Post-Earthquake Shift Detection: A Solution for Buildings That Kill

IN-PART’s Technology of the Week #42

Toppling walls, crumbling ceilings and piles of rubbles are often the aftermath of a major earthquake. But what about the buildings that remain standing? What risk do they pose for their occupants?

Engineers at a research institute in the United-States have designed an apparatus that can rapidly and accurately assess a building’s response to quakes. By measuring the post-earthquake shifts between two neighbouring floors, dubbed ‘interstory’, the device could be a life-saving mechanism for many living in areas prone to earthquakes.

The device, called ‘Interstory Drift Meter System’, is not only highly accurate, it also allows rapid measurement of interstory drift between the floor levels of a shaking building and can also be used to monitor potential damage to bridges.

During an earthquake, buildings shake and sway to dissipate the energy of the quake. How buildings withstand these shocks depends on various factors such as the building’s flexibility, the type of surface it sits on and the material the building is made of.

Solutions that limit the impact of earthquakes are based around constructing buildings that can absorb energy through their heights, and design devices that can rapidly and accurately assess the risk that buildings previously exposed to a quake pose to human safety. In geologically active zones where tremors are frequent, it is crucial to know whether buildings are safe for its occupants. This given, the need for devices such as the Interstory Drift Meter is very high.

But what makes this device so valuable? The new instrument developed by US researchers consists of an array of diodes, one of which is a laser source and the other a position sensitive detector. When the beam moves back and forth during an earthquake, the detector records the magnitude of this displacement, allowing specialists to make informed post-quake re-occupancy decisions.

Current procedures to assess building safety involve visual inspection by a structural engineer, an often inefficient solution due to the availability of qualified engineers and the time taken to assess a building. The sensitivity of the new device makes it an incredibly reliable tool which would thus remove the need for visual inspection.

Previous seismic research only focuses on assessing the effect of ground motion on different building materials such as concrete, steel, and plasterboards. But studies looking at ways to accurately analyse the relative movement of adjacent floors are scarce, making this new system the first of its kind.

After devastating earthquakes such as in Nepal last year and last week in central Italy, such systems make invaluable tools in the densely built urban environment.

The researchers developing this innovation have filed an international patent application and are looking for partners in industry for collaboration and licensing. More information about the device can be found via the following link after free registration to IN-PART’s industry-exclusive platform.

Written by Margaux Lesaffre,
IN-PART’s Community Engagement Officer