The components of the UPRM Shaking Table facility can be summarized in the following:

  1. Reaction Frame
  2. Simulator Rigid Platform
  3. Linear Roller Bearings
  4. Hydraulic Power Unit
  5. Servovalve and Actuator
  6. Servo-Controller


1. Reaction Frame

The entire simulator platform system (platform, linear bearing system, actuator and servovalve) are fixed to the reaction frame. The reaction frame provides a place for the actuator’s force to react. Figure 1, illustrates the reaction frame. The reaction frame is at the same time fixed to the Structural Laboratory’s strong floor.


Figure 1. UPRM Reaction Frame.

2. Simulator Rigid Platform


The simulator platform attached to the actuator system is shown in Figure 2. The simulator platform provides the surface for model attachment. It is mounted through a system of linear bearings to the reaction frame and its motion is controlled by the movement of the actuator.

(a)            Frame of the simulator platform


 (b) Simulator Platform with bolted steel plates.

Figure 2. UPRM Simulator Platform.

The plan dimensions of the platform were selected as 228.6 cm (7.5 ft) by 137.2 cm (4.5 ft) with the longer dimension in the translating direction. These dimensions are more than sufficient to accommodate the 137.2 cm (4.5 ft) by 91.44 cm (3.0 ft) plan dimensions of the 1:4 scale test structure. The simulator platform weighs approximately 9.79 kN (2,200 lb) and consists of a bolted steel frame built with three longitudinal wide flange beams, W10x33, four diagonal tube section beams at the corners, ST 3x3x0.25, and three 1.91 cm (0.75 in) thick steel plates at the top.


3. Linear Roller Bearings

The linear bearing system, shown in Figure 3, provides the sliding surface for the simulator platform to move with low friction. Figure 3 shows the Linear Bearing System consisting of four individual Crossed Roller Tables acting as a group. This was accomplished with an efficient leveling procedure.


Figure 3. UPRM Linear Bearing System.

The support method utilized to provide the sliding surface for the simulator platform is supplied by four-high accuracy, high-load capacity, preloaded and low-friction Crossed Roller Slide Tables (Steel). Model NBT-6310 Crossed Roller Slide Tables were chosen due to its long travel, high-load capacity and low friction

coefficient of 0.003.


4. Hydraulic Power Unit and Hydraulic Service Manifold

Hydraulic power systems typically consist of an arrangement of hydraulic power supplies, remote service manifolds, and accessory equipment. These components integrate into a hydraulic power distribution network to provide hydraulic fluid power to servo-controlled actuators. Figure 4 shows the HPU which creates the hydraulic power to move the simulator platform. The hydraulic power unit provides the distribution system with constant-pressure, high filtered hydraulic fluid power.


Figure 4. UPRM MTS 506.61 Hydraulic Power Unit.


The Hydraulic Power Supply (pump) installed in the laboratory is a MTS Model 506.61 and is rated at 265.0 l/min (70 gpm) of steady flow [24]. A Hydraulic Service Manifold (HSM) MTS Model 293.11, with a rated capacity of 190.0 l/min (50 gpm), is mounted between the HPS and the servovalves.



5. Hydraulic Service Manifold


Service Manifolds provide hydraulic accumulation and filtering functions for individual actuators in a system. Hydraulic hoses provide connection of components within the hydraulic power distribution on system. Figure 5 shows the HSM which distributes the hydraulic fluid from the HPU to the actuator.



Figure 5. UPRM MTS 293.11. Hydraulic Service Manifold.


6. Servovalve and Actuator


The servovalve shown in Figure 6 provides the final control element in a closed loop servo-hydraulic system. The servovalve ports the fluid, provided by the hydraulic power system, into the appropriate side of the actuator’s chambers. This causes the actuator’s piston to move the actuator’s arm in the desired direction.


Figure 6. MTS 252.25 Dual Servo-valves.


The servovalves, dual MTS Model 252.25 two-stage servovalves, are rated at 56.0 l/min (15gpm) each for a total of 112.0 l/min (30gpm) maximum flow.


7. Linear Hydraulic Actuator


The linear actuator consists of a cylinder that contains a piston. The LVDT, which measures displacement, is inside the piston rod. The linear actuator system also consists of a load cell transducer, which measures force. Figure 7 shows the linear hydraulic actuator.


Figure 7. MTS 244.11 linear hydraulic actuator.


The movement of the actuator piston rod is accomplished by supplying high pressure hydraulic fluid to one side of the actuator piston (actuator’s chamber) and opening the other side to the return line. The force rating of a linear actuator is equal to the effective piston area times the actuating pressure. The maximum flow rate available

also determines the maximum simulator platform velocity. The load cell is connected at the end of the actuator’s piston rod and in turn to a swivel mounting head. The swivel head connects the actuator-load cell system to the simulator platform, as illustrated in Figure 7.


The actuator MTS Model 244.21 Hydraulic actuator is rated at 48.93 kN (11 kips) and with an effective area of 25.16 cm2 (3.90 in2) and a stroke of ±7.62 cm (± 3.00 inches).


8. Servo Controller


The MTS FlexTest-60 Servo-controller consists of a one Model 494.06 Chassis that contains controller hardware and a computer workstation that runs MTS controller applications. The Servo-controller uses Series 793 Software to operate and the software is run by the Control computer. The system control is provided by a fully digital proportional, integral, derivative, feed forward (PIDF) Servo-controller algorithm.

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a) front view                b) back view.

Figure 8. MTS FlexTest-60 Servo-controller