Shake Table Laboratory
Figure 1. Columbia University Medium-Scale Dynamic Shake Table Facility in the Carleton Strength of Materials Laboratory
The Department of Civil Engineering and Engineering Mechanics has recently acquired a medium-scale shake table facility to conduct experimentation in structural dynamics and particularly how to monitor and actively control structures subjected to earthquake ground motions or other force excitations. The table, which was custom designed by ANCO Engineers for the Department, is capable of carrying a maximum 3-ton payload on the 5ft x 5ft table, and is capable of shaking a 2-ton payload with 3 g acceleration (i.e. three times the acceleration of gravity in the horizontal direction). The shake table is ideally suited to seismic applications, because the hydraulic actuator can produce a stroke of +/- 5 inches (10 inch total stroke). The actuator has a 3-stage servo-valve controlled by an analog inner-loop control system (displacement based), and a digital outer-loop control system (acceleration feedback based).
Figure 2. Design Spectrum of the Columbia Univ. Shake Table for 2-ton Payload. (Actual Performance Exceeds Design Spectrum)
Summary of Key Features
- Uniaxial horizontal motion
- 5ft x 5ft steel table
- Dual roller- rail bearings to guide table
- Peak-to-peak displacement of 10 inches double amplitude
- Peak velocity of 60 in/sec
- Peak acceleration (with 2-ton test specimen) of 3.0g
- Maximum test specimen weight of 2 tons
- Frequency range 0-100Hz (design) (Actual performance exceeds this spec.)
Data Acquisition System
The current data acquisition system includes the Data Physics digital controller, Microstar Labs and National Instruments data acquisition cards. Most of the data pre- and post-processing is performed in MATLAB on 2 dedicated computers which are also network accessible.
Figure 3. Data Acquisition and Table Control Computers. (Hydraulic Accumulators in Background).
Figure 4. Close-up of the 22 kip
actuator with its
3-stage servovalve.
For further information contact Andrew Smyth at +1.212.854.3369.