Performance-based Seismic Risk Assessment For Bridge Structure

In the context of next generation performance based seismic design and assessment,on the basis of performance-based framework from Pacific Earthquake Engineering Research Center(PEER), the seismic decision-making method is developed for those bridge with ill-informed seismic resource by the virtue of up-to-date findings,available structural test data and earthquake records, using numerical simulation technique under the requirements from the code of modern seismic design and assessment bridge in China. The simplified formulation of seismic hazard is examined.the seismic intensity measure and earthquake records are selected reasonably. The seismic demand and damange hazard are calculated, the economic and engineering measure for performance level of bridge is given with seismic loss and confidence intervel, which contributes to probabilistic performance-base seismic design and assessment for bridge, it shows that direct seismic economic risk could be used as assessment criterion, which provides the stakeholders or managers with comprehensive understanding to the seismic performance and post-earthquake function statistically on the basis of examining seismic fragility and risk for damage states to different components of bridge.The main work to the dissertation is as followings:1) On the basis of discussion on the seismicity and probabilistic implication amony seismic codes, the power-law seismic hazard simplified model is improved, and parabolic simplified model is proposed. The transfer formulation is derivated from binomial distribution. And several seismic hazard model is examined for applicability with comparison to seismic hazard data of 5 sites in China, USA and New Zealand.Results show that parabolic model and piece-wise power-law model can be used to calculate seismic hazard with higher accuracy for three seismic fortification level.2) Collect seismic infornation from PEER seismic database comprehensively, and program to obtain conditional mean spectra from seismic megadata and design spectrum for seismic design and assessment of bridge with ill-informed seismic information. -The earthquake records are selected under the control of mean value and variability as uncertainty source.3) In the view of uncoupled site-structure, analytical formulation of probabilistic seismic demand hazard is derivated, the effectiveness to the intensity measure of earthquake records are discussed. The probabilistic seismic demand analysis is conducted using IDA to examine the adequacy of the seismic intensity measure and analytical formulation.4) Collect the column test data from PEER test database, caliberate the damage state with hysteretic curve using OpenSees platform. The damage limit state for fragility analysis is identified with improved capacity spectrum method from FEMA- 440.5) A practical method for performance-based seismic economic risk assessment of bridge structure is provided and illustrated in a case study of seismic economic risk analysis for a large span rigid-frame bridge with high piers. The probabilistic implication of higher seismic fortification for a bridge in non seismic area, which provides constructive reference and basis for the applicabilty to probabilistic performance-based seisimic design and assessment based on code requirment.