scholarly journals Experimental Characterization of the Flow Field around Oblong Bridge Piers

Fluids ◽  
2021 ◽  
Vol 6 (11) ◽  
pp. 370
Author(s):  
Ana Margarida Bento ◽  
Teresa Viseu ◽  
João Pedro Pêgo ◽  
Lúcia Couto
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Shear Stresses ◽  
Velocity Measurements ◽  
Bridge Foundations ◽  
Scour Hole ◽  
Movable Bed

The prediction of scour evolution at bridge foundations is of utmost importance for engineering design and infrastructures’ safety. The complexity of the scouring inherent flow field is the result of separation and generation of multiple vortices and further magnified due to the dynamic interaction between the flow and the movable bed throughout the development of a scour hole. In experimental environments, the current approaches for scour characterization rely mainly on measurements of the evolution of movable beds rather than on flow field characterization. This paper investigates the turbulent flow field around oblong bridge pier models in a well-controlled laboratory environment, for understanding the mechanisms of flow responsible for current-induced scour. This study was based on an experimental campaign planned for velocity measurements of the flow around oblong bridge pier models, of different widths, carried out in a large-scale tilting flume. Measurements of stream-wise, cross-wise and vertical velocity distributions, as well as of the Reynolds shear stresses, were performed at both the flat and eroded bed stages of scouring development with a high-resolution acoustic velocimeter. The time-averaged values of velocity and shear stress are larger in the presence of a developed scour hole than in the corresponding flat bed configuration.

scholarly journals A Study on Interaction between Overfall Types and Scour at Bridge Piers with a Moving-Bed Experiment

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 152
Author(s):  
Wei-Lin Lee ◽  
Chih-Wei Lu ◽  
Chin-Kun Huang
Keyword(s):  
Large Scale ◽  
River Flow ◽  
Extreme Event ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Flow Conditions ◽  
Moving Bed ◽  
Directional Flow ◽  
Scour Hole ◽  
Additional Protection

River slopes can be changed due to an extreme event, e.g., a large-scale earthquake. This can uplift a riverbed greatly and thereby change the behavior of the river flow into a free or submerged overfall. Corresponding damage, including extreme erosion, on bridge piers located in the river can take place due to the aforementioned flow conditions. A reconstructed bridge pier in the same location would also experience a similar impact if the flow condition is not changed. It is important to identify these phenomena and research the mechanism in the interaction between overfall types and scour at bridge piers. Therefore, this paper is aimed at studying a mechanism of free and submerged overfall flow impacts on bridge piers with different distances by a series of moving-bed experiments. The experiment results showed clearly that bridge pier protection requires attention particularly when the pier is located in the maximum scour hole induced by the submerged overfall due to the z directional flow eddies. In many other cases, such as when the location of the bridge pier was at the upstream slope of a scour hole induced by a flow drop, a deposition mound could be observed at the back of the pier. This indicates that, while a pier is at this location, an additional protection takes place on the bridge pier.

scholarly journals A Hooked-Collar for Bridge Piers Protection: Flow Fields and Scour

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1251 ◽  
Author(s):  
Su-Chin Chen ◽  
Samkele Tfwala ◽  
Tsung-Yuan Wu ◽  
Hsun-Chuan Chan ◽  
Hsien-Ter Chou
Keyword(s):  
Laboratory Experiments ◽  
Horseshoe Vortex ◽  
Flow Fields ◽  
Bridge Pier ◽  
The Other ◽  
Bridge Piers ◽  
Vortex Strength ◽  
Numerical Tests ◽  
Scour Hole ◽  
New Type

A new type of collar, the hooked-collar, was studied through experiments and numerical methods. Tests were conducted using a hooked collar of a width of 1.25b and a height of 0.25b, where b is the bridge-pier width. The hooked-collar efficiency was evaluated by testing different hooked-collar placements within the bridge-pier, which were compared to the bridge-pier without any collar. A double hooked-collar configuration, one placed at the bed level and the other buried 0.25b, was the most efficient at reducing the scour hole. In other cases, a hooked-collar positioned 0.25b above the bed slightly reduced the scour hole and had similar scour patterns when compared to the pier without the hooked-collar. The flow fields along the vertical symmetrical plane in the experiments are also presented. Laboratory experiments and numerical tests show that maximal downflow is highly reduced along with a corresponding decrease in horseshoe vortex strength for the experiments with the hooked-collar, compared to cases without the hooked-collar. The flow fields reveal that the maximum turbulent kinetic energy decreases with the installation of the hooked-collar.

Seismic performance of a bridge pier reinforced with titanium alloy bars

2021 ◽  
Author(s):  
Mahesh Acharya ◽  
Mustafa Mashal ◽  
Jared Cantrell
Keyword(s):  
Titanium Alloy ◽  
Cyclic Loading ◽  
Seismic Performance ◽  
Large Scale ◽  
Plastic Hinge ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Structural Performance ◽  
Concrete Bridge ◽  
Hinge Zone

<p>The research in this paper focuses on the use of Titanium Alloy Bars (TiABs) in concrete bridge piers located in high seismic zones. The paper discusses a new bridge pier system that incorporates both seismic resiliency and durability concepts. A large-scale bridge pier, reinforced with TiABs and spiral, is tested under quasi-static cyclic loading protocol. The results are compared against a benchmark cast-in-place pier with normal rebars and spiral under the same loading protocol. Based on the testing results, the use of TiABs in concrete piers would reduce rebar congestion up to 50%, provide adequate ductility, and would result in reduced residual displacement following an earthquake. The pier reinforced with TiABs reached higher drift ratios compared to cast-in-place pier. Furthermore, smaller flexural cracks that are likely to appear in the plastic hinge zone during moderate earthquakes are not a major concern for structural performance and durability of bridge piers reinforced with TiABs.</p>

Turbulent flow field in a scour hole at a semicircular abutment

2005 ◽  
Vol 32 (1) ◽  
pp. 213-232 ◽  
Author(s):  
Subhasish Dey ◽  
Abdul Karim Barbhuiya
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Reynolds Stresses ◽  
Primary Vortex ◽  
Scour Hole ◽  
Turbulent Flow Field ◽  
Development And Validation ◽  
Bed Shear Stresses

The three-dimensional turbulent flow field in a scour hole at a semicircular abutment under a clear water regime was experimentally measured in a laboratory flume using an acoustic Doppler velocimeter. The distributions of time-averaged velocity components, turbulent intensity components, turbulent kinetic energy, and Reynolds stresses at different azimuthal planes are presented. Upstream, presentation of flow field through vector plots at azimuthal and horizontal planes shows the existence of a large primary vortex associated with the downflow inside the scour hole. On the other hand, downstream, the flow field is irregular. The bed shear stresses are determined from the Reynolds stresses and velocity gradients. The data presented in this paper would be useful for the development and validation of flow field models, which can be used to determine the strength of the primary vortex that is used to estimate scour depth at bridge abutments.Key words: bridge abutments, fluid flow, three-dimensional flow, turbulent flow, open channel flow, scour, sediment transport, hydraulic engineering.

Characterization of horseshoe vortex in a developing scour hole at a cylindrical bridge pier

2019 ◽  
Vol 34 (2) ◽  
pp. 118-124 ◽  
Author(s):  
Dawei Guan ◽  
Yee-Meng Chiew ◽  
Maoxing Wei ◽  
Shih-Chun Hsieh
Keyword(s):  
Horseshoe Vortex ◽  
Bridge Pier ◽  
Scour Hole

scholarly journals Non-Intrusive Underwater Measurement of Local Scour Around a Bridge Pier

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2063 ◽  
Author(s):  
Poggi ◽  
Kudryavtseva
Keyword(s):  
Low Cost ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Laser Source ◽  
Scour Depth ◽  
Spatial Evolution ◽  
Clear Water ◽  
Water Conditions ◽  
Scour Hole ◽  
Temporal And Spatial

A non-intrusive low-cost technique for monitoring the temporal and spatial evolution of the scour hole around bridge piers is presented. The setup for the application of the technique is simple, low-cost and non-intrusive. It couples a line laser source and commercial camera to get a fast and accurate measurement of the whole scour hole in the front and behind the bridge pier. A short campaign of measurements of the scour hole around a bridge pier in clear-water conditions is presented to provide a control test and to show how to apply the new method. Finally, the results are compared with two of the most used equations, for the time evolution of the maximum scour depth in clear-water conditions, to show the effectiveness of the proposed technique.

scholarly journals Influence of Scour Development on Turbulent Flow Field in Front of a Bridge Pier

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2370
Author(s):  
Jinzhao Li ◽  
Yilin Yang ◽  
Zhiwen Yang
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Reynolds Shear Stress ◽  
Bridge Pier ◽  
Scour Depth ◽  
Image Velocimetry ◽  
Scour Hole ◽  
Practical Engineering ◽  
Turbulent Flow Field ◽  
Variation Tendency

This study concerns the turbulent flow field influenced by the scour development around a bridge pier. The scour hole evolution as well as the temporal variation of scour depth around the pier were firstly analyzed. Subsequently, the flow fields in front of the pier at different instants during the scour process were measured using particle image velocimetry (PIV). It shows that the scour depth at the pier front exceeds that of the pier side at the later scouring stage. The temporal development of scour depth can be well predicted by a simple practical engineering model based on an exponential function with a change in the two adjustable coefficients. The flow field indicates that with the development of scour hole, the downward flow in front of the pier becomes more prominent, meanwhile the flow becomes more turbulent. The variation tendency for both velocities and turbulence intensities along the streamwise direction in front the pier shows similarity. The Reynolds shear stress generally increases with developing scour hole, and the region with large value enlarges and moves upstream of the scour hole.

Characteristics of Glottis-Induced Turbulence in Oscillatory Flow: An Empirical Investigation

1998 ◽  
Vol 120 (2) ◽  
pp. 217-226 ◽  
Author(s):  
Yongchul Choi ◽  
D. E. Wroblewski
Keyword(s):  
Oscillatory Flow ◽  
Shear Stresses ◽  
Circular Aperture ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Acceleration Phase ◽  
Component Velocity ◽  
High Turbulence ◽  
Decaying Turbulence

Turbulence inducement from the glottis was scrutinized by employing an idealized model of the larynx and trachea for oscillatory flow conditions. The characterization of turbulence was achieved with the two-component velocity measurements of split-film probe anemometry and with the flow visualization of a smoke-wire technique. The apertures of two different (triangular and circular) shapes were utilized in the airway model to address the distinct effects of the triangular-shaped glottal aperture on the generation, development, and decay of turbulence. One of the salient turbulence characteristics for the triangular aperture case was found to be the relatively high turbulence levels around the center region (2r/D ~ 0) in conjunction with the asymmetric mean axial velocity across the frontal-rear (A-O-P) plane of the trachea at one tracheal diameter (x/D = 1) downstream from the glottis. The detailed turbulence properties such as the Reynolds shear stresses and turbulence intensities for the triangular aperture case differed significantly from those for the circular aperture case within a few tracheal diameters (x/D < 7) downstream from the apertures. The glottis-induced turbulence was incipient during the acceleration phase of inspiration and convected downstream with the traits of decaying turbulence.

scholarly journals Evolution of Hydrodynamic Characteristics with Scour Hole Developing around a Pile Group

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1632 ◽  
Author(s):  
Yilin Yang ◽  
Meilan Qi ◽  
Jinzhao Li ◽  
Xiaodong Ma
Keyword(s):  
Flow Field ◽  
Turbulence Intensity ◽  
Large Scale ◽  
Pile Group ◽  
Horseshoe Vortex ◽  
Hydrodynamic Characteristics ◽  
Small Scale ◽  
Scour Hole ◽  
Scour Holes ◽  
Scouring Process

This study concerns the evolution of flow field and hydrodynamic characteristics within the developing scour hole around a four-pile group with 2 × 2 arrangement. The instantaneous velocities in scour holes at four typical stages during the scouring process were measured by an acoustic Doppler velocimeter (ADV). The evolution and spatial distribution of the time-averaged flow field, turbulence, and the corresponding hydrodynamic characteristics within scour holes were compared. The time-averaged flow field shows that the reverse flow, downward flow, and horseshoe vortex are formed in the upstream of the pile group. During the scouring process, the mean components of flow characteristics (i.e., mean velocity, vorticity, and bed shear stress) around the pile group decrease while the fluctuating components (i.e., turbulence intensity) intensify simultaneously. Similarity of turbulence intensity profiles was found within different scour holes. The horseshoe vortex at upstream of each pile merges and the shear layer in the gap region extends when the dimension of the scour hole increases to that of equilibrium scour status, indicating that the four piles behave more like a single bluff body. With the development of scour holes, the large-scale horseshoe vortex system becomes more stable and the dissipation of small-scale eddies becomes more significant.

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