Simplified Elasto-Plastic Response Analysis of Piping: Considering In-Plane, Out-of-Plane and the Mixed Bending of Elbow

2006 ◽  
Author(s):  
Akihito Otani ◽  
Syozaburo Toyoda ◽  
Izumi Nakamura ◽  
Hajime Takada
Keyword(s):  
Plastic Deformation ◽  
Seismic Excitation ◽  
Response Analysis ◽  
Plastic Response ◽  
Additional Method ◽  
Damping Effect ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending ◽  
Good Agreement

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. The method has taken the plastic deformation of in-plane bending elbows into consideration. The elasto-plastic response predicted by the method resulted in good agreement with piping model excitation tests. In this paper, we report an additional method to consider out-of-plane bending elbow and the mixed bending of in-plane and out-of-plane bending. The simulation results by this method and the comparisons with 3D piping model excitation tests are also reported.

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.

Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane, and Mixed Mode Bending Under Seismic Load: An Experimental Approach

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Dynamic Behavior ◽  
Failure Modes ◽  
Seismic Load ◽  
Piping System ◽  
Shake Table ◽  
Shake Table Tests ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending

Pressurized piping systems used for an extended period may develop degradations such as wall thinning or cracks due to aging. It is important to estimate the effects of degradation on the dynamic behavior and to ascertain the failure modes and remaining strength of the piping systems with degradation through experiments and analyses to ensure the seismic safety of degraded piping systems under destructive seismic events. In order to investigate the influence of degradation on the dynamic behavior and failure modes of piping systems with local wall thinning, shake table tests using 3D piping system models were conducted. About 50% full circumferential wall thinning at elbows was considered in the test. Three types of models were used in the shake table tests. The difference of the models was the applied bending direction to the thinned-wall elbow. The bending direction considered in the tests was either of the in-plane bending, out-of-plane bending, or mixed bending of the in-plane and out-of-plane. These models were excited under the same input acceleration until failure occurred. Through these tests, the vibration characteristic and failure modes of the piping models with wall thinning under seismic load were obtained. The test results showed that the out-of-plane bending is not significant for a sound elbow, but should be considered for a thinned-wall elbow, because the life of the piping models with wall thinning subjected to out-of-plane bending may reduce significantly.

Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane and Mixed Mode Bending Under Seismic Load: An Experimental Approach

2007 ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Failure Modes ◽  
Seismic Load ◽  
Piping System ◽  
Shake Table ◽  
Shake Table Tests ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending ◽  
The Difference

In order to investigate the influence of degradation on the dynamic behavior and failure modes of piping systems with local wall thinning, shake table tests using 3-D piping system models were conducted. About 50% full circumferential wall thinning at elbows was considered in the test. Three types of models were used in the shake table tests. The difference of the models was the applied bending direction to the thinned wall elbow. The bending direction considered in the tests was either of the in-plane bending, out-of-plane bending, or mixed bending of the in-plane and out-of-plane. These models were excited under the same input acceleration until failure occurred. Through these tests, the vibration characteristic and failure modes of piping models with wall thinning under seismic load were obtained. The test results showed that the out-of-plane bending is not significant for a sound elbow, but should be considered for a thinned wall elbow, because the life of piping models with wall thinning subjected to out-of-plane bending may reduce significantly.

Random Seismic Response Analysis of Leaning-Type Arch Bridge

2011 ◽  
Vol 378-379 ◽  
pp. 332-336
Author(s):  
Yong He Li ◽  
Ai Rong Liu ◽  
Qi Cai Yu ◽  
Pan Tang ◽  
Fang Jie Cheng
Keyword(s):  
Bending Moment ◽  
Internal Force ◽  
Response Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Arch Bridge ◽  
Space Truss ◽  
Out Of Plane ◽  
Plane Bending ◽  
The Impact

With an example of steel pipe concrete leaning-type arch bridge, space truss system Finite Element Analysis model is constructed using the Ruiz-Penzien random seismic vibration power spectrum model. The impact of inclined arch rib angle and the number of cross brace between main and stable arch ribs on the seismic internal force response under lateral random seismic excitation is also studied in this research. Research finding shows, the in-plane bending moment of main arch rib gradually increases with increasing stable arch rib angle and cross brace, whereas the out-of-plane bending moment and axial force display a decreasing trend. In general, this indicates that increasing stable arch rib angle and number of cross brace improves the lateral aseismatic performance of leaning-type arch bridge.

Effect of Local Wall Thinning on the Dynamic Behavior of Piping Systems

2005 ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Dynamic Behavior ◽  
Failure Behavior ◽  
Piping System ◽  
Test Model ◽  
System Models ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending ◽  
Local Wall Thinning

In order to investigate the influence of degradation on dynamic behavior and the failure mode of piping systems with local wall thinning, shake table tests using 3-D piping system models were conducted. The degradation considered in this study was wall thinning, which would be caused in piping systems due to the effects of aging. The degradation condition induced in the piping system model was 50% full circumferential wall thinning at an elbow. The test model was designed to cause out-of-plane bending moment to the thinned-wall elbow by excitation tests. The model without wall thinning was also used in the excitation test to compare the behavior of the piping system models. These models were excited under same input acceleration until fatigue cracks penetrated or an excessive deformation occurred to the models. Through these tests, the vibration characteristic and the process to failure of degraded piping models were obtained for the out-of-plane bending model. This paper describes the dynamic response and failure behavior of piping systems with wall thinning based on the test 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.

Effect of Bend Angle on Gross Plastic Deformation of Pipe Bends for Out-of-Plane Bending: A Study Using Plastic Work Curvature Method

2016 ◽  
Author(s):  
Anindya Bhattacharya ◽  
Sachin Bapat ◽  
Hardik Patel ◽  
Shailan Patel ◽  
Michael P. Cross
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Bending Moment ◽  
Plastic Work ◽  
Bend Angle ◽  
Piping System ◽  
Plastic Collapse ◽  
Pipe Bend ◽  
Out Of Plane ◽  
Plane Bending

Bends are an integral part of a piping system. Because of the ability to ovalize and warp they offer more flexibility when compared to straight pipes. Piping Code ASME B31.3 [1] provides flexibility factors and stress intensification factors for pipe bends. Like any other piping component, one of the failure mechanisms of a pipe bend is gross plastic deformation. In this paper, plastic collapse load of pipe bends have been analyzed for various bend parameters (bend parameter = tRbrm2) under internal pressure and out-of-plane bending moment for various bend angles using both small and large deformation theories. FE code ABAQUS version 6.9EF-1 has been used for the analyses. The goal of the paper is to develop an expression for plastic collapse moment for a bend using plastic work curvature method when the bend is subjected to out-of-plane bending moment and internal pressure as a function of bend angle and bend parameter.

Failure Modes of Piping Systems Under Seismic Loading and Evaluation

2019 ◽  
Author(s):  
Satoru Kai ◽  
Akihito Otani
Keyword(s):  
Plastic Deformation ◽  
Failure Modes ◽  
Seismic Loading ◽  
Response Analysis ◽  
Plastic Collapse ◽  
Stress Evaluation ◽  
Dynamic Reliability ◽  
Primary Stress ◽  
Input Force ◽  
Piping Systems

Abstract Failure modes of piping systems under seismic motions were discussed for several decades if the fatigue failure is dominant or there is some possibility that the plastic collapse could occur. A handful of ratchet-buckling failure observed in Pipe Fittings Dynamic Reliability Program by EPRI was frequently taken up as the evidence of the plastic collapse, and inclusion of seismic response on structures into the Primary stress evaluation for piping systems in the code evaluation was considered to be conventionally justified. Although prevention of the plastic collapse type failure is the purpose of imposing the Primary stress evaluation, the other experimental tests conducted in several countries for decades were unable to represent the plastic collapse of piping components exposed to seismic loading and the discussion was abandoned for a while. However, the drastically increased design seismic motions for nuclear power plants due to several huge earthquake occurred in Japan reminded us of exploring the fact of the plastic collapse and the necessity of the Primary stress evaluation. The load classification concept proposed by the authors introduces 3 conceptual force terms from the equation of motion to clarify the seismic loading from the aspect of the correlation of the said force terms. Based on the finding from the concept that the input force amplitude is to be evaluated for Primary stress, the gross-plastic deformation on a single cantilever with elastic-plastic analyses using multiple of single-cycle sinusoidal forcing functions was compared with the input force term. When the plastic collapse is defined as a gross-plastic deformation, the level of plastic collapse was found to be possibly anticipated with a static force evaluation that can be substitute for the conventional Primary stress evaluation with the dynamic response analysis.

Gross Plastic Deformation of Pipe Bends Under Internal Pressure and In- and Out-of-Plane Bending: A Study on the Sensitivity of the Finite Element Models

2014 ◽  
Author(s):  
Anindya Bhattacharya ◽  
Sachin M. Bapat
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Real Life ◽  
Bending Moment ◽  
Piping System ◽  
Plastic Collapse ◽  
Collapse Load ◽  
Pipe Bend ◽  
Out Of Plane ◽  
Plane Bending

Bends are an integral part of a piping system. Because of the ability to ovalize and warp they offer more flexibility when compared to straight pipes. Piping Code ASME B31.3 [1] provides flexibility factors and stress intensification factors for the pipe bends. Like any other piping component, one of the failure mechanisms of a pipe bend is gross plastic deformation. In this paper, plastic collapse load of pipe bends have been analyzed for various D/t ratios (Where D is pipe outside diameter and t is pipe wall thickness) for internal pressure and in-plane bending moment, internal pressure and out-of-plane bending moment and internal pressure and a combination of in and out-of-plane bending moments under varying ratios. Any real life component will have imperfections and the sensitivity of the models have been investigated by incorporating imperfections as scaled eigenvectors of linear bifurcation buckling analyses. The sensitivity of the models to varying parameters of Riks analysis (an arc length based method) and use of dynamic stabilization using viscous damping forces have also been investigated. Importance of defining plastic collapse load has also been discussed. FE code ABAQUS version 6.9EF-1 has been used for the analyses.

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