Response Of Piping System Research Articles

System Identification and Fractional-Order Proportional–Integral–Derivative Control of a Distributed Piping System

The vibration of piping systems is one of the most important causes of accelerated equipment wear and reduced work efficiency and safety. In this study, an active vibration control method based on a fractional-order proportional–integral–derivative (PID) controller was proposed to suppress pipeline vibration and reduce pipeline damage. First, a mathematical model of the distributed piping system was established using the finite element analysis method, and the characteristics of the distributed piping system were studied effectively. Further, the time-frequency domain parameter identification method was used to realise the system identification of the cross-point vibration transfer function between the brake and sensor, and the particle swarm optimisation algorithm was utilised to further optimise the transfer function parameters to improve the system identification accuracy. Therefore, a fractional-order PID controller was designed using the D-decomposition method, and the optimal controller parameters were obtained. The experimental and numerical simulation results show that the improved system identification algorithm can significantly improve modelling accuracy. In addition, the designed fractional-order PID controller can effectively reduce the system’s overshoot, oscillation time, and adjustment time, thereby reducing the vibration response of piping systems.

Effect of the plasticity of pipe and support on the seismic response of piping systems

Effect of the plasticity of pipe and support on the seismic response of piping systems

Floor Response Spectrum Method of Multiply Supported Piping System Assisted by Time History Analysis

Abstract The independent support motion (ISM) response spectrum method is currently used in seismic analysis to calculate the response of piping systems subjected to independent excitations at several points of a supporting structure. This approach leads to considerable overestimation when the maximum responses by multiple excitations are combined by the absolute sum rule, while this may result in underestimation when the maximum responses by the multiple excitations are combined by the square root of sum of squares rule. Then authors have developed an advanced method of the ISM approach named SATH (spectrum method assisted by time history analysis). In the SATH method, both floor response spectra and time histories of floor acceleration are used as independent inputs of support excitations. The information of the mode shapes, frequencies, and damping values for the supporting structure is not necessary. The maximum responses by multiple excitations are combined using correlation coefficients calculated by taking into account each time history of modal response due to independent inputs of support excitations. In this paper, it was confirmed that the SATH method has the advantage to derive a more realistic rule for combining the maximum responses by multiple excitations, and that it can be easily applied to the actual design as a response spectrum method.

Effect of Dynamic Vibration Absorber on Seismic Response of Piping Systems

The purpose of this study is to clarify the seismic response reduction effect of the piping system by a dynamic vibration absorber. The piping system with a dynamic vibration absorber was modeled into a two-degree-of-freedom system composed of a simple modal mass and a dynamic vibration absorber. Using this model, the floor response spectrum for the observed seismic waves was calculated. By comparing the changes in the two floor response spectra of the piping system with the dynamic vibration absorber and the piping system without the dynamic vibration absorber, the response reduction effect of the dynamic vibration absorber and the magnitude of the added damping ratio were discussed. When a dynamic vibration absorber was installed, the peak height of the floor response spectrum of the piping system decreased, and the effect was useful for the piping system with a smaller damping ratio. Dynamic vibration absorbers are suggested to be an effective method for reducing the seismic response of small-bore piping systems with a small damping ratio.

Impact of Inelastic Seismic Design Using Elastic–Plastic Pipe Supports on Vibration Response of Piping Systems

Abstract This study presents the response mitigation effect of piping systems by inelastic seismic design based on elastic–plastic property of steel pipe supports. The inelastic seismic design to control vibration by absorbing energy using elastic–plastic properties of materials can be one of useful ideas. The design idea to use the elastic–plastic behavior of pipe supports is addressed in Technical Code for Seismic Design of Nuclear Power Plants (JEAC4601) published by the Japan Electric Association in Japan. Here, the component named an elastic–plastic pipe support is proposed as an energy-absorbing element. However, in order to put the inelastic seismic design using the elastic–plastic pipe supports into practical use, it is necessary to accumulate more findings related to the seismic response and the application range. This study aims to investigate the applicability of the inelastic seismic design taking the elastic–plastic pipe supports in the piping systems and to increase the basic findings. In this study, the seismic response analysis using three-dimensional piping system with an elastic–plastic pipe support was conducted. As a result, it was found that the elastic–plastic pipe support affected the seismic response largely. Additionally, the vibration characteristics, the response acceleration, and the load generated in the piping system were discussed relating to the plastic deformation and the plasticity rate of the elastic–plastic pipe support.

Response of Piping System with Semi-active Magnetorheological Damper under Tri-directional Seismic Excitation

ABSTRACT Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure of piping system. Vibrations in the piping system can be reduced using passive control, active control, semiactive control and hybrid control. In this paper, semi-active magnetorheological (MR) dampers have been studied to mitigate seismic response and vibration control in piping system used in the process industries, fossil and fissile fuel power plant. The performance of MR dampers using various control algorithms is explored. A study is also conducted on the performance of control due to variation in the command voltage of MR dampers. The effectiveness of the MR dampers in terms of the reduction in responses, namely, displacements, accelerations and base shear of the piping system are compared with uncontrolled and passive controlled responses. This study is carried out under four artificial earthquake motions with increasing amplitudes in all the three directions of motion. The analytical results demonstrate that the MR dampers under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping system.

Experimental seismic response evaluation of suspended piping restraint installations

Observations from recent earthquakes have repeatedly demonstrated that damage to non-structural elements can significantly compromise the capacity of critical facilities to continue services during times of crises. Performance-based seismic design requires the harmonization of performances between structural and non-structural elements. Among the multitude of non-structural typologies, the seismic performance of piping systems is of paramount importance in order to guarantee the immediate post-event functionality of critical facilities. Few research studies are available in the literature that provide information on the seismic response of piping systems, and in particular of suspended piping restraint installations. This paper presents and discusses the results of an experimental program designed to evaluate the seismic behavior of suspended piping restraint installations. Four typologies of suspended piping restraint installations were tested under monotonic and reversed cyclic loading to determine their hysteretic responses and failure modes and to evaluate key response parameters.

Elasto-Plastic Response of Piping Systems with Pipe Support Structures Using Three-Dimensional Strong Excitation Test

Elasto-Plastic Response of Piping Systems with Pipe Support Structures Using Three-Dimensional Strong Excitation Test

Vibration Control of Nuclear Power Plant Piping System Using Stockbridge Damper under Earthquakes

Generally the piping system of a nuclear power plant (NPP) has to be designed for normal loads such as dead weight, internal pressure, temperature, and accidental loads such as earthquake. In the proposed paper, effect of Stockbridge damper to mitigate the response of piping system of NPP subjected to earthquake is studied. Finite element analysis of piping system with and without Stockbridge damper using commercial software SAP2000 is performed. Vertical and horizontal components of earthquakes such as El Centro, California, and Northridge are used in the piping analysis. A sine sweep wave is also used to investigate the control effects on the piping system under wide frequency range. It is found that the proposed Stockbridge damper can reduce the seismic response of piping system subjected to earthquake loading.

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

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.

Response of piping system with semi-active variable stiffness damper under tri-directional seismic excitation

Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure. In this paper, semi-active variable stiffness dampers (SAVSDs) have been studied to mitigate seismic response and vibration control of piping system used in the process industries, fossil and fissile fuel power plant. The SAVSD changes its stiffness depending upon the piping response and accordingly adds the control forces in the piping system. A study is conducted on the performance of SAVSD due to variation in device stiffness ratios in the switching control law and modified switching control law, which plays an important role in the present control algorithm of the damper. The effectiveness of the SAVSD in terms of reduction in the responses, namely, displacements, accelerations and base shear of the piping system is investigated by comparing uncontrolled responses under four different artificial earthquake motions with increasing amplitudes. The analytical results demonstrate that the SAVSDs under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping systems.

Response of piping system with semi-active variable friction dampers under tri-directional seismic excitation

Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure. In this paper, semi-active variable friction dampers (SAVFDs) have been studied to mitigate seismic response and vibration control of piping system used in the process industries, fossil and fissile fuel power plant. A study is also conducted on the performance of control due to variation in gain multiplier (a) in the present control law, which plays an important role in the present control algorithm of the damper. The effectiveness of the SAVFD in terms of reduction in the responses, namely, displacements, accelerations and base shear of the piping system is investigated by comparing uncontrolled responses under four artificial earthquake motions with increasing amplitudes. The analytical results demonstrate that the SAVFDs under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vi...

Study of dynamic response of piping system with gasketed flanged joints using finite element analysis

The dynamic response of piping system with gasketed flanged joints at various temperatures is studied using finite element analysis. FE simulation with thermo-mechanical analysis is performed, followed by modal and harmonic analysis. Important parameters affecting the vibration are discussed. Temperature of internal fluid induces thermal stresses which influence the natural frequencies significantly. A comparison has been made between metal gasket and spiral wound gasket. Results show that the natural frequencies corresponding to particular modes are influenced by the type of gasket used.

Study of the Resonance in Series Piping Systems with Oscillating Valve

In This search, the phenomena of resonance in series piping systems with oscillating valve have been studied. The one-dimensional flow, unsteady state flow, and partial differential equations have been solved by using transfer matrix method.The details of the transfer matrix method, the derivation of the field matrices and point matrices, and procedures for determining the natural frequencies and frequency response of piping system are then presented. A computer program (Resonance) was developed to calculate the pressure and discharge oscillations at the valve, the phase angle between the pressure head and relative gate opening of the valve, the phase angle between the discharge and the relative gate opening of the valve and the pressure and discharge oscillations at certain sections of the pipes. To verify the transfer matrix method, the results have been compared with impedance method and agreement has been found.

421 サポートの弾塑性特性が配管系の減衰特性に与える影響に関する検討(耐震II,OS-2 耐震・免震・制震,総合テーマ「伝統を,未来へ!」)

421 サポートの弾塑性特性が配管系の減衰特性に与える影響に関する検討(耐震II,OS-2 耐震・免震・制震,総合テーマ「伝統を,未来へ!」)

Efficient dynamic structural response modelling of bolted flange piping systems

The dynamic structural response of piping systems is studied and effective analysis techniques are recommended to assess the influence of a bolted flange with an elastic gasket. The influence of an elastic gasket is minimal for dynamic loadings, as shown in both the experimental and numerical results presented. An overhanging piping system at various span lengths with a flange at mid-length is used for a broad evaluation of potential applications. The testing configurations consist of two different diameter pipes, standard 2 (51 mm) and 4 in (102 mm) schedule 40 steel pipes and the corresponding ANSI B16.5 class 300-pound flanges. Included are fundamental resonant frequencies and their respective mode shapes for various span lengths and gasket configurations using experimental and finite element (FE) methods. The complex interaction between the flange and gasket has little impact on the dynamic structural response of a piping system. The results show that simple lumped mass pipe models provide adequate information in assessing dynamic behaviour of piping systems.

Optimum X-plate dampers for seismic response control of piping systems

In a vibrating system, the most effective mechanism to dissipate energy is the inelastic strain of supplemental metallic elements with plastic deforming characteristics. An X-plate damper (XPD) is one device that is capable of sustaining many cycles of stable yielding deformation resulting in a high level of energy dissipation or damping. The present paper focuses on a numerical study to investigate the seismic effectiveness of an XPD for piping systems in industrial units (e.g. chemical and petrochemical industries) and utilities such as thermal and nuclear power plants. The seismic performance of piping systems is investigated under important parametric variations of the damper properties (i.e. height, width and thickness of the XPD) under arbitrary ground motions. Investigations are reported for an industrial piping system equipped with an XPD and the response quantities of interest are the relative displacements, absolute accelerations and support reactions of the piping system. The response quantities of the controlled (with XPD) piping system are compared with the corresponding uncontrolled (without XPD) piping systems, to establish the seismic effectiveness of the XPD. Seismic energy dissipation in the piping system, which is represented by the hysteretic energy of the XPD, is also evaluated and compared. It is observed that the XPDs are very effective in reducing the seismic response of piping systems. Moreover, for a given piping system and ground motion, it is difficult to arrive at the optimum properties of an XPD from the parametric variation of the properties of the XPD and by monitoring the responses of the piping system. Therefore, use of hysteretic energy dissipation by an XPD is proposed to obtain the optimum properties of the XPD. Furthermore, the effects of the properties of an XPD on the free vibration characteristics of the piping system are also presented, which is crucial for the design of piping systems with XPDs.

Response of piping system on friction support to bi-directional excitation

Installation of friction devices between a piping system and its supporting medium is an effective way of energy dissipation in the piping systems. In this paper, seismic effectiveness of friction type support for a piping system subjected to two horizontal components of earthquake motion is investigated. The interaction between the mobilized restoring forces of the friction support is duly considered. The non-linear behavior of the restoring forces of the support is modeled as an elastic-perfectly plastic system with a very high value of initial stiffness. Such an idealization avoids keeping track of transitional rules (as required in conventional modeling of friction systems) under arbitrary dynamic loading. The frictional forces mobilized at the friction support are assumed to be dependent on the sliding velocity and instantaneous normal force acting on the support. A detailed systematic procedure for analysis of piping systems supported on friction support considering the effects of bi-directional interaction of the frictional forces is presented. The proposed procedure is validated by comparing the analytical seismic responses of a spatial piping system supported on a friction support with the corresponding experimental results. The responses of the piping system and the frictional forces of the support are observed to be in close agreement with the experimental results validating the proposed analysis procedure. It was also observed that the friction supports are very effective in reducing the seismic response of piping systems. In order to investigate the effects of bi-directional interaction of the frictional forces, the seismic responses of the piping system are compared by considering and ignoring the interaction under few narrow-band and broad-band (real earthquake) ground motions. The bi-directional interaction of the frictional forces has significant effects on the response of piping system and should be included in the analysis of piping systems supported on friction supports. Further, it was also observed that the velocity dependence of the friction coefficient does not have noticeable effects on the peak responses of the piping system.

Passive Control of Seismic Response of Piping Systems

Passive energy dissipating devices, such as elastoplastic dampers (EPDs) can be used for eliminating snubbers and reducing the response of piping systems subjected to seismic loads. Cantilever and three-dimensional piping systems were tested with and without EPD on shaker table. Using a finite element model of the piping systems, linear and nonlinear time-history analysis is carried out using Newmark’s time integration technique. Equivalent linearization technique, such as Caughey method, is used to evaluate the equivalent damping of the piping systems supported on elastoplastic damper. An iterative response spectrum method is used for evaluating response of the piping system using this equivalent damping. The analytical maximum response displacement obtained at the elastoplastic damper support for the two piping systems is compared with experimental values and time history analysis values. It has been concluded that the iterative response spectrum technique using Caughey equivalent damping is simple and results in reasonably acceptable response of the piping systems supported on EPD.

Genetic Algorithm-Based Decision Support for Optimizing Seismic Response of Piping Systems

This paper describes computational approaches used in a prototype decision support system (DSS) for seismic design and performance evaluation of piping supports. The DSS is primarily based on a genetic algorithm (GA) that uses finite element analyses, and an existing framework for high performance distributed computing on workstation clusters. A detailed discussion is presented on various issues related to the development of an efficient GA implementation for evaluating the trade-off between the number of supports and cost. An integer string representation of the type used in some existing studies, for instance, is shown to be inferior to a binary string representation, which is appropriate when supports are modeled as axially rigid. A novel seeding technique, which overcomes the inefficiencies of conventional methods in the context of pipe support optimization, is also presented. Finally, an efficient crossover scheme is proposed for generating trade-off curves and the approach is validated with respect ...