Site Response Studies for Purpose of Revising NEHRP Seismic Provisions

Crouse, C. B.; McGuire, J W

doi:10.1193/1.1585891

Cited by 56 publications

(47 citation statements)

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“…Alternatively, the developed far-ÿeld factors can be used to modify near-ÿeld predictions from one of the existing attenuation models. The e ect of soil ampliÿcation can be accounted for by incorporating representative site ampliÿcation factors (such as site factors developed by Crouse and McGuire [42] or resonance factors developed by the authors [7]). Figure 13 provides a diagrammatic illustration on how the relationships developed in this paper can be combined with relationships developed elsewhere to construct a displacement response spectrum model for engineering applications.…”

Section: Summary Of Findings and Closing Remarksmentioning

confidence: 99%

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An attenuation model for distant earthquakes

Chandler

Lam

2003

Earthq Engng Struct Dyn

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SUMMARYLarge magnitude earthquakes generated at source-site distances exceeding 100 km are typiÿed by lowfrequency (long-period) seismic waves. Such induced ground shaking can be disproportionately destructive due to its high displacement, and possibly high velocity, shaking characteristics. Distant earthquakes represent a potentially signiÿcant safety hazard in certain low and moderate seismic regions where seismic activity is governed by major distant sources as opposed to nearby (regional) background sources. Examples are parts of the Indian sub-continent, Eastern China and Indo-China. The majority of ground motion attenuation relationships currently available for applications in active seismic regions may not be suitable for handling long-distance attenuation, since the signiÿcance of distant earthquakes is mainly conÿned to certain low to moderate seismicity regions. Thus, the e ects of distant earthquakes are often not accurately represented by conventional empirical models which were typically developed from curve-ÿtting earthquake strong-motion data from active seismic regions. Numerous well-known existing attenuation relationships are evaluated in this paper, to highlight their limitations in long-distance applications. In contrast, basic seismological parameters such as the Quality factor (Q-factor) could provide a far more accurate representation for the distant attenuation behaviour of a region, but such information is seldom used by engineers in any direct manner. The aim of this paper is to develop a set of relationships that provide a convenient link between the seismological Q-factor (amongst other factors) and response spectrum attenuation. The use of Q as an input parameter to the proposed model enables valuable local seismological information to be incorporated directly into response spectrum predictions. The application of this new modelling approach is demonstrated by examples based on the Chi-Chi earthquake (Taiwan and South China), Gujarat earthquake (Northwest India), Nisqually earthquake (region surrounding Seattle) and Sumatran-fault earthquake (recorded in Singapore). Field recordings have been obtained from these events for comparison with the proposed model. The accuracy of the stochastic simulations and the regression analysis have been conÿrmed by comparisons between the model calculations and the actual ÿeld observations. It is emphasized that obtaining representative estimates for Q for input into the model is equally important. Thus, this paper forms part of the long-term objective of the authors to develop more e ective communications across the engineering and seismological disciplines.

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Section: Summary Of Findings and Closing Remarksmentioning

confidence: 99%

“…RSVmax on soil is the product of the RSVmax estimated on rock and a representative site factor in the velocity controlled range of the response spectrum (e.g. References [7] or [42]). 4.…”

Section: Summary Of Findings and Closing Remarksmentioning

confidence: 99%

An attenuation model for distant earthquakes

Chandler

Lam

2003

Earthq Engng Struct Dyn

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“…SHAKE is a robust seismic site response analysis program which provides reasonable approximation to the site response simulations with a minimal input. Borcherdt (1994) and Crouse and McGuire (1996) applied SHAKE in supplementing their analyses, which can further ascertain the program's validity in performing site response analyses. In this study, the shear modulus degradation and damping curves given by Seed and Idriss (1970) and Schnabel (1973) for sand average and rock have been used for soil and rock layers, respectively.…”

Section: Site Response Parameters For Soil Sites With Shallow Depth Omentioning

confidence: 99%

Influence of Rock Depth on Seismic Site Classification for Shallow Bedrock Regions

2013

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Seismic site classifications are used to represent site effects for estimating hazard parameters (response spectral ordinates) at the soil surface. Seismic site classifications have generally been carried out using average shear wave velocity and/or standard penetration test n-values of top 30-m soil layers, according to the recommendations of the National Earthquake Hazards Reduction Program (NEHRP) or the International Building Code (IBC). The site classification system in the NEHRP and the IBC is based on the studies carried out in the United States where soil layers extend up to several hundred meters before reaching any distinct soil-bedrock interface and may not be directly applicable to other regions, especially in regions having shallow geological deposits. This paper investigates the influence of rock depth on site classes based on the recommendations of the NEHRP and the IBC. For this study, soil sites having a wide range of average shear wave velocities (or standard penetration test n-values) have been collected from different parts of Australia, China, and India. Shear wave velocities of rock layers underneath soil layers have also been collected at depths from a few meters to 180 m. It is shown that a site classification system based on the top 30-m soil layers often represents stiffer site classes for soil sites having shallow rock depths (rock depths less than 25 m from the soil surface). A new site classification system based on average soil thickness up to engineering bedrock has been proposed herein, which is considered more representative for soil sites in shallow bedrock regions. It has been observed that response spectral ordinates, amplification factors, and site periods estimated using onedimensional shear wave analysis considering the depth of engineering bedrock are different from those Abstract: Seismic site classifications are used to represent site effects for estimating hazard parameters (response spectral ordinates) at the soil surface. Seismic site classifications have generally been carried out using average shear wave velocity and/or standard penetration test n-values of top 30-m soil layers, according to the recommendations of the National Earthquake Hazards Reduction Program (NEHRP) or the International Building Code (IBC). The site classification system in the NEHRP and the IBC is based on the studies carried out in the United States where soil layers extend up to several hundred meters before reaching any distinct soil-bedrock interface and may not be directly applicable to other regions, especially in regions having shallow geological deposits. This paper investigates the influence of rock depth on site classes based on the recommendations of the NEHRP and the IBC. For this study, soil sites having a wide range of average shear wave velocities (or standard penetration test n-values) have been collected from different parts of Australia, China, and India. Shear wave velocities of rock layers underneath soil layers have also been collected at depths from a few meters ...

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“…In addition, it provides reasonable approximation to the site response simulations with a minimal input ÿle. Borcherdt [23] and Crouse and McGuire [24] applied program SHAKE in supplementing their analyses, which can further ascertain its validity in performing site response analyses.…”

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confidence: 99%

Estimating non-linear site response by single period approximation

Tsang

Chandler

Lam

2006

Earthquake Engng Struct. Dyn.

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SUMMARYSite e ects characterize the ÿltering mechanisms within the soil sedimentary layers overlying bedrock. In regions of high seismicity such as California where strong motion records are relatively abundant, site coe cients can be developed by regression of recorded ground shaking parameters. In regions of low-to-moderate seismicity or of high seismicity but with a paucity of recorded strong motion data, such empirical models cannot be obtained in the same way.This study describes the theoretical development of a simple, rational manual procedure to calculate site coe cients, based on a single period approximation (SPA), and to construct displacement response spectra (RSD) for soil sites. The proposed simpliÿed model, which takes into account the non-linear behaviour of soil that is dependent on the level of shaking, impedance contrast at the soil-bedrock interface and the plasticity of soil material, has been veriÿed by comparison with results obtained from non-linear shear wave analyses and data recorded during the 1994 Northridge earthquake. The proposed model is believed to be a convenient tool for calculating non-linear site responses and constructing site-speciÿc response spectra, which has the potential of being incorporated into code provisions.

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Site Response Studies for Purpose of Revising NEHRP Seismic Provisions

Cited by 56 publications

References 0 publications

An attenuation model for distant earthquakes

An attenuation model for distant earthquakes

Influence of Rock Depth on Seismic Site Classification for Shallow Bedrock Regions

Estimating non-linear site response by single period approximation

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