The main cause of concern about the stability of bridge foundation is the occurrence of scour around the piers. Therefore, there is an interest in finding reliable ways to reduce and control local scour depth. The use of slot through a pier is one of the new proposed methods for controlling and reduction of local scour at bridge piers. This study examines the effect of using rectangular slots through the pier groups at clear water condition. The results of experiments show that in pier groups, reinforcing effect causes that the scour depth at front pier is more than that at a single pier. Also, sheltering effect causes that the scour depth at rear pier is less than that at a single pier. The presence of a slot in a two and three pier groups causes the reinforcing effect increases and sheltering effect decreases. The efficacy of a slot in rear pier is more than that in front pier and single pier for three and two pier groups with S=4b. It was also found that the efficacy of slot for two and three pier groups with S=2b for all piers are almost similar and similar to the single pier. Efficacy of slot in reduction of scour depth, increased with increasing pier spacing.

One of the most important issues in scour depth at bridge piers is effect of debris raft which convened by flood and by blocking all or a part of the bridge opening, changes the flow pattern and increases the maximum scour depth around bridge pier considerably. In this paper, the effect of debris dimensions on a maximum scour depth around vertical bridge pier groups was investigated. The studied bridge piers consisted of two rectangular piers with 2.5×3.5 cm dimensions, which installed on the foundation with 10cm × 16cm width and length, respectively. The experiments performed consisted of relative depth (the depth to width pier ratio) 3.7, 5.2 and 6.6, debris relative width (the debris width to pier width ratio), 6, the relative length (debris length in flow direction to pier width), 2 and 3, the relative thickness (debris thickness to pier width), 0.5 and 1 and different levels of foundation. All experiment conducted under clear water condition. Comparison of results indicated that increase of flow depth did not considerably affect the local scour depth. By increasing debris relative thickness, the maximum scour depth increased about 42% in comparison with no debris raft. Furthermore, with increase of relative debris length, the effect reduced and increase of the maximum scour depth reached up to 17%. As compared to without debris raft condition. Comparison of results indicated that by increasing the level of foundation, increase of the maximum scour depth was more in presence of debris raft.

In this study, a new structural system for either retrofitting or design of new structures has been presented that provides more resistance for lateral loading conditions in comparison with the conventional systems. This new structural system can be utilized for a wide range of steel or concrete infrastructure systems from bridges to jackets as offshore structures. In this paper, structural performance of the new systemis compared with conventional system for bridges. The structural response of piers in long- and medium-span bridges has been studied. A comparative study is carried out through static pushover analysis of four medium-span bridge piers and reveals the new system has a higher load-carrying capacity compared with the conventional system, whilst no significant changes are observed for period-based ductility. A probabilistic analysis of the structural collapse is carried out through incremental dynamic analysis (IDA). The results from IDA analyses show higher seismic safety for the new system compared to the conventional system. Besides, a time history analyses for far-field earthquake ground motions to evaluate structural response of a long span bridge was conducted. The results indicate that the stiffness degradation observed in the conventional system caused more damage than the stiffness degradation observed in the new system.

Hydraulic bridges are critical components in infrastructure network. One of the major causes of its collapse is due to local scouring of its foundations. Hence in this study, the mechanism and various factors affecting local scour around bridge piers was analyzed. For this, a software platform Hydrologic Engineering Center River Analysis System (HEC-RAS) was used to evaluate local scouring around piers of spillway bridge with radial gates of Telengiri Irrigation Project located in Koraput district of Odisha, India. Soil samples were collected at the site and tested in the laboratory to determine various properties required for model inputs and assess the vulnerability of soil for scouring. Geometric data and design specifications of radial-gated bridge structure along with soil properties of the case study were used to build HEC-RAS model and then steady-state flow profiles were given to calculate local scour depth. Analytical methods such as Kothyari, Richardson, and IRC equations were used to corroborate local scour depth values with the model. The model predicted scouring of 8.29m which is close enough to values predicted by Richardson equation (8.95 m). This small discrepancy was due to not accounting for bed conditions and armoring of bed material. Parameters were varied in the model such as discharge, width and geometry of piers, skew angle of bridge and piers, angle of attack, and different bed configurations to simulate their effect on local scour depth. The soil was found to be highly erodible as per the soil erodibility factor obtained from the Wischmeier equation.

Rivers during floods carry branches, leaves and trunks of trees that their accumulation in front of bridges, change the flow pattern and accelerate the scouring process around bridge piers by blocking the entire or part of the bridge span. In this case, intensification in scour depth and development of scour hole beneath lead collapsing the bridges with shallow foundation. In this paper, the effects of debris dimensions, pile cape thickness and installation levels, array and diameter piles on the maximum scour depth around inclined bridge pier groups were investigated experimentally. The bridge pier, consisting of two rectangular piers were used with 2. 5 and 3. 5 cm dimensions mounting at an angle of 28 degrees on a pile cap with 10 cm width, 16 cm length, 3 and 5cm thickness which placed on an array of 2×2 and 2×3 piles with different diameters. The experiments were performed for relative flow depth (y/D) 6. 42, 7. 85, relative pile cap levels (Z/Tpc) 0, 1, 1. 5, relative debris width and 2. 85 and length 2, the relative thickness 0. 85 and 1. 42, in clear water condition. Comparison of results proved that the increasing flow depth had no significant effect on maximum scour depth. Results also showed that in presence of the debris for pile cap relative level Z/Tpc=0, the maximum scour depth increased about 8. 5%, comparing with no debris. For pile cap relative level Z/Tpc=1, presence of the debris increased the maximum scour depth up to 4. 5% compared to no debris. By increasing the pile cap relative level to 1. 5, presence of the debris caused an increase in the maximum scour depth about 4%, comparing with no debris.

Bridges are the most useful structures on rivers which floods cause damage to them every year. One of the known factors in bridges destruction is local scouring around the bridge piers. In this study, to investigate the scour depth around the bridge pier in the river bend, experiments were performed in a laboratory flume with a 90-degree bend with  . By placing a cylindrical pier with a diameter of 45 mm at three locations of 30, 45 and 60 degrees along the bend, for three flow Froude numbers, the scouring around the pier under clear water condition was investigated. Natural sand with an average diameter of 0.85 mm is used for the bed materials. The results showed that the maximum scour depth around the bridge pier varies at a different location along the bend. Besides, the flow discharge increase grows the depth and volume of the scour hole at all positions. Additionally, maximum and minimum depth and volume of scouring hole occurs in the second half of the bend at 60- degree position and in the middle of the bend at 45- degree position, respectively. Finally, it was recorded that the development of the sedimentary hill after the pier and its extent in the first half of the bend was higher than the second half of bend. The result also indicated that the maximum and minimum scour depths relative to the pier diameter are equal to 2.24 and 1.22, respectively.

Bridges are the most useful structures on rivers which floods cause damage to them every year. One of the known factors in bridges destruction is local scouring around the bridge piers. In this study, to investigate the scour depth around the bridge pier in the river bend, experiments were performed in a laboratory flume with a 90-degree bend with  . By placing a cylindrical pier with a diameter of 45 mm at three locations of 30, 45 and 60 degrees along the bend, for three flow Froude numbers, the scouring around the pier under clear water condition was investigated. Natural sand with an average diameter of 0.85 mm is used for the bed materials. The results showed that the maximum scour depth around the bridge pier varies at a different location along the bend. Besides, the flow discharge increase grows the depth and volume of the scour hole at all positions. Additionally, maximum and minimum depth and volume of scouring hole occurs in the second half of the bend at 60- degree position and in the middle of the bend at 45- degree position, respectively. Finally, it was recorded that the development of the sedimentary hill after the pier and its extent in the first half of the bend was higher than the second half of bend. The result also indicated that the maximum and minimum scour depths relative to the pier diameter are equal to 2.24 and 1.22, respectively.

In addition to the strength and stability of the bridges, designers and engineers pay much attention to bridge appearance and scenery, which led to build bridges with inclined piers to the flow. Therefore, studying the hydraulic conditions and scour countermeasure of inclined bridge piers is necessary. In this study, the effect of collar on scour reduction at the base of vertical and angled cylindrical piers was investigated. The collar installed at the surface of the sediment bed for vertical and inclined piers. The result of experiments showed that the highest scour depth belongs to the inclined bridge pier toward the upstream direction, which is 15% more than the vertical pier. However, the maximum scour depth in front of the angled pier toward downstream was measured to be about 30% lower than the vertical pier. For the pier inclined toward the upstream direction, the collar reduced the scour in front of the pier about 63%. The collar for the pier inclined toward the downstream direction decreased the scour by about 67%. The result shows that the installation of collars can have a high effect on reducing the scour depth for inclined piers.

The construction of bridges within the river beds often makes changes to the shape and direction of the rivers. These changes take the natural actions of the river, that one of them is the local scouring around the bridges' piers and can cause annually damage. Therefore, many researches have been carried out to control and reduce the scouring. One of the methods presented by researchers is using slot at piers. In present study, the effect of Pier Opening Area on local scouring around the pier with rectangular section is experimentally investigated. For this purpose, piers with square shape slots and different dimensions were used. The piers were tested at three levels (near the water level, on the bed and under the bed) and four Froude numbers. The result showed that the maximum scouring depth and the volume of hole scour had a direct relationship with slot level relative to bed and Froude number and an inverse relationship with Pier Opening Area. The best performance belonged to the slot with greater dimensions which was located under the bed level in the minimum Froude number condition that reduced the depth of scouring about 55. 4 percent.

Many authors have tried to find out how to control scouring around a pier standing in the way of the straight path flow in a direct stream. The objective followed in the present research is thus to study a scour pattern around such a pier, but installed in a curved rivers, due to the fact that there probably are differences between a flow pattern on a direct path vs. on a meander. Throughout the present study, it is tried to check whether the use of either cable or collar alone or in a combination would affect scouring around a bridge's pier group constructed in the path of a river's meander. Two thicknesses of cable 0.2D and 0.4D and three steps of 0.2D, 0.5D and D were employed. The results revealed that scouring decreases with increase in cable diameter and a decrease in the pitch of the helix. As regards the pier groups that stand in the direction of water flow, scour depth for the first pier is more than that for a standing single pier. This represents the increase in the reinforcing phenomenon. Also scouring depth for the middle and back piers is less than that for a single pier, due to the sheltering phenomenon. As regards piers perpendicular to the flow direction, the maximum scour depth is observed in the middle pier. Also, in this case the scour depth is reduced by an increase in the distance between piers. Use of collar is more effective than cable for small distances between piers. Also it has been found that use of a combination of cable and collar results in the most reduction in scouring depth.