A Parametric Study of Independent Support Motion Method for the Steam Supply Piping Connected to the HP Turbine of APR 1400

2013 ◽  
Author(s):  
Dae Soo Kim ◽  
Joon Ho Lee ◽  
In Yeung Kim
Keyword(s):  
High Pressure ◽  
Power Plant ◽  
Support Groups ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Nuclear Industry ◽  
Combination Method ◽  
Piping System ◽  
Support Motion

The steam supply piping connected to the high pressure (HP) turbine of APR1400 (Korea’s advanced power plant 1400 MW-class) is a typical example of multi-supported piping system, and it is routed from the Containment building to the Turbine building via the Main Steam Isolation Valve House in the Auxiliary building. In the seismic analysis of this piping system, using the Enveloped Response Spectrum (ERS) method, a commonly used methodology for seismic analysis of nuclear power plant piping in industry circles, generates overly conservative analysis results. Therefore, Time History Method (THM) which applies excitation characteristic of each support attached to individual building was used to eliminate unnecessary conservatism. However, it was noticed that the Time History Method requires considerable amount of labor and time in generating combined time history equivalent to the spectrum applied for each support although it is regarded as the most exact and realistic method for seismic analysis. The nuclear industry has been making lots of efforts in finding out the mathematic logicality and practical applicability to resolve this issue. This paper deals with parametric research on combination effects of responses between support groups, damping effects, and modal combination method with close modes in applying the Independent Support Motion (ISM) method to the analysis model of the steam supply piping connected to the high pressure turbine of APR1400. Quantitative assessment and comparison with the analysis results of the ERS method and THM were also carried out. As a result, it is shown that the analysis results of the ISM method together with the SRSS combination between support groups, 4% damping with ±15% spectrum peak broadening and grouping of modal combination are remarkably similar to those of THM.

Sensitivity of the Effective Seismic Support Damping in a Class I Piping System to Analysis Parameters

2009 ◽  
Author(s):  
Nima Zobeiry
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Class I ◽  
Piping System ◽  
Frequency Content ◽  
Response Spectrum Analysis ◽  
History Analysis ◽  
The Coefficient Of Friction ◽  
Seismic Damping

It is understood that the level of seismic damping in a piping system is strongly influenced by the supports. Put differently, the supports contribute to an effective damping that can be considered in the seismic analysis of the piping system. This paper investigates the issue for the feeder pipes of a CANDU™ reactor. Feeders are numerous class I pipes in parallel, which are separated by frictional spacer elements. The results of a time history analysis, taking into account different damping mechanisms, are compared to those from a response spectrum analysis to deduce the effective damping in the system. The sensitivity of the effective damping to different parameters, such as the coefficient of friction and the input frequency content, is investigated.

Floor Response Spectrum Method of Multiply Supported Piping System Assisted by Time History Analysis

2020 ◽  
Author(s):  
Yoshihiro Takayama ◽  
Ayaka Yoshida ◽  
Iriki Nobuyoshi ◽  
Eiichi Maeda
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Correlation Coefficients ◽  
Time History Analysis ◽  
Piping System ◽  
Response Spectrum Method ◽  
Sum Rule ◽  
Spectrum Method ◽  
History Analysis

Abstract The independent support motion response spectrum method (ISM) is currently used for seismic analysis to calculate the response of multiply supported piping with independent inputs of support excitations. This approach may derive considerable overestimation in the combination of group responses under the absolute sum rule of NUREG-1061 [1]. Then authors have developed an advanced method of the ISM approach named SATH (Spectrum Method Assisted by Time History Analysis). In the SATH method, both of floor response spectra and time histories of floor acceleration are used as independent inputs of support excitations. The group responses are summed with correlation coefficients which are calculated by considering each time history of modal response by independent inputs of support excitations. In this paper, the necessity of taking the effects of correlation coefficients for the group responses into account in the ISM approach is examined. The SATH method has advantage to derive a more realistic sum rule of the group responses and applicability for the actual design.

Coupled Modelling of a “Flow-Piping” System in Dynamic Analysis

2006 ◽  
Author(s):  
Peter S. Vasilyev
Keyword(s):  
Finite Element ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Mode Shapes ◽  
Coupled Analysis ◽  
Feed Water ◽  
Piping System ◽  
Coupled Modelling ◽  
Basic Fluid

The paper considers the problem of simultaneous modeling of structure and flow in a piping system. It takes a middle road between full coupled analysis on the one hand, and the simplified case of treating the liquid as a rigid mass. The suggested method allows the use of standard beam and rod elements for the analysis. Two approaches to the problem of dynamic interaction between pipe and medium are compared in the given paper: 1) The first one treats medium as mass rigidly connected to the pipe finite-element model’s nodes. 2) In the second one medium is modeled by the finite-element system of rod-elements. In this case the basic fluid-structure interaction (FSI) effects are taken into account. The main techniques for FE modeling of some pipeline elements are presented in the paper. The second approach can be implemented by the use of general purpose FE programs. A model of a feed water pipeline of VVER-440 type NPP has been developed to study how the FSI affects on pipeline response. The results of the analysis which allow estimation of inaccuracy arising from medium dynamics neglecting are as follows: • calculation of eigen frequency and mode shapes; • seismic analysis using the response-spectrum method; • accidental blast impact assessment with the use of time history analysis; • operating vibration assessment on the basis of harmonic analysis. It has become apparent that the way of medium modeling has an essential influence on the dynamic behavior of pipelines.

Seismic Analysis Study of the HP Turbine Steam Supply Piping for APR1400

2010 ◽  
Author(s):  
Joon Ho Lee ◽  
In Yeung Kim ◽  
Jae Hwan Bae
Keyword(s):  
Support Groups ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Nuclear Industry ◽  
Seismic Evaluation ◽  
Peak Broadening ◽  
Piping Systems ◽  
Multiple Structures ◽  
Main Steam

The high pressure (HP) turbine steam supply piping for APR1400 (Korea’s advanced power reactor 1400 MW-class) is routed from the Containment Building to the Turbine building via the Main Steam Isolation Valve Room in the Auxiliary building and supported by multiple structures. As such, the seismic analysis utilizing the Independent Support Motion (ISM) is preferable to the Enveloped Response Spectrum (ERS) method which is overly conservative but more widely used in seismic evaluation of piping systems. The ISM method is a mathematically rigorous technique that utilizes the principle of modal analysis to calculate the piping responses from each structure or support group and combines them to obtain the final results. In spite of the more realistic and less conservative approach of the ISM method for the piping systems subjected to multiple support excitations, the application of ISM method on a regular basis has been limited in nuclear power plant piping design because guidelines from the nuclear industry and the regulator are conservative and unclear. In this study, several related studies are performed to evaluate the adequacy of utilizing the ISM method for seismic analysis of the HP turbine steam supply piping for APR1400. Topics studied include support grouping effects, combination effects of responses between support groups, damping effects between PVRC and 4% damping per Regulatory Guide 1.61, and closely spaced modes effects. The results show that the support grouping by each floor of buildings, SRSS combination of support groups, 4% damping with ±15% spectrum peak broadening and absolute double sum (ADS) of modal combination are technically sound and preferable.

Design Applicability of the Advanced Spectrum Method Assisted by Time History Analysis for Multiply Supported Piping System

2020 ◽  
Author(s):  
Ayaka Yoshida ◽  
Yoshihiro Takayama ◽  
Hiromichi Shudo
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Time History Analysis ◽  
Piping System ◽  
Acceleration Time ◽  
Spectrum Method ◽  
History Analysis ◽  
Acceleration Time Histories

Abstract The independent support motion response spectrum method (ISM) is currently used for seismic analysis to calculate the response of multiply supported piping system with independent inputs of support excitations. This approach may derive considerable overestimation in the combination of group responses under the absolute sum rule of NUREG-1061. To reduce the excessive overestimation, an advanced method named “Spectrum Method Assisted by Time History Analysis (SATH)” has been proposed. In the SATH method, modal responses by multiple excitations are combined with correlation coefficients which are calculated from the covariances and the standard deviations of time history responses of the oscillators having each of modal frequencies of piping system by each of the floor acceleration time history excitations. In this paper, the applicability of the SATH method to actual design which uses broadened Floor Response Spectra (FRS) was examined. Conservativeness of the SATH method is also discussed with presenting that responses derived from the SATH method tend to exceed responses by the time history analysis even when many different time intervals of acceleration time histories are used within the range of the FRS broadening.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 2 — Application of CCFS Method to the Multiply Supported Systems

2014 ◽  
Author(s):  
Koichi Tai ◽  
Keisuke Sasajima ◽  
Shunsuke Fukushima ◽  
Noriyuki Takamura ◽  
Shigenobu Onishi
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Time History ◽  
Piping System ◽  
History Analysis ◽  
Piping Systems ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Paper is focused on the seismic evaluation method of the multiply supported systems, as the one of the design methodology adopted in the equipment and piping system of the seismic isolated nuclear power plant in Japan. Many of the piping systems are multiply supported over different floor levels in the reactor building, and some of the piping systems are carried over to the adjacent building. Although Independent Support Motion (ISM) method has been widely applied in such a multiply supported seismic design of nuclear power plant, it is noted that the shortcoming of ignoring correlations between each excitations is frequently misleaded to the over-estimated design. Application of Cross-oscillator, Cross-Floor response Spectrum (CCFS) method, proposed by A. Asfura and A. D. Kiureghian[1] shall be considered to be the excellent solution to the problems as mentioned above. So, we have introduced the algorithm of CCFS method to the FEM program. The seismic responses of the benchmark model of multiply supported piping system are evaluated under various combination methods of ISM and CCFS, comparing to the exact solutions of Time History analysis method. As the result, it is demonstrated that the CCFS method shows excellent agreement to the responses of Time History analysis, and the CCFS method shall be one of the effective and practical design method of multiply supported systems.

scholarly journals Approach for Selection of Rayleigh Damping Parameters Used for Time History Analysis

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
R. E. Spears ◽  
S. R. Jensen
Keyword(s):  
Seismic Analysis ◽  
Time History ◽  
System Response ◽  
Piping System ◽  
Nuclear Facilities ◽  
Rayleigh Damping ◽  
Modal Damping ◽  
American Society ◽  
Selection Of ◽  
Civil Engineers

Nonlinearities, whether geometric or material, need to be addressed in seismic analysis. One good analysis method that can address these nonlinearities is direct time integration with Rayleigh damping. Modal damping is the damping typically specified in seismic analysis Codes and Standards (ASCE 4-98, 1998, “Seismic Analysis of Safety-Related Nuclear Structures and Commentary,” American Society of Civil Engineers, Reston, Virginia and ASCE/SEI 43-05, 2005, “Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities,” American Society of Civil Engineers, Reston, Virginia.). Modal damping is constant for all frequencies where Rayleigh damping varies with frequency. An approach is proposed here for selection of Rayleigh damping coefficients to be used in seismic analyses that is consistent with given modal damping. The approach uses the difference between the modal damping response and the Rayleigh damping response along with effective mass properties of the model being evaluated to match overall system response levels. This paper provides a simple example problem to demonstrate the approach. It also provides results for a finite element model representing an existing piping system. Displacement, acceleration, and stress results are compared from model runs using modal damping and model runs using Rayleigh damping with coefficients selected using the proposed method.

scholarly journals Review on Seismic Analysis of Multistoried Building in Hilly Region

2021 ◽  
Vol 9 (12) ◽  
pp. 73-79
Author(s):  
Harsh Joshi
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Center Of Mass ◽  
Time History ◽  
Lateral Loads ◽  
Base Shear ◽  
Building Frames ◽  
Building Frame ◽  
History Analysis ◽  
Hilly Region

Abstract: Due to sloping land and high seismically active zones, designing and construction of multistory buildings in hilly regions is always a challenge for structural engineers. This review paper focuses to establish a review study on the Possible Types of building frame configuration in the hilly region and he behavior of Such building frames under seismic loading conditions, and (3) The recent research and developments to make such frames less vulnerable to earthquakes. This paper concludes that the dynamics characteristics of such buildings are significantly different in both horizontal and vertical directions, resulting in the center of mass and center of stiffness having eccentricity at point of action and not vertically aligned for different floors. When such frames are subjected to lateral loads, due to eccentricity it generates torsion in the frame. Most of the studies agree that the buildings resting on slanting ground have higher displacement and base shear compared to buildings resting on plain ground and the shorter column attracts more forces and undergoes damage when subjected to earthquake. Keywords: Building frame configuration, Seismic behavior, Dynamic characteristics, Response spectrum analysis, time history analysis.

A Load Combination Method for Aseismic Design of Multiple Supported Piping Systems

1989 ◽  
Vol 111 (1) ◽  
pp. 10-16 ◽  
Author(s):  
K. Suzuki ◽  
A. Sone
Keyword(s):  
Structural Model ◽  
Response Spectrum ◽  
Reduction Factor ◽  
Combination Method ◽  
Piping System ◽  
Response Reduction Factor ◽  
Load Combination ◽  
Combination Scheme ◽  
Piping Systems ◽  
Reduction Effect

A new load combination scheme for seismic response calculation of piping systems subjected to multiple support excitations is presented. This scheme has an advantage, such that the cross-correlation among support excitations are properly taken into account by use of a stationary random vibration approach. The authors also present the idea of generating a “multi-excitation floor response spectrum.” First, using a simple analytical SDOF piping system to two support excitations and a simple Z-shaped piping model for shaking test, the combination law is supplied to various correlation cases of two support excitations and the maximum responses of piping in a fundamental mode is calculated. Second, nonlinear characteristics such as gap and friction appearing between piping itself and supports are specifically investigated. The response effect due to these nonlinearities is evaluated by the results through the shaking test with a piping-support structural model, and the amount of response reduction effect is represented by “a response reduction factor β.”

Evaluation of Seismic Integrity for an Integral Reactor Assembly

2004 ◽  
Author(s):  
Soon Myeon Wang ◽  
J. S. Kim ◽  
T. E. Jin ◽  
M. J. Jhung ◽  
Y. H. Choi ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Seismic Analysis ◽  
Coupling Effect ◽  
Response Spectrum ◽  
Safety Margin ◽  
Time History ◽  
Element Model ◽  
Seismic Safety ◽  
Reactor Assembly ◽  
Integral Reactor

The structural integrity of integral reactor assembly of 65Mwt thermal capacity is assessed by using the commercial finite element package ANSYS in order to evaluate the seismic safety margin. First of all, the modal analyses are performed using the various analysis models with/without the fluid coupling effect in order to validate a super element model and to evaluate the coupling effect on natural frequency. Based on the modal analysis results, the seismic analyses are performed using the ground response spectrum defined in Reg. Guide 1.60. Finally, time-history analyses are performed using the modal analysis results, the super element model and an inertia load approach. As a result, the reliable and efficient seismic analysis model for an integral reactor assembly is developed and it is found that an integral reactor assembly has the sufficient seismic safety margin.

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