scholarly journals Enhancement in the Seismic Performance of a Nuclear Piping System using Multiple Tuned Mass Dampers

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2077 ◽  
Author(s):  
Shinyoung Kwag ◽  
Jinsung Kwak ◽  
Hwanho Lee ◽  
Jinho Oh ◽  
Gyeong-Hoi Koo
Keyword(s):  
Optimal Design ◽  
Optimum Design ◽  
Seismic Performance ◽  
Response Analysis ◽  
Similar Degree ◽  
Seismic Load ◽  
Piping System ◽  
Tuned Mass Dampers ◽  
Seismic Safety ◽  
Design Values

In a nuclear power plant, it is essential to improve the seismic safety of the piping system for the coolant transfer to cool the high temperature caused by the nuclear reaction. Under this background, this study makes two major contributions. The first is that though tuned mass dampers (TMDs) were originally used only to reduce the vibration of piping itself, through this research, it was first proved that it had a positive effect on the improvement of the seismic performance of nuclear piping systems. Additionally, this study proposed a design approach that effectively obtains the optimal design values of TMDs associated with seismic performance. In order to effectively derive the TMD optimum design values, we not only utilized the existing TMD optimum design formula, but also additionally proposed a frequency response analysis-based TMD optimal design method. As a result, it was seen that primary responses of system were significantly reduced under the input seismic load due to the use of TMDs for the piping system. It was also confirmed that the use of the existing TMD formula brought about a similar degree of response reduction effect, while it was possible to get the improved effect when using the proposed method.

Seismic Performance Analysis of the Large Spherical Tank

2014 ◽  
Author(s):  
Zhirong Yang ◽  
Dayong Zhang ◽  
Longwei Guo ◽  
Baibing Yang ◽  
Guodong Wang
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Structure Design ◽  
Design Parameters ◽  
Response Analysis ◽  
Seismic Load ◽  
Special Equipment ◽  
Seismic Safety ◽  
Finite Element Software ◽  
Spherical Tank

The seismic safety problem of the spherical tank under seismic load has become one important subject in seismic research of special equipment. Based on the ANSYS finite element software, typical spherical tank mechanics model is established first of all, through precise time history response analysis under the seismic excitation to determine the significant location of the stress. Then, the seismic performance impact of the support structure design parameters is analyzed. Finally, the seismic performance of all kinds of spherical tank, such as the large, medium and small tank, is determined. This paper provides a reasonable basis for the anti-seismic safety security and design of the spherical tank.

Introduction of a Research Activity on the Seismic Safety Evaluation of Nuclear Piping Systems Taking the Effect of Elastic-Plastic Behavior Into Account

2015 ◽  
Author(s):  
Izumi Nakamura ◽  
Masaki Shiratori ◽  
Akihito Otani ◽  
Masaki Morishita ◽  
Tadahiro Shibutani ◽  
...  
Keyword(s):  
Seismic Load ◽  
Failure Behavior ◽  
Plastic Behavior ◽  
Piping System ◽  
Seismic Loads ◽  
Research Activity ◽  
Standard Analysis ◽  
Seismic Safety ◽  
Elastic Plastic ◽  
Piping Systems

According to investigations of several nuclear power plants (NPPs) hit by actual seismic events and a number of experimental researches on the failure behavior of piping systems under seismic loads, it is recognized that piping systems used in NPPs include a large seismic safety margin until boundary failure and the current code design allowable stresses are very conservative. Since the stress assessment based on the elastic analysis does not reflect actual response of piping systems including plastic region, rational procedures to estimate the elastic-plastic behavior of piping systems under a large seismic load are expected to be developed for piping seismic design applications. With the aim of establishing a procedure that takes into account the elastic-plastic behavior effect in the seismic safety estimation of nuclear piping systems, a research activity has been planned. Through the activity, the authors intend to establish two kinds of guidelines; 1) a guideline of a standard analysis procedure to evaluate elastic-plastic behavior of piping systems under extreme seismic loads with rational and conservative margins, and 2) a guideline that provide criteria for the seismic safety assessment of piping systems by the standard analysis to evaluate elastic-plastic behavior established by the above guideline. As the first step of making out the analysis guideline, benchmark analyses are conducted for a pipe element test and a piping system test. In this paper, the outline of the research activity and the preliminary results of benchmark analyses for a pipe element test are described.

Investigation of the Seismic Safety Capacity of Aged Piping System: Shake Table Test on Piping Systems With Wall Thinning by E-Defense

2011 ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Yuji Sato ◽  
Hajime Takada ◽  
Koji Takahashi ◽  
...  
Keyword(s):  
System Model ◽  
Seismic Load ◽  
Piping System ◽  
Shake Table ◽  
Shake Table Tests ◽  
Seismic Safety ◽  
System Models ◽  
Primary Stress ◽  
Wall Thinning ◽  
Piping Systems

In order to investigate the seismic safety capacity of the piping system with local wall thinning, shake table tests on 3-D piping system models were conducted using E-Defense. Two piping system models which were the same in appearance and different in degradation condition were arranged on the shake table of E-Defense. One of the models was put into degradation condition of about 50% wall thinning at four elbows and one tee. Modified seismic motions were applied to these models at the same time. As a result, the piping system model with wall thinning did not fail for the primary stress limit level of sound piping system model, though a ratchet deformation was observed on the thinned wall tee. The model with wall thinning finally failed at the thinned wall tee by over five times larger excitation than the limit level. From the experiment, it was found that the life of the piping system with wall thinning would be reduced compared with that of the piping system without wall thinning, but it was also found that the degraded piping system still had a certain seismic margin until the piping system failed by the seismic load.

Impact of Deformation Stiffness Beyond Yield Point of Pipe Support Structures on Nonlinear Seismic Response Analysis

2014 ◽  
Author(s):  
Tsuneo Takahashi ◽  
Akira Maekawa
Keyword(s):  
Plastic Deformation ◽  
Seismic Response ◽  
Safety Evaluation ◽  
Response Analysis ◽  
Seismic Load ◽  
Piping System ◽  
Support Structures ◽  
Seismic Response Analysis ◽  
Support Structure ◽  
Nonlinear Seismic Response

The importance of safety evaluation for beyond design conditions has come to be required since the accident at the Fukushima Daiichi Nuclear Power Plant as a consequence of the Great East Japan Earthquake. Real simulations of seismic response for the plant structures and components enhance establishment of reasonable design margins and safety evaluation criteria in a situation beyond design-basis accidents. For piping systems, nonlinear seismic response analysis considering plastic deformation of pipe support structures can lead to a safety evaluation based on more rational input values. This study discussed seismic response of a piping system and its appropriate analysis method when a plastically deformable pipe support structure was subjected to a much larger seismic load than the designed one. Seismic response analyses of the piping system including a plastically deformable pipe support structure were conducted for various input acceleration levels. The vibration characteristics, response acceleration, and moment of piping were compared in relation to the amount of plastic deformation of the pipe support structure. As a result of the comparisons, a support model with the elastic fully plastic property was proposed as a simple and proper method to calculate the seismic response of the piping system considering the plastic deformation of the pipe support structure.

Seismic Proving Test of Ultimate Piping Strength: Simulation Analysis of Simplified Piping System Test

2003 ◽  
Author(s):  
Kenichi Suzuki ◽  
Y. Namita ◽  
H. Abe ◽  
I. Ichihashi ◽  
Kohei Suzuki ◽  
...  
Keyword(s):  
Large Scale ◽  
Simulation Analysis ◽  
Safety Margin ◽  
Response Analysis ◽  
Piping System ◽  
Seismic Safety ◽  
Strain Behavior ◽  
Critical Elements ◽  
Seismic Design Code ◽  
Piping Systems

The six-year program for the Seismic Proving Test of Ultimate Piping Strength has been running since 1998 with the following objectives: i) to clarify the elasto-plastic response and ultimate strength of nuclear piping, ii) to ascertain the seismic safety margin of the current seismic design code for piping, and iii) to assess new allowable stress rules. To resolve outstanding technical issues before proceeding on to a seismic proving test of a large-scale piping system, a series of preliminary tests of materials, piping components and simplified piping systems is intended. A simulation analysis related to the simplified piping system test is described with a focus on the methodology of the non-linear dynamic response analysis of the whole piping system and the strain behavior of the localized critical elements, such as elbows and nozzles.

Risk-Based Seismic Performance Assessment of Pressurized Piping Systems Considering Ratcheting

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
A. Ravi Kiran ◽  
G. R. Reddy ◽  
M. K. Agrawal
Keyword(s):  
Performance Assessment ◽  
Seismic Performance ◽  
Fragility Curves ◽  
Limit State ◽  
Frequency Variation ◽  
Seismic Load ◽  
Piping System ◽  
Seismic Performance Assessment ◽  
Limit States ◽  
Piping Systems

Abstract A procedure is described for risk-based seismic performance assessment of pressurized piping systems considering ratcheting. The procedure is demonstrated on a carbon steel piping system considered for OECD-NEA benchmark exercise on quantification of seismic margins. Initially, fragility analysis of the piping system is carried out by considering variability in damping and frequency. Variation in damping is obtained from the statistical analysis of the damping values observed in earlier experiments on piping systems and components. The variation in ground motion is considered by using 20 strong motion records of the intraplate region. Floor motion of a typical reactor building of a nuclear power plant under these actual earthquake records is evaluated and applied to the piping system. The performance evaluation of the piping system in terms of ratcheting is carried out using a numerical approach, which was earlier validated with shake table ratcheting tests on piping components and systems. Three limit states representing performance levels of the piping system under seismic load are considered for fragility evaluation. For each limit state, probability of exceedance at different levels of floor motion is evaluated to generate a fragility curve. Subsequently, the fragility curves of the piping systems are convoluted with hazardous curves for a typical site to obtain the risk in terms of annual probability of occurrence of the performance limits.

scholarly journals Optimal Design of Tuned Mass Damper Inerter for Base-Isolated Buildings

2021 ◽  
Keyword(s):  
Optimal Design ◽  
Seismic Performance ◽  
Primary Structure ◽  
Tuned Mass Damper ◽  
Optimal Solutions ◽  
Tuned Mass Dampers ◽  
Stochastic Excitations ◽  
Mass Damper ◽  
Seismic Resilience ◽  
Original Configuration

Abstract. Tuned mass dampers (TMD) are installed in base-isolated building to suppress the excessive isolator displacement and acceleration responses of primary structure. By incorporating an inerter element into the original configuration, the seismic performance of TMD is significantly enhanced. In this work, optimal solutions of tuned mass damper inerter (TMDI) for improving the seismic resilience of base-isolated building are proposed. The analytical formulations of optimal design of TMDI are respectively developed to minimize the H2 norm of the displacement of primary structure relative to the base floor and the isolator displacement. The performance of presented optimal methods are validated by using stationary responses under the stochastic excitations. Additionally, the seismic performance of TMDI with parameters obtained from the proposed method are compared with the established methods.

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