海域地震动强度包络模型研究OA北大核心CSTPCD

Artificially simulated earthquake motion is currently the main seismic input for seismic anal-ysis of marine structures.The intensity envelope function,a crucial parameter for artificial simulation of ground motions(GMs),determines the non-stationary intensity characteristics of GMs and controls the duration.Existing intensity envelope models,derived from a large amount of onshore earthquake GM records,cannot accurately reflect the intensity distribution characteristics of offshore GMs.There-fore,this study focuses on intensity envelope models for offshore GMs.Firstly,an offshore earth-quake GM database was established based on the records selected from the K-Net strong motion obser-vatory network in Japan.The intensity distribution characteristics of offshore ground motions in the time domain were studied.Secondly,this study proposed a three-stage intensity envelope model suit-able for offshore GMs.Computational expressions for earthquake magnitude M,epicentre distance R,and key parameters including the rising segment t1,the steady segment ts,and the decay rate of the de-scending segment c(dimensionless)were derived through regression analysis.Thirdly,the impact of earthquake magnitude and epicentre distance on the intensity envelope model for offshore GMs was in-vestigated.At last,the similarities and differences between the intensity envelope models suitable for offshore and onshore GMs were compared.The research results indicate that:the key parameters,in-cluding the rising segment t1,the steady segment ts,and the decay rate of the descending segment c,have ranges of[13 s～52 s],[12 s～79 s],and[0.037～0.173],respectively,for the intensity envelope model of offshore ground motions.The effect of magnitude on key parameters(t1,ts,c)is greater than that of epicentre distance.Compared with onshore ground motions,the intensity envelope model for offshore GMs differs significantly in the attenuation rate c in the descending segment,and the distribu-tion range of each key parameter is larger.