Technological Frontiers in Smart Damping

8/2/2019 Technological Frontiers in Smart Damping

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Experimental Verification of Semiactive Control

for Nonlinear Structures UsingMagneto-Rheological Fluid Dampers

Investigator: Richard ChristensonDept. of Civil & Env. Engineering

University of Connecticut

Andrew EmmonsResearch Assistant CSM

Brent BassResearch Assistant UConn

NEES Facility Used:

University of Colorado at Boulder

Fast Hybrid Test Facility


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Overview

Analytical Studies

Fast Hybrid Test Setup

Preliminary Fast Hybrid Test Results

Conclusions & Continued Research

Outline


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Overview

Analytical Studies




Outline


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Structural control increases the safety and

performance of a traditional design by redistributing

and dissipating the energy of the structure

Structural control is typically designed for and

applied to linear structures, however, civil structures

are designed to yield during extreme dynamic events

Optimal design of a controlled structure may allow

damage to occur during extreme dynamic loading

Overview


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Examples of semiactive control devices

Overview

N(u)

variable friction device

ControlValve, u

controllable tuned liquid damperChoke

ER/MR

Fluid

controllable fluid damper

Control Valve, u

variable orifice damper


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Semiactive control devices are ideally suited for

demanding applications

reduce structural responses increasing performance provide controllable and inherently stable means of

structural control

low power requirements

This project will experimentally verify semiactive

structural control applied to building exhibitingnonlinear material behavior during severe seismic

events

Overview


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Overview

Analytical Studies




Outline


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The performance and reliability of a semiactive

controlled seismically excited 3-story steel-frame buildingis examined analytically prior to the experimental studies

Results submitted for publication to:

17th A&C Special Issue of the

Journal of Structural Engineering

Analytical Study


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Overview

Analytical Studies




Outline


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Full-scale nonlinear dynamic testing in the laboratory isdifficult and cost prohibitive

Fast Hybrid Testing can link physical full-scale (rate-dependant) semiactive dampers with simulated buildingsinreal-time

Utilizing the NEES FHT system at CU

Seismically Excited Building Fast Hybrid Test System

Computer Model (Structure)

Ground

1st

2nd

3rd

Simulated Building Model

200 kN MR Dampers


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Three sets of 20 ground motions developed for the SACSteel Project System Performance Team (Los Angeles suite)

Experimental Setup Ground Motions

averaged power spectrum


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Building is simulated in both Matlab and OpenSees

Although goal is to eventually simulate the 3-Story SACstructure, incremental steps are taken to first verify the

fast hybrid test methodology as applied here

An in-plane 1-story, 1-bay portal frame with potential

plastic hinges at the beam-column connections(0.9661 Hz fundamental frequency)

Experimental Setup Building Model

W33x118

W14x257

W14x257


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The building models will be controlled for seismicprotection using large-scale Magneto-Rheological (MR)

fluid dampers 58 length, weight 615 lbs, stroke 23, temp change


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Large-Scale Magnetorheological Fluid Damper


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Overview

Analytical Studies




Outline


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Challenges:

Sliding motion of dampers at ~20 kips

FHT algorithm applied to semiactive control devices

PreliminaryFHT Results


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MR Damper System Identification

Hyperbolic-tangent model (Gavin 2001)

Dynamics defined by:

m0

k

c1

f(t)

1

x0 x1

^

0 0

.

f (x )

0

k0

c

Preliminary Results


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MR Damper Model Comparison

0.5 Hz and 0.5 inch Sinusoidal excitation

Fast Hybrid Testing


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MR Damper Model Comparisons

Fast Hybrid Testing

0.5 Hz and 0.5 inch Sinusoidal excitation


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Low level testing at constant voltage

Preliminary Results Fast Hybrid Testing


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Low level testing at constant voltage (LA57 input, 0 amps)


time (sec)

displacement(in)

time (sec)

displacement(in)


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Low level testing at constant voltage (LA57 input, 0 amps)


time (sec)

d

amperforce(kip)

time (sec)

dam

perforce(kip

)


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Overview

Analytical Studies




Outline


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Preliminary results show positive results for the FastHybrid Testing of Semiactive Dampers

To do:

Full MR Damper system identification

FHT of controlled MR damper Testing of 3-Story 1-Bay nonlinear model (3 dampers)

Testing of SAC LA 3-Story SMRF nonlinear model

Open the experiment to interested researchers for thetesting of various control strategies



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Acknowledgements

NSF - Award CMS-0612661 (Pre-NEESR)

Lord Corporation NEES FHT staff at CU Boulder

NEESit staff


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Documents

Technological Frontiers in Smart Damping