Experimental Paper

8/3/2019 Experimental Paper

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Experimental Studies on use of Toggle Brace Mechanism Fitted with

Magnetorheological Dampers for Seismic Performance Enhancement

of 3-Storey SMRF Model

Rama Raju, K

Meher Prasad, A

Muthumani, K

Gopalakrishna, N

Nagesh R.Iyer

Lakshmanan, N

20.04.2011


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The output of a fluid damper is essentially out of phase with primary bending and

shearing stresses in a structure. This implies that a fluid damper can be used to

reduce both internal shear forces anddeflection in a structure.

Viscous Fluid dampers

A Piston in the damper housing filled with

a compound silicone or oil. Dissipates

energy through the movement of piston

South

North

H

Model RD-1003-5In this MR damper the viscous and shear properties

of the MR fluid are controlled by the applied magnetic

field, which is a function of the excitation current.

Magneto Rheological dampers


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Attachments of Dampers to Buildings

F=cos


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Main contribution

1. Mechanical characterization ofMR damper

2. An experimental investigation on a model of a 3-Storey SMRF model

conducted to show the efficiency of MR damper fitted with toggle type

mechanism


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This is a compact MR fluid damper unsurpassed in its combination of

controllability, responsiveness and energy density

In this MR damper the viscous and shear properties of the MR fluid are

controlled by the applied magnetic field, which is a function of the excitation

current.

Which can be applicable to,An adaptive space truss structures

Middle-sized passenger vehicle

Magneto Rheological dampers (RD-1003-5)-Lord corp.

The properties of damper

Compressed length = 155 mm

Extended Length = 208 mm

Body Diameter = 41.4 mm

Shaft Diameter = 10 mm

Weight = 800 g

Minimum tensile strength = 4.4kN,

Maximum Operating temperature= 71oCModel RD-1003-5

Dynamic performance evaluation of MR Damper by Experimental

Method


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A servo controller is used to conduct the experiment.

A RD-1005-3 was installed between the effectors of the system andmeasurements of force and displacement were made directly through the

servo controller.

The displacement of the damper rod was achieved by hydraulic actuator of

servo controller.

Input current was controlled with a voltage-regulated device controller RD-

3002-1 Wonder Box TM (WB) also from Lord Corporation.

Experiments were conducted to

measure the dynamic response of the

MR damper under a range of

frequencies, 2, 2.5 and 3Hz and

amplitudes of displacements 2, 3, 4,

5, 8, 12, 16 and 20mm as sinusoidal

and triangular wave forms.

Current Inputs: 0, 0.25, 0.5, 0.75 and

1A

Experimental Setup for MR Damper characterization

Mechanical characterization of MR damper continued


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Theoretical and experimental dynamic characterization of MR dampers

4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4

-2

-1

0

1

2

Time (s)

Force(KN)

a) Force Vs.Time

-3 - 2 - 1 0 1 2 3

-2

-1

0

1

2

b) Force Vs.Displacement

Displacement (mm)

Force(KN)

-40 -20 0 20 40

-2

-1

0

1

2

c) Force Vs.Velocity

Velocity (mm/s)

Force(KN)

0A 0.25A 0.5A 0.75A 1A

Mechanical characterization of MR damper continued ..


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Damper

Properties

Damper S.No:021602 for different current input and 2Hz frequency

-3000

-2000

-1000

0

1000

2000

3000

-0.3 -0.2 -0.1 0 0.1 0.2 0.3

Velocity (m/sec)

Force

(N)

0A-FVP Law

0.25A-FVP Law

0.5A-FVP Law

0.75A-FVP Law

1A-FVP Law

Damper S .No:015918 for different current input and 2Hz frequency

-3000

-2000

-1000

0

1000

2000

3000

-0.3 -0.2 -0.1 0 0.1 0.2 0.3

Velocity (m/sec)

Force

(N)

0A-FVP Law

0.25A-FVP Law

0.5A FVP Law

0.75A-FVP Law

1A-FVP Law

)(usignuCf oD E

!Fractional Velocity Power law,

Current (A)

Damper Properties

Damper S.No:015918 Damper S.No:021602

Damping

Coefficient

C0(N s/m)

Exponent

Damping

Coefficient

C0(N s/m)

Exponent

0 581 0.34 557 0.30

0.25 1632 0.34 2011 0.312

0.5 2700 0.28 2640 0.19

0.75 3150 0.21 3310 0.211 4150 0.21 4032 0.21

Mathematical Modelling of MR Dampers



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Dynamic performance evaluation of MR Damper by Experimental

Method

SUMMARY

The force-time, force-velocity, force-displacement relationships are

determined from the experimental results.

Experimental force-velocity relationships are fitted to a Fractional

Velocity Power law (FVP law). These relations are further used in

the analytical studies.



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Steel frame model with Toggle brace mechanism with

MR Dampers- Experimental investigation


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Plan Dimension : 1120 x 960mm

First Storey height : 850 mm

2nd,3rd storey height : 700 mm

Total height : 2300 mm

Column Section : ISLB 100 @ 8 Kg/m Beam Section : ISLB 100 @ 8 Kg/m

Gusset Plate Thickness : 6mm

Base Plate dimension : 300x300x10mm

Type of connection : Bolted connection ( 8,10 mmhigh strength Bolts with spring

washers) Pipe Section : OD21mm/ID17mm

Reinforced concrete slab : 1120x960x60 mm

DESCRIPTION OF FRAMEMODEL

Effectiveness of Nonlinear VFDs with Upper Toggle Brace Mechanism

Experimental investigation on a model of a 3-Storey SMRF continued


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SECTIONALVIEWOF THE TESTING MODEL

Pipe

OD21/ID17

Pipe

OD21/ID17

Pipe

OD21/ID17

200

850

ISLB 100

700

700

FRONT VIEW

All dimension are in mm

32

43

406

422

1120

Steel plate

Concrete Slab

ISLB100 ISLB100

Concrete Slab

Steel Plate

ISLB 100

Concrete Slab

Steel Plate

ISLB 100

Base plate(300x300x10)

Damper

638

693

474

407

Steel Plate

Steel Plate

Steel Plate

Concrete Slab

Concrete Slab

Concrete Slab

2----2

2-- 1----2

--1 1--

--1

ISLB100

ISLB100

ISLB100

960

TS100x50x6

ISLB100

850

700

700

1.ISA 100x100x5

2.6 mm plateSIDE VIEW

ISLB100

50

Base plate(300x300x10)

38

3D-VIEW



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The shake table was excited with low level acceleration.

Amplitude of base acceleration - between 0.02 to 0.1g.

Frequency was increased in the increments of 0.1 Hz - corresponding

FRF was noted up to first three modes

FreeVibration Test

Shake Table at SERC

Shaking table size : 2m x 2m

Vertical Actuators : 3 Nos. of capacity 100kN each

Vertical Actuators : 3 Nos. of capacity 50kN each

Weight of table : 5TAcceleration :1.0g (X, Y) and 0.75g (Z)

Frequency of operation : 0.1 Hz to 50 Hz

Velocity : 0.8 m/s (X, Y) and 0.4 m/s (Z)

0

10

20

30

40

50

0 5 10 15 20 25

FRF

Frequency

FRF (Freqency Response Function)



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Mode Shapes Comparison

4.17

12.52

19.52

4.0

12.5

20.0

1

2

3

AnalyticalExperimental

Natural Frequency (Hz)Mode

-0.064

1.000

-0.484

0.076

1.00

-0.49

1.00

0.25

-0.83

1.00

0.32

-0.75

0.59

0.85

1.00

0.66

0.99

1.00

1

2

3

Anal.Exp.Anal.Exp.Anal.Exp.

Third modeSecond modeFirst modeStorey

Frequency Comparison

Shows good agreement

0

1

2

3

0

1

2

3

-1.00 -0.50 0.00 0.50 1.00 1.50

Storey

Response Amplitude Factor

Mode I Exp.

Mode II Exp

Mode III Exp

Mode I Ana

Mode II Ana

Mode III Ana

Fundamental Natural frequencies for frame model withand without current input (Sine wave excitation, 0.1g)

Natural Frequency (Hz)

Current Input 0A 0.25A 0.5A 0.75A 1.0A

First Mode 4.5 6.0 6.0 5.5 6.0

Second Mode 18.5 18.0 17.5 17.5 17.5



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0

1

2

3

4

5

6

7

8

9

10

11

12

13

3 3.4 3.8 4.2 4.6 5 5.4 5.8 6.2 6.6 7FrequencyRe

sponseAmplitude,

(x0.1g)

Frequency ( Hz )

FRF measured at 3rd floor

Current input 0A

Input current = 0.25A



Input current = 1A

Frequency response function (FRF) measured in 3rd floor for different current inputs

Experimental Evaluation of damping using half-bandwidth method

Current input Amplitude

(mm)

Amplitude/ 2 f1 f2)f+f(

)f-f(=

21

21

1.0 9.5 6.72 5.1 5.9 0.073

0.75 8.7 6.15 5.3 6.1 0.067

0.50 7.6 5.37 5.3 6.1 0.070

0.25 5.5 3.89 4.6 6.1 0.133

0.0 7 4.95 4.1 5.0 0.100

Note: is damping ratio



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JT

J

TP

!\

EEE

E

2

111

2

2

2

miii

jj,mrroofm

j,Njj

dm

fuT

C jjjj

)(

)/(

j

j

jj

E

EP

E

+

+!

2

212

2

2

JT

J

T

EP

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E

2

111

2

2

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23

miii

jj,mrroofmj

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C jjjj

Lin YY, Chang KC, Chen CY. Direct displacement-based design for seismic

retrofit of existing buildings using nonlinear viscous dampers, Bull Earthquake

Eng 2008; 6:535-552.

(9)

(15)


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TableVI Effective damping ( d) values using Equation (9)

Current (A)

d ConsideringDampers at

I floorI & II floor

I, II & III

floorEq.(9) Exp.

0 585 0.34 0.0145 0.1 0.02 0.0226

0.25 1632 0.34 0.0405 0.13 0.0558 0.0631

0.50 2700 0.28 0.0695 0.070 0.0969 0.1104

0.75 3150 0.21 0.0847 0.07 0.1198 0.1378

1 4150 0.21 0.1116 0.073 0.1578 0.1816

Note: Here, Eq. = Equation and Exp.=Experimental

TableVII Effective damping ( d) values using Equation (15)

Current (A)

d ConsideringDampers at

I floorI & II floor

I, II & III

floorEq. (15) Exp.

0 585 0.34 0.0186 0.1 0.0256 0.0290

0.25 1632 0.34 0.0520 0.13 0.0715 0.08090.50 2700 0.28 0.0915 0.070 0.1275 0.1453

0.75 3150 0.21 0.1150 0.07 0.1626 0.1871

1 4150 0.21 0.1515 0.073 0.2143 0.2465

Note: Here, Eq. = Equation and Exp.=Experimental

E(s/m)Nco

coE(s/m)N


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Earthquake excitation exc1

-3

-2

-10

1

2

3

0 5 10 15 20 25 30 35 40 45 50 55 60

Time (s)

A

c

celeratio

n

m

/s

2

Earthquake excitation exc2

-4

-2

0

2

4

0 5 10 15 20 25 30 35 40 45 50 55 60

Time (s)

Ac

cele

ratio

n

m

/s

2

Excitations exc1 and exc2considered on the experimental 3-Storey model


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Results of Experimental investigation on use of MR dampers

0

1

2

3

0 5 10 15 20 25 30

Floor

Drift(mm)

Inter-storey drifts of3-storey frame subjected to exc2

WOD 0A 0.25A

0.5A 0.75A 1A

Frame subjected to excitations exc2

Inter-storey drift

Storey Shears

0

1

2

3

0 3 6 9 12 15

Floor

Drift(mm)

Inter-storey drifts of3-storey frame subjected to exc1

WOD 0A 0.25A

0.5A 0.75A 1A

Frame subjected to excitations exc1

Storey Shears

Inter-storey drift

Storey shears of the frame subjected to excitation exc1

0

1

2

3

10 15 20 25 30 35 40 45 50 55 60Shear(kN)

Floor

WOD 0A 0.25A 0.5A 0.75A 1AStorey shears of the frame subjected to excitation exc2

0

1

2

3

30 40 50 60 70 80 90 100 110 120

Shear(kN)

Floor

WOD 0A 0.25A 0.5A 0.75A 1A



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Table VIII Reduction in storey displacement, acceleration and drift ratio in 3-Storey frame with provision of MR dampers at differentcurrent inputs

EQ Config.Current

(A)

Storey displacements (mm) Inter-storey drifts (mm) Storey Shears (kN)

First Second Third First Second Third First Second Third

exc

1

WOD 11.5 8.9 11.6 11.50 14.50 2.80 5.802 4.673 2.646

WD

0.0 1.7 2.1 2.9 2.90 4.90 2.50 3.583 2.813 1.537

0.25 1.2 3.3 3.9 1.20 2.30 1.90 3.062 2.692 1.954

0.50 1.0 3.0 3.4 1.00 2.50 3.70 3.418 3.004 2.115

0.75 0.9 3.1 3.6 0.90 2.70 3.90 3.565 3.091 2.161

1.0 1.1 4.8 3.6 1.10 4.40 6.20 3.607 3.102 2.179

Reduction (%)

0.0 85.08 76.58 75.16 74.78 66.21 10.71 38.25 39.80 41.90

0.25 89.37 62.72 66.69 89.57 84.14 32.14 47.24 42.40 26.14

0.50 91.42 66.00 70.72 91.30 82.76 -32.14 41.10 35.72 20.07

0.75 91.85 64.49 69.08 92.17 81.38 -39.29 38.57 33.86 18.34

1.0 91.85 45.83 68.62 90.43 69.66 -121.4 37.84 33.62 17.65

exc

2

WOD 26.6 17.0 21.0 26.57 27.81 4.76 11.376 8.858 5.030

WD

0.0 7.2 9.6 8.4 4.76 27.81 26.57 7.184 5.407 3.644

0.25 5.7 6.5 7.1 6.04 8.63 9.15 5.836 4.689 3.633

0.50 2.6 6.0 8.6 4.33 5.81 7.63 7.896 5.878 4.792

0.75 15.9 5.5 8.6 3.07 5.84 2.82 7.994 6.330 4.863

1.0 11.8 5.9 7.7 3.31 20.63 15.86 8.080 6.483 4.963

Reduction (%)

0.0 73.07 43.31 60.20 65.55 68.97 26.90 36.85 38.96 27.56

0.25 78.53 62.09 66.35 71.28 79.10 9.10 48.69 47.07 27.78

0.50 90.40 64.91 58.89 89.38 79.01 35.57 30.59 33.65 4.74

0.75 40.32 67.66 59.27 40.32 25.83 30.47 29.73 28.55 3.33

1.0 40.32 65.54 63.51 55.73 57.87 25.65 28.98 26.82 1.33


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SUMMARY

1. Based on the experimental studies reported with regard to the dynamic response of

the MR damper, namely, force-velocity relationship it is inferred that it behaves as a

nonlinear viscous damper at different current inputs.2. A 3-storey SMRF model was fabricated to carry out experimental studies. The MR

damper with upper toggle brace mechanism is incorporated in a 3-Storey SMRF.

3. The damping ratio obtained from experimental studies varies from 0.07 to 0.13 only,

and for majority of the cases the average value may be taken as 0.085.However,

theoretical expectation showed significant variation in damping ratio with input

current.Hence it is clear that individual performance as a damper, and in a structuralscheme where-in there are other sub assemblies also could have an effect on

efficiency of the damper performance. This may be resolved only through further

experimentation.

4. In order to study the efficacy of provision of MR damper, the 3-Storey SMRF with

damper assembly is also excited using two time history signals, exc1 and exc2.

5. From experimental studies it has been demonstrated that the MR dampers are

effective in improving the performance of the building. The reduction in maximum

displacement, storey drift, acceleration and base shear shows the effectiveness of

dampers used with upper toggle brace configuration.

6. The results show that provision of MR dampers with upper toggle bracing

mechanism would act as vibration control device by dissipating energy at floor levelwhere they are placed and controls the vibration levels of floors above.


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Experimental Paper