Study on Pulse-like Ground Motion Intensity Measures for Seismic Analysis of Isolated Curved Girder Bridges
The selection of ground motion intensity measures is the basis for seismic analysis of bridges.This study investigates suitable intensity measures for isolated curved girder bridges subjected to pulse-like ground motions using a three-span isolated curved continuous girder bridge as a prototype.We selected 90 typical pulse-like ground motions and employed the finite element method to conduct seismic dynamic analyses of the bridge at various incidence angles. We examined the correlation between 19 intensity measures (categorized into three types) as well as the seismic responses of the bridge. The efficiency and sufficiency indices in the probabilistic seismic demand model were utilized to compare these intensity measures.In addition,we fitted the relationship between βD|IM and the intensity measure.The results reveal that velocity-related intensity measures,such as peak ground velocity (PGV) and peak spectral velocity (PSV),exhibit a strong correlation with the seismic dynamic responses of the isolated curved girder bridge,demonstrating good efficiency and sufficiency across different incidence angles. These findings suggest their suitability as primary parameters for selecting and adjusting pulse-like ground motions.Compared with the bending moment of the pier,the peak shear deformation of the isolation bearing is deemed more suitable as the seismic demand parameter.Finally,we found that a power function can effectively characterize the relationship between the mean value of the intensity measures and the seismic response when conducting probabilistic seismic demand analysis.These findings provide valuable insights for selecting seismic intensity measures in the analysis of isolated curved girder bridges.
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