Seismic Design of Geothermal Pipeline Supports

2002 ◽  
Author(s):  
Fjola Jonsdottir ◽  
Gunnlaugur O. Agustsson ◽  
Magnus T. Jonsson
Keyword(s):  
Seismic Design ◽  
Power Plants ◽  
Response Spectrum ◽  
Critical Factor ◽  
Seismic Loading ◽  
Support Design ◽  
Ground Acceleration ◽  
Piping Systems ◽  
Stiffness Characteristics ◽  
The Cost

Seismic loading is a critical factor in the structural design of piping systems for geothermal power plants in Iceland. It has been shown that the design of piping systems which is based on response spectrum static analysis can lead to overdesigned systems. The loading on the supports will be overestimated and, hence, the supports tend to be too stiff. This increased stiffness both increases the cost and reduces the quality of the seismic design. The systems response is highly dependent on the support stiffness. In this work, the design of a typical expansion loop with respect to seismic loading is discussed, with the goal being to minimize the loading from the ground acceleration. A typical pipe support is modelled, and its stiffness characteristics are evaluated and optimized. Finally, recommendations are made for improvements in pipeline support design.

Study on Far-Field Ground Motion Characteristics

2013 ◽  
Vol 438-439 ◽  
pp. 1471-1473
Author(s):  
Gong Lian Chen ◽  
Wen Zheng Lu ◽  
Lei Wang ◽  
Qi Wu
Keyword(s):  
Ground Motion ◽  
Seismic Design ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Engineering Application ◽  
Seismic Attenuation ◽  
Far Field ◽  
Propagation Process ◽  
Ground Acceleration ◽  
Motion Characteristics

In order to study the far-field ground motion characteristics and the attenuation of seismic waves, the peak ground acceleration (velocity, displacement), time of duration and response spectrum of the seismic waves were analyzed in this paper. Through the investigation of earthquake wave propagation process, the seismic attenuation low was analyzed. This study can provide technical support for the seismic design of long period structures and related engineering application.

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.

scholarly journals Improvement of the Performance-Based Seismic Design Method of Cable Supported Bridges with the Resilient-Friction Base Isolation Systems

2020 ◽  
Vol 10 (11) ◽  
pp. 3942 ◽  
Author(s):  
Heungbae Gil ◽  
Kyoungbong Han ◽  
Junho Gong ◽  
Dooyong Cho
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Response Spectrum ◽  
Design Procedure ◽  
Time History ◽  
Modal Shape ◽  
Ground Acceleration ◽  
Performance Based Seismic Design ◽  
Seismic Design Method ◽  
Shape Analyses

In areas of civil engineering, the resilient friction base isolator (R-FBI) system has been used due to its enhanced isolation performance under seismic excitations. However, because nonlinear behavior of the R-FBI should be reflected in seismic design, effective stiffness (Keff) of the R-FBI is uniformly applied at both peak ground acceleration (PGA) of 0.08 g and 0.154 g which use a multimodal response spectrum (RS) method analysis. For rational seismic design of bridges, it should be required to evaluate the dynamics of the R-FBI from in-field tests and to improve the seismic design procedure based on the performance level of the bridges. The objective of this study is to evaluate the dynamics of the R-FBI and to suggest the performance-based seismic design method for cable-supported bridges with the R-FBI. From the comparison between the experiments’ results and modal shape analyses, the modal shape analyses using primary (Ku) or infinite stiffness (fixed end) showed a great agreement with the experimental results compared to the application of Keff in the shape analysis. Additionally, the RS or nonlinear time history method analyses by the PGA levels should be applied by reflecting the dynamic characteristics of the R-FBI for the reasonable and efficient seismic design.

Development of Elastic-Plastic Constitutive Models for the Evaluation of Nuclear Piping Systems Under Severe Cyclic Loading

2012 ◽  
Author(s):  
Yukio Takahashi ◽  
Yoshihiko Tanaka
Keyword(s):  
Cyclic Loading ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Seismic Loading ◽  
Piping System ◽  
Elastic Plastic ◽  
Piping Systems

It is essential to predict the behavior of nuclear piping system under seismic loading to evaluate the structural integrity of nuclear power plants. Relatively large stress cycles may be applied to the piping systems under severe seismic loading and plastic deformation may occur cyclically in some portion of the systems. Accurate description of inelastic deformation under cyclic loading is indispensable for the precise estimation of strain cycles and accumulation potentially leading to the failure due to fatigue-ratcheting interaction. Elastic-plastic constitutive models based on the nonlinear kinematic hardening rule proposed by Ohno and Wang were developed for type 316 austenitic stainless steel and carbon steel JIS STPT410 (similar to ASTM A106 Gr.B), both of which are used in piping systems in nuclear power plants. Different deformation characteristics under cyclic loading in terms of memory of prior hardening were observed on these two materials and they were reflected in the modeling. Results of simulations under various loading conditions were compared with the test data to demonstrate the high capability of the constitutive models.

Study on Piping Seismic Response Under Multiple Excitation

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Satoru Kai ◽  
Tomoyoshi Watakabe ◽  
Naoaki Kaneko ◽  
Kunihiro Tochiki ◽  
Kazuyuki Tsukimori ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Response Spectrum ◽  
Tohoku Earthquake ◽  
Experimental Tests ◽  
Dynamic Responses ◽  
Plant Design ◽  
Analysis Methods ◽  
Multiple Input ◽  
Piping Systems

The uniform response spectrum (URS) analysis method is generally used to seismic qualification of piping systems in nuclear power plants (NPPs). This method can reasonably not only compute dynamic responses of the piping systems exposed to different seismic motions from the building but also tend to overestimate the responses due to an assumption while conservatively considering a variety of the characteristic among input loadings. Increases of design seismic motions for NPPs in Japan by 2–3 times due to the 2011 off Pacific Coast of Tohoku Earthquake resulted that structures, systems, and components such as piping systems are subject to numbers of additional supporting structures to meet the design code requirements. Use of multiple-input analysis methods (independent support motion methods) is expected to bring high degree of precision in dynamic responses than the URS method. However, existence of a handful of experimental tests prevents from utilizing the method in the design process for NPPs in Japan. In order to practically utilize the multiple-input analysis methods in the plant design, this paper provides validation analyses and results for the multiple-input analysis methods for piping by conducting excitation tests and validation analyses. Some recommendations were also found in the study for seismic design of NPPs.

scholarly journals Research on Improved Seismic Instrumentation System for Nuclear Power Plants

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4262
Author(s):  
Liang Li ◽  
Xiuli Du ◽  
Rong Pan ◽  
Xiuyun Zhu ◽  
Haiyan Luan
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Response Spectrum ◽  
Ground Acceleration ◽  
Cumulative Absolute Velocity ◽  
Safety Regulations ◽  
Seismic Instrumentation ◽  
Three Components

According to the requirements of nuclear safety regulations, nuclear power plants must be equipped with seismic instrumentation systems, which are mainly used for monitoring alarm and automatic shutdown alarm during an earthquake. Both the second and third generation NPPs adopt Peak Ground Acceleration (PGA). However, among the seismic acceleration characteristics, isolated and prominent single high frequency acceleration peaks have no decisive influence on the seismic response. Especially when the earthquake monitoring alarm is at 1 out of 7, it is likely to cause a false alarm or false shutdown. In addition, it usually takes one month or more for the NPPs to restart after the shutdown. In this paper, an improved seismic instrumentation system based on the existing system is proposed. For high intensity areas, three components resultant acceleration is used to judge the 2 out of 4 logic of the automatic seismic trip system(ASTS). For low intensity areas, the seismic failure level is evaluated quickly by using three components resultant acceleration, seismic instrument intensity, cumulative absolute velocity, floor response spectrum and other multi-parameters, avoiding unnecessary and long-term shutdown inspection.

Methods Used for Calculating Seismic Response of Multiply Supported Piping Systems

1992 ◽  
Vol 114 (1) ◽  
pp. 46-52 ◽  
Author(s):  
M. P. Singh ◽  
R. A. Burdisso ◽  
G. O. Maldonado
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Response Spectrum ◽  
Actual Practice ◽  
Seismic Input ◽  
Piping Systems ◽  
Simplifying Assumptions ◽  
Primary Structures

The paper describes the response spectrum methods which are being used currently in the industry for the calculation of seismic design response of piping systems supported at several points of primary structures. In actual practice, the seismic input motions at the piping supports are correlated to varying degrees. To include the effect of this correlation between different support motions in the calculation of piping response, several methodologies with different simplifying assumptions have been proposed. This paper evaluates the effect of these assumptions on the accuracy of the calculated piping response. For this evaluation the results obtained by some of the currently used approximate approaches have been compared with the results obtained by an analytically rational and a more accurate approach. The comparison shows large differences in the two sets of results. For the example problem, the response values calculated by the approximate approaches are rather on the overly conservative side. This conservatism is, however, neither uniform nor assured. The use of these approximate approaches is, therefore, not recommended.

Experimental and Numerical Studies of Ratcheting in a Pressurized Piping System Under Seismic Load

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
A. Ravikiran ◽  
P. N. Dubey ◽  
M. K. Agrawal ◽  
G. R. Reddy ◽  
R. K. Singh ◽  
...  
Keyword(s):  
Comprehensive Evaluation ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Seismic Loading ◽  
Seismic Load ◽  
Piping System ◽  
Inelastic Response ◽  
Design Procedures ◽  
Numerical Studies ◽  
Piping Systems

Rational seismic design procedures necessitate comprehensive evaluation of nuclear piping systems under large amplitude seismic loads. This comprehensive assessment requires accurate prediction of inelastic response of piping system till failure to ensure adequate margins for unexpected beyond design basis events. The present paper describes the details of experimental and numerical studies of inelastic response of pressurized piping system under seismic loading. Shake table test has been carried out on a three-dimensional stainless steel piping system under internal pressure and seismic load. The amplitude of base excitation has been increased till failure of the piping system. The tested piping system has been analyzed using iterative response spectrum (IRS) method for various levels of excitation. The comparison of numerical and experimental results is given in the paper.

Relaxed Hanger Spans for Non-Critical Piping

2003 ◽  
Author(s):  
Chakrapani Basavaraju ◽  
Ronald C. Fox
Keyword(s):  
Power Plants ◽  
Large Diameter ◽  
Combined Cycle ◽  
Dead Weight ◽  
Element Analysis ◽  
Industrial Facilities ◽  
Stress Maximum ◽  
Piping Systems ◽  
Large Diameter Pipes ◽  
The Cost

Piping systems are normally used to transport air, gases, steam, water, and other fluids. Piping systems in power plants, petro-chemical, and other industrial facilities that carry non-hazardous fluids like air, water, etc. with no significant pressures at moderate temperatures can be considered as non-critical. Codes such as ASME B31.1 provide suggested dead weight spans for the placement of supports. In this paper, relaxed hanger spans are computed for non-safety related piping systems taking in to consideration the maximum bending stress, maximum deflection or pipe sag, and bearing stresses due to dead weight for pipe sizes ranging from 1” to 42” diameter. For situations in which large diameter pipes are directly sitting on steel with a line contact, bearing stresses are computed using finite element analysis as well as simple formulas. A comparison of relaxed hanger spans with B31.1 suggested spans is presented. Significant benefits in lowering the cost due to reduced number of dead weight supports, and the associated savings due to reduction in materials, fabrication, and installation can be derived by using the relaxed spans. These relaxed hanger spans were utilized over the past nine years on a variety of non-safety related piping systems. Experience with more than a dozen power projects of Pulverized coal (PC), Cogen, Simple cycle, and Combined cycle types indicates that the piping systems, which used relaxed hanger spans, are operating normally and satisfactorily without any problems.

scholarly journals Construction of a Site- and Period-Specific Seismic Hazard Map for the Korean Peninsula

2020 ◽  
Vol 20 (2) ◽  
pp. 207-220
Author(s):  
Hyun Woo Jee ◽  
Sang Whan Han
Keyword(s):  
Seismic Hazard ◽  
Seismic Design ◽  
Korean Peninsula ◽  
Response Spectrum ◽  
Response Spectra ◽  
Earthquake Damage ◽  
Economic Damage ◽  
Hazard Maps ◽  
Ground Acceleration ◽  
Seismic Hazard Maps

The 2016 Gyeongju and 2017 Pohang earthquakes caused casualties and economic damage in the surrounding areas. Therefore, the importance of earthquake damage prediction and seismic design in the Korean peninsula has increased. Probabilistic seismic hazard analysis (PSHA) is one of the well-known methods for predicting earthquake damage. The objective of this study is to construct Korean Peninsula seismic hazard maps of 5% damped response spectrum acceleration and peak ground acceleration, using PSHA. To consider the local effects for each site's classification, seismic hazard maps were constructed by considering the site amplification model. To conduct seismic design, uniform hazard response spectra (UHRS) were also constructed for the Korean peninsula.

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