Major earthquakes can have a devastating impact on infrastructure. The effects of a severely damaged bridge, for example, are not limited to the tragedy that befalls people on it but extends to how the loss of access affects emergency services, evacuation efforts, and the transport of crucial supplies. Understanding how seismic activity impacts common bridge structures is therefore crucial, not only to build bridges that can withstand strong quakes, but how to prevent the failure of existing ones through effective reinforcement.

Though numerous models exist that are used to assess the resilience of bridge superstructures, for the most part, there are very few examples that examine how each part of the whole bridge structure behaves during large-scale earthquakes.

A team led by Professor Jun Murakoshi of Tokyo Metropolitan University has been studying detailed models that accurately reflect the real behavior of entire structures, with a focus on how they might inform new design strategies. They looked at the failure process and impact on load-bearing capacity caused by lateral shaking of an I-shaped girder bridge, a common bridge type with a span length of 30m, which consists of supported steel girders shaped to have a cross-section that looks like a capital "I" that carry a flat deck slab. They subjected their model bridge to the lateral forces commonly seen during quakes, considering the responses when the force was applied both in the longitudinal and transverse directions to the girders.