Energy based seismic vulnerability assessment tool for reinforced concrete bridges

Quantification of damage in RC bridges is a key requirement for seismic vulnerability assessment. The main aim of this study is to quantify the seismic damage of RC bridges under far-field and near-fault (pulse-like) ground motions. New definitions of “Damage Index” based on cumulative energy dissipation, and distinct “Damage States” are proposed. Different damage states are established on the basis of observed experimental and analytical results. Fiber based model centered on material strain limits is adopted while quantifying the damage during non-linear dynamic analyses. The proposed damage index is compared with some existing damage indices. Comparison indicated that existing damage models either overestimating or underestimating the damage values when compared with the experimental results corresponding to the specific loading stages. Proposed damage model shows gradual progression of damage with the progress in the loading stage. Further, in order to check the performance of proposed damage index in presence of superstructure and incorporating the effect of other structural components of bridge; a case study of seismic vulnerability assessment under the far field and near-fault (pulse-like) ground motions has been carried out. It is found that proposed damage model performs quite efficiently under seismic loadings. Incremental Dynamic Analysis is carried out and fragility curves are plotted for far-field and near fault (pulse-like) ground motions. This study will be useful for health monitoring, seismic vulnerability assessment and framing retrofitting strategies for reinforced concrete bridges.