Earthquake Engineering Research - HKU Libraries - The University ...

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PASSIVELY-COTROLLED BUILDING
EP-SYSTEM
Kf = Frame Stiffness
K d = Damper Elastic Stiffness
K b = Brace Stiffness
2 "i
Kif
f
^AVVv
VE-SYSTEM
ji d = EP Damper Ductility
T| d = VTE Damper Loss Factor
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Fig. 3
Example Passi\e Control Systems and SDOF Representations
F t j 4 ^:evss the chart created by Kasai's SDOF theory on passive control effectiveness (Refs. 1 and
2T Tn.s chart can be used to'determine the desired ratio between the above-mentioned stiffness
parameters as well as loss and ductility factors. For a given earthquake input, the peak displacement
and base shear of the frame prior to damper installment can be predicted easily from the response
spectrum. Then using the chart, for desired reduction ratios of the displacement and acceleration,
one can determine the "necessary stiffness of the damper and brace relative to that of the given frame,
as uel. as either ductility factor or loss factor of the damper. This chart was created by assuming
that pseudo-velocity response is constant relati\e to the building period, a typical design assumption
mace for a moderate to tall building in Japan. The design result for SDOF system can be equally
applied to sizing of the dampers in the multistory case as well. The accuracy of the method for the
system using \arious types of dampers has been examined by the System Design Methodology
\\ jrking Group (Table 1). and the results are briefly explained in Ref. 16.
O.Z 0.4 O.b OS
DISP. REDUCTION RATIO
•1 • | \ _>* U.23
l«V.4-->" _, "^ i 0.5
i 2 t|dKd J 'Ki >
i — i- *——•—,
i i —
02 0.4 H6 03
DISP. REDUCTION RATIO
1
-o— rjf-30
Fig. 4 Example Design Chart for Passive Control Systems
After the^ simplified procedure outlined abo\e, one can create a muiti-degree-of-freedom model, and
may perform time-history analyses using a series of earthquake records in order to confirm or make
modifications in design. The methods 10 create analytical model for the damper of the system are