Structural Health Monitoring of the Tech 21 All-Composite Vehicular Bridge

摘要

Ohio's first all-composite bridge, christened the Tech 21 Bridge, was installed on Smith Road in Butler County in July 1997. The bridge superstructure is made entirely of continuous E-glass reinforcement in a polyester matrix. Two-lane vehicular bridge is 10.1 m long, 7.3 m wide and satisfies all pertinent American Association of State Highway Transportation Officials' (AASHTO) design Specifications. The resulting bridge design, based on the HS20-44 Standard Truck Load and maximum live load deflection of L/800, is stiffness critical and has a surplus factor of safety in strength. Finite-element analysis (FEA) was utilized to verify the strength and deflection performance, and to determine the stress distribution throughout the bridge superstructure. A unique feature of the Tech 21 Bridge is the extensive instrumentation system, totaling over 120 permanent sensors, that was installed during fabrication and installation of the structure. These sensors have been monitoring strains and ambient temperatures at critical locations on the bridge and moisture absorption along the bondline since its inception. All sensors have been sampled continuously and the data have been downloaded remotely via a logger connected directly to a modem and a dedicated phone line. In addition, several full-scale live-load tests have been conducted during summer and winter to characterize structural performance under different ambient conditions.