Adaptive modal pushover analysis (ampa) procedure: application to bridge analysis

Abstract eng:
Modal Pushover Analysis (MPA) procedure is a widely accepted practice-oriented nonlinear analysis tool, which approximately considers the effects of higher modes in pushover analysis. In recent years the application of the procedure has been extended to bridges. In MPA, an auxiliary curve called “pushover curve” or “capacity curve” needs to be plotted for each mode in terms of certain response quantities of MDOF system, which is subsequently converted to a “capacity diagram” of the corresponding modal SDOF system to estimate the seismic demand. However the conversion is not unique, i.e., different MDOF system response quantities would yield different capacity diagrams, and hence result in different nonlinear response. This approximation especially affects MPA applications on bridges where the definition of the representative MDOF response quantities, i.e., the coordinates of the pushover curve can never be standardized. In this contribution, implementation of Adaptive Modal Pushover Analysis (AMPA) Procedure is attempted to avoid this approximation by eliminating the need for a pushover curve in each mode and yielding directly SDOF modal capacity diagrams. However, the procedure has not been always successful as demonstrated through the analysis examples performed on typical bridge systems, which involve a regular bridge and an irregular bridge. A second attempt is made to apply a Modified Modal Pushover Analysis (MMPA) procedure where MDOF response quantities are calculated for each mode utilizing the current deflected shape at each pushover step. It is observed that MMPA yields better results compared to AMPA with respect to nonlinear response history analysis results, which are also compared with those of Incremental Response Spectrum Analysis (IRSA) procedure.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket