Steel wires strengthen cable trays in full-scale earthquake tests

The shaking table began moving beneath a suspended cable tray system more than 10 meters (33 feet) long. In tests led by Professor Kazuhiro Matsuda at Meijo University, the equipment designed to hold the trays in place largely survived. The trays did not: under strong shaking, they deformed and suffered significant damage, making them the system's weakest link.

That distinction matters in buildings where cables carry power and communications. Hospitals, airports, factories, government facilities and data centers can remain structurally safe while damaged building services interrupt operations or injure occupants. The research team, which included Eisaku Asatsuma of Negurosu Denko, Professor Kazuhiko Kasai of Tokyo Institute of Technology and Professor Huanjun Jiang of Tongji University, was responding to lessons from the 2011 Great East Japan Earthquake, when nonstructural damage caused widespread disruption.

The proposed fix is deliberately simple. A single steel wire is laid alternately in diagonal and transverse directions, with the direction changing at seismic-resistant elements and at the midpoints between them. The researchers say this helps the wire accommodate the tray's movement and avoids the slippage that limits a diagonal-only arrangement. Laboratory tests found that reinforced trays performed substantially better than conventional designs.

So what changes in practice? Building owners could have a lightweight, inexpensive way to strengthen cable trays without major structural modifications, including in existing facilities where replacing an entire system would be disruptive. That could help preserve electrical and communication services during severe earthquakes. The method is not yet a field deployment: the evidence comes from full-scale shaking-table and additional loading tests, so its performance in operating buildings still needs to be established.