Shake Tables
The University at Buffalo’s Structural Engineering and Earthquake Simulation Laboratory
(SEESL) equipment includes:
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A set of two high-performance, six degrees-of-freedom shake tables, (Shake Tables A & B)
which can be rapidly repositioned from directly adjacent to one
another to positions up to 100 feet apart (center-to-center). Loacted in Test Area 2.
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Together, the tables can host specimens of up to 100 metric tons
and as long as 120 feet, and subject them to fully in-phase or totally
uncorrelated dynamic excitations.
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Next to the shake tables, a large reaction wall equipped with external
dynamic actuators will allow application of computer-simulated forces
on shake table-mounted substructures, thus simulating the reaction
of the entire structure (Real-Time Dynamic Hybrid Testing, or RTDHT).
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Equipment required to operate the shake tables, including a high-capacity,
high-performance hydraulic supply and distribution system (up to
1600 gpm), and numerous digital control systems.
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Networked tele-experimentation capabilities using modular and expandable
teleobservation and teleoperation equipment, tied to the testing
systems using discrete and global sensors, including high-resolution
digital video and imaging capabilities.
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Located in Test Area 1, the 3.66 by 3.66 m shake table (Shake Table O) has six controlled degrees of freedom (excluding the transverse translational movement). The longitudinal (horizontal), vertical and roll degrees of freedom are programmable with feedback control to simultaneously control displacement, velocity, and acceleration. This shake table has been in use at the University at Buffalo for nearly 20 years. In 2004, it has been refurbished with a new controller and re-built actuators.
Detailed Views of the lab with dimensions
Shake table A& B specifications:
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The two shake tables located in Test Area 2 (Shake Tables A and B) are designed for the following theoretical
performance
Note: Nominal performance specifications are for continuous uniaxial
sinusoidal motion with 20-ton rigid specimen and without table extension. System performance
levels will be reduced with payloads larger than nominal and/or with table extension in place.
Table platform size w/o table extension: |
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Table size w/ extension platform in place: |
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50 ton maximum / 20 ton nominal |
Maximum specimen mass with table extension platform in place: |
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Maximum Overturning Moment: |
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Maximum Off Center Loading moment: |
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.1~50 hertz nominal/100 hertz maximum
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Nominal Performance: |
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Stroke: |
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Velocity: |
1250 mm/sec 1250 mm/sec 500 mm/sec |
Acceleration: |
±1.15 g ±1.15 g ±1.15
g (w/20ton specimen) |
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Table Design and Manufacture (quantity = 2)
- A 3.6 x 3.6 meter table platform of welded steel construction with a weight of approximately 8 tons. The table has a painted top surface.
- A 7 x 7 meter shake table extension platform of welded steel construction with a weight of approximately 9.8 tons. The extension has painted top surface.
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Parking Frame System
A Parking Frame System consisting of a welded steel frame with electric actuators raises the table for repositioning within the length of the trench. The carrier capable of raising the table with the (4) horizontal actuators, (2) actuator buttresses, and (4) vertical actuators is attached. A beam for securing the horizontal actuator buttresses to the table during movement. The carrier rides on polyurethane wheels for ease of positioning and tracks along a center rail embedded in the trench floor being moved with a winch system.
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Hydraulic Actuator Assemblies
1. Longitudinal (X and Y-axis) hydraulic actuator (quantity = 2
each axis)
MTS Model 244.4 Hydraulic Actuator with a dynamic force rating of
21 metric ton and a dynamic stroke of 300 mm (±150 mm). The
actuator assembly includes the following:
a. Hollow single piece rod
b. Model 256.25S servovalve rated at 1000 lpm
c. LVDT type stroke transducers
d. Swivel heads and bases
e. Close-coupled pressure and return accumulators
f. Differential pressure cells
2. Vertical (Z-axis) hydraulic actuator (quantity =4)
MTS Model 206.S Hydraulic Actuator with a dynamic force rating of
25 metric ton and a dynamic stroke of 150 mm (±75 mm). The
actuator assembly includes the following:
a. Hollow single piece rod
b. Model 256.18s servovalve rated at 650 lpm
c. LVDT type stroke transducers
d. Swivel heads and bases
e. Close-coupled pressure and return accumulators
f. Differential pressure cells
g. Integral static support with 20 ton capacity (total static support
capacity is 20 ton x 4 = 80 ton) will all necessary nitrogen supply
and control system
- Hydraulic Power Supply Subsystem
MTS Model 506.92 HPS (quantity =4)
Rated at 185 gpm (700 lpm) at 3,000 psi (207 bar) each.
Shake table O specifications:
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Physical data:
- The five degree-of-freedom shake table has payload capacity of 50 tons and a useful frequency range of 0 to 50 Hz. The table is normally furnished with a reinforced concrete testing platform of 6.1 m by 3.66 m plan dimensions that extends the useful testing area beyond the table's dimensions but limits the payload to 42.5 tons. The testing platform has holes on a one foot square grid for attaching test specimens.
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Capacity data:
- The five degrees-of-freedom shake table is designed for the nominal performance shown in Table 2. These performance data are based continuous uniaxial sinusoidal motion with 20-ton rigid specimen. System performance levels will be reduced with payloads larger than nominal.
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50 ton maximum / 20 ton nominal |
Maximum Overturning Moment: |
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Maximum Off Center Loading moment: |
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Nominal Performance: |
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Stroke: |
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Velocity: |
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Acceleration: |
±1.15 g ±2.30
g (w/20ton specimen) |
Shake Table Drawings
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