Detecting hidden internal damage

Conventional inspection methods of bridges rely on direct visual checks and hammer tests, and judgments are made based on experience and intuition. Bridges with a certain level of deterioration can be hard to distinguish, with no discernible changes in the surface and the sound. With an increase in both the number and length of bridges over the years, this inspection method is becoming increasingly unrealistic.

The most significant aspect of Toshiba's structural health monitoring system is the brand-new sensing technology, which allows the system to visualize damage on the inside of the concrete, in areas where workers cannot see directly, and determine the level of deterioration. This technology provides the opportunity to prioritize bridges that needs urgent maintenance, and helps better the use of limited labor and budget.

The new sensing technology is elastic waves, a wave emitted by miniscule forms of damage in structures. The vibrations induced when a vehicle drives on the bridge causes several dozen to several hundred kHz worth of elastic waves to be emitted from cracks in the structures. The sensor measures these waves from where it is attached to the deck of the bridge, using a test called AE Method.

Toshiba sees potential in applying the AE method to roads, buildings, and even large-scale industrial machinery. For now, Toshiba will carry out verification tests, gather data, and improving system reliability, with an aim to reduce labor and cost for the maintenance of social infrastructure.