Which structural failure mode most critically challenged the integrity of elevated Roman aqueduct arches during seismic events?

💡 Explanation

During seismic events, shear stress concentrations at keystone joints occur because arches transfer loads unevenly under lateral acceleration, potentially causing cracking and collapse at the keystone. Therefore, keystone shear failure is critical, rather than tensile failure, liquefaction, or buckling which represent different mechanisms and environmental factors.

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