SEISMIC CONTROL OF BUILDINGS USING APPARENT MASS DAMPERS WITH ROTATIONAL

AMPLIFYING MECHANISMS

Assistant Prof. Ruifu Zhang

Research Institute of Structural Engineering and Disaster Reduction

Tongji University, China

BACKGROUNDMissing 2-node mechanical element and

ideas of a 2-node apparent mass device

Consider a simple SDOF system

k

c

m

• Spring Element

• Damping Element

2-nodes mechanical elements

2 1( )F k x x=- -

1x

2x

kFF

1x&

2x&FF

2 1( )F c x x=- -& &

c

A missing 2-nodes mechanical element

x&&F F mx=- &&

m

Chen, Michael ZQ, et al. "The missing mechanical circuit element." Circuits and Systems Magazine, IEEE 9.1 (2009): 10-26.

O1x&&

2x&&

Inertial Reference Frame

2 1( )mx x=- -&& &&

2-nodes Apparent Mass Devices

• Inerter (Smith, 2000)• Dynamic Mass (Furuhashi and Ishimaru, 2004)

2 1( )

dF m x x=- -&& &&

Inertia Pump using Fluid Mass (Kawamata, 1973)

Fluid

mass of the fluid filled in the tube:m

Sectional area: a

D D

Sectional area: A

Ad D

a

P

p md Bypass tube

Bellows

Fluid contai

2

AP md

aA

mDa

¢=

æ ö÷ç ¢÷=ç ÷ç ÷çè ø

&&

&&

2P A

mD a

æ ö÷ç ¢÷=ç ÷ç ÷çè ø&&

2-nodes apparent mass devices

• Hydraulic Inerter (Wang F-C. et al. 2010)• Leveraged-Pendulum System (Yamamoto, 1975)• Rack and Pinion System (Okumura, 2000)

Building Dampers using Apparent Mass • Apparent Mass Damper using Ball-Screw Mechanism

(Aragaki et al. 1999)

Building Dampers using Apparent Mass • Rotary Damping Tube (RDT)

The most viable and promising 2-nodes apparent mass device

Ball Screw

Silicone Oil

Cylindrical Flywheel

Photo of the full scale real-life damper

Apparent mass = 5400 t

Apparent mass device for seismic isolation

Full-Scale Real-Life Damper

Apparent Mass: 1250 t

RESPONSE CONTROL USING APPARENT MASS

Vibration Insulator• The 2-nodes apparent mass device cuts off the harmonic

excitation of a specific frequency (Okumura 2000)

• if , X = 0

mk

X

IX r

r

2

Im

r

0 0i tx X e

km

w=¢

Seismic Control• Hwang et al. (2007) studied seismic control of building

structures using an inerter-like or dynamic mass-like device combined with toggle amplifier.

• Seismic retrofit of existing high-rise building using an inerter-like device dynamic screw. (Matsui et al. 2012)

TMD-like system using an Apparent Mass • Tuned Viscous Mass Damper (Saito et al. 2008)• Application of Tuned Viscous Mass Damper (Sugimura et

al. 2012)

Tuned Viscous Mass Damper

k

m

TMDm

k

Supportingspring

Viscous massdamper

Tuned Mass Damper

Apparent Mass in Seismic Isolation

mdx0

xm

k

cd Apparent Mass

SDOF Base-isolated Building

Equation of Motion

0( )

d dm m x c x kx mx+ + + =-&& && &&

0( ) ( ) ( )d

d d d

c k mx x x x

m m m m m m+ + =-

+ + +&& && &&

Apparent input ground motion reduces by .

Note that it does not apply for acceleration .

( )d

mm m+

0x x+&& &&

An Issue the Previous Studies are Confronted by.

• Large floor response accelerations induced by the secondary apparent mass.

To Overcome the Issue …• Rotational friction mechanism is employed to restrict the excessive control force as well as to provide hysteretic energy dissipation to compensate the reduction of control force.

(Nakaminami et al. 2012)

Analytical Model Considering Control Force Restriction

Apparent Mass

Force LimiterSDOF Base-isolated Building

Conclusions

• Brief review of response control of civil engineering structures using 2-node apparent mass devices is given.

• Presently, one of the most viable promising options to implement a 2-nodes apparent mass device is to utilize ball screw mechanism.

Than you for your kind attention.