Remote Structural Infrasound: Case Studies of Real-Time Infrastructure System Monitoring

Abstract

Infrastructure in the continental United States is often used beyond its design life due to budgetary constraints and logistical hurdles. New structural health monitoring techniques have been developed to mitigate the increasingly constrained resources available by identifying the potential need to repair and retrofit aging infrastructure from modal signatures. Large structures, such as bridges and dams, emit infrasound (acoustic energy below that of human perception) at their natural modes of vibration, which can be related to structural health and capacity; this infrasonic energy can propagate tens of kilometers from the infrastructure. Currently, the determination of structural health requires intensive hands-on measurements of individual elements at repeated intervals. Persistent, remote infrasound assessment provides a method for standoff assessment of the modal behavior of structures for structural health monitoring and damage assessment. Case studies and demonstrations of this technology are presented for water control infrastructure systems, transportation infrastructure systems, and riverine infrastructure systems.