The Earthquake Engineering Online Archive

Executive summary on: Phase 3: evaluation and retrofitting of multilevel and multiple-column structures -- an analytical, experimental, and conceptual study of retrofitting needs and methods

Mahin, Stephen A.; Fenves, Gregory L.; Filippou, Filip C.; Moehle, Jack P.; Thewalt, Christopher R.

UCB/EERC-97/06, Earthquake Engineering Research Center, University of California, Berkeley, 1997-05, 103 pages (630/E93/1997)

This report summarizes the principal findings of a four year study for Caltrans of the seismic response of older multi-level, multi-column reinforced concrete bridge structures. Methods have been devised to improve prediction of the global response of these structures, to analyze and assess their local behavior, and to retrofit them to achieve adequate seismic behavior. The behavior of these structures has been found to be complex and influenced by a wide variety of parameters. Moreover, existing analysis methods often provide nonconservative estimates of behavior. The investigations conducted provide greater insight into the response characteristics of existing multiple column bridge structures. These have permitted development of improved analytical models and tools, retrofit strategies and design concepts. The findings included in this executive summary report are presented in depth in eight reports that have been submitted to Caltrans. This summary report is organized into the following sections: Introduction; Analysis issues, including the inelastic response of SDOF systems and design implications and multiple-frame response; Local and regional analysis, including regional analyses of characteristic bridge bents and local analyses of hysteretic behavior of critical regions; Behavior of reinforced concrete bridge components, including bridge columns, T-joints, and outrigger knee joints.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-97-06.pdf (7 MB)