Dynamic Analysis of NPP Piping Systems and Components With Viscoelastic Dampers Subjected to Severe Earthquake Motions

2016 ◽  
Author(s):  
Ichiro Tamura ◽  
Masashi Kuramasu ◽  
Frank Barutzki ◽  
Daniel Fischer ◽  
Victor Kostarev ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Characteristics ◽  
Seismic Analysis ◽  
Dynamic Properties ◽  
Maxwell Model ◽  
Shaking Table ◽  
Nonlinear Dependence ◽  
Piping System ◽  
Frequency Dependent ◽  
Viscoelastic Dampers

In Shimane nuclear power plant of Chugoku Electric Power Co., a number of safety improvements are planned to be implemented aiming for the highest level of safety in the world to be achieved. One of the new safety measures is the application of viscoelastic dampers for seismic protection of safety related piping system and components. High performance of viscoelastic dampers has been confirmed by direct testing of the piping natural scale model at the shaking table subjected to severe seismic accelerations up to 20 m/s2. However, viscoelastic dampers as a dynamic protection device have frequency-dependent dynamic characteristics, which are difficult to reproduce in the frame of conventional seismic analysis based typically on the use of response spectrum method. For example, the dynamic properties of viscoelastic dampers exhibit nonlinear dependence on dissipation energy, shear rate of viscous fluid, and temperature. Method for Seismic analysis of systems with viscoelastic dampers (SAVD-Method) is one of the analytical approaches capable of considering the dynamic properties and nonlinear behavior of viscoelastic dampers. The SAVD-Method is a comparatively simple but reliable approach for dynamic analysis of a piping system and components with viscoelastic dampers. Frequency-dependent dynamic characteristics of the viscoelastic dampers are able to be modeled by a four-parameter Maxwell model. To consider the nonlinearity of the dynamic properties of viscoelastic dampers, the Maxwell model parameters were determined for different usage conditions in conjunction with the adjustment dependent on the energy dissipation criteria. Direct comparison of the shaking table measurements and analysis according to SAVD-method shows good matching of results for all controlled parameters and levels of seismic excitation.

Seismic Analysis of Above Ground Piping in Process Plant

2014 ◽  
Author(s):  
Gaurav P. Bhende
Keyword(s):  
Dynamic Analysis ◽  
Seismic Analysis ◽  
Seismic Effect ◽  
Elastic Behavior ◽  
Piping System ◽  
Process Plant ◽  
Minimum Requirements ◽  
Computer Based ◽  
Design Requirements ◽  
Equivalent Method

The recent natural calamities, especially earthquakes, are making engineering design requirements stringent. The Process Plant Piping is no exception to it. Analyzing the seismic effect by ‘Static Equivalent Method’ is a common practice compared to performing ‘Dynamic Analysis’. This paper starts with the basic reason of earthquake and its effect on the above ground piping system. Further it compares between the results opted based on computer based ‘Spectrum Analysis (Dynamic Analysis) Method’ and ‘Static Equivalent Method’ as per the requirements of ASCE 7. One of the assumptions in Static or Dynamic seismic analysis is — ‘Pipe supports are rigid’. However, in reality the supports, especially structural supports, show elastic behavior based on their material and geometric properties. At the end, this paper compares between the results of seismic analysis performed by considering ‘Supports as rigid’ and ‘Supports as elastic’ and comments on it along with minimum requirements for safe design.

Effects of Uncertainties in Boundary Conditions on Dynamic Characteristics of Industrial Plant Components

2014 ◽  
Author(s):  
Oreste S. Bursi ◽  
Giuseppe Abbiati ◽  
Luca Caracoglia ◽  
Md Shahin Reza
Keyword(s):  
Boundary Conditions ◽  
Dynamic Characteristics ◽  
Seismic Risk ◽  
Dynamic Properties ◽  
Fragility Curves ◽  
Structural Safety ◽  
Industrial Plant ◽  
Piping System ◽  
Uncertain Boundary ◽  
Plant Components

Seismic risk assessment of industrial plants is of paramount importance to ensure adequate design against earthquake hazards. Seismic vulnerability of industrial plant components is often evaluated through a fragility analysis to conform to structural safety requirements. Fragility curves of single components are usually developed by neglecting the effect of actual boundary conditions. Thus, an incorrect evaluation of individual fragility curves can affect the overall fragility curve of a system. This may lead to “erroneous” seismic risk evaluation for a plant in comparison with its real state. Hence, it is important to study the effect of uncertainties, introduced at the boundaries when coupling effects are neglected, on the dynamic characteristics of a system. Along this line, this paper investigates the effects of uncertain boundary conditions on the probability distributions of the dynamic properties of a simple chain-like system with increasing number of degrees of freedom. In order to describe the uncertain boundary condition, a modified version of the well-known β distribution is proposed. Subsequently, the Analytical Moment Expansion (AME) method is employed to estimate the statistical moments of the output random variables as an alternative to more computationally-demanding Monte Carlo simulations. Finally, a preliminary extension of the proposed approach to a realistic piping system connected to a class of broad/slender tanks is discussed.

scholarly journals Study On The Vibration Amplitudes Of Reinforced Concrete Bridge Piers Using ABAQUS Software

2021 ◽  
Vol 28 (2) ◽  
pp. 37-45
Author(s):  
Mais Ghassoun ◽  
Ali Algharrash ◽  
Reem Alsehnawi
Keyword(s):  
Dynamic Analysis ◽  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Vibration Amplitude ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Response Amplitude ◽  
Experimental Results ◽  
Important Indicator ◽  
Design Values

The Dynamic characteristics such as damping ratio and natural frequency are an important indicator for predicting the dynamic behavior of bridges, but it is customary during the design that the designer assess the dynamic properties of the dynamic analysis because it is very difficult to determine the damping of the origin before construction and damping is taken as a predetermined constant value independent of the response amplitude and frequency of the structure. In the dynamic analysis of constructions design some experimental research has been concerned with the determination of dynamic structural properties and their relationship with the response amplitude experimentally, but the changes in dynamic properties with vibration amplitude has never been taken During dynamic analysis, further analytical treatments and computer modeling were required to study different cases based on the experimental results available by simulating them with a computer model. Dynamic characteristics are very essential to accurately determine the dynamic response, and it is necessary to study the effect of changes of the actual dynamic characteristics of bridges, which were determined by measuring their vibration in the results of dynamic analysis and comparing them with results that do not take into account the changes of dynamic properties and with laboratory results in order to assess the role of. Dynamic analysis inputs in simulating vibrations by monitoring their responses. As a result, it was found that the dynamic properties are independent of the shape of the external exactions. Also, it was concluded that relationships express the change of dynamic properties in terms of vibration amplitudes. And Similar reliance of the dynamic characteristics to the vibration amplitude is confirmed for the pier model, where the increase of the amplitude of the acceleration is accompanied by a decrease in the natural frequency, and an increase in the damping ratio is obvious. Before choosing design values when considering the dynamic characteristics of a structure, we need to give unique concentration to the predictable vibration amplitudes. Dynamic characteristics changes during dynamic analysis should be considered to produce analytical results that simulate experimental results and are closer to reality.

Shaking Table Tests of a Piping System With Viscoelastic Dampers Subjected to Severe Earthquake Motions

2016 ◽  
Author(s):  
Victor Kostarev ◽  
Ichiro Tamura ◽  
Masashi Kuramasu ◽  
Frank Barutzki ◽  
Petr Vasilev ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Piping System ◽  
Actual Behavior ◽  
Test Results ◽  
Viscoelastic Dampers ◽  
Piping Systems ◽  
Large Earthquakes ◽  
Very High

In Shimane Nuclear Power Plant of the Chugoku Electric Power Co. located in the West Japan area, a number of safety improvements are planned to be implemented aiming at achieving the highest world level in nuclear safety. One of the new safety approaches for seismic protection of NPPs is the application of viscoelastic dampers for safety related piping, systems and components. This technology is widely spread in nuclear power since 80s of the last century, [1 and 2]. In order to investigate and check the actual behavior of viscoelastic dampers installed at piping systems and subjected to severe earthquake motions, a shaking table test with full-scale piping and viscoelastic dampers was carried out. The shaking table test was performed for two general conditions. One is without aseismic devices and the other one is with viscoelastic dampers. It was confirmed by comparing the test results of the above mentioned two conditions that viscoelastic dampers provide to piping systems very high overall damping and protect piping systems even against large earthquakes.

scholarly journals Shaking Table Tests to Validate Inelastic Seismic Analysis Method Applicable to Nuclear Metal Components

2021 ◽  
Vol 11 (19) ◽  
pp. 9264
Author(s):  
Gyeong-Hoi Koo ◽  
Sang-Won Ahn ◽  
Jong-Keun Hwang ◽  
Jong-Sung Kim
Keyword(s):  
Seismic Analysis ◽  
Kinematic Hardening ◽  
Shaking Table ◽  
Plastic Behavior ◽  
Piping System ◽  
Test Results ◽  
Analysis Method ◽  
Shaking Table Tests ◽  
Hardening Model ◽  
Design Basis

The main purpose of this study is to perform shaking table tests to validate the inelastic seismic analysis method applicable to pressure-retaining metal components in nuclear power plants (NPPs). To do this, the test mockup was designed and fabricated to be able to describe the hot leg surge line nozzle with a piping system, which is known to be one of the seismically fragile components in nuclear steam supply systems (NSSS). The used input motions are the displacement time histories corresponding to the design floor response spectrum at an elevation of 136 ft in the in-structure building in NPPs. Two earthquake levels are used in this study. One is the design-basis safe shutdown earthquake level (SSE, PGA = 0.3 g) and the other is the beyond-design-basis earthquake level (BDBE, PGA = 0.6 g), which is linearly scaled from the SSE level. To measure the inelastic strain responses, five strain gauges were attached at the expected critical locations in the target nozzle, and three accelerometers were installed at the shaking table and piping system to measure the dynamic responses. From the results of the shaking table tests, it was found that the plastic strain response at the target nozzle and the acceleration response at the piping system were not amplified by as much as two times the input earthquake level because the plastic behavior in the piping system significantly contributed to energy dissipation during the seismic events. To simulate the test results, elastoplastic seismic analyses with the well-known Chaboche kinematic hardening model and the Voce isotropic hardening model for Type 316 stainless steel were carried out, and the results of the principal strain and the acceleration responses were compared with the test results. From the comparison, it was found that the inelastic seismic analysis method can give very reasonable results when the earthquake level is large enough to invoke plastic behavior in nuclear metal components.

scholarly journals Seismic Analysis of a 2-Storey Log House

2013 ◽  
Vol 778 ◽  
pp. 478-485 ◽  
Author(s):  
Jorge M. Branco ◽  
Paulo B. Lourenço ◽  
Chrysl A. Aranha
Keyword(s):  
Shaking Table Test ◽  
Seismic Analysis ◽  
Dynamic Properties ◽  
Test Procedure ◽  
Shaking Table ◽  
Fundamental Period ◽  
Mode Shapes ◽  
Seismic Behaviour ◽  
The University ◽  
Series Project

The current paper deals with the analysis of the results yielded by a series of tests performed to evaluate the seismic behaviour of a model log construction. The study was based on an experimental investigation performed to improve the existing knowledge on log houses subject to seismic events. The main part of the experimental work is based on a full scale shaking table test, conducted on a two-storey log house designed by the Portuguese company Rusticasa® in compliance with design rules for timber buildings. The test was performed by the University of Minho within the framework of the SERIES Project Multi-storey timber buildings and was coordinated by the University of Trento, at LNEC, Lisbon, Portugal. The geometry of the specimen, the design of the test, the setup and the instrumentation layout are first presented in this paper. The test procedure was conducted in stages with maximum accelerations (bi-directional) of 0.07g, 0.28g and 0.5g. During this incremental test procedure, whenever damage occurred, identification tests were performed to assess any variation in the fundamental period of the house. The experimental results of each test have been analyzed and the resultant values of inter-storey drift, wall slippage and uplift measurements, shear deformations and hold-down forces measured are presented. Most importantly, the dynamic properties (fundamental period and mode shapes) of the system have been determined.

Coupling Technique of Rotor-Fuselage Dynamic Analysis

1984 ◽  
Vol 106 (2) ◽  
pp. 235-238 ◽  
Author(s):  
D. M. Tang ◽  
M. Q. Wang
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Coupling Technique ◽  
Rotor Shaft ◽  
Reinforced Plastics ◽  
Natural Dynamic

In this paper is introduced a method of dynamic analysis of the helicopter rotor coupled with fuselage in the rotating plane. The method has been used to determine the inplane rotor-fuselage dynamic properties of a light helicopter with fiberglass-reinforced plastics rotor blades. This paper makes particular reference to the effect of anisotropic dynamic stiffness of the rotor shaft end of fuselage on the natural dynamic characteristics.

Measured natural periods of concrete shear wall buildings: insights for the design of Canadian buildings

2012 ◽  
Vol 39 (8) ◽  
pp. 867-877 ◽  
Author(s):  
Damien Gilles ◽  
Ghyslaine McClure
Keyword(s):  
Seismic Analysis ◽  
Dynamic Properties ◽  
Response Spectrum ◽  
Shear Wall ◽  
Mode Shapes ◽  
Design Stage ◽  
Base Shear ◽  
Period Equation ◽  
Input Load ◽  
Structural Engineers

Structural engineers routinely use rational dynamic analysis methods for the seismic analysis of buildings. In linear analysis based on modal superposition or response spectrum approaches, the overall response of a structure (for instance, base shear or inter-storey drift) is obtained by combining the responses in several vibration modes. These modal responses depend on the input load, but also on the dynamic characteristics of the building, such as its natural periods, mode shapes, and damping. At the design stage, engineers can only predict the natural periods using eigenvalue analysis of structural models or empirical equations provided in building codes. However, once a building is constructed, it is possible to measure more precisely its dynamic properties using a variety of in situ dynamic tests. In this paper, we use ambient motions recorded in 27 reinforced concrete shear wall (RCSW) buildings in Montréal to examine how various empirical models to predict the natural periods of RCSW buildings compare to the periods measured in actual buildings under ambient loading conditions. We show that a model in which the fundamental period of RCSW buildings varies linearly with building height would be a significant improvement over the period equation proposed in the 2010 National Building Code of Canada. Models to predict the natural periods of the first two torsion modes and second sway modes are also presented, along with their uncertainty.

scholarly journals A comparative study on a complex URM building: part II—issues on modelling and seismic analysis through continuum and discrete-macroelement models

2021 ◽  
Author(s):  
G. Castellazzi ◽  
B. Pantò ◽  
G. Occhipinti ◽  
D. A. Talledo ◽  
L. Berto ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Dynamic Properties ◽  
Limit State ◽  
Central Italy ◽  
Nonlinear Static Analysis ◽  
Structural Safety ◽  
Masonry Building ◽  
Maximum Acceleration ◽  
Capacity Curves ◽  
Comparison Of The Results

AbstractThe paper presents the comparison of the results obtained on a masonry building by nonlinear static analysis using different software operating in the field of continuum and discrete-macroelement modeling. The structure is inspired by an actual building, the "P. Capuzi" school in Visso (Macerata, Italy), seriously damaged following the seismic events that affected Central Italy from August 2016 to January 2017. The activity described is part of a wider research program carried out by various units involved in the ReLUIS 2017/2108—Masonry Structures project and having as its object the analysis of benchmark structures for the evaluation of the reliability of software packages. The comparison of analysis was carried out in relation to: global parameters (concerning the dynamic properties, capacity curves and, equivalent bilinear curves), synthetic parameters of structural safety (such as, for example, the maximum acceleration compatible with the life safety limit state) and the response in terms of simulated damage. The results allow for some insights on the use of continuum and discrete-macroelement modeling, with respect to the dispersion of the results and on the potential repercussions in the professional field. This response was also analyzed considering different approaches for the application of loads.

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