Seismic Fragility Analysis of Bridge by Combining the Uniform Design Method and Response Surface Method

In view of the large calculation research situation of the seismic fragility of bridges, the paper takes a continuous girder bridge as case-study, accounts for the uncertainties derived from the structural and earthquake ground motion. Combined with the uniform design (UD) and response surface methodology (RSM),an alternative seismic fragility analysis method is proposed. In order to verify the validity and applicability of the proposed method, what through comparisons in sampling frequency and computing time, response surface model accuracy and seismic fragility curves between the proposed method, Monte Carlo (MC), orthogonal design (OD) and central composite design (CCD) of response surface methodology. The case-study shows that the proposed method can be well applied to seismic fragility analysis efficiently and effectively. The results of fragility analysis of the proposed method are very close to Monte Carlo of response surface methodology. In terms of the sampling frequency and computing time, compared with Monte Carlo (MC), orthogonal design (OD) and central composite design (CCD) of response surface methodology, the proposed method is reduced by 99.70%, 58.49% and 8.70% respectively. And as for the structures response surface fit coefficients, compared with orthogonal design (OD) and central composite design (CCD) of response surface methodology, the proposed method are increased by 8% to 12% and 3% to 5% separately. Therefore, the proposed method has good application value in seismic fragility analysis.