Implementation of the IoT Technology in Structural Health Monitoring of Bridges: Case Study

Bridges are regarded as the backbone of the transportation infrastructure; therefore, it is essential that bridges are sustained and kept open to traffic to avoid costly delays and road closures. The nature of fatigue loading on bridges caused by the passage of millions of automobiles and heavy trucks imposes severe loading conditions on them. This is in addition to the influence of severe environmental conditions represented mainly by temperature variations, freeze-thaw cycles, contaminated water, deicers, materials aging, and wearing. Moreover, frequent vehicle collisions on bridges may result in fires and damage to the bridge’s structural components. Structural health monitoring (SHM) of bridges is a reliable method for ensuring the integrity of the bridge and the success of systematic repairs and restorations that are typically conducted. It is an investigative technology that can detect significant problems and failure causes to take proactive measures before the occurrence of catastrophic failures. Using SHM technology, the bridge control unit and operators are immediately notified of any severe problems. The current boom in the Internet of Things (IoT) provides an ideal foundation for its integration in the SHM of bridges by enabling interconnection and continuous data-sharing among the monitored elements. A network of various types of sensors (strain gages, temperature sensors, cracks detection sensors, etc.) installed at pre-identified locations can collect and transmit data for processing by an onsite intelligent control unit. In accordance with the urgency of the bridge condition, the bridge management unit can access the control unit for routine evaluations. When bridge girders are damaged or deteriorated, it is common to reinforce them with carbon fiber-reinforced polymer (CFRP) composites. The effectiveness of this repair technique is dominantly dependent on the bond between the concrete and the CFRP composites. The SHM technology is utilized in such repair procedure to ensure that the CFRP composites are in full composite action with the structural member. This paper presents a case study of a long-term SHM with the aid of IoT technology of damaged prestressed concrete girders of a bridge repaired with CFRP composites and instrumented with multiple strain gages connected to a control unit that transmits the strain values and temperature variations to the bridge management unit for continuous assessment.