Equivalent linear and nonlinear site response analysis for design and risk assessment of safety-related nuclear structures

Bolisetti, Chandrakanth; Whittaker, Andrew S.; Mason, H. Benjamin; Almufti, Ibrahim; Willford, Michael

doi:10.1016/j.nucengdes.2014.04.033

Cited by 78 publications

(24 citation statements)

References 16 publications

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“…At low-to-mid frequencies, nonlinear soil response means that more amplification occurs for larger input intensities because the induced strain is increased, and shear modulus (stiffness) is reduced which consequently shortens the predominant peak frequency. At higher frequencies, less amplification occurs for larger input intensities due to increased levels of induced strain and increased soil damping [64,67,68]. Based on the presented example in Figure 12, site amplification factors for all 68 locations were estimated in the same way and will be discussed in more detail with reference to the presented site response amplification maps.…”

Section: Assessment Of the Seismic Site Amplification Map For The Citmentioning

confidence: 99%

“…Figure 14 shows maps of the site response amplification factor at the surface (amplification of the peak ground acceleration-PGA) for input PGAROCK = 0.09 g (95-yrp) and 0.19 g (475yrp). The main observation is that the soft soil alluvial basin shows nonlinear behaviour when higher input ground motion (0.19 g) is induced, that is to say, amplification factors decrease significantly [66,67]. Figure 14.…”

Section: Site Response Amplification Map For the City Of Ivanecmentioning

confidence: 99%

“…The findings from the 1-D EQL site response analysis for all 68 local soil profiles ( Figure 11) based on the example in Figure 12 and site response amplification maps in Figures 13 and 14 can be summarized as follows: 1) for PGA ROCK = 0.09 g, the input motion is significantly amplified at the top layers of the soil profile; 2) AF is most prominent at a predominant peak frequency, particularly for softer soils with lower V S30 and thicker alluvium layers overlying bedrock; 3) at higher input motion levels PGA ROCK = 0.19 g, in softer soils with lower values of V S30 , reduction observed at the surface PGA relative to PGA ROCK in soft soil sites is attributed to the non-linearity of the soil [66,67,71] which in turn is due to the degradation of the shear modulus subject to large deformations, the AF@PGA decreases at a higher spectral frequency, and the predominant spectral frequency shifts to lower frequencies with decreasing AF@PF [67,68]; 5) for stiffer soil and soft rocks with higher values of V S30 , site amplification factors generally show small to no amplification, whereas in some cases significant amplification can be observed (for example location 64, Figure 7) in the presence of upper weaker soil materials (lower V S values) and very shallow bedrock (mainly in topographical areas) [72]. Local site amplifications can be correlated with the seismic ground motion polarization and directionality in both approaches, ambient noise vibrations and earthquake recordings at sites with pronounced topographies [70].…”

Section: Figure 14mentioning

confidence: 99%

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Assessment of the Seismic Site Amplification in the City of Ivanec (NW Part of Croatia) Using the Microtremor HVSR Method and Equivalent-Linear Site Response Analysis

et al. 2019

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The city of Ivanec is located between valley of the Bednja River and Mt. Ivanščica and this area can be prone to significant seismic site amplification due to local site characteristics. This study presents the first assessment of seismic site amplification for the city of Ivanec by the microtremor horizontal-to-vertical-spectral-ratio (HVSR) method and the equivalent-linear (EQL) site response analysis. Based on microtremor measurements and HVSR analysis, fundamental soil frequency and HVSR peak amplitude maps indicate potentially seismic danger zones. The 1-D EQL site response analysis was performed using multiple suites of earthquake ground motions scaled to the 95-and 475-year return periods of peak ground accelerations. Site amplification maps at the predominant peak frequency and ground surface indicate two microzones, one with high amplification in the central part of the city due to soft soil characteristics, and the other with small amplification in the transitional zone from alluvial basin towards the foothills of Mt. Ivanščica. HVSR peak amplitudes and site response peak amplifications showed similar spatial distributions with similar predominant peak frequencies but with different amplitude levels. Site amplification maps provided significant information about potential resonance effects for structures of certain heights that can be correlated with the local ground shaking characteristics.

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Section: Assessment Of the Seismic Site Amplification Map For The Citmentioning

confidence: 99%

Section: Site Response Amplification Map For the City Of Ivanecmentioning

confidence: 99%

Section: Figure 14mentioning

confidence: 99%

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Assessment of the Seismic Site Amplification in the City of Ivanec (NW Part of Croatia) Using the Microtremor HVSR Method and Equivalent-Linear Site Response Analysis

et al. 2019

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“…Two soil conditions are considered, namely stiff sand and competent rock, as being representative of the ground conditions in the Central and Eastern United States, respectively, see (Bolisetti et al, 2014).…”

Section: Overview Of the Npp Studiedmentioning

confidence: 99%

Seismically induced uplift effects on nuclear power plants. Part 1: Containment building rocking spectra

Sextos

Manolis

Athanasiou

et al. 2017

Nuclear Engineering and Design

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. focusing primarily on the response of the containment structure of a nuclear power plant.However, in current state-of-practice and in most seismic regulations worldwide, the consideration of soil-structure interaction and potential development of geometrically nonlinear effects, such as rocking and sliding with uplift, is not taken into consideration. To explore this issue, a refined 3Dfinite element model of a typical nuclear power plant containment structure is developed, comprising solid elements for the soil and foundation, plus shell elements for the structure. The aim is identification of foundation-soil separation phenomena under a suite of ground motions with distinct frequency content. At first, harmonic excitations are used, for both cases of stiff sand and rock subsoil profiles, leading to rocking spectra that depict the displacement demand in connection with nonlinear separation. Clear influence zones can be distinguished, especially in the low frequency bands for the stiff sand case. Next, three subsets of 30 ground motion records are carefully selected and grouped in ensembles according to their frequency content, normalized to a PGA of 0.36g, which corresponds to the highest design acceleration in Europe. Ground motions with low mean frequency content are observed to lead to the onset of geometrically nonlinear phenomena, along with a higher displacement demand. The interplay between ground motion characteristics, dynamic properties of the containment structure and stiffness of the soil is also highlighted. More specifically, it is shown that stiff containment structures on soft soils are more prone to foundation uplift. This possibility is often neglected in design codes and the consequence is that under certain circumstances, damage may be caused to the internal power generation equipment..

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“…Similarly, the use of equivalent linear model for the rock-footing system was warranted by the expected low level of strain in the rock mass under the considered seismic excitation. This assumption was backed up by the work of Bolisetti et al (2014), who compared equivalent linear and non-linear site response analysis for rock and soil sites and concluded that equivalent linear methods gave satisfactory results for low strain levels. Additionally, Strenk and Wartman (2011) reported an increase in the estimation of soil-foundation stiffness and hence reduced contribution of SSI, while using non-linear soil models as compared to equivalent linear model.…”

Section: Assumptionsmentioning

confidence: 99%

Effect of soil-foundation-structure interaction and pier column non-linearity on seismic response of bridges supported on shallow foundations

Chaudhary

2016

Australian Journal of Structural Engineering

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Traditionally, shallow spread footing-type foundations are used for medium span bridges supported on hard soil and rock strata. Such bridges are modelled with fixed supports and no soil-foundation-structure interaction (SSI) is normally considered. The investigation presented herein utilized a sub-structuring technique and finite element method (FEM) model for the analysis of a four-span bridge designed for five different rock classes and subjected to an ensemble of actual ground motions. SSI was incorporated through Winkler springs while nonlinear behaviour of reinforced concrete pier column was modelled by an equivalent linear model. The results of the study were evaluated to delineate the effect of SSI and pier column non-linearity on seismic response parameters of bridges founded on rock. It was found that the soil-foundation-structure interaction couldn't be neglected in all cases of rock classes and input ground motions. Furthermore, pier column non-linearity influenced bridge displacement and base shear more significantly than SSI. Impact of foundation rocking was also examined and was found to be rather insignificant on bridge response parameters due to high rocking impedance of properly designed bridge foundations.

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Equivalent linear and nonlinear site response analysis for design and risk assessment of safety-related nuclear structures

Cited by 78 publications

References 16 publications

Assessment of the Seismic Site Amplification in the City of Ivanec (NW Part of Croatia) Using the Microtremor HVSR Method and Equivalent-Linear Site Response Analysis

Assessment of the Seismic Site Amplification in the City of Ivanec (NW Part of Croatia) Using the Microtremor HVSR Method and Equivalent-Linear Site Response Analysis

Seismically induced uplift effects on nuclear power plants. Part 1: Containment building rocking spectra

Effect of soil-foundation-structure interaction and pier column non-linearity on seismic response of bridges supported on shallow foundations

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