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Directly
Connected
System
Wall lype Brace Type Shear Link Type
Indirectly
Connected
System
Stud Type Bracket Type Connector Type
Column Type |
Beam Type
Special
System
Fig. 2
Framing Types Considered in Manual
BASIC DESIGN METHOD
To date, design and performance prediction of passive control systems have typically been based on
iteration involving extensive response time history analyses or equivalent static analyses using
various types and sizes of dampers. The analysis methods are also different between the various
systems; these make direct comparison of the systems difficult. Moreover, they offer limited
information about the possible range of seismic performance variations and the complex
interactions between the dampers, their supporting members, frame, seismic input, and response.
The manual will propose a method to clarify the seismic performance of the various types by
commonly expressing their response effectiveness as a continuous function of the structural and
seismic input parameters. The method should promote understanding of the commonalities and
differences between the various types, which have distinct energy dissipation mechanisms. It
requires only simple calculations, and its prediction agrees well with the results of the extensive
multi-degree-of-freedom dynamic analyses performed [1, 2]. The method can also find an
optimum design solution to control both displacement and acceleration of the systems. The
method is briefly explained below:
Fig. 3 shows an example of such a method applied to the multi-story passive system using either a
viscoelastic damper or elastoplastic damper. The method considers an equivalent
single-degree-of-freedom system consisting of damper and supporting member such as brace that
are connected in series, as well as a frame connected in parallel with these components. The
parameters used to characterize the control effectiveness are: the 1st mode effective mass
approximately equal to 0.8 times total mass in a case of regular building; elastic stiffness of frame,
damper, and brace, and; ductility factor and loss factor that quantify the amount of energy
dissipation by the elastoplastic damper and viscoelastic damper, respectively.