Seismic hazard assessment of the Queensboro bridge

In this demonstration project, a team of NCEER researches and peer reviewers has provided the technical support and expertise necessary to permit a comprehensive evaluation to be made of the seismic vulnerability of the Queensboro Bridge. The results of this study are now being used by Steinman Engineers in the vulnerability assessment of the bridge. Preliminary results from this structural phase indicate that several critical elements in the bridge may require strengthening if it is to meet the seismic perfomance criteria previously defined. These elements include the connections between the superstructure and the masonry piers. The decision to retrofit the bridge has not yet been made but the process will probably extend beyond the seismological and engineering issues described above. Such a decision will likely include the socioeconomic considerations of retrofitting as compared to the consequences of closure and/or the repair/replacement of this critical lifeline for New York City, should an earthquake occur at a future date.(AU)

A seismic retrofitting manual for highway bridges

In 1993, the Federal Highway Administration (FHWA) published a set of guidelines for the seismic retrofitting of highway bridges. These guidelines has been prepared by the Applied Technology Council (as ATC 6-2) and represented what was then the state-of-the-art for screening, evaluating, and retrofitting of seismically deficient bridges. In the 10 years since the publication of these guidelines, there has been significant progress in understanding the seismic response of bridges and the development of new and improved retrofit technologies. It therefore appeared timely to revise this material based on this accumulated experience and to reissue it as a retrofit manual. The change from guideline to manual reflects the fact that this is a field which is changing rapidly, both in design and construction practice. In addition, there are several active research programs in progress at the present time and new techniques are being developed and tested which may greatly influence the state-of-the-art in the near future. It is therefore intented that this revision be an interim one which will be revisited in four or five years time for a second review based on the results of ongoing research and development activities.(AU)