Facilities › MAST System

Key features of the MAST System include:

Versatile large-scale structure testing apparatus

• Ability to conduct multi-axial quasi-static cyclic testing, quasi-static pseudo-dynamic testing, and continuous pseudo-dynamic testing on large-scale structural subassemblages including portions of beam-column frame systems, walls, bridge piers, abutments, towers, and other structures.
• Accommodates test specimens up to approximately 20 ft. (6.1 m) long and 28.75 ft. (8.7m) high. Longer test specimens may be managed by placement along the diagonal.
• Displacements of up to ±20 inches (±508 mm) and loads up to ± 1,320 kips (±5,900 kN) can be achieved in the vertical direction. Displacements of up to ±16 inches (±406 mm) and loads up to ±888 kips (±3,900 kN) can be achieved in each of the two horizontal directions.

Sophisticated control with ease of use

• Advanced six-degrees-of-freedom (6-DOF) servo-hydraulic control system, designed by MTS Control Systems, allows researchers to control the crosshead and specify the three translational three rotational DOFs in either displacement or mixed-mode control. DOFs may be constrained by a master-slave relation to be a linear combination of the values of other DOFs.
• Customized hydraulic control software is powerful yet simple to use, providing a comprehensive interface for researchers to interact with the MAST hardware controller.

Crosshead loading element

• The 6-DOF forces are transferred through the rigid steel crosshead (94,000 pounds) to the specimen, which is bolted to the underside of the crosshead and the strong floor. The actuators move the crosshead to apply desired loads and deformations.
• Strategically positioned mounting holes at the bottom of crosshead allow maximum flexibility for attaching test structures.

Actuator system

• Four ± 330 kip vertical actuators connect the crosshead and the strong floor and have a stroke of ± 20 inches. Vertical spacers can be used to vary the height of the crosshead.
• Four ± 440 kip horizontal actuators connect the crosshead and the L-shaped strong wall, with one pair in the lateral Y direction and one pair in the longitudinal X direction. Each pair provide lateral loads up to ±880 kips in the orthogonal directions with strokes of ± 16 in.
• Four ± 220 kip (± 975 kN) ancillary actuators with a displacement range of ± 10 inches (± 254 mm) permit displacements or loads at other locations on the test specimen.

Highly configurable reaction system

• The MAST reaction system is composed of an L-shaped strong wall and a strong floor, each seven feet thick and designed to accommodate a wide range of test structures. A prefabricated steel grid was used in their design, permitting precise placement of the holes used to tie down specimens.

Six Degrees-of-Freedom Control Technology

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Six Degrees of Freedom: isometric of crosshead positioned in strong walls

The MAST System's 6-DOFs (vertical, lateral, longitudinal, yaw, pitch, and roll) are driven by a sophisticated MTS controller. The controller seamlessly converts controls in six degrees-of-freedom space into drive commands for each of the eight actuators, accounting for geometric nonlinearity.

The controller provides mixed-mode control, which allows each DOF to be controlled either in displacement or force control. Moreover, the controller can slave any DOF to any combination of other DOFs. This technology opens up a wide range of testing possibilities. For example, the mixed-mode control features can be used to specify a lateral displacement history in the horizontal plane while maintaining a constant gravity load or varying axial load on the subassemblage to simulate overturning load effects.

In addition, moments can be controlled about orthogonal axes to simulate specified moment-to-shear ratios that would correspond to assumed lateral load distributions on the structural subassemblage. Rotation or moment about the vertical axis can be controlled to eliminate or simulate limited torsional effects on the test structure. Furthermore, the MAST System can test planar assemblies in a straightforward manner, which in traditional laboratory setups often requires cumbersome ancillary lateral framing schemes to constrain out-of-plane effects. At the MAST Lab, the 6-DOF control can be used to eliminate out-of-plane deformations.

Hydraulic Control Computer (HCC)

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In-house developed hydraulic control software, specialized for ramp and hold type test

Hydraulic control software (HCC) was developed in-house as the principal means of controlling the MAST System actuators. The HCC interfaces with the control software provided by MTS Systems to present a heads-up display of the system status and to enable control of the system using a ramp and hold protocol.

The target endlevels describing the new position or force level of the crosshead and ancillary actuators are input along with the time period to reach those levels. The MAST System operator then sets the move command and ramp function in order to achieve the desired endlevels.

Features of HCC include:

System Capacity

Non-concurrent Capacities of MAST DOFs

Main Actuators

Ancillary Actuators

Crosshead

Strong Wall

Strong Floor

Overview Literature

• Actuator System
• MAST Crosshead
• Strong Wall/Strong Floor
• Pump Room/Cooling Tower

Manuals & Guides

• Researcher's Resource Guide (pdf, 1.0MB)
• HCC User Guide (pdf, 1.9MB)

CAD Drawings

Below are links to as-built CAD drawings of the MAST System components. The files are either dwg or dxf format. CAD software such as AutoCAD or Autodesk is required to view these files.

• Crosshead
• Strong Floor
• North Strong Wall
• West Strong Wall
• Test Space Limitations (dwg)
• Test Space Limitations (pdf)

Geometric Limits of Crosshead Movement

We have prepared several Excel spreadsheets (one for each crosshead position) to help users calculate the geometric limits of the crosshead.

Because of the interactions between actuators due to the large possible movements, the reachable movement limits in the six-degrees-of-freedom space may be less than the limits for the individual actuators. The limits depend on the number of spacers in the vertical actuators.

• Download geometric limits spreadsheet.

Introductory Videos

These introduction videos were put together to showcase the capabilities of the MAST system.

• MAST Laboratory Video Presentation - 15 MB
• Capabilities Overview - 20.6 MB

Time Lapse Videos

These time lapse videos demonstrate the six degrees-of-freedom control motions of the MAST system. The video speed is about 16 times normal speed. These videos are available in both their original format and zipped up files to reduce file size.

• Floor View: 7.6 MB
• Crosshead Level: 7.1 MB
• Aerial View: 7.9 MB

Animations