LOAD REDISTRIBUTION AMONG STEEL PIERS IN CONTINUOUS ELEVATED-GIRDER BRIDGES SUBJECTED TO MULTI-DIRECTIONAL SEISMIC ACCELERATIONS
Toru Okumura 1*, Yoshiaki Goto 1
1 Earthquake Engineering Research Center Inc., Miyazaki, Japan
2 Nagoya institute of technology, Professor, Nagoya, Japan
To prevent the collapse of entire structures under mega earthquake ground motions that exceed the scale of design ground motion, the effect of load redistribution among the members of an elevated-girder bridge was investigated. Three types of ultimate states classified in terms of the levels of load redistribution were defined, and methods of evaluating the safety margin corresponding to each limit state were put forward. Based on a detailed numerical analysis, margins up to the respective ultimate states were determined. The numerical analysis shows that there exists a relatively significant margin between the safety limit state and the ultimate state of the entire bridge system. As such, it can be effective to adopt a strategy that can enhance the load redistribution capacity among members after the safety limit state is reached.
Elevated-girder bridge; Seismic design; Load redistribution; Limit state; Safety margin