Passive Control of Seismic Response of Piping Systems

2005 ◽  
Vol 128 (3) ◽  
pp. 364-369 ◽  
Author(s):  
Y. M. Parulekar ◽  
G. R. Reddy ◽  
K. K. Vaze ◽  
K. Muthumani

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.

Author(s):  
Y. M. Parulekar ◽  
G. R. Reddy ◽  
K. K. Vaze ◽  
K. Muthumani

Passive energy dissipating devices like Elasto-plastic dampers (EPDs) can be used for eliminating snubbers and reducing the response of piping systems subjected to seismic loads. Cantilever and 3-dimensional piping systems were tested with and without EPD on shake 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 Elasto-Plastic 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 Elasto-Plastic damper support for the two piping systems is compared with experimental values and time history analysis values. It has been concluded that, iterative response spectrum technique using Caughey equivalent damping is simple and results in reasonably acceptable response of the piping systems supported on EPD.


Author(s):  
Tadashi Iijima ◽  
Takaaki Sakakida ◽  
Satoru Ono

We examined two approaches for predicting the inelastic responses of piping systems. The first enabled us to evaluate accurate responses using nonlinear time-history analysis. We focused on a material model in this approach. Plastic deformation might exhibit a cyclic-hardening effect, which is dependent on the strain ranges, and this hardening affects the dynamic responses of piping systems. Therefore, we improved the hardening model developed by Ohno and Wang (OW model), which is one of the most sophisticated models for producing kinematic hardening behavior. We modified it to produce cyclic-hardening behavior dependent on strain ranges. The second was a simplified approach to evaluate inelastic responses without time-consuming time-history analysis. We developed a tool using equivalent linearization. The tool used analysis techniques including a model of elastic beam elements using flexibility factors for pipe elbows, and modal response spectrum analysis. Equivalent linearization made it possible to apply modal analysis to inelastic analysis. We demonstrated how applicable the approaches were by conducting test simulations.


2009 ◽  
Vol 25 (3) ◽  
pp. 583-605 ◽  
Author(s):  
Wei Chiang Pang ◽  
David V. Rosowsky

This paper presents a direct displacement design (DDD) procedure that can be used for seismic design of multistory wood-framed structures. The proposed procedure is applicable to any pure shear deforming system. The design procedure is a promising design tool for performance-based seismic design since it allows consideration of multiple performance objectives (e.g., damage limitation, safety requirements) without requiring the engineer to perform a complex finite element or nonlinear time-history analysis of the complete structure. A simple procedure based on normalized modal analysis is used to convert the code-specified acceleration response spectrum into a set of interstory drift spectra. These spectra can be used to determine the minimum stiffness required for each floor based on the drift limit requirements. Specific shear walls can then be directly selected from a database of backbone curves. The procedure is illustrated on the design of two three-story ATC-63 archetype buildings, and the results are validated using nonlinear time-history analysis.


2020 ◽  
Vol 86 (888) ◽  
pp. 20-00129-20-00129
Author(s):  
Yoshihiro TAKAYAMA ◽  
Ayaka YOSHIDA ◽  
Nobuyoshi IRIKI ◽  
Eiichi MAEDA

Author(s):  
Yoshihiro Takayama ◽  
Ayaka Yoshida ◽  
Iriki Nobuyoshi ◽  
Eiichi Maeda

Abstract The independent support motion response spectrum method (ISM) is currently used for seismic analysis to calculate the response of multiply supported piping with independent inputs of support excitations. This approach may derive considerable overestimation in the combination of group responses under the absolute sum rule of NUREG-1061 [1]. 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 of floor response spectra and time histories of floor acceleration are used as independent inputs of support excitations. The group responses are summed with correlation coefficients which are calculated by considering each time history of modal response by independent inputs of support excitations. In this paper, the necessity of taking the effects of correlation coefficients for the group responses into account in the ISM approach is examined. The SATH method has advantage to derive a more realistic sum rule of the group responses and applicability for the actual design.


Author(s):  
Ayaka Yoshida ◽  
Yoshihiro Takayama ◽  
Hiromichi Shudo

Abstract The independent support motion response spectrum method (ISM) is currently used for seismic analysis to calculate the response of multiply supported piping system with independent inputs of support excitations. This approach may derive considerable overestimation in the combination of group responses under the absolute sum rule of NUREG-1061. To reduce the excessive overestimation, an advanced method named “Spectrum Method Assisted by Time History Analysis (SATH)” has been proposed. In the SATH method, modal responses by multiple excitations are combined with correlation coefficients which are calculated from the covariances and the standard deviations of time history responses of the oscillators having each of modal frequencies of piping system by each of the floor acceleration time history excitations. In this paper, the applicability of the SATH method to actual design which uses broadened Floor Response Spectra (FRS) was examined. Conservativeness of the SATH method is also discussed with presenting that responses derived from the SATH method tend to exceed responses by the time history analysis even when many different time intervals of acceleration time histories are used within the range of the FRS broadening.


1999 ◽  
Vol 121 (1) ◽  
pp. 103-108 ◽  
Author(s):  
G. R. Reddy ◽  
K. Suzuki ◽  
T. Watanabe ◽  
S. C. Mahajan

Generally, industrial piping systems are supported on hangers, snubbers, friction supports, etc. Friction supports are used for free thermal expansion of the piping systems. They also have the property to absorb energy from earthquake excitation. In this paper, equivalent linearization techniques such as the Caughey method for bilinear system and the energy method are used to calculate equivalent damping of typical industrial piping system on friction support. These methods are compared in terms of the equivalent damping. An iterative response spectrum method is tried for evaluating response of the piping system using equivalent damping obtained by linearization techniques. Maximum response displacement obtained at friction support is compared with the experimental values. At the end it is concluded that the Caughey method and the energy method evaluate similar damping for the piping on friction support and also concluded that the iterative response spectrum method is easy and reasonable for use in design.


Author(s):  
Koichi Tai ◽  
Keisuke Sasajima ◽  
Shunsuke Fukushima ◽  
Noriyuki Takamura ◽  
Shigenobu Onishi

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Paper is focused on the seismic evaluation method of the multiply supported systems, as the one of the design methodology adopted in the equipment and piping system of the seismic isolated nuclear power plant in Japan. Many of the piping systems are multiply supported over different floor levels in the reactor building, and some of the piping systems are carried over to the adjacent building. Although Independent Support Motion (ISM) method has been widely applied in such a multiply supported seismic design of nuclear power plant, it is noted that the shortcoming of ignoring correlations between each excitations is frequently misleaded to the over-estimated design. Application of Cross-oscillator, Cross-Floor response Spectrum (CCFS) method, proposed by A. Asfura and A. D. Kiureghian[1] shall be considered to be the excellent solution to the problems as mentioned above. So, we have introduced the algorithm of CCFS method to the FEM program. The seismic responses of the benchmark model of multiply supported piping system are evaluated under various combination methods of ISM and CCFS, comparing to the exact solutions of Time History analysis method. As the result, it is demonstrated that the CCFS method shows excellent agreement to the responses of Time History analysis, and the CCFS method shall be one of the effective and practical design method of multiply supported systems.


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