In this study, coupled flutter stability is discussed from the unsteady pressure characteristics point of view. The roles played by each aerodynamic derivative in flutter stabilization were reviewed. Based on that, some conditions that the unsteady pressure characteristics should present so that flutter can be stabilized are pointed out. As a general rule, moving the peaks of the amplitudeCp(x*) distribution to downstream resulted in beneficial effects, provided the phase difference y(x*)between the maximum relative angle attack of the whole body and the maximum negative pressure at the deck surface was in the stability range. In this sense, the peaks of Cp(x*) usually presented at the leading edge of bridge decks were found to reduce the flutter onset velocity. Even though only cases that respect aerodynamic derivatives interdependence were considered, the procedures used in this study are applicable to any type of cross-section.
TREIN, Cristiano Augusto; SHIRATO, Hiromichi - Coupled Flutter Stability form the Unsteady Pressure Characteristics Point of View. Journal of Wind Engineering and Industrial Aerodynamics-Volume 99, issues 2-3. pg.114-122. 2011.DOI: 10.1016/j.jweia.2010.12.003.
Semi-empirical relationships to be used for the reproduction of the unsteady pressure characteristics of modified rectangular cylinders are investigated, as a step towards the proposition of a bridge deck design framework based on the manipulation of these characteristics. Even with different configurations of fairings and vertical plates of two different sizes installed at the leading edge and at the mid-chord line, the phase difference distribution of such a cross-section could be approximated by a sinusoidal equation, its amplitude distribution was found to follow a Weibull distribution and both showed themselves to be interrelated through the wave length developed along the body's surface. The efficacy of the formulation could be confirmed through wind tunnel tests.
TREIN, Cristiano Augusto; SHIRATO, Hiromichi; MATSUMOTO, Masaru - Semi-Empirical Evaluation of the Unsteady Pressure Characteristics of Bluff Bodies. Journal of Wind and Engineering-Volume 7, issue 2. pg.28-38. 2010. India
Empirical relationships to be used in the reproduction of the unsteady pressure characteristics of rectangular cylinders are investigated, as part of the development of a bridge deck design framework based on the manipulation of those characteristics. Even modified with different configurations of fairings and vertical plates of two different sizes installed at the leading edge, the phase difference distribution of such a cross-section could be approximated by a sinusoidal equation, its amplitude distribution followed a Weibull distribution and both distributions showed themselves to be interrelated through the wave length developed along the body's surface. The efficacy of the formulation could be confirmed through wind tunnel tests.
TREIN, Cristiano Augusto; SHIRATO, Hiromichi; MATSUMOTO, Masaru - On the Unsteady Pressure Characteristics of Modified Rectangular Cylinders. Proceedings of VII Asian Pacific Conference on Wind Engineering - APCWE-VII. 2009, November. Taipei - Taiwan
In this study, empirical equations to be used in the estimation of the unsteady pressure characteristics of rectangular cylinders are investigated, as part of the development of a bridge deck design framework based on the manipulation of these characteristics. Even by using different leading edges it could be verified that the phase difference distribution of such a bluff body can be approximated by a sinusoidal equation, the amplitude distribution follows a Weibull distribution and both are interrelated by the wave length developed along the body’s surface. The efficacy of the formulations could be confirmed through wind tunnel tests.
TREIN, Cristiano Augusto*; SHIRATO, Hiromichi; MATSUMOTO, Masaru - Unsteady Pressure Characteristics of Modified Rectangular Cross-sections. 第１回流体理工学研究部門公開セミナー; Proceedings of 1st Open Seminar on Fluid Sciences, 2009, march 18th, Kyoto University, Katsura Campus - Japan
Software presented in the "IV International Seminar - Using Steel Structures in Civil Buildings" and "I International Congress of Steel Construction - I CICOM".
CARVALHO, Paulo Roberto Marcondes de*; TREIN, C.A - Um Sistema Integrado CAE, CAD, CAM para Projetos de Estruturas de Aco.Sociedade Mineira de Engenheiros - SME (Brasil); The Steel Construction Institute - SCI (UK); Associacao Mineira da Construcao Metalica - AMICEM (Brasil) . Sao Paulo - Brazil, 2001
The proposition presented here is based on the idea of introducing a business opportunity associated to an environmentally positive image, which can bring economical and strategic advantages to Japan. It is not an innovative idea in terms of global entrepreneurism, however from the Japanese point of view it would be a manner of diversifying its sources of energy, contributing for the maintenance of the global environment.
TREIN, Cristiano Augusto* - Integrating Biofuels, environment and food production: an alterative for the oil industry. presented at 物理探査学会の６０周年記念 - 60th anniversary of the Society of Exploration Geophysicists of Japan. Published: Geophysical Exploration vol.62 issue 2. feb/2009. Japan
The flutter phenomenon is one of the divergent oscillations which directly leads to the failure of structure. So, the flutter stabilization is one of the most important subjects in the design of long-span bridge girders. For flutter analysis method, Complex Eigen-Value analysis is commonly used. Complex Eigen-Value analysis is not enough to discuss flutter control, while it is enough to discuss flutter stabilization. Then, Step-by-Step analysis which is based on flutter generation mechanisms was proposed. However some differences between both solutions have been observed. In Step-by-Step analysis, harmonic vibration is assumed, however its assumption is disadvantageous. When damping vibration is assumed and convergence calculations associated to flutter frequency and damping are carried out simultaneously, both solutions show the good agreement. In addition, new strategies for flutter control are investigated. And it is clarified that A1* is the most important aerodynamic derivative to stabilize the coupled flutter instability, considering the mutual relationships of aerodynamic derivatives. Moreover, it is made a study on Selberg's formula by Step-by-Step analysis and its elicitation process is clarified.
MATSUMOTO, Masaru; ITO, Yasuki; MATSUMIYA, Hisato; FUJIWARA, Shinya*, TREIN, Cristiano Augusto - Investigation of coupled flutter mechanism and Selberg's formula. The 20th KKCNN Symposium on Civil Engineering, South Korea, 2007
Branch switching characteristics for coupled flutter of structural rectangular sections are analyzed using step-by-step flutter analysis (SBSA). Prior to the appearance of coupled flutter instability, the torsional branch (TB) controls the instability. However, after flutter onset both TB and heaving branch (HB) coexist, with sudden switching in particular velocity ranges. For lower velocity ranges, very good agreement can be obtained between conventional Complex Eigen Value Analysis (CEVA) and SBS method, but for higher velocity ranges this agreement cannot be attained. So SBSA is revised, leading to fairly good convergence between both methods.
TREIN, Cristiano Augusto*; MATSUMOTO, Masaru; ITO, Yasuki; MATSUMIYA, Hisato; FUJIWARA, Shinya - Evaluation of Branch Switching Characteristics in Coupled Flutter through Revised Step-by-Step Analysis. Proceedings of 62a edition of Academic Meeting and National Convention on Civil Engineering, Japanese Society of Civil Engineering, JSCE 2008/1 monthly issue. Hiroshima, Japan 2007
Flutter instability is a catastrophic oscillation and its stabilization is an important issue in the design of long span bridges. In this study, a strategy for coupled flutter stabilization of long-span bridges is presented. The approach is based on the reduction of the absolute values of the aerodynamic derivativesA1* and H3*, by a proper arrangement of multiple bridge girders along the span direction of the bridge, which was proved effective through wind tunnel tests.
TREIN, C.A*.; MATSUMOTO, M.; ITO, Y.; MATSUMIYA, H.; KIM, G.; FUJIWARA, S. - Equivalent Aerodynamic Derivatives and their Influences on Coupled Flutter Instability. Proc. of Academic Meeting and National Convention on Civil Engineering, Japanese Society of Civil Engineering - Kansai Shibu. Osaka, Japan 2007.
As a bridge gets longer and slender, one of the main problems that have to be faced is the flutter instability of bridge girders such as the torsional flutter and the coupled flutter. Especially, the coupled flutter instability has become the most concerning issue in the design of long-span bridges, and the precise understanding on its generation mechanism is indispensable in order to effectively stabilize this divergent oscillation. In this study, the heaving/torsional 2-DOF flutter analyses and wind tunnel tests are carried out, focusing on the branch switching characteristics of the coupled flutter using B/D=20 rectangular section. Moreover, the branch co-existing characteristics in flutter onset velocity range is investigated in detail.
MATSUMOTO, M.; OKUBO, K.; ITO, Y.; MATSUMIYA, H.; TREIN, C.; KIM, G*. - Branch switching characteristics of coupled flutter instability. The Nineteenth KKCNN Symposium on Civil Engineering, Japan, 2006.
The current trend in the world of construction is the ever growing exploitation of the urban spaces by the usage of buildings that maximize the relation between built area and available urban space. That way, the vertical dimension of buildings is becoming more and more expressive. This, allied with the development of more resistant and lightweight materials as well as efficient construction techniques, has lead to lighter and more flexible structures. These structures are subject to the dynamic effects of wind.
The efficiency, safety and costs of this kind of buildings are directly connected to the precision that those wind dynamic effects are estimated and considered during the design. The analytic techniques for these estimations, when verified through real scale measures, have shown to be economically impracticable, because they overestimate the responses for safety.
On the other hand, the usage of experimental techniques, e.g. wind tunnel tests with reduced models, can show itself to be very efficient in terms of results prediction. These techniques still have room for improvement by incorporating the knowledge that is being created by the changes in modern Civil Engineering.
This work is inserted in this scenario. Using other researches as a knowledge base, an aeroelastic device for wind tunnel tests of tall buildings subject to wind dynamic loads is proposed, built and tested.
The tests results are compared with other researches conducted with similar prototype, as well as with the procedures stated in the Brazilian Code NBR-6123/88 and in the Supplement to the NBCC/85. The results certify the consistence and feasibility of using the modeling techniques proposed here.
TREIN, Cristiano Augusto*; LOREDO-SOUZA, Acir Mercio; PALUCH, Mario Jose - Modelagem dinâmica equivalente de edifícios altos submetidos à ação do vento. Programa de Pós-Graduação em Engenharia Civil, Universidade Federal do Rio Grande do Sul - UFRGS. Master Degree Thesis. Porto Alegre - Brazil, 2005
With the increase of the spans in the last decades, new concepts of projects and perceptions about bridges around the world have imposed the need of the development of new design techniques. Aerodynamic instabilities, which were not being of concern not long time ago, started to demand special care during all phases of the projects. Among them, coupledflutter instability has gained remarkable importance, due to its catastrophic consequences and impacts on the safety of the structure. Concerning coupled-flutter, aerodynamic derivatives have been regarded as fundamental components for the assessment of the stability of long-span bridges, resulting in that the focus during the proposition of the bridge deck geometry has been put essentially on the control of those empirical indices. The relationships between bridge deck geometric characteristics and the values assumed by those indices are recognized to be non-linear and straightforward approaches for their prompt evaluation are still not available. Because of that, trial and error experimental techniques based on wind tunnel tests have been regarded as main tools in the search of geometric configurations of bridge decks that satisfy the flutter stability requirements from the aerodynamic derivatives point of view. Since aerodynamic derivatives are resultant from the unsteady pressure characteristics developed along the bridge deck, it must be more rational to search for relationships between deck geometry and flutter stabilization from the unsteady pressure characteristics point of view. However, the complex geometric characteristics associated to modern longspan bridges may impose difficulties on the pressure measurements in wind tunnel tests, becoming counter-productive. So, the direct evaluation of the aerodynamic derivatives through alternative methods has been preferred in wind tunnel tests. In this research, the impacts of the deck geometric characteristics on the aerodynamic derivatives and, consequently, on flutter stabilization are assessed from the unsteady pressure characteristics point of view. Rectangular cross-sections arranged in single box and twobox configurations are used as base geometries and the influences of different geometric singularities (geometric modifications as leading edges, vertical plates and slots) on the unsteady pressure characteristics of those cylinders are systematized through the proposition of semi-empirical formulations. The knowledge generated herein may serve as a base for the development of a design framework based on the direct manipulation of the unsteady pressure characteristics of the deck through the use of geometric singularities, aiming the flutter stabilization by controlling indirectly the aerodynamic derivatives. Such a framework is to be used in substitution of some stages of wind tunnel test campaigns, and its feasibility is evaluated along the study. It was concluded that the relationships of geometric singularities with the unsteady pressure characteristics are much more linear and predictable than their relationships with the aerodynamic derivatives, opening a new methodology for the proposition of geometric improvements. Data regarding the geometries studied herein are also provided along the study, as reference for future development. this study, empirical equations to be used in the estimation of the unsteady pressure characteristics of rectangular cylinders are investigated, as part of the development of a bridge deck design framework based on the manipulation of these characteristics. Even by using different leading edges it could be verified that the phase difference distribution of such a bluff body can be approximated by a sinusoidal equation, the amplitude distribution follows a Weibull distribution and both are interrelated by the wave length developed along the body’s surface. The efficacy of the formulations could be confirmed through wind tunnel tests.
TREIN, Cristiano Augusto* - Study on the Unsteady Pressure Characteristics of Bluff Bodies focusing on Flutter Stabilization of Long-Span Bridges. Ph.D Thesis. 2009, september, Kyoto University, Katsura Campus - Japan
Robby Permata*; TREIN, Cristiano Augusto ; HONG, J. W. ; SHIRATO, H. - Effects of Fairings and Vertical Plates on Unsteady Pressure Characteristics and Flutter Stability of B/D=20 Rectangular Prism. The 24th KKCNN Symposium on Civil Engineering, 2011, Awaji. Proceedings of the 24th KKCNN Symposium on Civil Engineering, 2011.
Robby Permata*; TREIN, C. A. ; HONG, J. W. ; SHIRATO, H. . Control of flutter stability in the case of B/D=20 rectangular prism by manipulating unsteady pressure characteristics. In: 1st Symposium on Flutter Control and Application, 2011, Tokyo. Proceedings of 1st Symposium on Flutter Control and Application, 2011.
Trein, Cristiano Augusto . O papel da recuperação energética na Política Nacional de Resíduos Sólidos. CREA- Conselho em Revista, Brasil, p. 31 - 31, 01 jul. 2012.
This experimental study focus on the aerodynamic behavior of two-box girders from the unsteady pressure characteristics point of view. The motivation is to contribute to flutter stabilization eorts. Models with vertical plates and gratings in several gap length configurations are investigated and compared with single box cross-sections. The results show that the upstream box is barely aected by the slot and behaves mostly like a single box. However, the unsteady pressure characteristics of the dowstream box are strongly impacted by the gap. They are defined majorly by the geometry of the cross-section and by the characteristics of the gap, with low influence of the configuration of the upstream box. The findings suggest that results of investigations on single boxes can be extended to two-box cross-sections.
TREIN, Cristiano Augusto ; SHIRATO, H. ; MATSUMOTO, M. . Effects of the Gap on the Unsteady Pressure Characteristics of Two-Box Girders. In: 12th Americas Conference on Wind Engineering 2013, 2013, Seattle. 12th Americas Conference on Wind Engineering 2013, 2013. v. 2. p. 1262-1276.
This experimental study focuses on the unsteady pressure characteristics of two-box bridge decks. Models with vertical plates and gratings in several gap length configurations are investigated and compared with single-box cross sections. The results demonstrate that, with respect to unsteady pressure characteristics, the upstream box is barely affected by the slot and behaves similarly to the single-box model. In contrast, the unsteady pressure characteristics of the dowstream box are defined mainly by the characteristics of the slot and the geometry of its cross section. The upstream box geometric configuration plays only a minor role in the definition of the unsteady pressure characteristics of the dowstream box. An equivalent Theodorsen function to be used in the calculation of aerodynamic derivatives of two-box girders is proposed. Using this function, it is demonstrated that the only aerodynamic derivative that is aerodynamically dependent on the gap length is A2* . These findings suggest that the results of single-box investigations can be extended to two-box cross sections.
TREIN, Cristiano Augusto ; SHIRATO, Hiromichi ; MATSUMOTO, Masaru . On the effects of the gap on the unsteady pressure characteristics of two-box bridge girders. Engineering Structures , v. 82, p. 121-133, 2015.
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In this study the concept of Controlled Aerodynamic Instability Phenomena is proposed, as an alternative approach for Wind Power Generation systems. The concept is based on the idea that aerodynamic instability phenomena, such as Karman Vortex Shedding, Flutter, Galloping and Buffeting, can be driven into a useful motion and be used to extract energy from the flow. A case study using the flutter instability is presented and the concept is proved feasible. By using a forced torsional oscillation, the heaving motion is induced in a bluff body, so the energy generated by the heaving motion is estimated by both analytical and experimental processes, converging to the same conclusion. Finally, the results are discussed and alternatives for future developments are introduced.
MATSUMOTO, M.; TREIN, C*.; ITO, Y.; OKUBO, K.; MATSUMIYA, H.; KIM, G. - Controlled Aerodynamic Instability Phenomena - An Alternative Approach for Wind Power Generation Systems. The Nineteenth KKCNN Symposium on Civil Engineering, Japan, 2006.
This is an experimental study based on wind tunnel investigations. The main objective is to search for relationships between unsteady pressure characteristics and geometry in rectangular cylinders. The focus of the investigation is put on the effects of fairings and vertical plates disposed at the leading edge of B/D = 20 rectangular cylinders. It was identified a semi-empirical relationship between the phase difference distribution in rectangular cylinders and the theoretical wavelength in the wake of flat plates. Results indicate that the effects of vertical plates at the leading edge must be dependent on interactions between vertical plates and fairings. However, when the vertical plate is able to overcome the influences of the fairing, the unsteady pressure characteristics assume configurations similar to those obtained with rectangular cylinders of lower side ratios. Vertical plates showed
themselves good candidates to control the aerodynamic characteristics of rectangular cylinders, as their effects are prominent and measurable, including by breaking the similarity between heaving and torsional systems. The expansion of the scope of this investigation may result in a methodology in which geometric singularities are intentionally manipulated to lead unsteady pressure characteristics to assume any desirable configuration. The conclusions are to be inserted in a context in which flutter stabilization is pursued. .
TREIN, Cristiano Augusto ; SHIRATO, Hiromichi ; MATSUMOTO, Masaru . On the effects of the leading edge on the unsteady pressure characteristics of rectangular cylinders. 14th International Conference on Wind Engineering, 2015, Porto Alegre. ICWE14 - International Conference on Wind Engineering, 2015.