Julie Thurston Research Assistant Department of Civil and Environmental Engineering Duke University - PowerPoint PPT Presentation

Loading...

PPT – Julie Thurston Research Assistant Department of Civil and Environmental Engineering Duke University PowerPoint presentation | free to download - id: 95ce0-ZmRlM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Julie Thurston Research Assistant Department of Civil and Environmental Engineering Duke University

Description:

Julie Thurston. Research Assistant. Department of Civil and Environmental Engineering ... Schenck-Pegasus 4900 digital servo-hydraulic controller ... – PowerPoint PPT presentation

Number of Views:76
Avg rating:3.0/5.0
Slides: 22
Provided by: michaelt86
Learn more at: http://www3.nd.edu
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Julie Thurston Research Assistant Department of Civil and Environmental Engineering Duke University


1
Julie Thurston Research Assistant Department of
Civil and Environmental Engineering Duke
University
  • Advisor Dr. Henri Gavin
  • Structural Dynamics and the Seismic Response
    Control Laboratory

2
Duke University
  • Duke is a private university located in Durham,
    North Carolina. Established in 1924, it
    currently has a student population of 6300
    undergraduates and 4500 graduate and professional
    students.

3
Structural Dynamics Laboratory
  • Duke's structural dynamics laboratory features a
    wide array of sensors, actuators, and data
    acquisition systems for precise dynamic loading
    and response measurement of structural systems.
    The central facility is a single-axis,
    servo-hydrualic shaking table (50kN, 50cm/s,
    0-60 Hz, 15cm stroke, 5 ton payload).

4
SD-SRCL Shaking Table Properties
  • 1-axis, horizontal ... plan area 121 cm by 121
    cm table weight 210 kg.
  • Schenck-Pegasus 4900 digital servo-hydraulic
    controller
  • Shore-Western actuator 912-3.68-6.0-4-38 5
    ton, 15 cm stroke capacity.
  • Schenck-Pegasus servovalve model 142M, 38
    liter/minute
  • system velocity limit 50 cm/s
  • system integration Simulation Technologies, Inc.

5
Research Topics
  • ER/MR Materials
  • Vibration Control Devices
  • Vibration Control Algorithms and Shake-Table
    Testing

For additional information please
see http//www.duke.edu/hpgavin/research.html
6
Large-Scale Shake Table Testing of Semi-Active
Damping Devices
  • Julie Thurston
  • Department of Civil and Environmental Engineering
  • Duke University

Young Researcher Symposium Tokyo, Japan June, 2002
7
Introduction
  • Semi-Active damping allows us to control the
    damping properties of a structure in order to
    achieve minimum response during a seismic event

Limit base drift interstory drift floor
accelerations
  • Various configurations and types of dampers will
    be tested

8
Introduction (continued)
  • Testing will occur this summer in Tsukuba, Japan
  • National Institute for Earth Sciences and
    Disaster Prevention (NIED) testing facilities

9
Preparations for Experiments
  • Generate computer model of test frame to simulate
    response
  • Model damping characteristics of the structure
  • Determine scaling properties of model-to-prototype

10
Test Frame Elevations
x-z direction
y-z direction
3-story steel moment frame structure
11
Computer Model
  • First mode shape
  • fc 0.331 Hz

12
Damping Characteristics
  • Rayleigh Damping
  • Objective 2 damping ratios in all modes
  • Calculate constants a and b
  • Linear Least Squares

13
Damping Characteristics (continued)
  • Choose 4 frequencies and solve for constants

14
Damping Results
Damping ratio vs. frequency
Damping frequency values
15
Scaling Relationships
  • Maximum Table Displacement 22 cm
  • Maximum Table Velocity 100 cm/s
  • Model Floor-to-Floor Height 1.8 m
  • Prototype Floor-to-Floor Height 3 m
  • Length Scale Factor 0.6
  • Maximum Prototype Disp. 36 cm

16
Scaling Limitations
  • Time Scale Factor
  • Ground acceleration relationship is preserved
  • Earthquake acceleration must not be scaled
  • Length Scale Factor 0.6
  • Time Scale Factor 0.775

17
Loma Prieta Earthquake Example
  • Maximum ground displacement 70 cm
  • Table disp. 0.6 (70 cm) 42 cm gt 22 cm
  • Scale factor resulting from this disp
  • Earthquakes must be modified to accommodate table
    restrictions

18
Displacement Calculations
  • Displacements double integral of acceleration
    records
  • Fast Fourier Transforms
  • Filter out low frequency components
  • Corrupted data caused by electrical drift and
    sensor noise
  • Typical frequency cut-off 0.05 Hz
  • Increase cut-off freq. until maximum
    displacements fit table requirements

19
Results
  • Low frequency cut-off values and corresponding
    table displacements
  • Note 0.22 Hz 4.5 second period

20
Testing Objectives
  • Develop control rules to obtain maximum
    performance of damping devices
  • Evaluate performances of varying devices and
    configurations
  • Compare results to responses using a passive
    damping system

21
Acknowledgements
  • Dr. Henri Gavin, Duke University
  • Dr. Chikahiro Minowa, NIED
  • Dr. Hideo Fujitani, BRI
  • Natural Hazard Mitigation Program
  • National Science Foundation and the Summer
    Institute Program
About PowerShow.com