Loading and Boundary Condition Boxes (LBCB)

The LBCBs utilize six actuators each, hence for three independent boxes, a total of eighteen actuators are required.  The question arises: why use LBCB boxes and not the eighteen independent actuators? The response to this question lies in the efficiency and modularity of the testing system.  By utilizing each six actuators inside a box with a contact platform, the system is configured and calibrated only one.  It is then 'sealed' for use at any location within or outside of the Newmark Laboratory with no further adjustments required.  The setup time for tests using the LBCBs is therefore minimized.  A researcher requiring use of the NEES facility has no need to design a detailed set of contact points and the LBCB platform is a loading and boundary conditions point where any combination of six actions (three forces and three moments) and six movements (three rotations and three translations) may be controlled through the readily available software.  The six DOF boxes may be attached at the bottom (on the strong floor), on the side (on the reaction wall) or at the top (through an A-frame reacting onto the strong floor) of test specimens.  Further, the boxes also serve as suitable storage units for the actuators when not in use, thus minimizing clutter in the laboratory space and reducing maintenance costs for the actuators and the swivel joints.

Layout of 6 DOF LBCB.

Each LBCB provides six degree-of-freedom control and consists of a reaction box, six actuators (960/1459 kN tension/compression) and a loading platform. The overall dimensions of the reaction box are approximately 3.6 m long, 1.8 m wide and 1.8 m high. The loading platform is approximately 2.7 m long and 1.2 m wide. Three vertical actuators are used to control the z, theta-x (roll) and theta-y (pitch) position of the loading platform.  Each of these actuators is anchored to the base of the reaction box and attached to the underside of the loading platform.  Two horizontal actuators that are attached to the end of the reaction box are used to control the x and theta-z (yaw) position of the loading platform.  One additional horizontal actuator is used to control the y-direction position of the loading platform. Pillow Block Spherical Bearings have been selected so that the motion of the loading platform is not unduly restricted in any of the six degrees of motion.

The LBCBs are uniquely designed to be portable so that they can be anchored on any reaction structure that has a compatible arrangement of anchorage holes.  This design facilitates the use of the LBCB at the Geotechnical Testing Site in Rantoul, Illinois.