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  • 1International Conference on Earthquake Analysis and Design of Structures (EQADS 2011), December 1-3, 2011 Department of Civil Engineering, PSG College of Technology,

    Coimbatore, Tamilnadu, India

    Dr.AjaySharmaAssociateProfessor

    DepartmentofStructuralEngineering,FacultyofEngineering,J.N.V.UniversityJodhpur

  • 2Overviewy Introductiony BaseisolatedBuildingy SemiactiveDampers

    PredictiveControlledSemiactiveFrictionDamperResettingSemiactiveStiffnessDamperMRDamper

    y NumericalStudyNumericalStudyy Conclusions

    2

  • 3Introductiony Baseisolationy NearfieldEarthquakesy SemiactiveDampersy StructuralResponseBasedisplacementAbs.FlooraccelerationBaseShearBaseShearStoreyDrift

    3

  • 4BaseisolatedBuilding

    4

  • 5NearfieldEarthquakes

    15202530 Sylmar

    Rinaldi Kobe Jiji

    Spectral acceleration (m/s2)

    2.53.03.54.0

    0.1 1 1005

    1015

    Spectral Velocity (m/s)

    Erzincan

    Time(sec)

    0.1 1 100.00.51.01.52.0

    0.8

    1.0

    Time (sec)

    Spectral displacement(m)

    5

    0.1 1 10

    0.0

    0.2

    0.4

    0.6

    5 percent damping

    Time (sec)Figure 4: Response Spectrums of the Earthquakes

  • 6SEMIACTIVEDAMPERSPredictiveControlledSemiactiveFrictionDamper

    L [2004] d l d i ti f i ti d hi h i bl t dj t itLu [2004] developed a semi-active friction damper which is able to adjust itsslip force by controlling its clamping force in real-time in response to astructures motion during an earthquake such that it always remains in slipstate. The semiactive friction damper utilizes the control named predictivecontrol.

    ( ) ( ) ( ) ( )gz t Az t Bu t Ew t= + +The force vector u (t) depends not only on the damper properties (the friction

    coefficient, time-varying clamping forces and dampers stiffness, etc.), butalso on the structural dynamic response and can be expressed as

    ( ) ( ) ( )( ) [ { ( ) ( 1)} ( 1)]i g d i d i d i iu t k z t z t u t= +

    ( ) ( ) ( ) ( )g

    6

  • 7R tti S i ti Stiff D

    SEMIACTIVEDAMPERSResettingSemiactiveStiffnessDamper

    Yang et al., [4] derived a general resetting control law based on theLyapunov theory, which resets the RSASD stiffness at each momentwhen the relative velocity cross the damper reaches zero. When thevalve is closed the damper serves as a stiffness element with anvalve is closed, the damper serves as a stiffness element with aneffective stiffness kd provided by the bulk modulus of the fluid inside.

    ( ) ( )i d pu t k x x=

    7

  • 8SEMIACTIVEDAMPERSMRDMRDampers

    820 Ton Magnetorheological fluid Damper (Yang and Spencer 2002)

  • 9NUMERICALSTUDYThe overall governing equation of motion of complete structures can be written for the condensed linear-elastic superstructure with controlled isolated base, th ti f ti ithe equation of motion is

    { }0 0

    0 0

    00b b b bb b

    M M R C K UU UR M R M R M C K UU U

    M RU

    + + + + +

    9

    { }gC bB

    Uf R M R Mf

    + + = +

  • 10

    46

    4 3 5

    S y lm a r X d ire c t io n Y d ire c tio n4 .8 6 4 .7 44 5 6

    -4-202

    4 .3 5

    F P S B a s e - is o la te d S A F r ic tio n

    4 .5 6

    0246

    4.35 Sylmar X direction Y direction4.74.74

    4.85

    0369

    Base-isolated M R Damper4.354.91

    7.91

    4.74

    3 6 9 12-4-20

    3 6 9 12 15FPS

    Basr-isolated SA Stiffness

    10

    3 6 9 12-6-30

    3 6 9 12 15

    Time-history response of Top floor absolute acceleration of the Base-isolated Building

  • 11

    0.6

    nt (m

    )

    S ylm ar X direction Y direction B ase-isola tedS A F ric tion

    3 6 9 12-0 .6

    -0 .3

    0.0

    0.3

    3 6 9 12 15

    B

    ase

    disp

    lace

    me n S A F ric tion

    T im e (sec) T im e (sec)

    0 .5020 .47 8 0 .35 9

    0 .41 9

    0 .3

    0 .6 X -D irectionSylm ar Y -D irection B ase-isola ted S A S tiffness

    3 6 9 120.6

    0 .3

    0 .0

    3 6 9 12 150 .5 0 2

    0 .4 7 3 0 .3 6 10 .4 1 9

    0 00 .30 .60 .9

    Y -D irec tion B ase-iso la tedM R D am p er

    X -D irec tionS ylm ar

    11

    3 6 9 1 20 .60 .30 .0

    3 6 9 1 2 1 50 .5 0 2

    0 .3 4 8 0 .1 6 3 0 .4 1 9

    Time-history response of Base displacement of the Base-isolated Building

  • 12

    5 0 0 0 07 5 0 2 0

    6 8 0 9 0 5 6 8 2 0

    3 5 5 6 0

    B ase-iso la ted M R D am p er

    3 6 9 1 2

    5 0 0 0 0

    0

    3 6 9 1 2 1 5

    3 5 5 6 0

    0

    50000

    ear (

    kN)

    3 6 9 12

    -50000

    0

    3 6 9 12 15

    75020 7821056820

    54300

    T ime (sec)T ime (sec)

    Bas

    e sh

    e

    Base-isolated SA stiffness

    0

    500007 5 0 2 0

    6 8 0 9 0 5 6 8 2 0

    3 5 5 6 0

    B ase-isolated M R D am per

    12

    3 6 9 12

    50000

    3 6 9 12 15

    Time-history response of Base Shear of the Base-isolated Building

  • 13

    0.005

    0.010 Base-isolatedSA Friction

    Sylmar X direction Y direction

    3 6 9 12-0.010

    -0.005

    0.000

    3 6 9 12 150.0094 0.0103

    0.00850.0085

    0.000

    0.005

    0.010Sylmar

    ft (m

    )

    X direction Y direction

    3 6 9 12-0.010

    -0.005

    3 6 9 12 15

    St

    ory

    drif

    T ime (sec) Time (sec)

    0.0094 0.00990.0085 0.0082 Base-isolated

    SA Stiffness

    .000

    .005

    .010 Sylmar X direction Y direction Base-isolated MR Damper

    13

    3 6 9 12.010

    .005

    3 6 9 12 150.0094 0.0068 0.0085

    0.0051

    Time-history response of Storey Drift of the Base-isolated Building

  • 14

    PeakValuesofStructuralParametersunderdifferentconditions

    Peak Values Condition Sylmar Rinaldi Kobe Jiji Erzincan

    Base Shear (kN)

    Fixed 199205 265628 214740 127738 123116

    Isolated 75048.49 60738.5 28541.09 107173.5 69143.18

    SA Friction Damper 80990.78 68797.65 32215.29 106060.9 73976.71

    SA Stiffness Damper 78239.76 64340.41 30660.58 98092.56 71141.35

    MR Damper 68120.14 65835.9 32245.36 75532.76 60644.48

    Isolated 0.50179 0.37117 0.21626 0.78836 0.50646

    SA F i i

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    Base Displacement (m)

    SA Friction Damper 0.47808 0.37882 0.20293 0.67445 0.47841

    SA Stiffness Damper 0.4726 0.364 0.20138 0.62836 0.466

    MR Damper 0.34822 0.32728 0.1443 0.48577 0.33857

  • 15

    Fixed 0.04545 0.09176 0.08768 0.03696 0.03784

    Isolated 0.016226 0.015635 0.009769 0.024566 0.016753

    Story Drift (m) SA Friction Damper 0.018281 0.016773 0.010368 0.022501 0.018079

    SA Stiffness Damper 0.017108 0.016239 0.010037 0.020408 0.017348

    MR Damper 0.016207 0.015436 0.015339 0.01625 0.01463

    Abs. Floor Acceleration (m/s2)

    Fixed 17.842 27.518 27.059 11.582 11.125

    Isolated 4.5388 7.5424 5.1293 3.5483 2.5505

    SA Friction Damper 4.873007 5.428201 3.497105 5.509789 2.73764

    SA S iff D 4 848028 5 419945 3 504952 5 537238 2 642188

    15

    SA Stiffness Damper 4.848028 5.419945 3.504952 5.537238 2.642188

    MR Damper 7.916139 5.853629 5.88858 4.71399 3.461321

  • 16

    RMS Base Displacement (m)

    Isolated 0.15429 0.08142 0.04227 0.2794 0.14988

    SA Friction Damper 0.13568 0.08139 0.04264 0.21977 0.1327

    SA Stiffness Damper 0.12391 0.07221 0.04147 0.20515 0.12508

    MR Damper 0.06749 0.05924 0.03312 0.12391 0.08393

    Fixed 2.267 5.681 5.165 2.507 2.379

    Isolated 0.915891 0.795738 0.865654 1.840038 0.930855

    RMS Abs. Floor Acceleration (m/s2)

    SA Friction Damper 0.924392 0.860956 0.910435 1.689969 0.948888

    SA Stiffness Damper 0.847722 0.84289 0.906044 1.540652 0.889127

    MR Damper 0.777966 1.096831 1.314699 1.165429 0.867645

    SA F i ti D 8238 28 7665 5 4318 191 11394 66 8798 873

    16

    PeakControl Force (kN)

    SA Friction Damper 8238.28 7665.5 4318.191 11394.66 8798.873

    SA Stiffness Damper 7505.04 6440.726 3507.768 10165.83 7937.672

    MR Damper 16535.46 18497.54 13848.27 14646.51 14301.21

  • 17

    ConclusionsThe comparative performances of semiactive dampers inbaseisolated building under the action of strongearthquakes acting bidirectionally have beenevaluated. The role of semiactively controlledstiffness/ friction dampers along with MR dampers inreducing the large base displacement in base isolatedreducing the large base displacement in baseisolatedbuilding are found suitable since they do not increasethe structural response like, top floor accelerations,base shear etc. to alarming level. MR dampers provedcomparatively better semiactive controlled dampers incomparatively better semiactive controlled dampers incomparison to friction or stiffness dampers.

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    2) Spencer,Jr.,B.F.,andSain,M.K.,Controllingbuildings:anewfrontierinfeedback,SpecialIssueoftheIEEEControlSystemsMagazineonEmergingTechnology,17(6),

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