Available Technology

Optically-based Interstory Drift Meter System for Rapid Assessment of Earthquake Response of Buildings and Structures

Immediately after the occurrence of a major earthquake, there is a strong motivation for developing a rapid assessment of the degree to which a building or structure has been shaken, and for determining if significant damage has occurred to the building or structure. This is particularly important given that external visual observations of the building cannot reliably indicate whether there has been significant damage to the building’s structural system over the duration of the seismic shaking. In addition to uncertainties related to the risk to human safety, an inability to rapidly assess building integrity can have a major impact on timely re-occupancy and resumption of functional operations. In an urban environment, where literally thousands of buildings can be shaken in a major earthquake, there is an immediate and enormous demand for understanding whether a large inventory of buildings/structures present occupant safety risks. Typical procedures for engineering inspections are time consuming and constrained by lack of availability of a sufficient number of qualified structural engineers after a major earthquake – a lesson learned in California’s Loma Prieta earthquake in 1989. A system that can immediately and efficiently yield data on the integrity of a building/structure would be useful for informing appropriate post-earthquake actions in a densely built urban environment. A fundamental measurement of building response during an earthquake is the building interstory drift, which is computed as the relative displacement between two adjacent floors of a building. Interstory drift is a measure of the deformation and stress demand on a building system and represents fundament design variable in many seismic design codes.
Patent Abstract: 
LLNL’s Optically-based Interstory Drift Meter System provides a means to accurately measure the dynamic interstory drift of a vibrating building (or other structure) during earthquake shaking. This technology addresses many of the shortcomings associated with traditional strong motion accelerometer based building monitoring.
Internal Laboratory Ref #: 
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