Structural Dynamics - Seismic Response Control Laboratory

Structural Dynamics and the Seismic Response Control Laboratory
Room 122, Hudson Engineering Center
Department of Civil and Environmental Engineering
Edmund T. Pratt School of Engineering
Duke University - Box 90287, Durham, NC 27708-0287

Henri Gavin - Associate Professor - Henri.Gavin@Duke.edu - tel: 919-660-5201 - fax: 919-660-5219

Map and directions to the Hudson Engineering Center Map of the Duke Campus

An article in the October 2, 2002 issue of ABCNews.com
An article in the September 5, 2001 issue of Space.com
An article in the 1999-2000 issue of Duke Research
An article in the February 18, 2000 issue of the Duke Dialogue

The primary research activity at the Structural Dynamics and Seismic Response Control Laboratory (SD-SRCL) addresses the protection of structural systems from earthquake hazards through the use of devices with controllable damping and stiffness properties. The approach taken by researchers at SD-SRCL focuses on the use of electrorheological (ER) and magnetorheological (MR) suspensions. These fluids are highly sensitive to their electro-static (for ER) or magneto-static (for MR) environments. Specifically, when subjected to intense electric or magnetic fields, the visco-elastic and yielding properties of these materials increase by more than an order of magnitude. This change in physical properties occurs within milliseconds and is completely reversible upon removal of the field.

The SD-SRCL is one of six laboratories associated with Duke's Center for Applied Control. The central facility of the lab is a 1.3 meter by 1.3 meter hydraulically actuated shaking table. The shaking table can drive a 4 ton payload at 1 g, and with a velocity of 50 cm/sec. The lab's instrumentation includes digital data acquisition, real time digital signal processing and control, and an array of acceleration, velocity, displacement, force, and pressure sensors.

Specific projects currently undertaken at SD-SRCL include:

The characterization of visco-elastic and visco-plastic behaviors of electrorheological (ER) and magnetorheological (MR) materials under oscillatory shear and pressure-driven flow.
The design, testing, and modeling of devices using electrorheological and magnetorheological materials.
The synthesis of control algorithms tailored to the specific dynamics of electrorheological and magnetorheological devices.
The testing and validation of control systems using numerical simulation and physical experiments.

This work encompasses the disciplines of electro-magnetics, non-Newtonian fluid mechanics, rheology, earthquake engineering, non-linear structural dynamics, signal processing, and controls. Vibration control using devices with controllable damping and stiffness properties is often referred to as semi-active control because the device forces are controllable only within their passivity constraints. A feature of this approach is that the mechanical power regulated by these devices is orders of magnitude greater than the electrical power required to operate them.

Other activities underway at SD-SRCL include:

Instrumentation and monitoring of large scale structures for serviceability evaluation. This includes monitoring of ambient vibration (micro-g) at Duke's Free Electron Laser Laboratory (FELL).
System identification and parameter estimation of linear and non-linear dynamic systems.
Chaotic dynamics of high order dynamical systems.
Application of semi-active control methods for mechanical engineering and aerospace applications.

We gratefully acknowledge research support provided by:


National Science Foundation CMS Division	Ford Motor Corporation Scientific Research Laboratory	Oak Ridge Associated Universities	National Research Institute for Earth Science and Disaster Prevention	Nippon Shokubai Co., Ltd.	Bridgestone- Firestone