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Christopher Rojahn

Publications and source records attributed to Christopher Rojahn.

5 recordsLinked to original sources
USGS2005

Coordinating NEHRP Post-Earthquake Investigations: Exercising the Plan

Three exercises of The Plan to Coordinate NEHRP Post-Earthquake Investigations were developed and implemented in late 2003 and early 2004 in order to test the Plan itself via realistic scenarios, and for the NEHRP agencies to learn how to coordinate post-earthquake investigations. The exercises were selected to cover a range of seismic activity and consequences, and were based on scenario events: (1) a Hayward Fault Mw 7 event without foreshocks; (2) a New Madrid seismic zone Mw 7 event with foreshocks, and (3) a Puerto Rico Mw 8 subduction event on the Puerto Rican Trench accompanied by a tsunami affecting the eastern seaboard of the United States. Each exercise consisted of a four-hour telephone conference call with a Web-based electronic link and post-exercise evaluations fed back to participants. Evaluation of the exercises found the Plan to be adequate, with implementation of the Plan by the NEHRP agencies improving with each exercise. Based on the exercises, recommendations were provided that a Plan coordinator should be designated within USGS, an annual exercise of the Plan should be conducted in different regions of the United States, a permanent NEHRP electronic link should be created, and coordination of post-earthquake data collection, preservation, archiving, and dissemination should be greatly improved.

Earthquake Spectra↗
USGS1978

Use and interpretation of strong-motion records from highway bridges

This report describes how strong-motion records obtained from the earthquake-induced motions of highway bridges may be analyzed for use in the evaluation of bridge designs and bridge design procedures. This report is divided into five principal sections. The first section describes strong-motion instrumentation and strong-motion records. In the second section, a mathematical model for the dynamic response of bridges to strong ground shaking is formulated. The third section describes how analog records scaled by hand can be analyzed. Force levels throughout bridges and mathematical model parameters are found from hypothetical strong motions for two example bridges. The fourth section describes how digitized records can be analyzed. A linear least-squares fitting procedure in the time domain for identifying mathematical model parameters from recorded strong motions is described. Hypothetical motions for three example bridges are analyzed using this procedure to yield best-fit mathematical models. The last section consists of appendices. Included are a more extensive introduction to dynamics of structures and listings of the programs used to identify the best-fit mathematical models.

Open-File Report↗