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![Locations of stations during the 1999 Chi-Chi, Taiwan earthquake (after Wang et al. [7])](profile/Amr-Elnashai/publication/265663897/figure/fig1/AS:654054871027720@1532950241250/Locations-of-stations-during-the-1999-Chi-Chi-Taiwan-earthquake-after-Wang-et-al-7.png)
Source publication
The vertical component of earthquake ground motion has been the focus of attention in the past ten years, following field observations pointing towards damage patterns that could have only been caused by severe vertical vibrations. Since the vertical component is rarely used in analysis to evaluate design actions, it follows that there is a potenti...
Contexts in source publication
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... time. The epicenter was near the town of Chi-Chi (Figure 1). This earthquake was generated by reverse, left lateral slip of the Chelungpu Fault, characterized by a long rupture of more than 80 km (Figure 1) and long duration of about 30 s (Ma et al. [6]). ...
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... epicenter was near the town of Chi-Chi (Figure 1). This earthquake was generated by reverse, left lateral slip of the Chelungpu Fault, characterized by a long rupture of more than 80 km (Figure 1) and long duration of about 30 s (Ma et al. [6]). It originated at a very shallow focal depth of about 7 km. ...
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... shaking exceeded 1.0 g in many places and triggered hundreds of strong motion instruments across Taiwan. Locations of the free-field stations that recorded vertical motions during this earthquake are shown in Figure 1. A total of 52 free-field records with PVA greater than 0.1 g from this earthquake were investigated in this study. ...
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... this regard, delineation of near-field versus far-field records by the 15 km closest distance to fault does not appear to be an effective approach. As mentioned earlier, the fault line (Figure 1) is more than 80 km long, and recording stations are present on both sides of this line within a range of about 40 km. Figure 8 shows the different near-field average response at 2% damping including and excluding the 1999 Chi-Chi, Taiwan, earthquake in the entire data set of Elgamal and He [3]. The average of the Chi-Chi earthquake alone is also shown in Figure 8. ...
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... inclusion of this earthquake only results in slightly higher response at longer periods in the case of far-field records (Figure 9), while Chi-Chi earthquake itself has much higher response spectra at longer periods. Near-field average response spectra at 2% damping Elgamal and He [3]) Chi-Chi, Taiwan 1999 earthquake included Chi-Chi, Taiwan 1999 earthquake only Far-field average response spectra at 2% damping Elgamal and He [3] Chi-Chi, Taiwan 1999 earthquake included Chi-Chi, Taiwan 1999 earthquake only Figure 9. Far-field average response with and without the 1999 Chi-Chi, Taiwan, earthquake records at 2% damping Figures 10 and 11 show the response spectra of the 1999 Kocaeli and the 1999 Duzce, Turkey earthquakes at 2% damping. Peak response of all near-field records occurs at a period of about 0.1 second. ...
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... is the only far-field record with distance to causative fault of 17.6 m (Table 4). Compared to near- field record, the BOL contains energy over a longer period range, with a smaller peak response occurring at a somewhat longer period (Figure 11). This observation agrees well with that of Elgamal and He [3]. Figure 12 compares the near-field average spectrum of the two Turkey earthquakes with those of Elgamal and He [3] based on California earthquakes, showing good agreement in the short period range. ...
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... observation agrees well with that of Elgamal and He [3]. Figure 12 compares the near-field average spectrum of the two Turkey earthquakes with those of Elgamal and He [3] based on California earthquakes, showing good agreement in the short period range. Averages of both Turkey and Elgamal and He [3] have peak amplification at a period of about 0.1 second although the Turkey average has a somewhat larger peak response. ...
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... longer period, the average of Turkey is somewhat higher. When the Turkey earthquakes are included in the entire data set, no appreciable difference is observed ( Figure 12). As there is only one far-field record from the Turkey earthquakes, no comparison of far-field averages is made herein, with results of earlier studies. ...
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... the quite complex source of the 1999 Chi-Chi, Taiwan earthquake (Shin and Teng [12]), design spectra for vertical ground motions (based on average spectral response) are recommended for the following three situations while maintaining the distinction between near-field and far-field cases ( Figures 13 and 14 Based on average response spectra, Figure 13 and Figure 14 show the three situations for near-field and far-field respectively. The key parameters that define these shapes at 2% damping are listed in Table 5. ...
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... the quite complex source of the 1999 Chi-Chi, Taiwan earthquake (Shin and Teng [12]), design spectra for vertical ground motions (based on average spectral response) are recommended for the following three situations while maintaining the distinction between near-field and far-field cases ( Figures 13 and 14 Based on average response spectra, Figure 13 and Figure 14 show the three situations for near-field and far-field respectively. The key parameters that define these shapes at 2% damping are listed in Table 5. ...
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... the quite complex source of the 1999 Chi-Chi, Taiwan earthquake (Shin and Teng [12]), design spectra for vertical ground motions (based on average spectral response) are recommended for the following three situations while maintaining the distinction between near-field and far-field cases ( Figures 13 and 14 Based on average response spectra, Figure 13 and Figure 14 show the three situations for near-field and far-field respectively. The key parameters that define these shapes at 2% damping are listed in Table 5. ...
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... that the cases excluding the Chi-Chi earthquake are essentially the ones recommended by Elnashai and Papazoglou [2] and Elgamal and He [3]. Spectra for other damping ratios can be defined with the aid of Far-field design response spectra at 2% damping Excluding Chi-Chi earthquake Including Chi-Chi earthquake Exclusively for Chi-Chi earthquake Figure 14. Far-field design response spectra at 2% damping Table 5 Key parameters of the recommended near-field and far-field design spectra (2% damping) ...
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Citations
... However, their review Advances in Civil Engineering and analysis are more focused on seismological aspects rather than impacts of strong vertical shaking on buildings. Similar seismological studies regarding the strong vertical shaking in near-field regions are also performed by several researchers (see, e.g., [37][38][39][40][41][42][43][44]). Mazza and Vulcano [45] performed analysis on the effects of combined vertical and horizontal components of near-fault ground motions in the nonlinear dynamic response of the base-isolated building. ...
Strong vertical excitation may lead to detrimental consequences on structures and infrastructures. To date, the impacts of strong vertical shaking on structures and infrastructures are considered for near-field regions only. However, anomalies in terms of recorded evidence and damage occurrence in the central Himalayan earthquakes dragged the attention of the researchers to explore the possibility of strong vertical shaking in far-field regions as well. Systematic review approach is used to sum up the findings from scholastic works reported to date and juxtaposed the findings with the evidence from central Himalayan earthquakes. It is concluded that the strong vertical shaking in the far-field is undeniable, at least in the central Himalayas; thus, incorporation of strong far-field vertical shaking in structural analysis and design is required. This paper reports the evidence reported in the literature for strong vertical shaking and adds evidence from Nepal focusing on strong far-field vertical excitation.
... Conversely, there is a considerable body of evidence (e.g. Ambraseys and Simpson, 1996;Bozorgnia and Campbell, 2004;Papazouglou and Elnashai, 1996;Elgamal et al., 2004) that in the vicinity of the causative fault of moderate-to-strong earthquakes the V/H ratio exceeds unity and hence exceeds the values assumed in design. For instance, for the Imperial Valley 'EO6 ', U.S., 1979 andMorgan Hill 'G07', U.S., 1984, events, the V/H ratio was 3.70 and 3.52, respectively. ...
... Bozorgnia et al., 1998;Ghobarah and Elnashai, 1998;Papazouglou and Elnashai, 1996;amongst others). Recently, new approaches have been suggested to rationally account for VGM (Elnashai and Papazouglou, 1997;Collier and Elnashai, 2001;Elgamal et al, 2004), which lead to the adoption of more realistic VGM spectra in design (EC8, 2004). ...
In the vicinity of the source of moderate-to-strong earthquakes, the ratio of peak vertical to horizontal acceleration (V/H) often exceeds the values around 2/3rd adopted in design codes. The difference in frequency content between the vertical and horizontal ground motions (VGM and HGM, respectively), when coupled with difference between the vertical and horizontal dynamic characteristics of structures, cast doubt regarding the adequacy of the simplified approach adopted in seismic design codes. There are also increasing field evidences confirming the significance of VGM. These evidences were even observed in regions where state-of-the-art in earthquake design practice is applied, such as Japan and the USA. The objective of this paper is to investigate the effect of VGM on seismic response and force reduction factors 'supply' of multi-storey RC buildings located in the vicinity of active faults and designed to modern seismic codes employing capacity design principles. A comprehensive set of local and global response parameters is selected to assess the building response under multi-axial earthquake loading (HGM and VGM). These include assessment of the shear supply-demand response of structural members using a realistic ductility- and axial force- sensitive shear strength approach. Near-field earthquake records with moderate-to-high V/H ratios are selected to provide realistic conclusions regarding the effect of VGM. The wide range of buildings and performance criteria selected and the state-of-the-art modeling approaches adopted render the results of this study indicative of response trends. It is concluded that the lower the contribution of horizontal seismic forces to the seismic response, the higher is the significance of vertical motion. The fluctuation of axial force in vertical structural members significantly increases when including VGM. This not only has direct consequences on tension and compression response but also has considerable impact on the shear capacity. Although the investigated buildings are designed and detailed according to modern seismic codes, the importance of including VGM in seismic design and assessment of RC buildings in the vicinity of active faults is emphasized.
