Deck Shape Research Articles

Determination of the Hydrodynamic Load on an Inundated Bridge Deck by Measurements Performed on a Physical Model

The paper describes the options for the determination of the hydrodynamic load on an inundated bridge deck based on experimental measurements performed on a physical model. The motivation for resolving the given issue came from real-world cases where options are limited as regards modifications to the level of the bridge superstructure and the road in the immediate surroundings of the bridge. Under these conditions, the given bridge should be evaluated in greater detail from the aspects of both flood discharge capacity and the potential hydrodynamic load if water flow inundates the bridge structure. The subject of the experimental measurements was the determination of what are known as drag, lift and moment coefficients, which are essential for quantifying individual components of hydrodynamic load. The research focused on a special type of load-bearing bridge structure with minimized structural height designed for railroad tracks. Before the actual measurements took place it was necessary to determine a set of measuring equipment that would be economically acceptable for the purposes of research and engineering practice. The results of our experimental measurements confirmed that the selected specific bridge deck shape has a clear and significant influence on the drag coefficient values obtained. The lowest values were achieved by the bridge deck shape with chamfered edges. The correctness of the achieved results was verified by comparison with published domestic and foreign papers on the given field. The achieved results enable the determination of the hydrodynamic load of the examined types of load-bearing bridge structures during the reconstruction or building of new bridges. Other fundamental uses are expected, e.g., in the verification of numerical hydrodynamic models.

Shape optimization of streamlined decks of cable-stayed bridges considering aeroelastic and structural constraints

Structural optimization techniques have the potential to become a powerful tool in the design of long-span bridges. The search for more efficient and reliable designs involves considering shape variations in the deck cross-section, which is one of the key features of the bridge. This affects the deck aerodynamics and its mechanical properties, and consequently to the aeroelastic response of the bridge. A numerical approach pursuing to optimize a long-span bridge needs to explore changes in the deck shape, including structural and aeroelastic responses as design constraints. Therefore, the flutter response of the bridge must be computed numerically for every candidate proposed by the optimization algorithm.This work presents a novel approach to conduct the optimization of deck shape and cables size of a long-span cable-stayed bridge considering simultaneously aeroelastic and structural constraints. The design variables are the cross-section area and prestressing force of each stay, the deck plates thickness and the width and depth of a streamlined box deck. The aeroelastic constraint is evaluated based on the fully numerical procedure developed in an authors' previous work. A series of parameter variation studies, that are instrumental for the sound interpretation of the optimum designs, are also reported.

CFD-based aeroelastic characterization of streamlined bridge deck cross-sections subject to shape modifications using surrogate models

The classical approach currently used in the bridge engineering industry for the structural and aeroelastic design of bridges is based on an iterative heuristic process which includes wind tunnel testing. The dependency on experimental techniques for the aeroelastic characterization of the bridge deck cross-section requires a substantial amount of resources, and consequently the number of potential candidate designs must be limited.The fast improvements in Computational Fluid Dynamics (CFD) techniques in recent years have led to its use in the industrial field, and consequently bridge design methods must be updated. This paper proposes a fully numerical strategy to overcome the classical iterative process in bridge deck shape design. Firstly, it consists in constructing a surrogate model of the aerodynamic response of the baseline cross-section and the allowed shape variations by conducting a set of CFD simulations of several sample designs. Then, the force coefficients and their slopes can be obtained for every design included in the design domain, the flutter derivatives can be approximated by the quasi-steady formulation, and the flutter velocity can be computed. This procedure is applied to two cable-stayed bridges with different spans, and the reported results are validated with wind tunnel tests.

Resistance and Stability Analysis for Catamaran Fishing Vessel with Solar Cell in Calm Water

The use of solar cell as the moving force for the ship's tour seems to be an important theme in action to create a sea transportation that is environmentally friendly as contribution of the Energy Efficiency Design Index (EEDI) for the decrease of pollutant levels. The electrical energy produced by solar cell is not as much energy from fuels so that the solar energy powered ship that can only be followed with a limited range and speed. This type of multi hull design like catamaran that has two symmetrical hull which is possible to have an more expansive main deck, small boat boundaries and good stability. The ship deck shape is going to contribute the extension of solar panels that can be used as a generator of power needed at the time of calculation of powering the ship. The analysis of the stability of the ship carried out numerically bu using references from the IMO regulations which require minimum value stability arm at certain angles. Load cases are definitely varied in 2 (two) conditions and compared in full and light load. The goal of this research is catamaran fishing vessel that have battery, solar panel, electric motor and all of supporting solar energy moving with speed 5 knots.

Design and performance optimization of gravity tables using a combined CFD-DEM framework

In this paper we formulate a computational framework for the characterization and performance optimization of gravity tables. Segregation of a multi-dispersed population of grains is assessed using a comprehensive numerical framework integrating Computational Fluid Dynamics (CFD) simulations with a Discrete Element Method (DEM) setup in the open-source software OpenFOAM. We have carried out combined qualitative and quantitative assessments of process conditions, such as deck shape, deck inclination (longitudinal and transverse), vibration speed and fluidizing air velocities at the surface. We assess the performance of our framework by employing a quantitative metric rhostat, which represents the efficiency of separation in terms of density differences between the two separated product fractions. Additionally, qualitative flow behaviour is evaluated by examining relevant velocity and material distribution trends. We show that these separation profiles are highly sensitive to changes in the process conditions, with the presence of discernible optimal operating points. For the chosen gravity table, we have identified a longitudinal tilt of 6°, an eccentric speed between 300 and 350RPM, deck air velocities of up to 1.5m/s and a transverse tilt of 0.75° as a set of optimal operating conditions.

Influence of transverse loading onto push-out tests with deep steel decking

This paper presents the results of 20 push-out tests on shear stud connectors, placed centrally in the ribs of 58mm and 80mm deep steel decking. The tests were designed to investigate the realistic load–slip behaviour of the shear connectors and the influence of transverse loading. The tests considered two different stud diameters and the effect of concentric and eccentric transverse loading. In addition, the influence of a second layer of reinforcement, the welding procedure and the number of shear connectors in each rib have been considered. The observed influence of these parameters on the load–slip behaviour is presented and explained with regard to material properties and load-bearing models. In addition, the test results are compared with the current analytical approaches, which are shown to be non-conservative in some cases, because the presented deck shapes were not well considered in the development and calibration of EN 1994-1-1.

Drainage Systems for Sloping Roofs and Possibilities of Rain Water Use

The roof represents an inevitable part of each building. From the architectonic and construction point of view it completes its shape solution and serves an important role of a protective cover. It has to fulfil its protective function without failures and deformations. Shape, construction and material solution of roof deck must go hand in hand with safe method of roof drainage. Correctly drained roof is the basic prerequisite of the whole structure operation. The main and primary role of the drainage system lies in drainage of rain water in as fast and safe method as possible from the roof into the sewage system or absorbing system. Rain water is not a drinking water, but it is clean water which can be used for various purposes in the household.

Identification of Aerodynamic Derivatives of Two Box Girder of Cable Stayed Bridge

Motion or self-induced forces can cause the aeroelastic instability phenomenon called flutter. Flutter stability is an important design criterion for long span bridges, because flutter leads to large vibration amplitudes or even the total collapse of the bridge. The flutter derivatives are the essential parameters in the estimation of the critical flutter wind speed. The aerodynamic derivatives, also known as flutter derivatives, are coefficients of the mathematical model for the aeroelastic forces. These coefficients are expressed in a non dimensional form and used to determine the flutter analysis of flexible bridges. One of the coefficients is A2*, this coefficient provides very useful information to judge and compare the aerodynamic stability. In order to determine the flutter derivatives, the wind tunnel tests using sectional model are very common. In the present work, the free vibration test method is used to extract the flutter derivatives of the Musi III cable stayed bridge. Estimated the A2* coefficient changes from negative to positive values around u/fb = 2.5, this value indicates, that the bridge was in a stable condition at the value for u/fb below 2.5. To improve the stability of the bridge, the shape of this bridge deck should be modified.

Dynamic interaction between vehicle and bridge deck subjected to support settlement

Many bridges inevitably experience foundation settlement during their lifetime. Structural engineers need to limit the foundation settlement so that the bridge structure does not develop intolerable stresses. One factor in the effect of foundation settlement on bridge structures that has not been considered so far is the dynamic interaction between bridge and moving vehicle. In this study, Hamilton principle is adopted to derive the governing equations for the vibration of line supported orthotropic thin plates due to moving vehicles. The effect of foundation settlement on the bridge–vehicle interaction (BVI) is investigated by modifying the interaction forces due to the deformed shape of deck. The effect of fully or partially developed membrane stresses on the BVI will be also discussed. The results show that dynamic load allowance (IM) increases depending on the support location where settlement occurs, mode of settlement, span length, and magnitude of the foundation settlement. However the effect of membrane stresses on IM is insignificant. The analysis results indicate importance of considering the effect of bridge support settlement on the dynamic BVI.

Vortex induced vibrations of a bridge deck: Dynamic response and surface pressure distribution

This paper describes selected results collected during the wind tunnel tests carried out at Politecnico di Milano Wind Tunnel on the deck sectional model of the Messina Strait Bridge. It is a long span suspension bridge characterized by a multi box deck. Aerodynamic forces and surface pressure distributions have been measured in order to characterize static and dynamic response of the deck. Vortex induced vibrations phenomenon has been studied with particular attention: it represents one of the most important aspects to be considered while designing the deck shape of long span bridges and it has to be carefully analyzed. In fact, even if it can be separated from the stability problem for the modern bridges, VIV, in case of low Scruton numbers, can lead the deck to reach very large vibration amplitudes, also at very low wind speeds.

선수갑판형상이 갑판침입수에 미치는 영향에 관한 실험 및 수치적 연구

In this paper, the effects of bow deck shape on the green water are studied by numerical and experimental method. Varying the deck shapes to triangular, elliptic and circular, the thickness and advancing velocity of green water leading edge are compared using numerical method. Also the motion, the pressure on the vertical wall and the height on the deck of green water are compared among the three bow deck shapes in the heave and pitch motion free condition by experimental method. To remove the effects of the difference of motions among the deck shapes, numerical simulations are performed varying the deck shape with the same motion. In the same motion condition, smallest impulsive pressure occurred in the condition of elliptic deck shape.

Yaw wind effect on flutter instability of four typical bridge decks

When evaluating flutter instability, it is often assumed that incident wind is normal to the longitudinal axis of a bridge and the flutter critical wind speed estimated from this direction is most unfavorable. However, the results obtained in this study via oblique sectional model tests of four typical types of bridge decks show that the lowest flutter critical wind speeds often occur in the yaw wind cases. The four types of bridge decks tested include a flat single-box deck, a flat <TEX>${\Pi}$</TEX>-shaped thin-wall deck, a flat twin side-girder deck, and a truss-stiffened deck with and without a narrow central gap. The yaw wind effect could reduce the critical wind speed by about 6%, 2%, 8%, 7%, respectively, for the above four types of decks within a wind inclination angle range between <TEX>$-3^{\circ}$</TEX> and <TEX>$3^{\circ}$</TEX>, and the yaw wind angles corresponding to the minimal critical wind speeds are between <TEX>$4^{\circ}$</TEX> and <TEX>$15^{\circ}$</TEX>. It was also found that the flutter critical wind speed varies in an undulate manner with the increase of yaw angle, and the variation pattern is largely dependent on both deck shape and wind inclination angle. Therefore, the cosine rule based on the mean wind decomposition is generally inapplicable to the estimation of flutter critical wind speed of long-span bridges under skew winds. The unfavorable effect of yaw wind on the flutter instability of long-span bridges should be taken into consideration seriously in the future practice, especially for supper-long span bridges in strong wind regions.

데크의 논슬립가공 표면형태 변이에 따른 마찰성능 변화 평가

최근 국내에서 목질계 재료를 이용한 데크의 설치사례는 증가하는 추세이나, 상대적으로 데크의 기초 물성과 안전성에 관련된 연구는 미흡한 상황이다. 신발과 데크 사이에서 발생하는 마찰력은 보행자의 기동 능력에 많은 영향을 미친다. 이러한 마찰력은 바닥재의 재료 특성, 바닥재의 요철무늬 형상, 신발 밑창의 형태, 바닥재와 신발 사이 접촉면의 습윤도 등 여러 인자에 의해 영향을 받는다. 본 연구에서는 보행안전성 평가를 위하여 데크의 요철무늬에 따른 마찰력 변화를 측정하고 미끄럼 정도를 평가하였다. 실험에 이용된 데크의 재료는 천연목재와 합성목재의 두 종류이고, 신발과 접촉하는 데크표면은 데크의 길이 방향으로 홈가공처리를 한 단일 논슬립가공 형태와 길이방향에 더불어 가로방향에 추가로 홈 가공처리를 한 이중 논슬립가공 형태 두 종류이다. 실험에 사용된 신발의 밑창 형태는 더블유형(W형)과 네모형(<TEX>${\Box}$</TEX>형)의 두 종류를 사용하였고, 데크 표면의 함수율 상태에 따른 마찰력변화를 알아보기 위하여 대기와 평형을 이룬 건조상태와 수분습윤상태에서 측정하였다. 각각의 조건에서 마찰계수를 결정하고 각각의 인자가 마찰력에 미치는 영향을 분석하였다. Installation of deck has been on the rise in Korea recently, but there is little of research on the safety of deck. One of the major factors affecting maneuverability of a pedestrian is frictional force between an outsole of shoe and a surface of the deck. The frictional force is influenced by many factors such as raw material variance of deck, surface convex shape of deck, outsole patterns of shoes, and moist condition of contact surface between deck and shoes. This study focused on evaluating the effect of these factors on the frictional force. Two kinds of deck, which were made of natural wood and wood plastic composite, were used in this study. The surface convex patterns of deck were classified to single nonslip (longitudinal groove processing) and double nonslip (longitudinal and transverse groove processing). Two kinds of shoe outsole patterns, W-shape and rectangle-shape, were used in the tests. Also, the friction tests were carried out at dried surface conditions and water-adsorbed surface condition.

Wind tunnel measurements of crosswind loads on high sided vehicles over long span bridges

This paper presents the results obtained from a series of wind tunnel experiments undertaken in order to assess (and improve) the operation of a generic long span bridge subjected to strong winds (the operation of the bridge is evaluated in terms of the aerodynamic loads on a number of vehicles—in all cases the mean crosswind is greater than or equal to 10m/s). The aerodynamic loads, in terms of mean and peak side and lift force coefficients and rolling moment coefficient are presented for three 1:40 scale model vehicles placed on the bridge: a Van, a Bus and a Lorry. These vehicles were tested under static conditions (i.e., the motion between the vehicle and the bridge deck was not simulated), and subjected to a uniform turbulent crosswind at different incoming directions. Two separate bridge deck scenarios were examined—an ‘Ideal’ and a ‘Typical’ deck shape. The data show a good agreement with the findings of previous research with respect to the ‘Ideal’ bridge geometry. The Typical bridge section enables the differences between the idealised bridge and a more realistic deck geometry to be explored. The work indicates that the Lorry, rather than the Van or the Bus, is the critical vehicle in terms of overturning stability (as characterized by the highest magnitudes of the rolling moment coefficient). An approximately linear decrease of the side force and rolling moment coefficients is found on the Typical deck when the vehicle is positioned at a progressively larger distance from the windward edge. The research provides novel data and interpretation on the aerodynamic loads experienced by road vehicles.

사장교 케이블 최적 장력 보정에 관한 연구

사장교의 시공에 있어서 보강형과 주탑의 형상 및 케이블 장력은 형상관리시 주요한 관리 항목이다. 특히 보강형의 형상은 Keg Segment의 원활한 폐합뿐만 아니라 계획된 종단 및 횡단 선형을 구현하기 위해 필수적으로 관리되어야 한다. 사장교에서 단계별 시공을 진행함에 따라 보강형 레벨과 케이블 장력 오차는 피할 수 없으며, 이러한 오차는 크게 재료 물성치와 모델링상의 오차, 제작 및 시공에 의해 발생하는 오차 등으로 나눌 수 있다. 이러한 오차로 인해 케이블의 장력과 구조물의 처짐 또는 변위가 이론적인 해석값과 다르게 나타나며, 이에 대한 보정은 케이블의 길이 조정으로 수행하게 된다. 본 연구에서는 제2돌산대교에서 사용된 오차를 보정하는 새로운 최적화 기법을 소개하고자 한다. During construction of the cable-stayed bridge, not only shape of deck and pylon but also cable forces are main factors for geometry control. Especially, geometry control of deck must be controlled for adjusting design value of vertical and lateral alignment as well as closing of key segment. Also, both the deck level error and cable force error occur necessarily during the construction stage in cable stayed bridge. The errors are caused by different of material properties and computer modeling, and construction mistake, and so on. These causes bring about that the forces of cable and the displacement of deck show different tendency from the theoretical values. Therefore, these errors must necessarily be adjusted and can be improved through adjustment of cable length. In this study, a new optimization tool is proposed to adjust the errors of the second Dolsan cable-stayed bridge.

Effects of frequency ratio on bridge aerodynamics determined by free-decay sectional model tests

A series of wind tunnel free-decay sectional model dynamic tests were conducted to examine the effects of torsional-to-vertical natural frequency ratio of 2DOF bridge dynamic systems on the aerodynamic and dynamic properties of bridge decks. The natural frequency ratios tested were around 2.2:1 and 1.2:1 respectively, with the fundamental vertical natural frequency of the system held constant for all the tests. Three 2.9 m long twin-deck bridge sectional models, with a zero, 16% (intermediate gap) and 35% (large gap) gap-to-width ratio, respectively, were tested to determine whether the effects of frequency ratio are dependent on bridge deck cross-section shapes. The results of wind tunnel tests suggest that for the model with a zero gap-width, a model to approximate a thin flat plate, the flutter derivatives, and consequently the aerodynamic forces, are relatively independent of the torsional-to-vertical frequency ratio for a relatively large range of reduced wind velocities, while for the models with an intermediate gap-width (around 16%) and a large gap-width (around 35%), some of the flutter derivatives, and therefore the aerodynamic forces, are evidently dependent on the frequency ratio for most of the tested reduced velocities. A comparison of the modal damping ratios also suggests that the torsional damping ratio is much more sensitive to the frequency ratio, especially for the two models with nonzero gap (16% and 35% gap-width). The test results clearly show that the effects of the frequency ratio on the flutter derivatives and the aerodynamic forces were dependent on the aerodynamic cross-section shape of the bridge deck.

Analytical verification of a composite level of bolted GFRP bridge deck-to-girder connection system

There are various ways to connect a GFRP deck and girder which have been adopted as systems worldwide such as connection systems that use shear connectors and mechanical connection systems that use bolts or clamps, and recently there has been a study on a system to connect GFRP deck and steel girder using a bonding agent. In this study, an attempt was made to review and analyze the composite level of GFRP decking and a girder bolt connection system using the already proposed GFRP deck shape. In addition, an attempt was made to estimate the decreased rate of the composite level at various bolt connection intervals using the calculated strain and deflection, and also the analytical values of the composite level were compared with prior test results.

Crew Production Rates for Contract Time Estimation: Beam Erection, Deck, and Rail of Highway Bridges

Both the importance and process of estimating highway construction time have increased in significance as roadway user costs themselves have become more significant. In estimating construction time, few parameters are more significant than work item crew production rates and factors significantly affecting those rates. A standardized data collection tool was used to acquire a total of 67 data points from 25 ongoing Texas highway projects between February 2002 and May 2004, for three selected critical work items: beam erection, bridge deck, and bridge rail. With the data, several hypothesized drivers of the crew production rates were analyzed. While the factor of shape of deck (straight versus curved) was identified as a statistically significant driver of bridge deck crew production rate, no statistically significant drivers were found for work items of beam erection and bridge rail. The study also found that both formwork and rebarwork crew sizes have significant relationships with bridge deck production rate. Findings from this study will enable highway agencies to enhance accuracy of contract time estimation for highway bridge construction. The methodology for obtaining field-based production rates will also be beneficial for future researchers.

On the vortex shedding forcing on suspension bridge deck

Vortex-induced vibrations are not negligible while evaluating the aerodynamic and aeroelastic behavior of a long-span suspension bridge. This kind of forcing, that can produce high vibration levels, occurs at very low reduced velocities concerning low wind speed and high-frequency modes. This work presents results of experimental tests performed on the multibox deck shape of the Messina Strait bridge investigating vortex shedding phenomena and developing a numerical model to reproduce the vortex shedding forcing. The experimental tests, focused on low reduced velocities, highlight the typical non-linear pattern of the vortex shedding.

MUSIC方式方向探知システムの大型船舶への適用研究

The MUSIC (Multiple Signal Classification) method is different from the conventional direction finder by the Goniometer method and Doppler method that has been using on vessels, in having capability of the measurement the direction of radio wave in azimuth and elevation, and even during jamming. The MUSIC method direction finder in a short wave band is using practically for radio wave monitor in the land. This time, Authors investigated the performance and the usefulness on vessel. The authors measured direction of radio signal in the land. Arrangement of the antennas which were set on circumference with diameter of 80 meters in the land was like a ship, and its interval are similar to actual deck shape of the hull, and measurement precision depend on its strength of radio signals, and the situation that did not become same became clear. In addition, the authors measured direction of radio signal on the actual vessel, and made the electromagnetic model of the hull, and became clear that a measurement error by the hull reduced by adopting the electromagnetic steering vector.