Passive Control of Liquid Sloshing in Floating Roof Tank With Multi Dynamic Absorber

2013 ◽  
Author(s):  
Nobuyuki Kobayashi ◽  
Tomohiro Sato ◽  
Ayako Torisaka
Keyword(s):  
Passive Control ◽  
Point Of View ◽  
Liquid Sloshing ◽  
Natural Period ◽  
Earthquake Motion ◽  
Parameter Variance ◽  
Dynamic Absorber ◽  
Periodic Components ◽  
Sloshing Suppression ◽  
Actual Size

A multi dynamic absorber for suppressing liquid sloshing in a floating roof tank is presented. As well known, many seismic damages on floating roof tanks by the sloshing of their contained liquid due to long periodic components of earthquake motion were reported. Since the natural period of sloshing varies according to the height of liquid surface, robustness for parameters such as natural period is required for the sloshing suppression device to obtain a good suppression performance. From this point of view, we developed a multi dynamic absorber instead of the single dynamic absorber which is sensitive to the parameter variance. A multi degree of freedom mechanical model for sloshing of the contained liquid and the presented multi dynamic absorber which sets up on the floating roof of the tank is derived to design the optimal tuning for parameters of the multi dynamic absorber and to evaluate the sloshing suppression performance. Numerical simulations for an actual size floating roof tank were conducted to examine the performance of the present device. As the result the effect of the presented multi dynamic absorber was effective to suppress the sloshing response of the floating roof and to be robust for the natural period variance.

Brief Introduction of Traditional Seismic Technology and Emerging Isolation Technology

2014 ◽  
Vol 1010-1012 ◽  
pp. 250-253
Author(s):  
Ji Yang Li ◽  
Wen Fang Zhang
Keyword(s):  
Control System ◽  
Seismic Response ◽  
Seismic Isolation ◽  
Passive Control ◽  
Base Isolation ◽  
Seismic Structure ◽  
Natural Period ◽  
Isolation Layer ◽  
Passive Seismic

Seismic can be divided into passive seismic and active seismic. Seismic isolation technology belong to the second type. Base isolation structure is defined by setting the isolation layer between the superstructure and foundation building, to extend the natural period architecture, increasing the damping to reduce structural seismic response. It is a passive control system. Compared with the traditional seismic structure, it mainly through the isolation layer to absorb and dissipate energy, reducing the response to the earthquake.

Vibration Control of Horizontally Excited Structures Utilizing Internal Resonance of Liquid Sloshing in Nearly Square Tanks

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Takashi Ikeda ◽  
Yuji Harata
Keyword(s):  
Frequency Response ◽  
Internal Resonance ◽  
Passive Control ◽  
Harmonic Excitation ◽  
Liquid Sloshing ◽  
Maximum Efficiency ◽  
System Response ◽  
Response Curves ◽  
System Parameters ◽  
Theoretical Results

Passive control of vibrations in an elastic structure subjected to horizontal, harmonic excitation by utilizing a nearly square liquid tank is investigated. When the natural frequency ratio 1:1:1 is satisfied among the natural frequencies of the structure and the two predominant sloshing modes (1,0) and (0,1), the performance of a nearly square tank as a tuned liquid damper (TLD) is expected to be superior to rectangular TLDs due to internal resonance. In the theoretical analysis, Galerkin's method is used to determine the modal equations of motion for liquid sloshing considering the nonlinearity of sloshing. Then, van der Pol's method is used to obtain the expressions for the frequency response curves for the structure and sloshing modes. Frequency response curves and bifurcation set diagrams are shown to investigate the influences of the aspect ratio of the tank cross section and the tank installation angle on the system response. From the theoretical results, the optimal values of the system parameters can be determined in order to achieve maximum efficiency of vibration suppression for the structure. Hopf bifurcations occur and amplitude modulated motions (AMMs) may appear depending on the values of the system parameters. Experiments were also conducted, and the theoretical results agreed well with the experimental data.

Response Spectra for Explosion Resistant Design and Assessment

2006 ◽  
Author(s):  
Steve Walker ◽  
Brian Corr ◽  
Vincent Tam ◽  
Roland Martland ◽  
Rashid Shahsavar
Keyword(s):  
Response Spectrum ◽  
Structural Response ◽  
Response Spectra ◽  
Response Surfaces ◽  
Point Of View ◽  
Response Curves ◽  
Natural Period ◽  
Equivalent Static Load ◽  
Explosion Test ◽  
Static Resistance

This paper describes a project to examine the explosion test results obtained at Spadeadam in the 1990’s from the point of view of structural response. At an early project phase, when reliable simulations may not be available, nominal explosion overpressures and durations or past experience from similar situations may be used as inputs to the Response Spectrum approach. The results, however, will only be as accurate as the estimated loading. Structural engineers are often presented with complex pressure traces and are expected to design efficient structures to resist these loads without any further guidance. Response surfaces, representing peak deflection against scaled natural period and structural resistances, have been calculated for a large number of experimental and simulated pressure traces. Biggs response curves are a special case corresponding to triangular loading time histories. The Response Spectra are obtained from these response surfaces by taking horizontal sections of these surfaces at allowable ductility values. The required static resistance for a structure with a given natural period and pre-determined allowable ductility may be read from these curves. The design or assessment may then proceed with this required static resistance which may be reinterpreted as an equivalent static load. The project team has had access to FLACS simulated pressure traces corresponding to the Spadeadam tests. This has enabled a comparison to be made between experimental and simulated traces taking into account the target structures’ characteristics. A description of the method has been included in reference [1], in the Commentary of the new API RP on Fire and Blast which will be made available during 2006, and in a forthcoming OTO (HSE) report.

Study on Abnormal High Intensity of Hanyuan during Wenchuan Earthquake Based on Resonance Effect

2012 ◽  
Vol 588-589 ◽  
pp. 1899-1902
Author(s):  
Wen Hao Qi ◽  
Jing Shan Bo ◽  
Ping Li
Keyword(s):  
Wenchuan Earthquake ◽  
High Intensity ◽  
Resonance Effect ◽  
Structure Type ◽  
Point Of View ◽  
Empirical Formulas ◽  
Natural Period ◽  
2008 Wenchuan Earthquake ◽  
Seismic Records ◽  
County Town

In order to find the reason why a rare distant-earthquakes abnormal high intensity occurred in Hanyuan county town during 2008 Wenchuan Earthquake of China, the earthquake damage was studied from resonance effect point of view. The seismic records of Wenchuan Earthquake in Hanyuan were collected, and their dominant periods were obtained from their Fourier spectra. Based on transfer function of 3 engineering geological boreholes surveyed in Hanyuan county town, the fundamental period of the sites the was calculated. The natural vibration periods of the structures there were estimated by the empirical formulas of natural period according to their structure type. It was found that the tree periods were close very much, and the resonance was prone to occur. The resonance effect was one of the main reasons which caused abnormal high intensity in Hanyuan county town.

scholarly journals Frequency spectrum and fatigue analysis of T-bolt fracture in DT III fastener based on Refined Model

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042095013
Author(s):  
Xiao Hong ◽  
Wang Jiaqi ◽  
Zhang Moyan ◽  
Liu Guangpeng ◽  
Mahantesh M. Nadakatti
Keyword(s):  
Frequency Spectrum ◽  
Field Studies ◽  
Critical Issue ◽  
Point Of View ◽  
Contact Theory ◽  
Critical Area ◽  
Refined Model ◽  
Railway Operations ◽  
Nonlinear Contact ◽  
Actual Size

It is observed that T-bolt fracture of DT III fastener affects the safety of railway operations. The present study is aimed at finding solution to this critical issue of DT III T-bolt fracture. The paper is based on outcomes of field studies and analysis of relationship between bolt installation torque and stress. A refined DT III fastener model is established based on test data and nonlinear contact theory as per the actual size of each component. It is being observed that head-shank joint is a critical area during service. With respect to fatigue and stress, when the installation torque is less than 300 KN-mm, the bolt is prevented from yielding during installation. To a certain extent it also improves the fatigue life of bolt. From the frequency spectrum point of view, the vibration sensitive frequency band (1050–1100 Hz, 1230–1270 Hz) of bolt in service is very close to the main frequency of bolt vibration (1200 Hz). It may cause bolt fracture. In order to avoid resonance, the train operational speed should be strictly controlled between 115 km/h and 120 km/h.

Viscoelastic plate-fluid interactive vibration and liquid sloshing suppression

1990 ◽  
Vol 6 (3) ◽  
pp. 273-280 ◽  
Author(s):  
Wang Zhaolin ◽  
Quan Bin ◽  
Cheng Xuduo
Keyword(s):  
Viscoelastic Plate ◽  
Liquid Sloshing ◽  
Sloshing Suppression

Recent Advances in Liquid Sloshing Dynamics

2001 ◽  
Vol 54 (2) ◽  
pp. 133-199 ◽  
Author(s):  
R. A. Ibrahim ◽  
V. N. Pilipchuk ◽  
T. Ikeda
Keyword(s):  
Passive Control ◽  
Wide Spectrum ◽  
Research Work ◽  
Liquid Sloshing ◽  
Modern Theory ◽  
Nonlinear Phenomena ◽  
Resonance Effects ◽  
Research Activities ◽  
Sloshing Dynamics ◽  
Elevated Water

A liquid free surface in partially filled containers can experience a wide spectrum of motions such as planar, non-planar, rotational, quasi-periodic, chaotic, and disintegration. Civil engineers and seismologists have been studying liquid sloshing effects on large dams, oil tanks and elevated water towers under ground motion. Since the early 1960’s, the problem of liquid sloshing dynamics has been of major concern to aerospace engineers studying the influence of liquid propellant sloshing on the flight performance of jet vehicles. Since then, new areas of research activities have emerged. The modern theory of nonlinear dynamics has indeed promoted further studies and uncovered complex nonlinear phenomena. These include rotary sloshing, Faraday waves, nonlinear liquid sloshing interaction with elastic structures, internal resonance effects, stochastic sloshing dynamics, hydrodynamic sloshing impact dynamics, g-jitter under microgravity field, cross-waves, and spatial resonance. The dynamic stability of liquid gas tankers and ship cargo tankers, and liquid hydrodynamic impact loading are problems of current interest to the designers of such systems. This article will address the means of passive control of liquid sloshing and the use of liquid sloshing forces to control vibratory structures. Other important contributions include the development of digital computer codes to solve complex problems that were difficult to handle in the past. The purpose of this article is to review the research work developed in different applications. It will highlight the major achievements and results reported in the literature. Some early work will be cited very briefly in order to provide an updated bibliography of liquid sloshing dynamics. This review article contains 1,319 references.

scholarly journals Developing flexibility in solving arithmetic word problems: comparing strategies through semantic analysis.

2020 ◽  
Author(s):  
scheibling ◽  
Emmanuel Sander ◽  
Elena Pasquinelli
Keyword(s):  
Active Control ◽  
Word Problems ◽  
Passive Control ◽  
Semantic Analysis ◽  
Point Of View ◽  
Control Group ◽  
Control Groups ◽  
Post Test ◽  
Transfer Problems ◽  
Experimental Group

This study develops and evaluates an intervention aimed at improving flexibility in arithmetic word problems. 9 classes (4th-5th Grades) were divided between experimental, active and passive control groups, and followed this protocol: pre-test, 5 learning sessions for experimental and active control groups, post-test. During learning sessions, both groups learned to solve arithmetic word problems with two strategies — expansion and factorization — by comparing them. But comparing strategies was based on a semantic analysis and choice in point of view for the experimental group whereas comparing strategies was based on identifying keywords and calculations. The experimental condition was expected to promote flexibility in strategy for new transfer problems. At posttest, the active control group and the experimental group got similar scores for learning problems, higher than the passive control group. But for transfer problems, the experimental group was more flexible than the two other groups. Educational entailments of our finding are discussed.

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