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A combine method to establish attenuation law of wide response spectrum
Published in B.F. Spencer, Y.X. Hu, Earthquake Engineering Frontiers in the New Millennium, 2017
Compared with the analog accelerometer, the frequency response of the digital accelerometer improved a lot, and the long-period error introduced by digitizing of analog record is avoided. So the digital records are generally considered reliable to study the long-period ground motion and some researchers hereby have calculated the long-period response spectra (e.g., Xie et al., 1990). Nevertheless, some recent researches show that when the period is longer than 10 sec, the record of digital accelerograph is unreliable due to background noise. Both the actual recording and the shaking table experiment get the same result (Chiu, 1997; Zhou et al., 1997). Fortunately, the digital seismographs used by seismologist have wide frequency response. For example, the VBB system of Chinese Digital Seismograph Network (CDSN) which is a sub-network of the Global Seismographic Network, has a flat frequency band of 8.5∼0.003Hz and the FBA-23 system of CDSN has a band of 40∼0.001Hz. Both systems were digitized at 24-bit resolution.
Earthquake Effects on Buildings
Published in Bungale S. Taranath, Tall Building Design, 2016
The three components of ground motion recorded by a strong-motion accelerograph provide a complete description of the earthquake, which would act upon any structure at that site. However, the most important features of the record obtained in each component from the standpoint of its effectiveness in producing structural response are the amplitude, the frequency content, and the duration. The amplitude generally is characterized by the peak value of acceleration or sometimes by the number of acceleration peaks exceeding a specified level. The frequency content can be represented roughly by the number of zero crossings per second in the accelerogram and the duration by the length of time between the first and last peaks exceeding a given threshold level. It is evident, however, that all these quantitative measures taken together provide only a very limited description of the ground motion and certainly do not quantify its damage-producing potential adequately.
Earthquake activity
Published in F.G. Bell, Geological Hazards, 1999
Data relating to ground motion is essential for an understanding of the behaviour of structures during earthquakes. From the engineering point of view, the strong-motion earthquakes are the most important, since they damage or even destroy man-made structures. Records of shocks produced by such earthquakes are obtained by using ruggedly constructed seismometers called accelerometers. These are designed to operate only where earthquake vibrations are strong enough to actuate them. The accelerograph simultaneously records the two orthogonal horizontal and vertical components of ground acceleration as a function of time. The period and damping of the pick-ups are selected so that the recorded motions are proportional to the ground acceleration over the frequency range of about 0.06 to 25 cps, which encompasses the range of periods exhibited by typical engineering structures. The instrument has a resolution of the order of 0.001 g and is operative to about 1.0 g.
Duration Effects of Near-Fault Ground Motions on Structural Seismic Responses
Published in Journal of Earthquake Engineering, 2023
Guohai Chen, Guiqiang Guo, Yi Liu, Dixiong Yang
Since the first strong motion accelerograph was used in 1933, more than 20,000 earthquake records have been collected worldwide (Zhai and Xie 2007). Several dozens of indices representing the ground motion intensity and earthquake action were proposed (Ebrahimian et al. 2015; Marafi, Berman, and Eberhard 2016; Riddell and Garcia 2001), including the peak values of ground motion records and the indirect indices derived from the records. To implement the probabilistic seismic hazard analysis and performance-based seismic design (Cornell 1968; Ghobarah 2001), the concepts of intensity measures (IMs) of ground motions and engineering demand parameters (EDPs) are advised successively (Baker 2007; De Biasio et al. 2015; Kostinakis, Fontara, and Athanatopoulou 2018; Luco and Cornell 2007; Wang, Shafieezadeh, and Ye 2018). For more than 20 years, there were intensive studies on near-fault ground motions and structural seismic effects, due to the distinct characteristics including forward-directivity effect, fling-step effect, and hanging wall effect, as well as the severe damages from the velocity pulses with long period and large amplitude to civil infrastructures (Alonso-Rodríguez and Miranda 2015; Cao et al. 2017; Fang et al. 2018; Kalkan and Kunnath 2006; Li et al. 2017; Mavroeidis, Dong, and Papageorgiou 2004; Somerville et al. 1997; Yang and Zhou 2015). The structural dynamic responses and damage closely correlate with the amplitude, frequency content, and duration of ground motions. These correlations need to be considered in structural seismic design under near-fault ground motions.
The effect of ductility on the seismic collapse risk of residential steel moment-resisting frames at Alborz and Zagros Seismic zones, Iran
Published in Sustainable and Resilient Infrastructure, 2022
Ali Jafari, Elham Rajabi, Gholamreza Ghodrati Amiri, Seyed Ali Razavian Amrei
In order to perform cloud analysis, a set of earthquakes recorded in the seismic zones of Alborz and Zagros is collected. Since a relatively complete knowledge of the Iranian earthquakes and the related information, including earthquake recording method and local site conditions, are available, more than 300 far-field ground motions at Alborz and Zagros seismic zones are selected from among 1800 records that have been recorded by the Iranian accelerograph networks up to year 1997, based on the following factors.. Data availability of causative earthquake related to each selected earthquake recordPossibility for appropriate data correctionSufficient subsoil information about earthquake recording stations.
Strong Ground-Motion Characteristics Observed in the November 12, 2017, Mw7.3 Sarpol-e Zahab, Iran Earthquake
Published in Journal of Earthquake Engineering, 2022
Saeid Naserieh, Hadi Ghofrani, Jafar Shoja-Taheri, Mohsen Dezvareh, Hossein Mirzaei Alavijeh
The Sarpol-e Zahab earthquake was recorded by a network of 113 strong-motion accelerograph stations of the Iranian Strong Motion Network (ISMN) maintained by the Road, Housing, and Urban Development Research Center (BHRC). The stations were equipped with SSA-2 and Guralp (CMG-5TD) accelerometers. Among these, 38 stations were located within an epicentral distance range of 36 to 200 km (based on the epicenter coordinates reported by IRSC), with the recorded maximum acceleration ranging from 6 to 663 cm/sec2. Table 2 lists the accelerograph stations that recorded this earthquake within an epicentral distance of less than 200 km. Figure 3 shows the geographic distribution of these stations along with a map of PGA values recorded for this event. The largest PGA is about 663 cm/sec2, recorded on the N-S component of Sarpol-e Zahab station (SPZ) 36 km south of the epicenter. As can be seen in Figure 3, due to the occurrence of the earthquake near the Iran–Iraq border, a complete azimuthal coverage by the ISMN accelerograph stations was not possible.