| Abstract |
The report presents a collection of practical and readily implementable recommendations for the modeling and analysis of highway bridges and overpasses subjected to earthquake ground motions. The specifications are applicable for Ordinary Standard Bridges in California as defined according to Caltrans Seismic Design Criteria (SDC) 2004. The main emphasis of the document is the implementation of nonlinear analysis procedures intended primarily to estimate seismic demand on critical bridge components and systems. These guidelines are not intended for evaluation of bridge system or component capacity. An extended literature review of the current engineering practice and code criteria for bridge design, modeling, and analysis was carried out concurrently throughout this document, focusing on design documents such as SDC 2004, BDS 2000, BDS 2003, ATC-32, MTD 20-1, AASHTO LRFD Specifications, 3rd edition, to guarantee consistency with the proposed modeling guidelines and recommendations. The modeling guidelines and recommendations presented in this report are expected to ensure that accurate nonlinear modeling techniques are employed by Caltrans engineers and that PEER researchers realistically model typical Caltrans bridge systems and details. Bridge components that require special modeling considerations and nonlinear characterization are identified in this document, establishing specific criteria for the level of modeling sophistication required to estimate seismic demand with sufficient accuracy. Several incompatibilities or inconsistencies between SAP2000 and OpenSees finite element software analysis tools were investigated to identify underlying causes and to reduce possible analysis errors while using a particular structural analysis tool. Numerous recommendations for linear and nonlinear analysis of bridge structures appropriate for any structural analysis program, as well as specific details on the use of SAP2000 software for such analysis, are presented. Simultaneously, a general review and definitions related to structural dynamics, applicable to both linear and nonlinear analysis, are presented throughout. |
