A Frequency-Modulated Instrumentation System for High-Explosive Ground Motion, Airblast, and Structure Response Tests

1977 ◽  
Author(s):  
David J. Ray
Keyword(s):  
Ground Motion ◽  
High Explosive ◽  
Structure Response

Seismic Qualification by Testing for Electrical and Active Mechanical Equipment to be Installed in Hard-Rock High Frequency Sites

2009 ◽  
Author(s):  
Pei-Ying Chen ◽  
Ching Hang Ng
Keyword(s):  
Ground Motion ◽  
Seismic Design ◽  
High Frequency ◽  
Power Plants ◽  
Hard Rock ◽  
Response Spectra ◽  
Nuclear Industry ◽  
Mechanical Equipment ◽  
Regulatory Requirements ◽  
Structure Response

All electric and active mechanical equipment important to safety must be seismically qualified by either analysis, testing, or a combination of both. The general requirements for seismic qualification of electric and active mechanical equipment in nuclear power plants are delineated in Appendix S to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50), item 52.47(20) of 10 CFR 52.47, and Appendix A to 10 CFR Part 100. The staff at the US Nuclear Regulatory Commission (NRC) has recognized that the Certified Design Ground Motion may be exceeded by the site-specific ground motion. The exceedances are generally in the high-frequency range for the Central and Eastern US sites. For equipment seismic qualification consideration, the exceedances must be addressed at both the ground level and the floor level where the equipment is located. Thus, the in-structure response spectra at some locations may exceed those in-structure response spectra generated by the certified seismic design response spectra. The U.S. nuclear industry and the NRC have initiated activities to address this issue. Two scenarios that revealed themselves during the review activities of the design certification and combined license applications for new reactors will be expounded upon in the paper. In Case I, equipment seismic qualification has been approved for a certified design and equipment is to be installed at a hard-rock high frequency (HRHF) site with certified seismic design response spectra (CSDRS) exceeded by the Ground Motion Response Spectra (GMRS) of the hard-rock site. In Case II, equipment seismic qualification has not been approved for a design certification and there is an application with GMRS exceeding the not-yet-approved CSDRS. In the paper, the staff will begin the discussion with the regulatory requirements for seismic qualification of electric and mechanical equipment. The focus of the paper is to identify the staff concern and illustrate the resolution between the NRC staff and an applicant on the seismic qualification of equipment by testing, in particular for equipment to be installed in hard-rock high frequency sites, to meet the regulatory requirements.

The Effects of Discretization Errors on the High Frequency Content of In-Structure Response Spectra

2016 ◽  
Author(s):  
Greg Mertz ◽  
Robert Spears ◽  
Thomas Houston
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Time History ◽  
Response Spectra ◽  
Frequency Content ◽  
Time Step ◽  
Structure Response ◽  
Time History Response ◽  
Ground Motion Records ◽  
High Frequency Content

The next generation ground motion prediction equations predict significant high frequency seismic input for rock sites in the Central Eastern United States (CEUS). This high frequency motion is transmitted to basemat supported components and may be transmitted to components supported on elevated slabs. The existing ASCE 4 analysis requirements were initially developed based on seismic motions having lower frequencies, typical of ground motions in the Western United States (WUS). The adequacy of the existing ASCE 4 analysis requirements are examined using high frequency CEUS spectral shapes and the potential error inherent in using the existing approach to computing in structure response spectra is quantified. Modifications to reduce potential error in the existing ASCE 4 criteria are proposed. In structure response spectra are typically generated for a subsystem given the time history response of a building region. The building time history response is based on analyses that use either modal time history superposition, direct integration or complex frequency response analysis of the building and supporting soil. Input to the building analyses consist of either real or synthetic discretized ground motion records. The discretized ground motion records are often based on recorded ground motion seeds and are often limited to a 0.005 second time step. Thus the time step of the seed record often limits the frequency content of the problem. Both the building analyses and in structure response spectra subsystem analysis may interpolate the discretized ground motion records to obtain stable results. This interpolation generates errors that are propagated through the analyses used to calculate in structure response spectra. These errors may result in extraneous high frequency content in the in structure response spectra. Errors are quantified by comparison of time history parameters, Fourier components and in structure response spectra.

Effects of SSI on EPR™ In-Structure Response for a Rock Site: Coherent and Incoherent High Frequency Ground Motion

2010 ◽  
Author(s):  
James J. Johnson ◽  
Oliver Schneider ◽  
Werner Schuetz ◽  
Philippe Monette ◽  
Alejandro P. Asfura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Ground Motions ◽  
Free Field ◽  
Response Spectra ◽  
Frequency Content ◽  
Structure Response ◽  
Standard Design ◽  
Rock Site ◽  
High Frequency Content

Recently, probabilistic seismic hazard assessments (PSHAs) performed for hard sites world-wide have yielded uniform hazard response spectra (UHRS) with significant high frequency content, i.e., frequency content greater than 10 Hz. This high frequency content is frequently due to near-field relatively low magnitude events. It is well known that these high frequency ground motions are not damaging to ductile structures, systems, and components (SSCs). One method of addressing the effect of these high frequency ground motions on structure response is to take into account the incoherency of ground motion. Over the past 25 years, free-field ground motion has been recorded providing an adequate basis for the development of ground motion coherency functions necessary to assess the effect of incoherence on nuclear power plant structures. The subject of this study was the AREVA NP EPR™ (European Power Reactor) nuclear island (NI) standard design. The effect of incoherency of ground motion on in-structure response spectra (ISRS) was assessed for the NI founded on a stiff rock site and subjected to high frequency enhanced input for hard rock sites. The ISRS at numerous locations and directions in the structures were calculated and compared. SSI is shown to be an important phenomenon for structures founded on stiff sites and subjected to high frequency ground motions.

Generation of In-Structure Response Spectra for Nuclear Power Plants Subjected to High-Frequency Ground Motion

2012 ◽  
Author(s):  
Luis M. Moreschi ◽  
Qin Pan ◽  
Shen Wang ◽  
Sanjeev R. Malushte
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Nuclear Power ◽  
Power Plants ◽  
Response Spectra ◽  
Frequency Range ◽  
Modeling And Analysis ◽  
Analysis Techniques ◽  
Structure Response ◽  
Selection Of

The purpose of seismic qualification of Structures, Systems and Components (SSCs) in nuclear power plants is to ensure that their intended safety function will not be compromised during and after a postulated earthquake event. The seismic performance of the equipment is generally evaluated using In-Structure Response Spectra (ISRS) at equipment-support locations as an input motion. Traditionally, these ISRS are generated based on design ground spectra prescribed by either U.S. Nuclear Regulatory Commission Regulatory Guide 1.60 or other design spectral shapes, which normally consider the frequencies content up to 33Hz. However, it has been recently recognized that probabilistic hazard-based site specific ground motion response spectra (GMRS) for Central and Eastern United States (CEUS) hard rock sites contains significant energy in the high frequency range, far beyond 33Hz. Since the motion at equipment support locations is highly affected by the dynamic characteristics of the soil or rock surrounding the building foundations and those of the structure itself, the adequacy of dynamic modeling and analysis techniques for determining the ISRS is critical to seismic qualification of safety-related equipment. This paper provides examples on dynamic modeling and analysis techniques required to accurately capture the structural responses for purposes of calculating ISRS throughout the frequency range of interest, including the high frequency responses typically expected at the CEUS sites. The discussion includes the selection of finite element mesh size, and sensitivity analysis performed to demonstrate that the propagation of these high frequencies through the different levels of the structure is properly captured. Other analytical considerations, such as the selection of time step size, for conducting time-history analysis, are also presented.

Insights into seismic hazard from big data analysis of ground motion simulations

2019 ◽  
Vol 9 (1) ◽  
pp. 01-12 ◽  
Author(s):  
Kristy F. Tiampo ◽  
Javad Kazemian ◽  
Hadi Ghofrani ◽  
Yelena Kropivnitskaya ◽  
Gero Michel
Keyword(s):  
Big Data ◽  
Data Analysis ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Big Data Analysis ◽  
Ground Motion Simulations

Reliable Seismic Structural Analysis using Interval Ground Motion

2013 ◽  
Vol 2 (1) ◽  
pp. 6-13
Author(s):  
Mehdi Modares ◽  
◽  
Adam Venezia ◽  
Keyword(s):  
Structural Analysis ◽  
Ground Motion
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