NEES earthquake simulation equipment development at RPI centrifuge
Ricardo Dobry, Tarek Abdoun, Mourad Zeghal, Thomas F. Zimmie
Rensselaer Polytechnic Institute, Troy, NY 12180
Ahmed-W. M. Elgamal
University of California, San Diego, La Jolla, California 92093
ABSTRACT
The existing 100 g-ton geotechnical centrifuge at Rensselaer Polytechnic Institute (RPI) has been selected as one of the experimental sites of the new Network for Earthquake Engineering
Simulation (NEES) supported by the National Science Foundation in the US. As part of this 4year effort that will be completed in September 2004, the in-flight earthquake simulation capability of the centrifuge will be significantly upgraded including an improved, Web-based data acquisition capability, and the facility will be networked with other earthquake engineering experimental and computational facilities. Teleobservation and teleoperation of centrifuge modeling experiments will be explored.
Rensselaer's centrifuge was commissioned in 1989 and started conducting physical model simulations of soil and soil-structure systems subjected to in-flight earthquake shaking in 1991. In this decade of successful operation, the facility has published results of about 360 earthquakerelated model simulations, served as the basis for 12 Ph.D. theses at RPI (10 Ph.D. theses in the last five years), contributed to the research of RPI faculty and students as well as of dozens of visiting scholars and outside users from the US, Asia, Europe and Latin America, and provided data and research results to many people and organizations around the world. This centrifuge earthquake research has been conducted with two existing one-dimensional in-flight shakers, which can accommodate respectively 90 kg and 400 kg payloads.
In addition to the 100 g-ton centrifuge located at the RPI campus, other equipment currently in use for in-flight model testing includes: (i) a 90-kg electrohydraulic 1D shaker, (ii) a 400 kg electrohydraulic 1D shaker, (iii) a 1D, 25.4Wx45.7Lx25.4H (cm) rectangular flexible wall laminar box model container, (iv) a number of rigid wall model containers, (v) in-flight static cone penetration (CPT) system, (vi) in-flight soil reinforcement system, (vii) static and dynamic loading actuators, (viii) instrumented shallow and pile foundation models and quay wall models,
(ix) LVDT, accelerometer, pore pressure, and earth pressure sensors as well as load cells and strain gages, (x) a 32-channel data acquisition system with 15 kHz sampling rate, (xi) miscellaneous peripheral equipment.
The new, upgraded earthquake engineering capability for the RPI centrifuge to be installed as part of the NEES effort includes: (i) a 2D in-flight earthquake shaker (two prototype horizontal components) and associated 2D laminar box container to allow for more realistic 2D modeling;
(ii) a four degrees of freedom (4D) robot capable of performing in flight operations such as construction and excavation, pile driving, ground remediation, cone penetration, and static and cyclic loading tests without stopping the centrifuge; (iii) a networked data acquisition system with
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Internet Teleobservation / Teleoperation capability, to be linked to the high-speed RPI Gigabit
Ethernet Backbone;(iv) two high-speed cameras and image processing software; (v) development of a new generation of advanced and improved sensors capable of providing a better resolution of the measured model response (being done in cooperation with the centrifuge facility at the U. of
California, Davis, also a member of NEES); and (vi) other equipment aimed at increasing the capability of the centrifuge to test a greater number and wider variety of earthquake engineering models.
Especially important in the vision embodied in this upgrading/networking project is the future use of dense arrays of advanced sensors and of high speed cameras to provide high resolution measured model response. In conjunction with the new networked data acquisition system with remote access capability, this is expected to allow for a qualitative change in the use of the data at
RPI and throughout NEES, including teleobservation, shared-used of data, test visualizations, system identification, numerical computations and development of model-based simulations. In addition, the requested equipment will allow for teleoperation/control over the Internet, which at the beginning will focus on the use of the robot before and in between shakings by remote observers. A specific teleobservation / teleoperation pilot project along these lines will be implemented with the participation of researchers and students at RPI and at the U. of California,
San Diego.
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