drift demands are smaller for the structures with fundamental periods equal to 1.37 s than for those with periods around 1.07 s due to the softening phenomenon that these structures suffer; it occurs because as the seismic intensity increases and the structure presents inelastic nonlinear behavior, the effective period of vibration
becomes larger, which implies that it becomes closer to the peak ordinate of the spectrum.
In the middle of the graph, the collision of the vocal folds consumes half of the period of vibration
, creating a longer flat portion.
The characteristics of the device at this frequency are: one period of vibration
7=14.28 x [10.sup.-5] s, oscillation pulsation [omega]=43.98 x [10.sup.-3] [s.sup.-1], and maximum sonic pressure [p.sub.S max] = 29.187 bar.
In fact, the improvement of muscular performance after a short period of vibration
training has been quoted to be similar to what occurs after several weeks of heavy resistance training.