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.

Improved Model Tests to Investigate the Failure Modes of Pipes Under Beyond Design Basis Earthquakes

2018 ◽  
Author(s):  
Izumi Nakamura ◽  
Naoto Kasahara
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Piping System ◽  
Input Frequency ◽  
Shaking Table Tests ◽  
Pure Lead ◽  
Design Basis ◽  
Improved Model

In order to investigate the failure modes of piping systems under the beyond design basis seismic loads, the authors proposed an experimental approach to use pipes made of the simulation material instead of steel pipes in the previous study. Though the ratchet-collapse (ratchet and subsequent collapse) was successfully obtained as the failure mode through the shaking table test using the pure lead (Pb) pipes as the simulation material pipe specimens, there was concern that characteristics of pure lead was somewhat extreme considering the analogy with the stress-strain relationship of steel. In order to resolve such concern, a modified experimental procedure has been developed. In the modified procedure, lead-antimony (Pb-Sb) alloy is used as the simulation material. Through the shaking table tests on single elbow pipe specimens made of Pb-Sb alloy, it is found that the typical failure mode is the ratchet and subsequent collapse, as same as the results by the shaking table tests of the Pb pipe specimens. The results indicate that the lower input frequency than the specimen’s natural frequency is prone to cause failure to the specimen, while the higher input frequency hardly causes the failure. The tendency of the global behavior of specimens is similar each other between the Pb pipe specimens and the Pb-Sb alloy specimens, but the strength of self-weight collapse of the Pb-Sb alloy pipe specimen is much higher than that of the Pb pipe specimen. Due to such higher strength of Pb-Sb alloy pipes, a prospect to conduct an excitation test on a more complicated piping system model is obtained.

The Fracture Limit of Steel-Frame Members Under Dynamic Repeated Loads Through the Shaking Table Test

2018 ◽  
Author(s):  
Kensuke Shiomi ◽  
Yusuke Wada
Keyword(s):  
Plastic Deformation ◽  
Dynamic Load ◽  
Evaluation Method ◽  
Shaking Table Test ◽  
Seismic Analysis ◽  
Steel Frame ◽  
Shaking Table ◽  
Test Results ◽  
Structural Members ◽  
Worst Case

Recently, much larger earthquakes are considered in the seismic designs of steel-frame structures in Japan. Under these severe ground motions, it is expected that not only the elasto-plastic deformation but also the fracture of the structural members could occur during the earthquakes. And through these situations, the more advanced seismic design or evaluation method which allow the partial destruction inside the structure and prevent from the worst-case scenario like the whole collapse are coming to be demanded. One of the ways to achieve this demand is considering the effects of not only the elasto-plastic deformation but also the fracture of structural members in the seismic analysis. In order for that, it is important to clarify the fracture limit of steel-frame members precisely under the dynamic load. Many static tests to clarify the members’ ultimate behavior were conducted in the past, but the dynamic tests were not well enough. In this research, the vibration tests were conducted to clarify the fracture limit of steel-frame members under the dynamic load. The behavior of the steel-frame members until the fracture was obtained by applying the repeated dynamic bending deformation with the shaking table. Also, The FEM analysis for the shaking table test results was conducted. Through the tests and the analysis study which simulates the test results, the mechanism of the member fracture occurred in the test under the dynamic loads were examined.

Plastic Deformation Behavior of Type 316 Stainless Steel Subject to Out-of-Phase Strain Cycles

1985 ◽  
Vol 107 (4) ◽  
pp. 286-292 ◽  
Author(s):  
Y. Ohashi ◽  
E. Tanaka ◽  
M. Ooka
Keyword(s):  
Stainless Steel ◽  
Kinematic Hardening ◽  
National Laboratory ◽  
Plastic Behavior ◽  
Hardening Model ◽  
Oak Ridge ◽  
316 Stainless Steel ◽  
Plastic Deformation Behavior ◽  
Series Of Experiments ◽  
Tubular Specimens

To elucidate the plastic behavior of metals under out-of-phase strain cycles, a series of experiments was performed on square strain trajectories in a vector space of deviatoric strain by applying combined axial force and torque to thin-walled tubular specimens of type 316 stainless steel. It was confirmed that strain hardening under out-of-phase cycles is much more significant than that under simple cycles. Though the combined isotropic-kinematic hardening model based on the concept of a nonhardening strain region proposed by Ohno gave qualitatively better predictions than the kinematic hardening model by Oak Ridge National Laboratory, there was still a considerable discrepancy between the former theory and the experiment.

Investigation of Method of Elasto-Plastic Analysis for Piping System Excited by Multi-Direction Input

2018 ◽  
Author(s):  
Takuro Kabaya ◽  
Nobuyuki Kojima ◽  
Masashi Arai ◽  
Satoru Hirouchi ◽  
Masatsugu Bando
Keyword(s):  
Ultimate Strength ◽  
Seismic Design ◽  
Strain Range ◽  
Plastic Behavior ◽  
Piping System ◽  
Japan Society ◽  
Analysis Method ◽  
The Past ◽  
Plastic Analysis ◽  
Piping Systems

This paper provides investigation on method of an elasto-plastic analysis for practical seismic design of nuclear piping systems, which are excited by multi-direction input. The Japan Society of Mechanical Engineers (JSME) established a task group to develop an elasto-plastic analysis method for nuclear piping systems, and prepared a case example code proposal for JSME.[1],[2] Our studies in past (ASME PVP2016-63186[3] and ASME PVP2017-65341[4]) were implemented on tests with unidirectional excitation using simple piping systems. In order to examine the applicability of the proposed case example code for JSME in piping of actual systems, it is necessary to examine cases in which there is multidirectional input excitation in piping systems in scales comparable to those of the piping in actual systems. We therefore conducted an analytical examination on demonstration of “the ultimate strength of piping system,” which was implemented at NUPEC. [5] We confirmed in the results of analytical examination that the strain range could be calculated at precision nearly equivalent to our examinations in the past, and that the draft code case was applicable. However, we also found a problem which needs to be solved. In addition, we were able to confirm that the local damping increase caused by the elasto-plastic behavior of the elbow which was subject to examination in this study was 1% or larger.

scholarly journals Shaking Table Tests of a Piping System Supported by a Semiactive Damper.

1993 ◽  
Vol 59 (12) ◽  
pp. 2037-2042
Author(s):  
Hirokazu SHIMODA ◽  
Kenichiro OHMATA ◽  
Fumiaki OKAMOTO
Keyword(s):  
Shaking Table ◽  
Piping System ◽  
Shaking Table Tests

Investigation on Method of Elasto-Plastic Analysis for Piping System (Benchmark Analysis)

2016 ◽  
Author(s):  
Masashi Arai ◽  
Nobuyuki Kojima ◽  
Takuro Kabaya ◽  
Satoru Hirouchi ◽  
Masatsugu Bando
Keyword(s):  
Yield Point ◽  
Kinematic Hardening ◽  
Strain Range ◽  
Fatigue Curve ◽  
Piping System ◽  
Analysis Method ◽  
Benchmark Analysis ◽  
Hardening Law ◽  
Plastic Analysis ◽  
Piping Systems

This report proposes an elasto-plastic analysis method to be used for practical aseismic designing of nuclear piping systems. JSME (the Japan Society of Mechanical Engineers) initiated a task to establish an elasto-plastic analysis method for nuclear piping systems. During this task, benchmark analysis was conducted in order to examine the elastic-plasticity analytical method, in which our company decided to participate. Our policy for evaluation was that the material characteristics to be used in benchmark analysis were based on the standards for nuclear designs in Japan. As a consequence, we prepared a method to accurately simulate the vibration test on piping systems. The recommended elasto-plastic analysis method is thus specified as follows: 1) The elasto-plastic analysis method comprised of dynamic analysis on piping system modeled using beam elements and static analysis of the deforming elbow which was modeled using shell elements. 2) Bi-linear was applied as the elasto-plastic characteristics. The yield point was the standardized yield point times 1.2, and the second gradient was 1/100 the Young’s modulus. Kinematic hardening law was used as the hardening law. 3) Rain flow method and fatigue curve of an existing research were used to evaluate the fatigue life for the strain range obtained by elasto-plastic analysis.

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