Shake Tables

Test specimen on shake table with extension.

For earthquake simulations, one of the services we provide are shake tables. Currently, there are two, relocatable, 7.0m x 7.0m platforms with six-degrees of freedom. Each table is capable of 50 tons payload.

Overview

Shake table without the extension

Two high-performance, relocatable, six-degrees of freedom shake tables are located in a trench along the north wall of the main laboratory.
The tables can be controlled either independently or as a single, synchronized table. Together, the tables can support specimens weighing up to 100 metric tons with a length up to 120 feet.
Synchronized table motions can be fully in-phase or uncorrelated.
Adjacent to the shake tables, a large reaction wall equipped with dynamic actuators allows the 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).
The equipment to operate these shake tables include a high-capacity, high-performance hydraulic supply and controller along with numerous digital control systems.

Technical Specifications

The tables are designed with the following theoretical performance:

Note: Nominal performance specifications are for continuous uniaxial sinusoidal motion with 20-ton rigid specimen and without the table extension. System performance levels will be reduced with payloads larger than nominal and/or with the table extension in place.

Table platform size w/o table extension:	3. 6 meter x 3.6 meter
Table size w/ extension platform in place:	7 meter x 7 meter
Maximum specimen mass:	50 ton maximum / 20 ton nominal
Maximum specimen mass with table extension platform in place:	40 ton maximum
Maximum Overturning Moment:	46 ton meter
Maximum Off Center Loading moment:	15 ton meter
Frequency of Operation:	.1~50 hertz nominal/100 hertz maximum
Nominal Performance:	X, Y, and Z axes
Stroke	±.150 m ±.150 m ±.075 m
Velocity:	1,250 mm/sec 1,250 mm/sec 500 mm/sec
Acceleration:	±1.15 g ±1.15 g ±1.15 g (w/20ton specimen)

Table design

A 3.6 x 3.6 meter table platform of welded steel construction with a weight of approximately 12 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.
A parking frame system, consisting of a welded steel frame with electric actuators raises the table from repositioning within the length of the trench. The carrier is capable of raising the table with the (4) horizontal actuators, (2) actuator buttresses, and (4) vertical actuators are attached. A beam for securing the horizontal actuator buttresses to the table during movement. The carrier rides on the polyurethane wheels for ease of positioning and tracks along a center rail embedded in the trench floor being moved with a winch system.

side view of shake table.

Side view of shake table, without extension

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:
    - Hollow single piece rod
    - Model 256.25S servo valve rated at 1000 lpm
    - LVDT type stroke transducers
    - Swivel heads and bases
    - Close-coupled pressure and return accumulators
    - 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:
    - Hollow single piece rod
    - Model 256.18S servo valve rated at 650 lpm
    - LVDT type stroke transducers
    - Swivel heads and bases
    - Close-coupled pressure and return accumulators
    - Differential pressure cells
    - Integral static support with 20 ton capacity (total static support capacity is 20 ton x 4 = 80 ton) with 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.

Table Drawings - PDF

Bare table hole pattern

Table and table extension hole patterns

Table extension frame

Double shake table and bridge

Table extension walking mesh

Shake table dimensions and clearances

Testing frame Drawings for the testing frame for ceiling tiles, walls, pipes, and other configurations.

Testing frame for both tables and bridge Drawings to include the testing frames on both tables and the bridge spanning both tables.

Sides of test frame Drawings for the testing frame's sides.

Research Projects

Achieving Resilient Multi-Span Bridge by using Buckling-Restrained Braces
6/16/22
The concept uses inexpensive braces called Buckling Restrained Braces (BRBs) and sliding bearings that work together to protect the bridge columns and superstructure from damage, so that the bridge can withstand the three-dimensional ground motions caused by earthquakes.
Experimental investigation of a mid-height seismic isolation for slender safety-class equipment in advanced nuclear power plants
6/3/22
Recent studies have shown that the seismic load case can substantially increase the overnight capital cost (OCC) of safety-class equipment in advanced nuclear power plants.
Earthquake simulator experiments for validation of numerical models for seismic fluid-structure interaction analysis of advanced reactors
5/26/22
An experimental program using a 6 degree-of-freedom earthquake simulator at the University at Buffalo was executed to generate data for supporting validation of numerical models for seismic fluid-structure interaction analyses of conventionally supported and base-isolated advanced reactor vessels.
Analytical and Numerical Studies of Seismic Fluid-Structure Interaction in Liquid-Filled Vessels
9/2/20
Seismic design, qualification, and risk assessment of liquid-filled advanced nuclear reactors will rely on verified and validated numerical models for seismic fluid-structure interaction (FSI) analysis.
Combined Horizontal-Vertical Seismic Isolation System For High-Voltage Power Transformers
2/25/19
A three dimensional seismic isolation system was developed and experimentally validated for high-voltage electric power transformers of weight in the range of 300 to 800kip. Although the validation concentrated on electrical transformers, the system is currently (2019) under construction in a hospital in California.
Open Space Damping System
2/25/19
A novel configuration for damping devices with the main advantage of preserving open space within the frame of installation was developed and tested. The acquired test data were used for validating analytical and computational models.
NEESWood: Development of a Performance-Based Seismic Design Philosophy for Mid-rise Woodframe Construction
2/25/19
A full-scale, two-story, light-frame wood townhouse building, designed according to modern US engineered seismic design requirements, was tested on two tri-axial shake tables operating in unison, as part of the testing program defined for the NEESWood Project.
Hybrid Sliding-Rocking (HSR) Segmental Bridges
2/23/19
A novel damage-resistant system that combines accelerated bridge construction (ABC) with seismic resilience and is suitable for applications in seismic areas.
Seismic Retrofit of Pipelines with CIPP liners
2/22/19
Seismic response and failure mechanism of ductile iron push-on joints retrofitted with two different types of cured-in-place-pipe (CIPP) liners are investigated to verify and quantify the contributions of the liners to the seismic performance of the buried pipelines.
Seismic Protection of Electrical Transformer Bushing Systems by Stiffening Techniques
2/22/19
The addition of flexural stiffeners on the transformer cover plates was explored as a means to stiffen the base of the bushings and mitigate their seismic vulnerability. Numerical and experimental studies were conducted as part of this project.