Motion pulse
![motion pulse motion pulse](https://thumbs.dreamstime.com/z/colorful-abstract-line-light-art-conceptual-art-showing-motion-pulse-city-helsinki-darkness-night-created-165740059.jpg)
Although numerous researchers have acknowledged the velocity record as an appropriate indicator to explain the nature of the near-fault records, they attempted to present several models for estimating this pulse-type part of the record and evaluating the relevant parameters to the structural responses under such records. On the other hand, the reported records of the near-fault ground motions show that a large amount of energy of these records are expressed cumulatively and in the form of a pulse-type factor in the velocity record of these ground motions. This is computationally both time-consuming and costly. Hence, using this method, the records should be scaled from a very low intensity measure (IM) to a very high one. The IDA entails conducting non-linear analysis on the structural model under a set of earthquake records scaled in several intensity levels and imposed to the structure so that it undergoes from a linear elastic stage to non-linear complete collapse stage. The incremental dynamic analysis (IDA) is an appropriate and precise method for probabilistic evaluation of the collapse of the structures. The collapse prevention of the structures is one of the most important threshold levels to evaluate the performance of the structures under the seismic excitations. Keywords: near-fault ground motions, extracted pulse, collapse intensity measure, collapse fragility curve, collapse capacity median, special moment resisting frame (SMRF). Nevertheless, if the structure is designed for collapse prevention (CP) performance level and experiences high level of non-elastic displacements, the extracted pulses provide a conservative estimation of the collapse capacity, which is in the safe side. From the numerical analysis performed in the present study, it is found that if a given structure is designed for immediate occupancy (IO) performance level (low drift), the application of the extracted pulses overestimates the structure capacity, which is in the unsafe side. The results of this study revealed that the efficiency of the extracted pulses to estimate the structure capacity depends on the structural performance levels. Subsequently, an incremental non-linear dynamic analysis (IDA) was conducted to evaluate the non-elastic response of an example frame subjected to these original records and their extracted pulses to examine the efficiency of the extracted pulse of the records instead of the original accelerograms in dynamic analysis. In the present study, by using a wavelet analysis, the long period pulses exist in the velocity records of 28 near-fault ground motions, selected from the PEER NGA database, were first separated from the original records.
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Earthquake accelerograms recorded in the near-fault regions have special characteristics including the long-period pulse in velocity records as well as high frequency content in acceleration records.