The Large Scale Structures Laboratory has two separate systems for the simulation of seismic mass, known as mass-rigs. The mass-rigs were born from the need for a safe and effective way of applying the correct inertial loads to test specimen.
The job of the mass-rig is to support the vertical load of the mass while allowing the required degrees of freedom to correctly load the specimen during shake table testing.
Uniaxial Mass-Rig Specifications
The uniaxial mass-rig consists of a moment frame in the out-of-plane (relative to experiment) and a sway frame in the testing plane.
The mass-rig provides 20 kips (89 kN) of lateral effective weight to which an additional 120 kips (533 kN) may be added.
The frame allows approximately ±15 inches (±381 mm) of displacement before the cable restrainers are engaged.
Biaxial Mass-Rig (BMR) Specifications
The BMR consists of a four-column frame that is installed onto the table. Atop the columns, a platform that rides on bearings carries the desired lateral effective weight.
A series of links then connect the platform to the test specimen. This arrangement allows specimens to be subjected to biaxial earthquake motions.
The BMR was designed to allow up to 90 kips (400 kN) of weight and ±15 inches (381 mm) of displacement.