Damping in LMFBR Pipe Systems

1985 ◽  
Vol 107 (4) ◽  
pp. 366-372 ◽  
Author(s):  
M. J. Anderson ◽  
D. A. Barta ◽  
M. R. Lindquist ◽  
E. J. Renkey ◽  
J. A. Ryan
Keyword(s):  
Excitation Amplitude ◽  
Test Facility ◽  
Seismic Events ◽  
Seismic Loads ◽  
Modal Damping ◽  
Water Plant ◽  
Pipe Systems ◽  
Vibration Tests ◽  
Recent Laboratory

Liquid Metal Fast Breeder Reactor pipe systems typically utilize a thicker insulation package than that used on water plant pipe systems. They are supported with special insulated pipe clamps. Mechanical snubbers are employed to resist seismic loads. Recent laboratory testing has indicated that these features provide significantly more damping than presently allowed by Regulatory Guide 1.61 for water plant pipe systems. This paper presents results of additional in-situ vibration tests conducted on Fast Flux Test Facility pipe systems. Pipe damping values obtained at various excitation levels are presented. Effects of filtering data to provide damping values at discrete frequencies and the alternate use of a single equivalent modal damping value are discussed. These tests further confirm that damping in typical LMFBR pipe systems is larger than presently used in pipe design. Although some increase in damping occurred with increased excitation amplitude, the effect was not significant. Recommendations are made to use increased damping values for seismic events in design of heavily insulated pipe systems.

scholarly journals Damping Assessment of Lightweight Timber Floors Under Human Walking Excitations

2019 ◽  
Vol 9 (18) ◽  
pp. 3759 ◽  
Author(s):  
Alexander Opazo-Vega ◽  
Francisco Muñoz-Valdebenito ◽  
Claudio Oyarzo-Vera
Keyword(s):  
Social Housing ◽  
Damping Ratio ◽  
Human Walking ◽  
Structural Elements ◽  
Housing Projects ◽  
Frequency Decomposition ◽  
Modal Damping ◽  
Vibration Tests ◽  
Stochastic Identification

Vibrations on timber floors are among the most common serviceability problems in social housing projects. The presence of low damping levels on these floors could cause excessive vibrations in a range of frequency and amplitude that generate discomfort in users. This study focuses on the influence of the damping ratio in the dynamic serviceability of social housing timber floors due to walking excitations. More than 60 human-walking vibration tests were conducted on both laboratory and in-situ timber floors. The floors were instrumented with accelerometers, and fundamental modal damping ratios were estimated by applying Enhanced Frequency Decomposition Domain (EFDD) and Subspace Stochastic Identification (SSI) methods. The vibration dose value (VDV) was used to estimate the dynamic serviceability of floors. The results indicated that timber floors had an impulsive-type vibration response, with fundamental damping ratios between 1.9% and 14.8%, depending on their constructive characteristics. The in-situ floors had damping ratios between two to three times greater than the laboratory floors due to the presence of non-structural elements. Finally, it was possible to demonstrate that the floors with the highest damping ratios reached lower vibration dose values and, therefore, a better dynamic serviceability performance.

Characterization of sandwich beams with shear damages by linear and nonlinear vibration methods

2017 ◽  
Vol 52 (1) ◽  
pp. 47-60
Author(s):  
Imen Ben Ammar ◽  
Abderrahim El Mahi ◽  
Chafik Karra ◽  
Rachid El Guerjouma ◽  
Mohamed Haddar
Keyword(s):  
Nonlinear Vibration ◽  
Excitation Amplitude ◽  
Intact Specimen ◽  
Modal Damping ◽  
Resonance Frequencies ◽  
Linear And Nonlinear ◽  
Materials Used ◽  
Vibration Tests ◽  
Vibration Parameters ◽  
Sandwich Materials

The aim of the present work is to study the vibration behavior of sandwich composites with shear damages on the foams. The effect of the densities of damage on the linear and nonlinear vibration parameters is studied. The sandwich materials used in this study is constructed with glass fiber laminates as skins and with PVC closed-cell foams with density 60 and 100 kg m−3 as core. After a serie of vibration tests, the change of natural frequencies and modal damping due to the damage and the foam densities. For an intact specimen, the resonance frequency was constant when we increase the excitation amplitude. For damaged specimens, the resonance frequencies decrease and the loss factors increase proportionally with the increasing excitation amplitude. The nonlinear parameters corresponding to the elastic modulus and damping were determined for each frequency modes and each damage and foam densities. The results showed that nonlinear dissipative parameters were more sensitive to damage than linear elastic and dissipative parameters.

In-Plane Vibration Damping of a U-Tube With Wet and Dry Flat-Bar Supports

2014 ◽  
Author(s):  
Paul A. Feenstra ◽  
Victor P. Janzen ◽  
Bruce A. W. Smith
Keyword(s):  
Energy Dissipation ◽  
Plane Motion ◽  
Test Facility ◽  
Vibration Energy ◽  
Test Rig ◽  
Two Phase ◽  
Support Conditions ◽  
Vibration Tests ◽  
Energy Dissipated ◽  
Steam Generator Tubes

Tests are being planned which will use AECL’s MR-3 Freon test facility and a Multi-Span U-Bend (MSUB) test rig to investigate the dynamics of tube vibration in two-phase flow, in particular those mechanisms that can cause excessive damage to steam-generator tubes. In preparation for the tests, free- and forced-vibration tests were conducted to measure the vibration energy dissipation (damping) of a single U-bend tube in air, with dry and wet anti-vibration bars, under a variety of tube-support conditions. This paper presents the relevant damping mechanisms and documents methods used to conduct the tests and to analyze the energy dissipated at the supports. Results indicate that for in-plane motion without tube-to-support contact, viscous damping related to wet AV B supports is much smaller than guidelines based on other types of supports suggest. To begin to examine the effects of the tube coming into contact with its supports, such as friction-related energy dissipation, the results of tests with light tube-to-support preloads are also presented.

scholarly journals Ground motion prediction from nearest seismogenic zones in and around Greater Cairo Area, Egypt

2010 ◽  
Vol 10 (7) ◽  
pp. 1495-1511 ◽  
Author(s):  
Keyword(s):  
Ambient Noise ◽  
Ground Motions ◽  
Empirical Relationship ◽  
Seismic Events ◽  
Ground Motion Prediction ◽  
Source Characterization ◽  
Source Characteristics ◽  
Rupture Length ◽  
Greater Cairo

Abstract. This paper reviews the likely source characteristics, focal source mechanism and fault patterns of the nearest effective seismogenic zones to Greater Cairo Area. Furthermore, Mmax and ground accelerations related to the effective seismic events expected in future from those seismogenic zones are well evaluated. For this purpose, the digital waveform of earthquakes than ML=3 that occurred in and around Greater Cairo Area from 1997 to 2008 which have been recorded by the Egyptian National Seismological Network, are used to study source characterization, focal mechanism and fault pattern of the seismogenic zones around Greater Cairo Area. The ground motions are predicted from seismogenic zones to assess seismic hazard in the northeastern part of Greater Cairo, where three effective seismogenic zones, namely Abou Zabul, southeast Cairo trend and Dahshour area, have the largest effect to the Greater Cairo Area. The Mmax was determined, based upon an empirical relationship between the seismic moment and the rupture length of the fault during the earthquake. The estimated Mmax expected from Abou Zabul, southeast Cairo trend, Dahshour seismic sources are of Mw magnitudes equal to 5.4, 5.1, and 6.5, respectively. The predominant fundamental frequency and soil amplification characteristics at the area were obtained using boreholes data and in-situ ambient noise measurement.

scholarly journals Evaluation of the Structural Stability of an Octagonal Dome with Meridional Cracks. Case Study: Temple of Santa Lucia, Ambalema, Colombia

2017 ◽  
Vol 2 (2) ◽  
pp. 25
Author(s):  
Jorge Olmedo Montoya ◽  
Olimpia Niglio ◽  
Karol Brigith Romero
Keyword(s):  
Structural Stability ◽  
Dynamic Loads ◽  
Seismic Events ◽  
Seismic Loads ◽  
Construction Process ◽  
Analysis Software ◽  
Historical Structures ◽  
The Temple ◽  
Typical Process

This work performed a comparative analysis between the construction process carried out when building the dome at the Temple of Santa Lucía, in Ambalema-Colombia and the typical process of an octagonal dome. Additionally, the structural stability is assessed of the dome of the case study against service and dynamic loads. To compare with the case study, known domes were taken as examples from structures in Italy and Spain. The analysis includes a study on the dome’s geometry and the constructive errors found. Methodology: The dome’s stability was evaluated through structural analysis software for which the dome was simplified into a system of four articulated arches. Conclusions: As a result, it was found that the dome of the temple of Santa Lucía does not have a system to counteract lateral thrusts (a drum or its similar), which permitted the appearance and widening of meridional cracks. These cracks propagate from the base to the crown, but do not compromise the structure’s stability for service loads. The analysis for seismic loads indicates that the dome is at risk of collapse upon seismic events, even of moderate magnitudes. Originality: The study is aimed at architects and engineers interested in the theme of restoration of historical structures.

Predicting the azimuth of natural fractures and in-situ horizontal stress: A case study from Sichuan Basin, China

Geophysics ◽  
2021 ◽  
pp. 1-97
Author(s):  
kai lin ◽  
Bo Zhang ◽  
Jianjun Zhang ◽  
Huijing Fang ◽  
Kefeng Xi ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Seismic Data ◽  
Sichuan Basin ◽  
Horizontal Stress ◽  
Seismic Attributes ◽  
Seismic Events ◽  
Natural Fractures ◽  
Microseismic Data ◽  
Maximum Horizontal Stress

The azimuth of fractures and in-situ horizontal stress are important factors in planning horizontal wells and hydraulic fracturing for unconventional resources plays. The azimuth of natural fractures can be directly obtained by analyzing image logs. The azimuth of the maximum horizontal stress σH can be predicted by analyzing the induced fractures on image logs. The clustering of micro-seismic events can also be used to predict the azimuth of in-situ maximum horizontal stress. However, the azimuth of natural fractures and the in-situ maximum horizontal stress obtained from both image logs and micro-seismic events are limited to the wellbore locations. Wide azimuth seismic data provides an alternative way to predict the azimuth of natural fractures and maximum in-situ horizontal stress if the seismic attributes are properly calibrated with interpretations from well logs and microseismic data. To predict the azimuth of natural fractures and in-situ maximum horizontal stress, we focus our analysis on correlating the seismic attributes computed from pre-stack and post-stack seismic data with the interpreted azimuth obtained from image logs and microseismic data. The application indicates that the strike of the most positive principal curvature k1 can be used as an indicator for the azimuth of natural fractures within our study area. The azimuthal anisotropy of the dominant frequency component if offset vector title (OVT) seismic data can be used to predict the azimuth of maximum in-situ horizontal stress within our study area that is located the southern region of the Sichuan Basin, China. The predicted azimuths provide important information for the following well planning and hydraulic fracturing.

In-Situ Static and Dynamic Testing and Numerical Modelling of the Dome of the Siena Cathedral (Italy)

2015 ◽  
pp. 85-114
Author(s):  
Gianni Bartoli ◽  
Michele Betti ◽  
Saverio Giordano ◽  
Maurizio Orlando
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
13Th Century ◽  
Structural Behaviour ◽  
Destructive Testing ◽  
Dynamic Vibration ◽  
Heritage Buildings ◽  
Siena Cathedral ◽  
Vibration Tests

The chapter reports on the in-situ experimental campaign and the numerical modelling that were performed to assess the static and dynamic behaviour of the Cupola of the Siena Cathedral in Italy: an irregular polygonal masonry structure built in the 13th century and composed of two domes. The research was motivated by the failure of some of the stone-trusses which connect the two masonry domes and consists of: a) single and double flat-jack tests in the internal dome, b) dynamic vibration tests on the Cupola under environmental (wind) and artificial (vibrodyne) loads and c) dynamic vibration tests on the double colonnade located below the Cupola (hammer impact tests). Results of tests were employed to identify a numerical model of the Cupola, which allowed to simulate its structural behaviour and to account for the failure of the stone-trusses between the two domes. The numerical model was later extended to the whole Cathedral. Through the discussion of an emblematic case study, the chapter shows a careful application of non-destructive testing (NDT) and numerical modelling in the field of assessment (and rehabilitation) of heritage buildings.

scholarly journals The High Energy Materials Science Beamline (HEMS) at PETRA III

2013 ◽  
Vol 772 ◽  
pp. 57-61 ◽  
Author(s):  
Norbert Schell ◽  
Andrew King ◽  
Felix Beckmann ◽  
Torben Fischer ◽  
Martin Müller ◽  
...  
Keyword(s):  
Smart Materials ◽  
Materials Science ◽  
High Energy ◽  
Test Facility ◽  
Polycrystalline Materials ◽  
Energy Materials ◽  
Friction Stir ◽  
Materials Research ◽  
Set Up

The HEMS beamline at PETRA III has a main energy of 120 keV, is tunable in the range 30-200 keV, and optimized for sub-micrometer focusing with Compound Refractive Lenses. Design, construction, and main funding was the responsibility of the Helmholtz-Zentrum Geesthacht, HZG. Approximately 70 % of the beamtime is dedicated to Materials Research, the rest reserved for “general physics” experiments covered by DESY, Hamburg. The beamline P07 in sector 5 consists of an undulator source optimized for high energies, a white beam optics hutch, an in-house test facility and three independent experimental hutches, plus additional set-up and storage space for long-term experiments. HEMS has partly been operational since summer 2010. First experiments are introduced coming from (a) fundamental research for the investigation of the relation between macroscopic and micro-structural properties of polycrystalline materials, grain-grain-interactions, recrystallisation processes, and the development of new & smart materials or processes; (b) applied research for manufacturing process optimization benefitting from the high flux in combination with ultra-fast detector systems allowing complex and highly dynamic in-situ studies of microstructural transformations, e.g. in-situ friction stir welding; (c) experiments targeting the industrial user community.

scholarly journals Integrated photothermal microscope and laser damage test facility for in-situ investigation of nanodefect induced damage

2003 ◽  
Vol 11 (20) ◽  
pp. 2497 ◽  
Author(s):  
Annelise During ◽  
Mireille Commandre ◽  
Caroline Fossati ◽  
Bertrand Bertussi ◽  
Jean-Yves Natoli ◽  
...  
Keyword(s):  
Test Facility ◽  
Laser Damage ◽  
In Situ Investigation
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