Impact Assessment of Pier Shape and Modifications on Scouring around Bridge Pier
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Previous experimental research on utilizing pier modifications as countermeasures against local scour has focused primarily on circular pier. It is of utmost importance to further investigate the most suitable pier shape for pier modification countermeasure separately and in combination. This experimental study aims to reduce the stagnation of the flow and vortex formation in front of the bridge pier by providing a collar, a hooked collar, a cable, and openings separately and in combination around a suitable pier shape. Therefore, six different pier shapes were utilized to find out the influence of pier shape on local scouring for a length–width ratio smaller than or equal to 3. A plain octagonal shape was shown as having more satisfactory results in reducing scour compared to other pier shapes. Furthermore, the efficiency of pier modification was then evaluated by testing different combinations of collar, hooked collar, cable, and openings within the octagonal bridge pier, which was compared to an unprotected octagonal pier without any modification. The results show that by applying such modifications, the scour depth reduced significantly. The best combination was found to be a hooked collar with cable and openings around an octagonal pier. It was revealed that the best combination reduced almost 53% of scour depth, as compared to an unprotected octagonal pier.Keywords:
Collar
Collar
Abutment
Bridge (graph theory)
Countermeasure
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The structure design of shirt collar,which is the technical difficulty in sheet pattern design,is studied with the help of garment CAD software.By way of pattern experiments,writer has analyzed and compared the different dress effect when collar stand bottom line and collar surface bottom line change from a straight line into a curve as well as the curvature correlation between the collar surface and stand.The study results show that collar bottom line is the key factor which determines the style of shirt collar.When the collar surface curvature is similar to curvature of collar stand,the collar surface capacity is moderate and the collar can stand more vertically,at the same time,the collar surface is more close to the collar stand and usually the width difference between collar stand and collar surface is 1cm;The bending amount of collar surface is twice as many as the upturned amount of collar stand and they are in direct proportion.The study provides a theoretical basis for the collar pattern design.
Collar
Line (geometry)
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Laboratory data, showing the effect of simulated floating debris accumulation at bridge piers on the local scour depth, are presented. The experiments are conducted using idealized impermeable cylindrical debris shapes attached concentrically to a cylindrical pier. The maximum scour depth recorded is 3.6 times the pier diameter. The design method proposed by Melville and Sutherland in 1988 is shown to predict the maximum possible local scour for a pier with simulated floating debris accumulation provided that an effective pier width is substituted for the actual pier width. The effective pier width is calculated as a weighted average of lengths (vertical dimension) of the debris and exposed pier.
Bridge scour
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Previous experimental research on utilizing pier modifications as countermeasures against local scour has focused primarily on circular pier. It is of utmost importance to further investigate the most suitable pier shape for pier modification countermeasure separately and in combination. This experimental study aims to reduce the stagnation of the flow and vortex formation in front of the bridge pier by providing a collar, a hooked collar, a cable, and openings separately and in combination around a suitable pier shape. Therefore, six different pier shapes were utilized to find out the influence of pier shape on local scouring for a length–width ratio smaller than or equal to 3. A plain octagonal shape was shown as having more satisfactory results in reducing scour compared to other pier shapes. Furthermore, the efficiency of pier modification was then evaluated by testing different combinations of collar, hooked collar, cable, and openings within the octagonal bridge pier, which was compared to an unprotected octagonal pier without any modification. The results show that by applying such modifications, the scour depth reduced significantly. The best combination was found to be a hooked collar with cable and openings around an octagonal pier. It was revealed that the best combination reduced almost 53% of scour depth, as compared to an unprotected octagonal pier.
Collar
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Flow Characteristics and Scour Depth in Lenticular Shaped Pier: Case Study at Ciujung Bridge, Banten
Abstract Pier is part of the structure under the bridge. The existence of a pier in the river flow causes changes in river flow patterns. Changes in the flow pattern will result in local scouring around the pier. This study aims to determine the effect of the shape of the pier on the potential for local scour that occurs around the pier, and the flow characteristics around the pier. This studymodelled the existing conditions of the Ciujung Bridge, where the Ciujung Bridge uses an oblong pier shape, and the shape will be replaced with a lenticular model pier. FLOW-3D (CFD) software will be used to modelled flow characteristics and the depth of scour that occurs.
Bridge scour
Bridge (graph theory)
Flow conditions
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Unsafe Ship-handling model (US-model) is known as an evaluation method which analyzes the potential risk of marine accidents. In previous paper, this model was improved for evaluating small obstacles, definitely. This research aims to evaluate the influence of the pier arrangement by applying the improved US-model to the bridge design on a straight channel and a curved channel. In ship-handling simulator, a bridge with the various pier-pier distances was set on the straight channel. The potential collision risk to the pier decreases when the pier-pier distance is wide enough, such as 2000m by the experiment results. In the traffic simulation, pier-pier distances, pier arrangement types and curved angles were set on the curved channel. The potential collision risk extremely increases at the following conditions. (1) The pier-pier distance is less than 1500m. (2) The curved angle becomes severe at the pier-pier distance is 1000m. (3) The arranged pair of pier is set on the backward side from the curved corner. In conclusion, it can be said that the improved US-model could evaluate the influence of the pier arrangement on a straight and a curved channel clearly.
Bridge (graph theory)
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There are many kinds of commonly-used bridge pier types. This paper researches the selection principle and optimal type of the bridge pier types from the perspective of reducing backwater. This paper also tests and analyzes the high resistance water for different types of bridge pier under different flow velocities and conditions of water resistance ratio through establishment of a physical model of wide water channel. The result shows that, the bridge pier has an optimal profile curve, and the characteristic parameter (b’/L) is from 0.071 to 0.083; three kinds of commonly-used pier types – square pier, streamline pier and bicircular pier have different strength angles. If the angle between the axis of bridge pier and the water flow direction is less than 36°, it should give priority to the streamline pier; if the angle is greater than 36°, then it should give priority to the bicircular pier.
Bridge (graph theory)
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Biaxial testing of unbonded post‐tensioned rocking bridge piers with external replacable dissipaters
Abstract The biaxial response of two bridge piers is experimentally investigated. A post‐tensioned precast bridge pier with external replaceable mild‐steel dissipaters is tested under biaxial loading. The performance of the post‐tensioned bridge pier is compared with a conventionally reinforced monolithic bridge pier. The experimental biaxial response is then compared with previous uniaxial experimental testing of identical bridge piers to understand the influence of biaxial loading, specifically concerning post‐tensioned rocking sections. A 3‐dimensional moment–curvature and moment–rotation analysis program is created to generate the monotonic section response of a conventional and post‐tensioned bridge pier. After comparing the accuracy of the section analysis program to the experimental testing of the monolithic pier, the program is validated against the experimental testing of the post‐tensioned bridge pier. This section analysis program is then used in the calibration of a macro‐model to capture the entire cyclic response of the post‐tensioned bridge pier. The macro‐model adopts multiple linear‐elastic compression‐only springs at the rocking interface, combined with non‐linear inelastic springs for each of the mild‐steel dissipaters and returns encouraging results at both local and global levels. The paper concludes with a number of biaxial moment‐interaction design charts for monolithic and post‐tensioned bridge piers as a function of mechanical and geometric section properties. The design charts define the biaxial yield surface at nominal yield and at the design section capacity defined by one of three material limit states. Copyright © 2011 John Wiley & Sons, Ltd.
Precast concrete
Bridge (graph theory)
Prestressed concrete
Macro
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Bridge pier is a crucial part for the transportation in marine structures. Scouring is a major cause for the failure of the pier. slot among the other countermeasures increases the efficiency of scour reduction and minimizes the failure due to scour.as we provide the slot; the strength of the pier reduces compared to the conventional pier. change in reinforcement pattern in slotted bridge pier changes the behavior of the pier under similar loading conditions. blast occurrence has increased in recent times and rehabilitation of a structure and improvement of strength against explosion is necessary in structure. this paper studies the behavior of slotted bridge pier under blast loading and compares theoretical and analytical aspects for the same. Design criteria for blast load according to NCHRP 12-72 are followed to carry out theoretical load response of the pier under blast loading. Analytically the behavior of pier is checked using coupled eulerian lagrangian approach using ABAQUS software. a detailed eulerian domain and slotted pier with reinforcement is assembled in ABAQUS to analyze the behavior of pier under explosion using TNT of 100kg at a scaled distance of 4ft for the period of 0.02seconds. this design gave better result in terms of mitigating effects of blast on slotted bridge pier.
Bridge (graph theory)
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