Impact Of Strong Ground Motion's Process Procedure On The Structural Elastic/inelastic Response

With the continuous improvement of computer performance,the hardware and software technology of structural elastoplastic modeling is becoming more and more mature,and the application range of elastoplastic time history analysis is wider and wider.Although there have been a lot of academic research results on the ground motion input selection as the main source of uncertainty,the attention paid to the strong ground motion process procedure to the structural elastoplastic response is very lacking.As a key link for removing noise and retaining effective information of ground motion,the strong ground motion process procedure is the basic work of subsequent earthquake engineering and structural engineering research.The strong ground motion input of engineering concern often comes from strong destructive earthquakes,such as the Wenchuan earthquake,the Chi-Chi earthquake,the 2011 earthquake of the Pacific coast of T?hoku,etc.The near-field strong ground motions of the above-mentioned earthquakes often contain velocity pulses,and permanent displacements are different from ordinary ones.The characteristics of the mid-and far-field strong ground motions.Although scholars have proposed many strong ground motions processing schemes,the above research is often limited to the recording processing procedure itself,but it is not systematically analyzed from the perspective of engineering input and structural response.In view of the above problems,this paper intends to study the effects of strong vibration filtering and baseline correction procedures on the elastoplastic response of structures.The specific research contents are as follows:(1)In this paper,the strong ground motions is divided into four types according to whether it contains velocity pulse and permanent displacement.Considering several kinds of strong ground motion process procedures such as polynomial baseline correction,Butterworth filtering,and baseline trend line correction.The strong ground motions in the Hualien earthquake,the Chi-Chi earthquake,the 2011 earthquake of the Pacific coast of T?hoku and the El-centro wave are taken as examples.The analysis results show that the Butterworth filter procedure not only affects the residual permanent displacement,but also greatly affects the shape of speed pulse.In the selected procedure,the best effect on the permanent displacement information of the strong ground motions is Wu&Wu's procedure.Under the condition of reasonable selection of parameters,the corrected calculated displacement is consistent with the GPS coseismic displacement.(2)Starting from the elastoplastic response of the single(multiple)degree of freedom system,the effects of different treatment procedures on the elastoplastic response of the structure are discussed from the perspectives of structural elastoplastic demand and layer ductility requirements.The single-degree-of-freedom elastoplastic displacement ratio spectrum in the three non-filtering modes,the difference between the 9-layer and 14-layer multi-degree-of-freedom layer ductility requirements is negligible,even at larger strength reduction factors or lower shears.This ratio is still true.The result of the filtering procedure is that the elastoplastic response of the long-period part is quite different from that of the other procedures.The ductility requirement of the MDOF layer also appears different from the rest of the processing procedures.(3)The elastoplastic time-history response analysis of the 3-layer and 15-layer planar RC frame structures and the 115 m high-rise core tube structure was carried out using OpenSees.The calculation results of the planar RC frame show that the strong ground motions with velocity pulse,the response obtained by the Butterworth filter procedure will obviously underestimate the maximum interlayer displacement angle,and the maximum acceleration of the apex and the maximum shear force at the bottom are also significantly different from the other procedures.The strong ground motions with permanent displacement,the interlayer displacement angle obtained by the Butterworth filter procedure,the maximum apex acceleration and the maximum shear force at the bottom are different from the results of the other procedures.The calculation results of the concrete core tube structure show that different treatment procedures have an impact on the estimation of structural collapse performance.In summary,for strong ground motions that do not contain velocity pulses or permanent displacements,the effect of recording processing on the results of elastoplastic time history analysis is not significant.In practice,high-low frequency noise is filtered by simple Butterworth filter.Just fine.For strong ground motionss containing velocity pulses and/or permanent displacements,Butterworth filtering also has a large effect on the velocity pulse shape and permanent displacement of the surface while filtering out noise,and is passed to the final elastoplastic time history analysis.And may have an impact on short,medium,and long-period structures.When using the large-seismic near-seismic strong ground motions including velocity pulse and permanent displacement as the ground motion input,it is recommended to use the baseline trend line correction based processing procedure.In addition,although the residual permanent displacement information obtained by different baseline trend line correction procedures is different,it has little effect on the velocity pulse waveform,and its structural response is not significantly different.