Shake Table Test Facility
The shake table platform is a pyramidal structure with a flat top of 3.5 m X 3.5 m driven by three actuators: one horizontal and two vertical. These actuators are of electro-hydraulic double acting culinder with double acting servo controlled low aspect ratio piston type. Each of these actuators is fitted with a 28 L accumulator on the pressure side and 1 L accumulator on the return side. The table also incorporates a preload facility of 200 kN thrust for supporting the dead load of table platform and pay load. The pressure for the shake table is supplied by an electrically driven hydraulic power pack containing an oversize water heat exchanger with a separate oil circulating pump to the oil reservoir and delivering to the actuators a maximum flow of 500 L/min by a variable displacement constant pressure controlled pump of 210 bar. The maximum thrust delivering capacity, maximum displacement, maximum velocity and maximum flow through the servo valve of each of these actuators is as follows:
|Specification(s)||Horizontal Actuator||Vertical Actuator|
|1. Thrust||(i) Static||250kN||150kN|
|2. Stroke||+/- 150 mm||+/- 150 mm|
|3. Velocity||1000 mm/sec||1000 mm/sec|
|4. Flow at maximum velocity||750 L/min||375 L/min|
A square grid pattern of bushes of special alloy steel is provided at 400 mm c/c on the top plate of the shake table platform for mounting test specimen on the table. Only four bushes are capable of carrying the maximum payload through static friction. The zero-period acceleration (ZPA) can be upto 3 g depending on the payload.
The digital control of the shake table is through INSTRON RS-8800 controller and it supported by a 128 channel data acquisition system to record dynamic response of the test specimen using accelerometers, LVDT, and strain gauges.