Key Upgrade at the NHERI OSU Wave Laboratory

New force balance plate measures wave and debris impacts on coastal structures

Published on August 23, 2022


Rendering of the submersible force balance plate.

The submersible force balance plate.

Researchers at the Oregon State University now have access to a submersible force balance plate for use in the Large Wave Flume or Directional Wave Basin. Balance plates are typically used to measure 6DOF (six-degree-of-freedom) forces and moments of animated bodies and structures subject to the action of fluid flow. At the NHERI OSU facility, the apparatus provides the ability to measure hurricane wave and tsunami forces and moments acting on coastal structures. Investigators exploring forces of breaking waves or the impact of waterborne debris on coastal structures will find it particularly useful, and several upcoming users have already requested it.

Due to its specialized use in the wave laboratory, the team at OSU worked in collaboration with Advanced Mechanical Technology Inc. (AMTI) to custom-design an underwater force balance plate (up to 5 meters in fresh water). The device is made of four tri-axial piezoresistive load cells and is oil-filled and pressure compensated. It has a vertical capacity of 54 kN (over 12,000 pounds), a horizontal capacity of 27 kN (over 6,000 pounds), and a footprint of 813 by 812 mm, providing massive capacity for bending moments.

The force balance plate will be used for the first time during a blind model study of wave impact forces on overhanging slabs. These experiments are scheduled in the the Large Wave Flume this fall and are part of the capacity building of the facility for upcoming NHERI projects.

Design of the new force balance plate at NHERI Oregon State University