Cristiano Augusto Trein

On the effects of the leading edge on the unsteady pressure characteristics of rectangular cylinders

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. A semi-empirical relationship was identified 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 are 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 to be 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. Expanding 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.

On the effects of the gap on the unsteady pressure characteristics of two-box bridge girders

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 downstream 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 downstream 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.

Effects of the Gap on the Unsteady Pressure Characteristics of Two-Box Girders

This experimental study focuses on the aerodynamic behavior of two-box girders from the unsteady pressure characteristics point of view. The motivation is to contribute to flutter stabilization efforts. 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 affected by the slot and behaves mostly like a single box. However, the unsteady pressure characteristics of the downstream box are strongly impacted by the gap. They are defined mainly 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.

The role of energy recovery of solid wastes in the National Policy for Solid Wastes

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.

Control of flutter stability in the case of B/D=20 rectangular prism by manipulating unsteady pressure characteristics

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.

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Effects of Fairings and Vertical Plates on Unsteady Pressure Characteristics and Flutter Stability of B/D=20 Rectangular Prism

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.

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Coupled Flutter Stability from the Unsteady Pressure Characteristics Point of View

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 amplitude Cp(x*) distribution to downstream resulted in beneficial effects, provided the phase difference w(x*) between the maximum relative angle of 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 Evaluation of the Unsteady Pressure Characteristics of Bluff Bodies

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

On the Unsteady Pressure Characteristics of Modified Rectangular Cylinders

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 were found to be interrelated through the wavelength 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

Study on the Unsteady Pressure Characteristics of Bluff Bodies focusing on Flutter Stabilization of Long-Span Bridges

With the increase in spans in recent decades, new project concepts and perceptions about bridges worldwide have imposed the need for the development of new design techniques. Aerodynamic instabilities, which were not a concern until recently, have begun to demand special care during all project phases. Among them, coupled-flutter instability has gained remarkable importance due to its catastrophic consequences and impacts on structural safety. Concerning coupled-flutter, aerodynamic derivatives have been regarded as fundamental components for assessing the stability of long-span bridges, with the focus during bridge deck geometry proposition essentially on controlling these indices. The relationships between bridge deck geometric characteristics and the values assumed by these indices are recognized to be non-linear, and straightforward approaches for their prompt evaluation are still unavailable. Because of this, trial-and-error experimental techniques based on wind tunnel tests have been regarded as the main tools in the search for geometric configurations of bridge decks that satisfy the flutter stability requirements from the aerodynamic derivatives point of view. Since aerodynamic derivatives result from the unsteady pressure characteristics developed along the bridge deck, it is 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 with modern long-span bridges may impose difficulties on pressure measurements in wind tunnel tests, becoming counter-productive. Therefore, the direct evaluation of the aerodynamic derivatives through alternative methods has been preferred in wind tunnel tests. In this research, the impacts of 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 two-box configurations are used as base geometries, and the influences of different geometric singularities (geometric modifications such as leading edges, vertical plates, and slots) on the unsteady pressure characteristics of these cylinders are systematized through the proposition of semi-empirical formulations. The knowledge generated herein may serve as a basis for developing a design framework based on the direct manipulation of the unsteady pressure characteristics of the deck through the use of geometric singularities, aiming at flutter stabilization by indirectly controlling 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 throughout 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 throughout the study, as a reference for future development. 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 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 wavelength 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

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Unsteady Pressure Characteristics of Modified Rectangular Cross-sections

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 wavelength developed along the body's surface. Wind tunnel tests confirmed the efficacy of the formulations.

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

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Integrating Biofuels, environment and food production: an alternative for the oil industry

The proposition presented here is based on the idea of introducing a business opportunity associated to an environmentally positive image, which can bring economic and strategic advantages to Japan. It is not an innovative idea in terms of global entrepreneurship, however from the Japanese point of view, it would be a way of diversifying its energy sources, contributing to 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

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Investigation of coupled flutter mechanism and Selberg's formula

The flutter phenomenon is one of the divergent oscillations that directly leads to structural failure. Therefore, flutter stabilization is one of the most important subjects in the design of long-span bridge girders. For flutter analysis, Complex Eigenvalue analysis is commonly used. While Complex Eigenvalue analysis is sufficient to discuss flutter stabilization, it is not enough to discuss flutter control. 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, but this assumption is disadvantageous. When damped vibration is assumed, and convergence calculations associated with flutter frequency and damping are carried out simultaneously, both solutions show good agreement. In addition, new strategies for flutter control are investigated. It is clarified that A1* is the most important aerodynamic derivative for stabilizing coupled flutter instability, considering the mutual relationships of aerodynamic derivatives. Moreover, a study on Selberg's formula is conducted using 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

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Evaluation of Branch Switching Characteristics in Coupled Flutter through Revised Step-by-Step Analysis

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 the heaving branch (HB) coexist, with sudden switching in particular velocity ranges. For lower velocity ranges, very good agreement can be obtained between conventional Complex Eigenvalue Analysis (CEVA) and the SBS method, but for higher velocity ranges, this agreement cannot be attained. Therefore, 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

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Equivalent Aerodynamic Derivatives and their Influences on Coupled Flutter Instability

Flutter instability is a catastrophic oscillation, and its stabilization is an important issue in the design of long-span bridges. 1 In this study, a strategy for coupled flutter stabilization of long-span bridges is presented. The approach is based on reducing the absolute values of the aerodynamic derivatives A1* and H3* by properly arranging multiple bridge girders along the span of the bridge. This approach was proven 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.

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Controlled Aerodynamic Instability Phenomena - An Alternative Approach for Wind Power Generation Systems

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 harnessed to produce useful motion and extract energy from the flow. 1 A case study using flutter instability is presented, and the concept's feasibility is demonstrated. By using forced torsional oscillation, heaving motion is induced in a bluff body, and the energy generated by this heaving motion is estimated through both analytical and experimental processes, with both converging on the same conclusion. Finally, the results are discussed, and alternatives for future development 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.

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Branch switching characteristics of coupled flutter instability

As a bridge becomes longer and more slender, one of the main problems that must be addressed is the flutter instability of bridge girders, such as torsional flutter and coupled flutter. 1 Coupled flutter instability, in particular, has become the most concerning issue in the design of long-span bridges, and a precise understanding of its generation mechanism is indispensable for effectively stabilizing this divergent oscillation. In this study, heaving/torsional two-degree-of-freedom (2-DOF) flutter analyses and wind tunnel tests are conducted, focusing on the branch switching characteristics of coupled flutter using a B/D=20 rectangular section. Moreover, the branch coexistence characteristics within the flutter onset velocity range are 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.

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Equivalent Dynamic Modeling of Tall Buildings Subjected to the Action of the Wind

The current trend in construction is the ever-growing exploitation of urban spaces through the use of buildings that maximize the ratio between built area and available urban space. Consequently, the vertical dimension of buildings is becoming increasingly expressive. This, combined with the development of more resistant and lightweight materials, as well as efficient construction techniques, has led to lighter and more flexible structures. These structures are susceptible to the dynamic effects of wind.

The efficiency, safety, and cost of these kinds of buildings are directly related to the precision with which these wind dynamic effects are estimated and considered during design. Analytical techniques for these estimations, when verified through real-scale measurements, have proven economically impractical because they overestimate the responses for safety.

On the other hand, the use of experimental techniques, e.g., wind tunnel tests with reduced models, can be very efficient in predicting results. These techniques still have room for improvement by incorporating the knowledge generated by advances in modern civil engineering.

This work is situated within this context. Using other research as a knowledge base, an aeroelastic device for wind tunnel tests of tall buildings subjected to wind dynamic loads is proposed, built, and tested.

The test results are compared with other research conducted with a similar prototype, as well as with the procedures outlined in the Brazilian Code NBR-6123/88 and the Supplement to the NBCC/85. The results confirm the consistency 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

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An CAE, CAD, CAM Integrated System for Steel Structures Design

Software presented at the "IV International Seminar - Using Steel Structures in Civil Buildings" and the "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

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