Back to Research Page

Documentation for Assessment of Modal Pushover- based Scaling Procedure for Nonlinear Response History Analysis of “Ordinary Standard” Bridges


Printable USGS Open File Report 2010 - 1328, 56 p. (15 Mb)

Erol Kalkan, U.S. Geological Survey, Menlo Park, ekalkan@usgs.gov

Neal S. Kwong, University of California, Berkeley, nealsimonkwong@berkeley.edu

 

Plain English Summary

The earthquake engineering profession is increasingly utilizing nonlinear response history analyses (RHA) to evaluate seismic performance of existing structures and proposed designs of new structures. One of the main ingredients of nonlinear RHA is a set of ground-motion records representing the expected hazard environment for the structure. When recorded motions do not exist (as is the case for the central United States), or when high-intensity records are needed (as is the case for San Francisco and Los Angeles), ground motions from other tectonically similar regions need to be selected and scaled. The modal-pushover-based scaling (MPS) procedure (Kalkan and Chopra, 2010) recently was developed to determine scale factors for a small number of records, such that the scaled records provide accurate and efficient estimates of “true” median structural responses. The adjective “accurate” refers to the discrepancy between the benchmark responses and those computed from the MPS procedure. The adjective “efficient” refers to the record-to-record variability of responses. Herein, the accuracy and efficiency of the MPS procedure are evaluated by applying it to four types of existing “ordinary standard” bridges typical of reinforced-concrete bridge construction in California. These bridges are the single-bent overpass, multi span bridge, curved-bridge, and skew-bridge. As compared to benchmark analyses of unscaled records using a larger catalog of ground motions, it is demonstrated that the MPS procedure provided an accurate estimate of the engineering demand parameters (EDPs) accompanied by significantly reduced record-to-record variability of the responses. Thus, the MPS procedure is a useful tool for scaling ground motions as input to nonlinear RHAs of “ordinary standard” bridges.

Resumen Espanol

La profesión de la ingeniería sísmica cada vez más utiliza el análisis no-lineal de la historia de respuesta (ARS) para evaluar el desempeño sísmico de estructuras existentes y propuestas de diseño de nuevas estructuras. Uno de los principales ingredientes de RHA no-lineal es un conjunto de registros de movimiento del suelo que representa el entorno de previsible riesgo para la estructura. Cuando los movimientos registrados no existen (como es el caso del centro de Estados Unidos), o cuando los registros de alta intensidad son necesarios (como es el caso de San Francisco y Los Ángeles), movimientos de tierra de otras regiones tectónicamente similares deben ser seleccionados y amplificados. La modales en presa fácil(MPS) procedimiento de amplificacion (Kalkan y Chopra, 2010) recientemente fue desarrollado para determinar los factores de amplificacion para un pequeño número de registros, de modo que los registros amplificados proporcionan estimaciones precisas y eficientes de las "verdaderas" respuestas estructurales medianas. El adjetivo "preciso" se refiere a la discrepancia entre las respuestas de referencia y los calculados a partir del procedimiento de MPS. El adjetivo "eficiente" se refiere a la variabilidad de registro a registro de las respuestas. En esto, la precisión y la eficiencia del procedimiento de MPS son evaluados por su aplicación a cuatro tipos existentes de puentes "estándar ordinario" típicos de la construcción de puentes de hormigón armado en California. Estos puentes son el puente de un solo doblado, puente abarcan múltiples, curva del puente, y el puente oblicuo. En comparación con los análisis de referencia de los registros sin amplificacion con un catálogo más amplio de movimientos del terreno, se demuestra que el procedimiento de MPS proporciona una estimación precisa de los parámetros de ingeniería de la demanda (PEIP), acompañado por la variabilidad reducida significativamente de registro a registro de las respuestas. Por lo tanto, el procedimiento de MPS es una herramienta útil para amplificar los movimientos de tierra, como aporte a las ARS no-lineal de puentes "corriente estándar.”

Computer Codes (Matlab and OpenSees)

MPS Example: Skew Bridge (All essential MatLAB and OpenSees codes with clear explanations, 23 Mb)

Related Publications

Kalkan E., Kwong N.S., 2012, Assessment of Modal Pushover-based Scaling Procedure for Nonlinear Response History Analysis of “Ordinary Standard” Bridges, ASCE Journal of Bridge Engineering, 17(2): 272-288

Kalkan E., Chopra A.K., 2010, Practical Guidelines to Select and Scale Earthquake Records for Nonlinear Response History Analysis of Structures, U.S. Geological Survey Open-File Report 2010-1068, 126 p.

Kalkan E. and Chopra A. K., 2011, Modal-Pushover-based Ground Motion Scaling Procedure, ASCE Journal of Structural Engineering, Vol. 137, no. 3, pp. 298-310.

Reyes J.C. and Kalkan E.. 2011, Required Number of Records for ASCE/SEI 7 Ground Motion Scaling Procedure, U.S. Geological Survey Open-File Report 2011 - 1083, 34 p.

Kalkan E., Chopra A. K., 2012, Evaluation of Modal Pushover-based Scaling of one Component of Ground Motion: Tall Buildings, Earthquake Spectra, 28(4): 1469-1493.

Comparison of median engineering demand parameters (EDPs) based on the modal pushover-based scaling procedure (MPS) with benchmark EDPs for multi span "ordinary standard" bridge; individual results for each of the seven scaled ground motions in three different sets are also presented. MPS procedure is accurate (that is, the median values of EDPs due to very small subset of scaled ground motions closely match the benchmark results). The dispersion of the EDP values due to the seven scaled records about their median values is small indicating that the MPS method is efficient.