Advances in seismic isolation technology and the potential benefits that seismic isolation offers have generated much interest in recent years. However, the lack of independent, full-scale dynamic characterization data and the correlation with scaled data has kept many public agencies from benefitting from what appears to be a promising technology. As a result, in 1994, in cooperation with the Federal Highway Administration (FHWA), the California Department of Transportation (Caltrans) and the Highway Innovative Evaluation Center (HITEC), a full-scale dynamic testing program was lunched to evaluate the available systems. This program is the first of its kind in the United States and in the world. Over a dozen companies from five countries participated in the testing program, which will lead to uniform guidelines for prototype and verification testing as well as design guidelines and contract specifications for each of the different systems.

The objectives of the evaluation program were to:

1. Implement a program of full-scale dynamic testing sufficient to characterize the fundamental properties and performance characteristics of the devices evaluated;

2. Provide guidance on the selection, use, and design of seismic isolation and energy dissipating devices for different levels of performance; and

3. Help with the development of suggested guide specifications for the use of seismic isolation and energy dissipating devices in new bridges and retrofit projects.

The evaluation program examined characteristics such as range, capacity, resilience, performance under service and dynamic loads, energy dissipation, functionality in extreme environments, resistance to accelerated aging, predictability of response, fatigue and wear, and size effects.

These properties provide the bridge designer with critical information on the suitability of the devices for specific design applications and also provide insight into the reliability, longevity, and predictability of response. Furthermore, the program addressed the ability of the vendor or manufacturer to provide a quality product and predict product response.

This paper provides an overview of the testing program, the evaluation process and the findings.

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