Response Characteristics of Piping System Supported by Visco-Elastic and Elasto-Plastic Dampers

1990 ◽  
Vol 112 (1) ◽  
pp. 34-38 ◽  
Author(s):  
T. Chiba ◽  
H. Kobayashi
Keyword(s):  
Energy Dissipation ◽  
Seismic Design ◽  
Damping Ratio ◽  
The Other ◽  
Piping System ◽  
Response Level ◽  
Response Characteristics ◽  
Damping Effect ◽  
Component Test ◽  
Piping Systems

Improving the reliability of the piping systems can be achieved by eliminating the mechanical snubber and by reducing the response of the piping. In the seismic design of piping system, damping is one of the important parameters to reduce the seismic response. It is reported that the energy dissipation at piping supports contributes to increasing the damping ratio of piping system. Visco-elastic damper (VED) and elasto-plastic damper (EPD) were developed as more reliable, high-damping piping supports. The dynamic characteristics of these dampers were studied by the component test and the full-scale piping model test. Damping effect of VED is independent of the piping response and VED can be modeled as a complex spring in the dynamic analysis. On the other hand, damping ratio of piping system supported by EPD increases with the piping response level. So, these dampers are helpful to increase the damping ratio and to reduce the dynamic response of piping system.

Numerical Study on Inelastic Seismic Design of Piping Systems Using Damping Effect Based on Elastic–Plastic Property of Pipe Supports

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Akira Maekawa ◽  
Tsuneo Takahashi
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Plastic Property ◽  
Damping Coefficient ◽  
Seismic Load ◽  
Piping System ◽  
Elastic Plastic ◽  
Damping Effect ◽  
Modal Damping ◽  
Piping Systems

This study describes inelastic seismic design of piping systems considering the damping effect caused by elastic–plastic property of a pipe support which is called an elastic–plastic support. Though the elastic–plastic support is proposed as inelastic seismic design framework in the Japan Electric Association code for the seismic design of nuclear power plants (JEAC4601), the seismic responses of the various piping systems with the support are unclear. In this study, the damping coefficient of a piping system is focused on, and the relation between seismic response of the piping system and elastic–plastic behavior of the elastic–plastic support was investigated using nonlinear time history analysis and complex eigenvalue analysis. The analysis results showed that the maximum seismic response acceleration of the piping system decreased largely in the area surrounded by pipe elbows including the elastic–plastic support which allowed plastic deformation. The modal damping coefficient increased a maximum of about sevenfold. Furthermore, the amount of the initial stiffness of the elastic–plastic support made a difference in the increasing tendency of the modal damping coefficient. From the viewpoint of the support model in the inelastic seismic design, the reduction behavior for the seismic response of the piping system was little affected by the 10% variation of the secondary stiffness. These results demonstrated the elastic–plastic support is a useful inelastic seismic design of piping systems on the conditions where the design seismic load is exceeded extremely.

The Influence of Support Hardware and Piping System Seismic Response on Snubber Support Damping

1997 ◽  
Vol 119 (4) ◽  
pp. 451-456 ◽  
Author(s):  
C. Lay ◽  
O. A. Abu-Yasein ◽  
M. A. Pickett ◽  
J. Madia ◽  
S. K. Sinha
Keyword(s):  
Seismic Response ◽  
Fundamental Frequency ◽  
Damping Ratio ◽  
Damping Coefficient ◽  
Piping System ◽  
Nodal Displacement ◽  
Damping Coefficients ◽  
Fundamental Frequencies ◽  
Piping Systems

The damping coefficients and ratios of piping system snubber supports were found to vary logarithmically with pipe support nodal displacement. For piping systems with fundamental frequencies in the range of 0.6 to 6.6 Hz, the support damping ratio for snubber supports was found to increase with increasing fundamental frequency. For 3-kip snubbers, damping coefficient and damping ratio decreased logarithmically with nodal displacement, indicating that the 3-kip snubbers studied behaved essentially as coulomb dampers; while for the 10-kip snubbers studied, damping coefficient and damping ratio increased logarithmically with nodal displacement.

Main Issues on the Seismic Design of Industrial Piping Systems and Components

2013 ◽  
Author(s):  
Fabrizio Paolacci ◽  
Md. Shahin Reza ◽  
Oreste S. Bursi ◽  
Arnold M. Gresnigt ◽  
Anil Kumar
Keyword(s):  
Seismic Design ◽  
Seismic Analysis ◽  
Experimental Investigations ◽  
Piping System ◽  
Analysis And Design ◽  
Correct Definition ◽  
Component Design ◽  
Piping Systems ◽  
Current Design ◽  
Bolted Flange

A significant number of damages in piping systems and components during recent seismic events have been reported in literature which calls for a proper seismic design of these structures. Nevertheless, there exists an inadequacy of proper seismic analysis and design rules for a piping system and its components. Current seismic design Codes are found to be over conservative and some components, e.g., bolted flange joints, do not have guidelines for their seismic design. Along this line, this paper discusses about the main issues on the seismic analysis and design of industrial piping systems and components. Initially, seismic analysis and component design of refinery piping systems are described. A review of current design approaches suggested by European (EN13480:3) and American (ASME B31.3) Codes is performed through a Case Study on a piping system. Some limits of available Codes are identified and a number of critical aspects of the problem e.g., dynamic interaction between pipes and rack, correct definition of the response factor and strain versus stress approach, are illustrated. Finally, seismic performance of bolted flange joints based on the results of experimental investigations carried out by the University of Trento, Italy, will be discussed.

Performance-Based Analysis of Coupled Support Structures and Piping Systems Subject to Seismic Loading

2015 ◽  
Author(s):  
Oreste S. Bursi ◽  
Fabrizio Paolacci ◽  
Md Shahin Reza
Keyword(s):  
Seismic Design ◽  
Seismic Analysis ◽  
Design Method ◽  
Design Guidelines ◽  
Piping System ◽  
Support Structures ◽  
Limit States ◽  
Piping Systems ◽  
Allowable Stress Design

The prevailing lack of proper and uniform seismic design guidelines for piping systems impels designers to follow standards conceived for other structures, such as buildings. The modern performance-based design approach is yet to be widely adopted for piping systems, while the allowable stress design method is still the customary practice. This paper presents a performance-based seismic analysis of petrochemical piping systems coupled with support structures through a case study. We start with a concept of performance-based analysis, followed by establishing a link between limit states and earthquake levels, exemplifying Eurocode and Italian prescriptions. A brief critical review on seismic design criteria of piping, including interactions between piping and support, is offered thereafter. Finally, to illustrate actual applications of the performance-based analysis, non-linear analyses on a realistic petrochemical piping system is performed to assess its seismic performance.

Improvement of the Damping Constants for Seismic Design of Piping System for NPP

2002 ◽  
Author(s):  
Kei Kobayashi ◽  
Takashi Satoh ◽  
Nobuyuki Kojima ◽  
Kiyoshi Hattori ◽  
Masaki Nakagawa ◽  
...  
Keyword(s):  
Power Plant ◽  
Seismic Design ◽  
Nuclear Power ◽  
Power Plants ◽  
Estimation Method ◽  
Piping System ◽  
Piping Systems ◽  
Support Element ◽  
Present Design ◽  
Bolt Support

The present design damping constants for nuclear power plant (NPP)’s piping system in Japan were developed through discussion among expert researchers, electric utilities and power plant manufactures. They are standardized in “Technical guidelines for seismic design of Nuclear Power Plants” (JEAG 4601-1991 Supplemental Edition). But some of the damping constants are too conservative because of a lack of experimental data. To improve this excessive conservatism, piping systems supported by U-bolts were chosen and U-bolt support element test and piping model excitation test were performed to obtain proper damping constants. The damping mechanism consists of damping due to piping materials, damping due to fluid interaction, damping due to plastic deformation of piping and supports, and damping due to friction and collision between piping and supports. Because the damping due to friction and collision was considered to be dominant, we focused our effort on formulating these phenomena by a physical model. The validity of damping estimation method was confirmed by comparing data that was obtained from the elemental tests and the actual scale piping model test. New design damping constants were decided from the damping estimations for piping systems in an actual plant. From now on, we will use the new design damping constants for U-bolt support piping systems, which were proposed from this study, as a standard in the Japanese piping seismic design.

Simplified Elasto-Plastic Response Analysis Method of Piping

2004 ◽  
Author(s):  
Akihito Otani ◽  
Izumi Nakamura ◽  
Hajime Takada
Keyword(s):  
Plastic Deformation ◽  
Damping Ratio ◽  
Fem Analysis ◽  
Simulation Method ◽  
Response Analysis ◽  
Plastic Response ◽  
Dissipation Energy ◽  
Equivalent Damping ◽  
Damping Effect ◽  
Piping Systems

When piping systems are subjected to extreme seismic excitation, they undergo a plastic deformation that produces a large damping effect via energy dissipation. Based on our studies of the damping effect of the elasto-plastic response of piping, we have presented a simplified method for predicting the elasto-plastic response of piping in PVP conferences over the last several years. Yet the elasto-plastic response of piping calculated by this method resulted in conservative predictions compared with the results of piping model excitation tests. In the proposed method, we calculate the vibration energy of piping and the dissipation energy with plastic deformation by FEM analysis and obtain the equivalent damping ratio as a ratio between the two. The equivalent damping ratio and response are interdependent and can be calculated as a pair of converged values. In this paper we report simulation results from 3D piping model excitation tests as well as the results from 2D piping model tests. The simulation method is a modified and improved version of the method reported earlier. The results obtained by the revised method more closely matched the results of the excitation tests.

Applicability of Optimal Seismic Design Methodology for Piping Systems Subjected to Seismic Waves With Various Frequency Characteristics

2007 ◽  
Author(s):  
Tomohiro Ito ◽  
Katsuhisa Fujita ◽  
Masashi Michiue
Keyword(s):  
Seismic Design ◽  
Design Methodology ◽  
Seismic Waves ◽  
Structural Integrity ◽  
Frequency Characteristics ◽  
System Model ◽  
Piping System ◽  
Optimal Conditions ◽  
Piping Systems ◽  
Support Devices

In this study, the optimal seismic design methodology which can consider the structural integrity of both piping systems and elasto-plastic support devices are developed. This methodology employs genetic algorithm and can search the optimal conditions such as supporting locations, capacity and stiffness of supporting devices. A lead extrusion damper is treated here as a typical elasto-plastic damper. Numerical simulations are performed using a simple piping system model for the various kinds of seismic waves with different frequency characteristics. As a result, it is shown that the optimal seismic design methodology proposed here is applicable to the seismic design of piping systems supported by elasto-plastic dampers subjected to the seismic waves with various kinds of frequency characteristics.

Results From Dynamic Tests and Analyses of a Medium Diameter LMFBR Piping System

1986 ◽  
Vol 108 (3) ◽  
pp. 330-333
Author(s):  
G. A. Schott ◽  
G. M. Hulbert ◽  
C. F. Heberling
Keyword(s):  
Seismic Design ◽  
Large Diameter ◽  
Piping System ◽  
Fast Breeder Reactor ◽  
Test Results ◽  
Dynamic Tests ◽  
Test Program ◽  
Piping Systems ◽  
Seismic Tests ◽  
Medium Diameter

This paper presents results and observations from dynamic tests and analyses performed on an 8-in. (0.20-m) diameter, thin-walled piping system. The piping system is a scaled representation of a Liquid Metal Fast Breeder Reactor (LMFBR) large diameter piping loop. Prototypic piping restraints were employed, including mechanical snubbers, rigid struts, pipe hangers and nonintegral pipe clamps. Snap-back, sine-sweep and seismic tests were performed for various restraint configurations and piping conditions. The test results are compared to analytical predictions for verification of the methods and models used in the seismic design of LMFBR piping systems. Test program conclusions and general recommendations for piping seismic analyses are presented along with a discussion of test and analysis results.

Application of JSME Seismic Code Case by Elastic-Plastic Response Analysis to Practical Piping System

2018 ◽  
Author(s):  
Akihito Otani ◽  
Satoru Kai ◽  
Naoaki Kaneko ◽  
Tomoyoshi Watakabe ◽  
Masanori Ando ◽  
...  
Keyword(s):  
Seismic Design ◽  
Evaluation Methodology ◽  
Design Rule ◽  
Design Evaluation ◽  
Response Analysis ◽  
Piping System ◽  
Plastic Response ◽  
Seismic Code ◽  
Elastic Plastic ◽  
Piping Systems

A Code Case in the framework of JSME Nuclear Codes and Standards is being developed to incorporate a seismic design evaluation methodology for piping by means of advanced elastic-plastic response analysis methods and strain-based fatigue criteria. The Code Case as an alternative seismic design rule over the current rule will provide a more rational seismic design evaluation than the current criteria. This paper demonstrates an application result of the JSME Seismic Code Case to an actual complex piping system. The secondary coolant piping system of Japanese Fast Breeder Reactor, Monju, was selected as a representative of the complex piping systems. The elastic-plastic time history analysis for the piping system was performed and the piping system has been evaluated according to the JSME Seismic Code Case. The evaluation by the Code Case provides a reasonable result in terms of the piping fatigue evaluation that governs seismic integrity of piping systems. Moreover, it is found that the supporting forces and the response accelerations of the piping system obtained by the elastic-plastic response analysis also become more rational results than those with the current elastic response analysis. The contradiction of two requirements in piping design, flexibility for thermal expansion and rigidity for seismic response, can be effectively relaxed by use of the Code Case being developed.

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.

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