Lateral Structure Interaction With Seismic Waves

1971 ◽  
Vol 38 (1) ◽  
pp. 125-134 ◽  
Author(s):  
R. J. Scavuzzo ◽  
J. L. Bailey ◽  
D. D. Raftopoulos
Keyword(s):  
Half Space ◽  
San Francisco ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Structural Characteristics ◽  
Free Field ◽  
Elastic Half Space ◽  
Inertia Force ◽  
Ground Acceleration

The interaction of lateral structural inertia forces with horizontal seismic motion is formulated in terms of an integral equation of the Volterra type. By means of normal mode theory the inertia force at the base of the structure is expressed as a function of the foundation motion. After the motion of the two-dimensional elastic half space resulting from a uniform horizontal foundation force varying arbitrarily with time over a specified interval on the boundary of the half space has been determined, the interaction equation is derived. Numerical studies for two free-field acceleration inputs are made for different ground stiffnesses and structural characteristics. The first of these free-field inputs is a ramp sine function and the second is the east-west ground acceleration recorded at Golden Gate Park during the 1957 San Francisco earthquake. The interaction effects for structures similar to nuclear power plants prove to be significant.

scholarly journals EXCEPTIONAL GROUND MOTION DURING THE SHALLOW Mw 4.9 2019 LE TEIL EARTHQUAKE, FRANCE

2020 ◽  
Author(s):  
Mathieu Causse ◽  
Cécile Cornou ◽  
Emeline Maufroy ◽  
jean-robert grasso ◽  
Laurent Baillet ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Strong Motion ◽  
Seismic Hazard Assessment ◽  
Motion Sensors ◽  
Ground Acceleration ◽  
Near Surface ◽  
Numerical Predictions

On November 11, 2019, an unusually damaging Mw4.9 earthquake occurred in the south east of France within the lower Rhône river valley, an industrial region hosting several operating nuclear power plants. This event is exceptional considering its very shallow depth (<1 km). Based on farfield seismological observations, we demonstrate that the rupture properties are consistent with the ones commonly observed for large deeper earthquakes, implying that the near-surface faulting generated strong high-frequency seismic waves. In the absence of strong motion sensors in the fault vicinity, we perform numerical predictions of the ground acceleration on a virtual array of near-fault stations, that matches with the locations of independent quantitative estimations from in-situ observations of displaced objects (natural and anthropic). Both numerical and in-situ analyses converge toward an exceptional level of ground acceleration in the fault vicinity, exceeding gravity, and at the origin of the damage. This dramatically changes the perception of the impacts of superficial moderate earthquakes on seismic hazard assessment.

scholarly journals A Method to Avoid Underestimated Risks in Seismic SUPSA and MUPSA for Nuclear Power Plants Caused by Partitioning Events

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2150
Author(s):  
Woo Sik Jung
Keyword(s):  
Exact Solutions ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fault Tree ◽  
Ground Acceleration ◽  
Special Operations ◽  
Core Damage ◽  
Full Power ◽  
Conditional Events

Seismic probabilistic safety assessment (PSA) models for nuclear power plants (NPPs) have many non-rare events whose failure probabilities are proportional to the seismic ground acceleration. It has been widely accepted that minimal cut sets (MCSs) that are calculated from the seismic PSA fault tree should be converted into exact solutions, such as binary decision diagrams (BDDs), and that the accurate seismic core damage frequency (CDF) should be calculated from the exact solutions. If the seismic CDF is calculated directly from seismic MCSs, it is drastically overestimated. Seismic single-unit PSA (SUPSA) models have random failures of alternating operation systems that are combined with seismic failures of components and structures. Similarly, seismic multi-unit PSA (MUPSA) models have failures of NPPs that undergo alternating operations between full power and low power and shutdown (LPSD). Their failures for alternating operations are modeled using fraction or partitioning events in seismic SUPSA and MUPSA fault trees. Since partitioning events for one system are mutually exclusive, their combinations should be excluded in exact solutions. However, it is difficult to eliminate the combinations of mutually exclusive events without modifying PSA tools for generating MCSs from a fault tree and converting MCSs into exact solutions. If the combinations of mutually exclusive events are not deleted, seismic CDF is underestimated. To avoid CDF underestimation in seismic SUPSAs and MUPSAs, this paper introduces a process of converting partitioning events into conditional events, and conditional events are then inserted explicitly inside a fault tree. With this conversion, accurate CDF can be calculated without modifying PSA tools. That is, this process does not require any other special operations or tools. It is strongly recommended that the method in this paper be employed for avoiding CDF underestimation in seismic SUPSAs and MUPSAs.

Seismic waves from a horizontal stress discontinuity in a layered solid

1982 ◽  
Vol 72 (5) ◽  
pp. 1483-1498
Author(s):  
F. Abramovici ◽  
E. R. Kanasewich ◽  
P. G. Kelamis
Keyword(s):  
Half Space ◽  
Seismic Waves ◽  
Horizontal Stress ◽  
Radial Component ◽  
Elastic Half Space ◽  
Homogeneous Layer ◽  
Approximate Methods ◽  
Crustal Layer ◽  
Finite Fault ◽  
Stress Discontinuity

abstract The displacement components for a horizontal stress discontinuity along a buried finite fault in an elastic homogeneous layer on top of an elastic half-space are given analytically in terms of generalized rays. For a particular case of a concentrated horizontal force pointing in an arbitrary direction, detailed time-dependent expressions are given. For a simple model of a “crustal” layer over a “mantle” half-space, the numerical seismograms in the near- and intermediate-field show some interesting features. These include a prominent group of compressional waves whose radial component is substantial at distances four times the crustal thickness. All the dominant shear arrivals (s, SS, and sSS) are important and show large variations of amplitude as the source depth and receiver distance are varied. Some of the prominent individual generalized rays are shown, and it is found that they can be grouped naturally into families based on the number of interactions with the boundaries. The subdivision into individual generalized rays is useful for analysis and for checks on the numerical stability of the synthetic seismograms. Since the solution is analytic and the numerical evaluation is complete up to any desired time, the results are useful in comparing other approximate methods for the computation of seismograms.

Vertical soil-structure interaction effects

1979 ◽  
Vol 69 (1) ◽  
pp. 221-236
Author(s):  
R. R. Little ◽  
D. D. Raftopoulos
Keyword(s):  
Nuclear Power ◽  
Soil Structure ◽  
Power Plants ◽  
Structural Model ◽  
Free Field ◽  
Interaction Effects ◽  
Soil Structure Interaction ◽  
Response Curves ◽  
Transformation Techniques ◽  
Structure Interaction

abstract An analytical expression describing the three-dimensional vertical soil-structure interaction effects is developed using Laplace and Hankel transformation techniques. Utilizing these transformation techniques and normal mode theory of vibration, an N-mass structural model is coupled to an elastic half-space representing the earth. The resulting interaction equation is solved by numerical iteration techniques for a model of a nuclear power plant subjected to actual earthquake ground excitation. The effects of the soil-structure interaction are evaluated by comparing free-field acceleration spectrum response curves with similar curves determined from the foundation motion. These effects are found to be significant for structures typical of modern nuclear power plants subjected to seismic ground motions.

Periodic Materials-Based 3D Seismic Base Isolators for Nuclear Power Plants

2014 ◽  
Author(s):  
Y. Yan ◽  
A. Laskar ◽  
Z. Cheng ◽  
F. Menq ◽  
Y. Tang ◽  
...  
Keyword(s):  
Earthquake Engineering ◽  
Structural Damage ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Natural Frequencies ◽  
Field Tests ◽  
Band Gaps ◽  
Solid State Physics ◽  
Periodic Materials

The concept of periodic materials, based on solid state physics theory, is applied to earthquake engineering. The periodic material is a material which possesses distinct characteristics that do not allow waves with certain frequencies to be transmitted through; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. In designing a periodic foundation, the first step is to match band gaps of the periodic foundation with the natural frequencies of the superstructure. This is an iterative process. Starting with a design of the periodic foundation, the band gaps are identified by performing finite element analyses using ABAQUS. This design process is repeated until the band gaps match natural frequencies of the superstructure, and the field tests of a scaled specimen are conducted to validate the design. This is an on-going research project. Presented in this paper are the preliminary results, which show that the three dimensional periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitations.

scholarly journals STRUCTURAL CHARACTERISTICS OF REINFORCED CONCRETE FOUNDATION FOR SEISMIC ISOLATED NUCLEAR POWER PLANTS

2017 ◽  
Vol 82 (733) ◽  
pp. 433-440
Author(s):  
Hideyoshi WATANABE ◽  
Masahiko WATANABE ◽  
Hideo HIRAI ◽  
Kunihiko SATO ◽  
Tetsuo IMAOKA ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Structural Characteristics ◽  
Concrete Foundation

scholarly journals Assessment of Adequate Margin to Liquefaction for Nuclear Power Plants

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Tamás János Katona
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Ground Acceleration ◽  
Design Basis ◽  
Essential Question ◽  
Radioactive Release ◽  
Adequate Margin

Design of nuclear power plant shall provide an adequate margin to protect items ultimately necessary to prevent an early large radioactive release in the case of earthquakes exceeding those considered in the design. An essential question is how large the margin should be to be accepted as adequate. In the practice, depending on the country regulation, a plant margin of at least 1.4 or 1.67 times the design basis peak ground acceleration is required to be demonstrated. The catastrophe at the Fukushima Daiichi Nuclear Power Plant revealed the fundamental experience that the plants designed in compliance with nuclear standards can survive the effects of the vibratory ground motion due to disastrous earthquake but may fail due to effects of phenomena accompanying or generated by the earthquakes. Liquefaction is one of those secondary effects of beyond-design basis earthquakes that should be investigated for NPPs at soil sites. However, the question has not been investigated up to now, whether a “margin earthquake”, vibratory effects of which the plant can withstand thanks to design margin, will not induce liquefaction at soil sites and will not result in loss of safety functions. In the paper, a procedure is proposed for calculation of the probability and margin to liquefaction. Use of the procedure is demonstrated on a case study with realistic site-plant parameters. Criteria for probability for screening and acceptable probabilistic margin to liquefaction are proposed. The possible building settlement due to margin earthquake is also assessed.

Seismic Analysis Approach Applied to a Small Size Next Generation Nuclear Reactor

2008 ◽  
Author(s):  
G. Forasassi ◽  
R. Lo Frano
Keyword(s):  
Nuclear Power ◽  
Nuclear Reactor ◽  
Seismic Analysis ◽  
Methodological Approach ◽  
Free Field ◽  
Time History ◽  
Future Generation ◽  
Energy System ◽  
Ground Acceleration ◽  
Input Motion

The aim of the paper is to evaluate the behaviour of a Near Term nuclear energy system example with reference to IRIS (International Reactor Innovative and Safety) project. As it is well known the development of new and future-generation nuclear power plant (Gen IV NPP) is strictly related to the sustainability, safety and reliability as well as to the proliferation resistance. In this paper, the safety aspects related to the effects of a severe earthquake (Safe Shutdown Earthquake) as well as to the induced loads are treated by means the Substructure and Time History Approaches, assuming a free field Peak Ground Acceleration equal to 0.3 g as input motion. The analyses and upgrading of the geometry structures with highest probability of criticality are performed on rather complex and detailed 3D finite element (FE) models. The main goals were: the evaluation of the dynamic characteristics of each considered structure, the verification of the load bearing structures in order to obtain a preliminary assessment of the adopted methodological approach and structural models. The analyses results and dynamic response of internal components (e.g. Nuclear Buildings, etc.) seem to confirm the possibility to upgrade the geometry and the performances of the proposed design choices.

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