Wavelet-based Analysis Of Whiplash Effect

Judging from the large number of seismic records, the seismic response of thesurface is different. Even in the same earthquake, if the distance is only a few tens ofmeters, the phase, amplitude and spectral about vibration characteristics are different.By using the B-spline wavelet, research on seismic response and analysis of thestructure in the different frequency domain.In this paper, taking a four-story frame with appendage as an example, assumingthat the frame structures in case of no appendage and one-floor appendage, two-floorappendage. The severity of the whiplash effect and the impact of the whiplash effect onthe main structure under different frequency components of earthquake when toincrease the floor of appendage. Which be decomposed by using the B-spline waveletand measured records of5.12Wenchuan earthquake. Therefore, which be calculatedthe displacement modes and the shear modes of four-story frame with appendage. Themain work and achievements are as follows:1.From the5.12Wenchuan earthquake database, the Wolong waves that is19kmfrom the epicenter, the Shifang waves that is82km from the epicenter and theLongxian waves that is536km from the epicenter. Which be decomposed the seismicwaves by means of the B-spline wavelet, and wavelet components is inputted the timehistory analysis of the whiplash effect.2.Editing calculation procedures of the stiffness matrix and structure of thedisplacement, the shear by MATLAB. Analyze the structure of the displacement andshear withstand multi-occurred earthquake.3.Under the original wave and its wavelet components, with the floor ofappendage increasing, appendage of the displacement is increases, four-story framewith two-floor appendage of the shear is less than four-story frame with one-floor appendage of the shear, the more obvious of the whiplash effect. Predominant periodand long-period component play leading role to displacement and the shear, the mainlyreflected in wavelet components of the four periods is0.32s to0.64s,0.64s to1.28s,1.28s to2.56s,2.56s to5.12s.4.Obtained by the structure analysis that, in the case of the same main structure, toincrease the floor of appendage, results in the structural cycle of the main modeincreasing, leading to the first natural vibration period and the second natural vibrationperiod get closer, the more obvious of the whiplash effect. Therefore, whiplash effectof reinforced concrete frame structure under earthquake, with the floor of appendageincreasing, it needs to pay attention to the impact of long-period.The results show: obtained by the displacement modes analysis that, lower ordermodes play leading role to displacement of bearing, with the floor of appendageincreasing, the high-order modes play more important to the appendage, it needs to payattention to the impact of higher modes. Obtained by the shear modes analysis that,low order modes have more effect under the long-period; and the influence ofhigh-order modes is obvious under the short-period components.