Dense networks of low-cost wireless sensors have the potential to facilitate prolific data collection in large and complex infrastructure at costs lower than those historically associated with tethered counterparts. While wireless telemetry has been previously proposed for structural monitoring, comparatively less research has focused on the creation of a complete and scalable data management system that manages the storage and interrogation of wireless sensor data. This paper reports on the development of a novel wireless structural monitoring system specifically tailored for large-scale civil infrastructure systems by architecturally combining dense wireless sensor networks with a suite of information technologies remotely accessible by the Internet. The architectural overview of the proposed Internet-enabled wireless structural monitoring system is presented including a description of its functional elements (for example, wireless sensors, database server, and application programming interfaces). The monitoring-system architecture proposed is validated on the New Carquinez (Alfred Zampa Memorial) Bridge in Vallejo, California. A permanent wireless monitoring system is installed consisting of 28 wireless sensor nodes collecting data from over 80 channels. The bridge sensor data are transferred by a wireless cellular connection to a remote database server where it is stored and available for interrogation by software clients granted access to the data. To illustrate the ability to autonomously process the bridge response data, the stochastic subspace identification method is used to extract accurate modal characteristics of the bridge that are used to update high-fidelity finite-element models of the bridge. The Internet-enabled wireless structural monitoring system proved to be scalable to a large number of nodes and has thus far proven stable and reliable over long-term use.

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For the first time in the United States, earthquake energy dissipation devices have been used for the seismic upgrade of a building located in San Francisco, California. The devices used are Added Damping and Stiffness (ADAS) elements which consist of 50 ksi steel plates which deform plastically during severe earthquakes to dissipate energy. The ADAS elements were used in conjunction with steel chevron braces as part of the seismic upgrade of a 2-story nonductile concrete frame structure built in 1967. The building suffered both structural and nonstructural damage during the 1989 Loma Prieta Earthquake and appeared to be a life safety hazard for a major earthquake. The ADAS upgrade scheme was selected over other more conventional schemes, in part, because the design seismic force could be limited to the capacity of the existing foundation system. The paper provides a case study and summarizes the seismic evaluation and upgrade design, the linear and nonlinear analyses performed, modeling assumptions, unique design details, the permit approval process, and final construction. In addition, comparisons are presented showing shear forces and displacements for the original building and the final design with chevron braces and ADAS elements.

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