Seismic analysis of the pile foundation of the reactor building of the NPP Angra 2

Generally, for the seismic analysis of nuclear power plant structures, requirement of coupling equipment is checked by applying USNRC decoupling criteria. This criteria is developed for the equipment connected to the structure at one location. In this paper, limitations of this criteria and modifications required for application to real life structures such as pressurized heavy water reactor building are discussed. In addition, the authors endeavor to present a decoupling model for multi-connected structure-equipment. The applicability of the model is demonstrated with pressurized heavy water reactor building internal structure and steam generator.

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Study on Methods for HCLPF Value of Nonlinear Supports System of Steam Generator

Volume 2: Plant Systems, Structures, Components, and Materials; Risk Assessments and Management ◽

10.1115/icone26-81279 ◽

2018 ◽

Author(s):

Feng-chun Cai ◽

Xian-hui Ye ◽

Qian Huang ◽

Wenzheng Zhang

Keyword(s):

Steam Generator ◽

Nonlinear Model ◽

Seismic Analysis ◽

Time History ◽

Nonlinear Time History Analysis ◽

Cost Calculation ◽

Seismic Capacity ◽

Ground Acceleration ◽

Reactor Building ◽

Nonlinear Time History

High confidence of low probability of failure (HCLPF) values of equipment, representing the seismic capacities of the equipment, are the fundamental ingredient in seismic probability safety assessment (SPSA) and seismic margin analyses (SMA). In this paper, two methods for calculating the HCLPF values of equipment were investigated, fragility analysis, and conservative deterministic failure margin (CDFM). These methods are linear methods. Based on these methods, HCLPF value of equipment can be computed conveniently by scaling the results of the existing seismic analysis. For a nonlinear systems, the HCLPF values based on these linear scaling methods are unrealistic. For a complicated nonlinear equipment or structure, a detail nonlinear model was used to derive the seismic capacity. The results by this method are realistic, but cost calculation time. In this paper, a nonlinear model of reactor coolant system coupled reactor building was built. This model includes the steam generator and considers the nonlinear factors of steam generator such as gap in the supports, plasticity of hot leg and cold leg. Forced motion was applied to the base of reactor building. And seismic response of the steam generator was calculated iteratively by scaling the ground motion level step by step. Based on these calculations, a curve of load on the supports VS peak ground acceleration (PGA) can be obtained. Then based on these curves and allowable load of supports of steam generator, which derived from stress analysis on support of steam generator, seismic capacity of the supports of steam generator was determined. Then the HCLPF Value of the supports of steam generator was obtained by this nonlinear time history analysis and was compared with the results based on the CDFM. The two results were different. Therefore, the HCLPF seismic capacity of equipment with nonlinearity, such as gap nonlinearity, should be calculated by nonlinear time history method.

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Seismic bridge pier analysis for pile foundation by force and displacement based approaches

Facta universitatis - series Architecture and Civil Engineering ◽

10.2298/fuace1502155s ◽

2015 ◽

Vol 13 (2) ◽

pp. 155-166

Author(s):

NP.R. Singh ◽

Hemant Vinayak

Keyword(s):

Pile Foundation ◽

Seismic Analysis ◽

Slenderness Ratio ◽

Soft Soil ◽

Time History ◽

Bridge Pier ◽

Base Shear ◽

Displacement Based ◽

Shear Demand ◽

Analytical Approaches

Seismic analysis of bridge pier supported on pile foundation requires consideration of soil-pile-structure (kinematic and inertial) interactions. This paper presents the design forces generated for bridge piers with varying height and constant diameter for medium and soft soils in earthquake probability zones considering contribution of soil-pile-structure interactions by developed analytical approaches. The results have shown that the difference in base shear demand between force based and displacement based approach and that between capacity spectrum and displacement based method in general decreases with the increase in slenderness ratio of the pier. The base shear demand by non-linear time history analysis has been found to be much higher compared to that by other methods. The relationship between height and pier cross-section has been developed for different soils and seismic zones such that the base shear demands by force based and displacement based method are of the same order. The overall value of the slenderness ratio works out to be such that failure of the pile shall be as a short column for both medium and soft soil.

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Pushover Analysis of Pile-Supported Bridge Piers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.681.234 ◽

2013 ◽

Vol 681 ◽

pp. 234-239

Author(s):

Chang Feng Wang ◽

Yi Jun Bao

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Pile Foundation ◽

Seismic Analysis ◽

Pushover Analysis ◽

Element Model ◽

Vertical Force ◽

Skeleton Curve ◽

Seismic Design Code ◽

Rare Earthquake

According to Japan Railway seismic design code, truss finite element model is established considering the pile components and foundation nonlinear finite element model in this paper, an analysis on the ultimate horizontal bearing capacity of bridge pile foundation of passenger dedicated line is made and the results of m-method calculation are compared. The analysis results show that: when horizontal force at the top of pier is larger, with the pile side soil horizontal and vertical force continuously into the plastic, the calculation results differ greatly with two seismic specification; the pier top level force-displacement skeleton curve considered pile-soil interaction is available in trilinear description, the analysis results can provide a theoretical basis for the seismic analysis of the pile foundation under rare earthquake.

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Seismic Analysis of Pile Foundation Passing Through Liquefiable Soil

Lecture Notes in Civil Engineering - Smart Cities—Opportunities and Challenges ◽

10.1007/978-981-15-2545-2_45 ◽

2020 ◽

pp. 539-553

Author(s):

Musabur Rehman ◽

S. M. Abbas

Keyword(s):

Pile Foundation ◽

Seismic Analysis ◽

Liquefiable Soil

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Criteria for High Frequency Cutoff Based on ABWR Reactor Building Vibratory Loads

Volume 3: Design and Analysis ◽

10.1115/pvp2013-98034 ◽

2013 ◽

Author(s):

Evren Ulku ◽

Cagri Ozgur ◽

Mustafa Kemal Ozkan ◽

Nish Vaidya ◽

Hari Srivastava ◽

...

Keyword(s):

United States ◽

High Frequency ◽

Strain Energy ◽

Seismic Analysis ◽

Response Spectrum ◽

Cutoff Frequency ◽

Mode Shapes ◽

Eastern United States ◽

Missing Mass ◽

Reactor Building

In the seismic analysis practice, the calculation of modal response has traditionally been limited to a cutoff frequency of about 33 Hz based on United States Nuclear Regulatory Commission (US NRC) Regulatory Guide (RG) 1.60 [1] response spectra. The structural response in higher modes is calculated as a missing mass correction by static analysis. Seismic ground motions at several sites (such as Central and Eastern United States) exhibit high frequency content, up to about 100 Hz. Additionally, the reactor building vibratory (RBV) loads that result from the suppression pool hydrodynamic loads due to loss of coolant accident (LOCA), and the annulus pressurization (AP) load from a postulated pipe break at the reactor pressure vessel (RPV) safe ends and shield wall generate peaks at frequencies in excess of 100 Hz. The qualification of safety equipment supported in the reactor building needs to reflect these high frequency motions. Extracting frequencies and mode shapes up to zero period acceleration (ZPA) frequencies in these cases may not be practical or economical. Therefore, the cutoff frequency criteria for these types of high frequency loads need to be evaluated so that the analysis produces a representative and a reasonably conservative response. In this study, the equipment response is described in terms of stress quantities, member forces, and moments resulting from the solution up to a cutoff frequency. The responses are compared to the full solution up to the ZPA frequency under hydrodynamic and AP loads using the Response Spectrum Method. The cutoff frequency is deemed adequate if the ratio of the truncated response considering missing mass to the full response is 90% or greater. The internal strain energy (or its surrogate kinetic energy) for all modes with frequencies below the cutoff is also studied to assess the missing strain energy in modes in excess of the cutoff. The evaluation presented also examines how well the strain energy correlates with calculated stresses.

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The effectiveness of the implementation of pile foundations on the example of the reactor building of a nuclear power plant with VVER-1000

Structural Mechanics of Engineering Constructions and Buildings ◽

10.22363/1815-5235-2020-16-1-14-21 ◽

2020 ◽

Vol 16 (1) ◽

pp. 14-21

Author(s):

Akop E. Sargsyan ◽

Elena G. Gukova

Keyword(s):

Comparative Analysis ◽

Pile Foundation ◽

Circular Cross Section ◽

Pile Foundations ◽

Normal Operation ◽

General Character ◽

Soil Medium ◽

Vertical Movements ◽

Reactor Building ◽

Calculation Results

Aims. The purpose of this work is to justify the reliability of the developed models of pile foundations on the data of field observers and to demonstrate the feasibility of using pile foundations to increase the stability and bearing capacity of the NPP structures foundation using the example of reactor building (RB). Methods. The data of field observers for the settlement of the RB are presented. The expressions for calculation of the static stiffness of the contact surface of the slab bottom and soil medium, as well as for pile foundations taking into account the effects of interaction of grillage and pile field with the soil media with a general character of displacement of a circular cross section pile are submitted. A spatial three-dimensional finite element static model of RB was developed together with the soil base. Isolines of vertical movements of RB fundamental slabs for natural foundations, as well as for pile foundations for normal operation are shown. A comparative analysis of the data of field observers with the calculation results allows us to justify the reliability of the developed model of the pile foundation. Results. The calculations of the foundation yield correspond to all the period of operation including construction, and the results of observations relate only to the period of operation that explain the difference. A comparative analysis of the data of field observers with the calculation results allows us to justify of the strong effectiveness of realization of pile foundation for the massive structures on soft soil bases.

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Seismic Analysis of Deep Water Pile Foundation Based on Three-Dimensional Potential-Based Fluid Elements

Journal of Construction Engineering ◽

10.1155/2013/874180 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Kai Wei ◽

Wancheng Yuan

Keyword(s):

Experimental Data ◽

Deep Water ◽

Pile Foundation ◽

Seismic Analysis ◽

Three Dimensional ◽

Time History ◽

Water Systems ◽

Interface Elements ◽

Complex Effect ◽

Structure Interaction

This paper investigates the use of three-dimensional (3D) ϕ-u potential-based fluid elements for seismic analyses of deep water pile foundation. The mathematical derivations of the potential-based formulations are presented for reference. The potential-based modeling technique is studied and validated through experimental data and analytical solutions. Earthquake time history analyses for a 9-pile foundation in dry and different water environments are conducted, respectively. The seismic responses are discussed to investigate the complex effect of earthquake-induced fluid-structure interaction. Through the analyses, the potential-based fluid and interface elements are shown to perform adequately for the seismic analyses of pile foundation-water systems, and some interesting conclusions and recommendations are drawn.

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