Horizontal UHS Amplitudes for Regions with Deep Soil Atop Deep Geological Sediments—An Example of Osijek, Croatia

Bulajić, Borko Đ.; Hadzima-Nyarko, Marijana; Pavić, Gordana

doi:10.3390/app11146296

Cited by 4 publications

(2 citation statements)

References 31 publications

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Section: The Results Of Variation In the Silty Clay Thicknesssupporting

confidence: 90%

“…Under the action of the extremely rare earthquake, the response spectrum curve shows an obvious "double peak phenomenon", and the second peak point appears in the period of 0.5-0.7 s. The amplitude of the response spectrum increases with the thickness of the overlying silty clay layer under frequent earthquakes, basic earthquakes, and rare earthquakes. Under the extremely rare earthquake, the response spectrum curve shows strong dispersion before 0.3 s. This result is surprisingly similar to the findings of another recent study on the effects of deep soil sites atop deep geological sediments on surface ground motion, in which a spectral peak at 0.5 s was also found [24]. As shown in Figure 9, the pebble soil site in the Zhongwei Basin has an obvious amplification effect on the short-period seismic waves, and the periodic peak points of the response spectrum are all within 0.1-0.2 s. Under the action of frequent earthquakes, basic earthquakes, and rare earthquakes, the site significantly amplifies the short-period component of the earthquake but has little effect on the long-period component.…”

Section: The Results Of Variation In the Silty Clay Thicknesssupporting

confidence: 90%

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Study on the Seismic Effect of the Pebble Soil Site in the Zhongwei Basin

Yang

Han²,

Lei

et al. 2022

Applied Sciences

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Based on a large amount of drilling and geophysical exploration work in the Zhongwei Basin, and combined with the collected borehole data of a seismic safety assessment, this paper summarizes and builds 16 typical pebble soil layer calculation models. The effects of the thickness of the pebble layer, the thickness of the overlying silty clay, the top interface of the pebble layer on the peak acceleration and the response spectrum of the site seismic response were analyzed using the equivalent linearization method of the one-dimensional soil layer seismic response. The analysis results showed that the variation in pebble layer thickness had no obvious effect on the peak acceleration of the ground surface under different inputs; the influence of the pebble layer thickness on the ground acceleration response spectrum was primarily concentrated in the middle/high-frequency band of 0.2–0.6 s. Within this range, the acceleration response spectrum of the site with a 30 m pebble layer thickness was small, and the response spectrum curve showed a “trough” shape with a certain “weak isolation” effect. Under the same pebble layer thickness, the upper ground surface peak acceleration with a silty clay layer thickness increased with the increase in the central basin pebble soil field, where a short cycle of the seismic wave amplification effect was more obvious. The response spectrum peak period points were within 0.1–0.2 s and were influenced by the action of rare earthquakes. Moreover, the response spectrum curve showed a more obvious phenomenon of “twin peaks”, and the second peak point appeared in the period of 0.5–0.7 s. With the increase in the input intensity, the PGA amplification ratio of the pebble-top interface was significantly smaller than that of the site surface; under different intensities of input, the acceleration response spectrum of the pebble-top interface showed a “trough” phenomenon that was lower than the bedrock input at approximately 0.1 s. Under the action of rare ground motion, the acceleration response spectrum curve of the pebble-top interface showed a “double peak” phenomenon, and within 0.24–0.4 s, the spectrum value was lower than the bedrock input, showing an obvious shock absorption and isolation effect. Under the action of an earthquake, the energy of the pebble-top interface was concentrated in the low-frequency range of 1.1–2.2 Hz, and the amplification effect was obvious. In the range of 8–10 Hz, the amplitude was lower than the bedrock input, and the seismic isolation effect was obvious.

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Section: The Results Of Variation In the Silty Clay Thicknesssupporting

confidence: 90%

Section: The Results Of Variation In the Silty Clay Thicknesssupporting

confidence: 90%

Study on the Seismic Effect of the Pebble Soil Site in the Zhongwei Basin

Yang

Han²,

Lei

et al. 2022

Applied Sciences

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Maintenance Condition and Seismic Vulnerability of Buildings in Rural Areas – A Case Study of Two Rural Settlements in Osijek-Baranja County

Hadzima-Nyarko

Stojnović

Pavić

et al. 2021

30th International Conference on Organization and Technology of Maintenance (OTO 2021)

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Vertical to Horizontal UHS Ratios for Low to Medium Seismicity Regions with Deep Soil atop Deep Geological Sediments—An Example of the City of Osijek, Croatia

2021

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The severity of vertical seismic ground motions is often factored into design regulations as a component of their horizontal counterparts. Furthermore, most design codes, including Eurocode 8, ignore the impact of local soil on vertical spectra. This paper investigates vertical pseudo-absolute acceleration spectral estimates, as well as the ratios of spectral estimates for strong motion in vertical and horizontal directions, for low to medium seismicity regions with deep local soil and deep geological sediments beneath the local soil. The case study region encompasses the city of Osijek in Croatia. New regional frequency-dependent empirical scaling equations are derived for the vertical spectra. According to these equations, for a 0.3 s spectral amplitude at deep soils atop deep geological sediments compared to the rock sites, the maximum amplification is 1.48 times. The spectra of vertical components of various real strong motions recorded in the surrounding region are compared to the empirical vertical response spectra. The new empirical equations are used to construct a Uniform Hazard Spectra for Osijek. The ratios of vertical to horizontal Uniform Hazard Spectra are generated, examined, and compared to Eurocode 8 recommendations. All the results show that local soil and deep geology conditions have a significant impact on vertical ground motions. The results also show that for deep soils atop deep geological strata, Eurocode 8 can underestimate the vertical to horizontal spectral ratios by a factor of three for Type 2 spectra while overestimating them by a factor of two for Type 1 spectra.

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Horizontal UHS Amplitudes for Regions with Deep Soil Atop Deep Geological Sediments—An Example of Osijek, Croatia

Cited by 4 publications

References 31 publications

Study on the Seismic Effect of the Pebble Soil Site in the Zhongwei Basin

Study on the Seismic Effect of the Pebble Soil Site in the Zhongwei Basin

Maintenance Condition and Seismic Vulnerability of Buildings in Rural Areas – A Case Study of Two Rural Settlements in Osijek-Baranja County

Vertical to Horizontal UHS Ratios for Low to Medium Seismicity Regions with Deep Soil atop Deep Geological Sediments—An Example of the City of Osijek, Croatia

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