Seismic Effects on Elevated Transit Lines of the New York City Transit Authority

Keywords: Lifelines, Transportation Facilities, Seismic Risk Assessment, New York City Transit Authority (NYCTA), Structural Dynamics, Elevated Structures, New York, United States.

Abstract: This study performed a broad assessment of the structural facilities of the New York City Transit Authority (NYCTA) system. The aim of the study was to determine those facilities, if any, which could most likely sustain significant structural damage when subjected to relatively low level seismic events which may be expected to occur in the New York City area. In this initial assessment, the types of primary structural damage considered were limited to overstressing of the moment connection at the column, bent girder joint at the top of the traverse frame, and the potential for overturning of the pedestal footings at the column base which are typical of the footings used along the lines when these are subjected to horizontal seismic motions. Based on this initial assessment, it was found that the elevated structure typical of the NYCTA system is in fact sensitive to the dynamic loads that would be imposed by such events. These structures were also found to have relatively low capacity to sustain such lateral load inputs.