Shake Tables

Test specimin 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

Table without extension

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: 1250 mm/sec 1250 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 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.
  • 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:
    • MTSL Model 506.92 HPS (quantity = 4)
    • Rated at 185 gpm (700 lpm) at 3,000 psi  (207 bar) each.

Table Drawings

overall view drawing of table

Overall View

top view drawing of table extension platform

Top View of Table Extension Platform

drawing of table extension platform

Plan View of Table Extension Platform

Drawing of top of table

Top View

Drawing of bottom of table

Bottom View

side view drawing of table

Side View

drawing of mounting bolt details

Mounting Bolt Details