Bridge Pier Model Research Articles

Seismic performance assessment of existing low-ductility reinforced concrete double-column bridge piers retrofitted with buckling-restrained braces

In this study, buckling-restrained braces (BRBs) are utilized to improve the seismic performance of existing reinforced concrete (RC) double-column bridge piers. Two 1/2-scale models of RC double-column bridge piers—one retrofitted with a BRB (RC-Pier-BRB) and the other without a BRB (RC-Pier)—were designed and compared. The failure mode, stiffness, strength, energy dissipation, and curvature of RC-Pier-BRB and RC-Pier were compared through pseudo-static tests. Fiber finite element models were created using OpenSees to replicate the experimental results. The findings showed that BRBs effectively controlled seismic damage; compared to RC-Pier, RC-Pier-BRB demonstrated a 44.8 % reduction in the maximum curvature. The strength of RC-Pier-BRB increased by 59.2 %, and its energy-dissipation capacity grew by 18–40 % after BRB retrofitting. The numerical model accurately reproduced the trends in the strength, strength degradation, seismic behavior after BRB fracture, and curvature in the plastic zone of the test models. The differences in the peak strengths of RC-Pier and RC-Pier-BRB between the numerical and experimental results were 3.90 % and 0.43 %, respectively. The errors in the maximum curvatures for RC-Pier and RC-Pier-BRB between the numerical and experimental results were 2.03 % and 8.53 %, respectively. Therefore, retrofitting the existing RC double-column bridge piers with BRBs can improve seismic performance and damage control. Furthermore, the connection bases and plates of the BRB remained useable after the BRB buckled and fractured, suggesting a reliable technology for the replacement and recovery of the BRB after an earthquake.

Enhancing tsunami resilience for coastal bridge piers through seawall-integrated breakwaters: An experimental study

In ocean engineering, breakwater plays a crucial role in protecting coastal structures such as bridge pier from the impact of extreme sea waves. However, enhancing the existing breakwaters' ability to withstand extreme wave remains an urgent issue to address. This study explores the reinforcement strategy of breakwater against extreme sea waves by installing seawalls on the breakwater. Utilizing dam-break wave generation techniques to simulate tsunamis, the study experimentally evaluates the effectiveness of seawalls in reducing the tsunami forces exerted on bridge pier model and numerically investigates the tsunami forces on the seawalls. The focus of this research is to analyze the pressure distribution on seawalls and the impact of different seawall configurations on the reduction of tsunami forces on bridge pier model. Results show that: Under the tested wave condition (a) The height of the seawall on the breakwater is a critical parameter, as increasing wall height reduces the tsunami forces exerted on the bridge pier behind it. The taller seawalls are subjected to greater tsunami forces in tested cases; (b) The trend of extreme pressure values for different seawalls starts increasing at the bottom and then decreases; (c) There is a critical distance that the breakwater being most effective at reducing tsunami impact forces between the bridge pier model and the breakwater. This study not only deepens the understanding of the interaction between tsunami waves and seawalls but also offers practical guidance for designing structures with disaster resilience, significantly influencing the future design and construction of tsunami-resistant coastal infrastructure.

Analytical design of non-grounded tuned mass-damper-inerter for base-excited structures

This research contributes new analytical formulae for H∞ optimal tuning of non-grounded tuned mass-damper-inerter (TMDI) for minimizing free-end displacement of base-excited cantilevered structures. The derivation relies on the fixed-point theory, making use of single-mode modelling of the cantilevered structure while accommodating arbitrary TMDI placement along the structural height. Optimal TMDI tuning parameters are derived for given dominant mode shape of structure and TMDI inertial properties (i.e., secondary mass and inertance) under two different types of harmonic excitations with frequency-independent displacement and acceleration amplitudes. The applicability of the derived TMDI tuning formulae for response mitigation of lightly damped cantilevered structures under stationary broadband support excitation is established through comparisons with numerically optimal TMDI properties for a wide range of TMDI inertial properties. Moreover, the analytical TMDI tuning formulae derived in this study achieve enhanced structural performance for base-excited structures compared to those from the literature, derived under various modelling assumptions and optimality criteria. Lastly, the potential of the proposed TMDI tuning for structural response mitigation is numerically evaluated by examining displacement, acceleration, and energy dissipation response history data of an experimentally identified reinforced concrete bridge pier model subjected to 100 earthquake ground motion (GM) records. Overall, reported results demonstrate that the derived analytical formulae can significantly extend the practical application of TMDI as a bona fide dynamic vibration absorber for base-excited structures by circumventing the need for computationally demanding numerical TMDI tuning optimization.

Experimental study on Local Scour around Bridge Pier Models generated by Flash Floods carrying Debris

The analysis of local scouring around bridge piers currently is based on typical river flood discharges. However, extreme events like flash floods with high velocity and discharge, carry wooden debris that accumulates upstream of the bridge pier. This results in additional forces due to flow diversion and reduction in flow area, so impacting hydraulic structures and exacerbating the scouring process. The study objective was to examine the impact of debris transported by flash floods on the depth and distribution patterns of scouring around bridge piers. This research was conducted in a 15.5-m-length, 0.5-m-width, and 1.0-m-height glass flume, layered by 25 cm thick of sand which is d50=0.52 mm and σg=2.327. Flash flood simulations were conducted by flowing the water mixed with debris content of 0, 5, 10, and 15% to hit a sharp nose pier model which is installed in the channel. Scour depth was measured using point gauges at 50 points around the pier. The findings indicated that an irregular distribution pattern of scour is formed around the pier, and scour depth decrease when increasing debris content. It is necessary to corrected in the range of 0.65-1.43 for 0-15% debris content carried by the flash flood compared to normal flood.

Cycle Tests and Structure Repair of Bridge Pier Models

This research was conducted in anticipation of the risk of fatal damage to the structure due to the earthquake. In this study, experiments were carried out on the test object in the form of a bridge pillar model, which consisted of 2 test steps. The cyclic test is in the form of a pier bridge model and is continued in step 2 in the form of repairs with grouting and carbon wrapping materials as well as conducting another cyclic test to evaluate the performance of the repair materials used. This study uses the pier model, which consists of two test objects, namely a column with dimensions of 0.25x0.25x1.68 meters and a column cap of 1.20x0.55x0.36 meters. This test provides a constant axial load of 0.2 fc’.Ag and a cyclic lateral load. Phase 1 testing was carried out until the drift ratio was 3.5%. The achieved lateral peak strength is 8,606 tonf with a drift ratio of 2.20%. Lateral strength experienced a decrease in peak lateral strength of 86.93%. The damage is dominated by shear cracks which are characterized by the number of cracks with a diagonal pattern. Structural performance analysis was carried out according to ACI 374.1-05. The results of the theoretical analysis of the peak strength of the pier model were 15.2144 tonnes in the tensile direction, while the experimental ones were 8.606 in the pushing direction and -7.812 in the pulling direction.

Repair of Pier Bridge Model Post-Earthquake

This study concentrates on the bridge pier model which was damaged by the earthquake and repaired using grouting and carbon wrapping materials. This research consists of a one pier bridge model with two steps of testing, namely step 1 in the form of a cyclic test of the pier bridge model which will be followed by step 2 in the form of structural repairs with grouting and carbon wrapping materials and retesting. to evaluate the performance of the structural repair technology used. This research will show the cyclic test results using the repair material applied to the same sbr latex concrete material test object. The test object used is a pier bridge model with dimensions of 0.25×0.25×1.68 meters. The material specifications used are concrete f'c 30, fy 400 MPa deformed longitudinal reinforcement and stirrups fy 240 MPa. The test was carried out with a constant axial load of 0.2.f'c.Ag and a cyclic lateral load. Structural performance analysis was carried out according to ACI 374.1-05. Step 1 cyclic test was carried out until the drift ratio was 3.5%. The lateral peak strength achieved was 8.606 tonf with indications of shear damage indicated by the number of cracks in the web area. The second step of the cyclic test was carried out to a drift ratio of 6.25% with a lateral peak strength of 8.640 tonf with indications of flexural damage. Cyclic test results show that repair with a grouting material and carbon wrap can restore peak strength, deformation capacity, and stiffness degradation.

Rehabilitation of Severely Damaged RC Bridge Piers: Experimental and Numerical Investigation

ABSTRACT This study explored rehabilitation of severely damaged bridge pier models using reinforced concrete jacketing method adopting a plastic hinge relocation technique. The test specimens were tested under cyclic loading. The important seismic performance parameters were evaluated for the rehabilitated specimen. A 3D finite element model was simulated considering concrete-rebar interaction and jacket-pier interface shear. Calibration of the numerically simulated model was done by comparing with experimentally observed responses. Additionally, a parametric study was conducted to investigate the effect of shear connectors on performance of the rehabilitated test specimen.

Influence of Hydrodynamic Effect on Dynamic Response of Bridge with Complex Piers Submerged in Reservoir

In order to clarify the influence of hydrodynamic on dynamic response of bridge with complex piers submerged in reservoir, based on the continuous beam of a 4-column pile column frame pier in Xiaolangdi Reservoir of Yellow River, taking 4-column pile column frame pier and bridge as the object separately, the numerical analysis model of bridge (pier) - water interaction is established by ANSYS. The flow around deep-water piers is analyzed. For the single pier (SP) and the pier of the bridge (BP), the dynamic responses of different flow velocities, water depths and wave heights and the combined action are studied. The research shows that detouring flow analysis shows that velocity field and pressure field of each column are asymmetric. Specifically, for this bridge, due to the columns interfere with each other, the velocity difference of 1#, 4# column is more obvious than that of 2#, 3# column. Maximum and stability values of the dynamic response of SP and BP increase with the increase of flow velocity and depth. Specifically, as the water flow velocity increases, the maximum response of the dynamic response increases linearly, while the stable response of the dynamic response increases in the form of a quadratic curve. When the water depth does not exceed 50 m, the maximum and stable values of the dynamic response gradually increase in the form of a quadratic curve. When the wave acts alone, the dynamic response of SP and BP is the largest at the wave crest and the smallest at the wave trough. The maximum dynamic response at the wave crest and trough increases with the increase of wave height. With the increase of water depth, the dynamic effects of waves on SP and BP are more significant. Under the combined action of wave and current, the dynamic response of SP and BP increases with the increase of wave height and water depth. For different flow velocities, the maximum value of dynamic response at wave crest increases with the increase of flow velocity, and the maximum absolute value of dynamic response at wave trough decreases with the increase of flow velocity. Dynamic response under the combined action of wave and current is not the superposition of the dynamic response under the separate action of wave and current. The maximum value of dynamic response appears in wave crest and wave trough, indicating that the current does not change the action of wave field, and the wave still plays a leading role. Specifically, the influence of water on the dynamic response of BP is: pier bottom bending moment > pier bottom shear force > pier top displacement and the influence of water on the dynamic response of SP is: pier bottom bending moment > pier top displacement > pier bottom shear force.

Displacement-based seismic performance of RC bridge pier

To correctly manage the road infrastructure before and after an earthquake, it is necessary to estimate and even predict the seismic performance of the bridge. The quantification of the bridge's seismic performance response was present in terms of displacement and also based on previous research of reinforced concrete bridge pier models. The displacement did define from a force lateral-displacement response diagram corresponding to the capacity curve, calculated through a non-linear static pushover analysis of the reinforced concrete bridge pier model for each limit state, from intact state to collapse. Thus, six defined displacements correspond to the cracking displacement, the yielding displacement, the spalling displacement, the crushing displacement, the buckling displacement, and the fracturing displacement. The six defined limit states correspond to the cracking limit state, the yielding limit state, the spalling limit state, the crushing limit state, the buckling limit state, and the fracturing limit state. Also, parametric analysis did carry out to evaluate the influence, relative importance, and trend of the input parameters in response to the seismic performance of the reinforced concrete bridge pier model. Eleven input parameters did analyze as the concrete compressive strength, the yield stress of reinforcing steel, the concrete cover thickness, the pier aspect ratio, the configuration of the transverse reinforcement, the spacing of the transverse reinforcing steel, the transversal diameter of the transverse reinforcing steel, the longitudinal reinforcement ratio, the transversal diameter of the longitudinal reinforcing steel, the axial load ratio, and coefficient of subgrade reaction.

Hybrid Simulation for Evaluation of Seismic Performance of Highway Bridge with Pier Retrofitted Using Fe-SMA Strips

The present research investigates the use of Fe-based shape memory alloy (SMA) strips for seismic retrofitting of rehabilitated RC bridge pier models. Four severely damaged bridge pier models were first rehabilitated by RC jacketing to retrieve at least their lost strength. Three configurations of Fe-SMA strips namely hoop (H), end-anchored (EA), and a combination of previous two approaches (EAH) were adopted. Prestrained Fe-SMA hoops, placed in the plastic hinge region of the bridge pier model, aims at utilizing the recovery stress developed upon thermal activation for application of active confinement pressure on the test specimen. The EA Fe-SMA strips utilize precompression developed in the concrete in the plastic hinge region of the test specimen. The EAH reinforcement scheme was studied for both precompression and active confinement. To compare the seismic performance of the various Fe-SMA retrofitted test specimens with respect to the control specimen, hybrid simulation (pseudodynamic) of an existing highway bridge located in Tripura, India was carried out with the scaled bridge pier test models as experimental elements. Earthquake excitations of different intensity levels were applied in a sequential manner to analyze the behavior of the structure over a damage spectrum ranging from minor cracking to major damage. To determine the ultimate capacity of the test specimens, cyclic tests were carried out after completion of a hybrid simulation. Bridge pier specimens with Fe-SMA in the form of EA reinforcement exhibited enhanced load-carrying capacity but marginal improvement in ultimate displacement while Fe-SMA hoops improved the ultimate displacement of the test specimen with marginal improvement in the peak lateral load. A combination of EA and hoop Fe-SMA reinforcement was found to be more efficient in improving all the seismic performance parameters such as lesser damage and higher load-carrying capacity, stiffness, and energy-dissipation capacity.

Damage modelling of a bridge pier subjected to multiple earthquakes: a comparative study

This paper discusses and compares two recently developed methodologies for the prediction of damage accumulation in structures subjected to multiple earthquakes within their lifetime, one based on a regression model and one based on a Markov-chain based approach. A stochastic earthquake hazard model is considered for generating sample sequences of ground motion records that are then used to estimate the probabilistic distribution of the damage accumulated during the time interval of interest using the various methodologies. A simulation-based approach provides a reference solution against which the other methodologies are compared. Besides assessing the effectiveness and accuracy of the two methodologies, some improvements of the regression model are proposed and evaluated. The comparison between the methodologies is carried out by examining a reinforced concrete (RC) bridge pier model and using the Park–Ang damage index to describe the damage accumulation. The study results demonstrate the importance of considering the possibility of occurrence of multiple shocks in estimating the life-cycle performance of structures and highlight strengths and drawbacks of the investigated methodologies.

A comparative study of scour around various shaped bridge pier

The study of scouring around bridge piers is very significant and plays a very important role in the safe and economical design of bridge piers. The term scouring is a process by which bed particles around the periphery of the pier get eroded and removed over a certain depth resulting in the formation of a scour hole around the bridge piers. This paper presents a detailed investigation of local scouring around six different shapes namely rectangular, circular, chamfered, joukowsky, oblong, and sharp-nosed of bridge pier models for selecting the best and most economical bridge pier shapes based on local scouring. For the experimental studies, local scour depth is measured around all six different shapes of bridge piers with varying discharges and velocities of 0.0169 m3 s−1 to 0.0355 m3 s−1 and 0.17 m s−1 to 0.30 m s−1 respectively. It is found that scour depth around the rectangular shape of bridge pier is larger due to development of strong intensity of horseshoe vortex caused by flat exposed frontal area and scour depth around the sharp nose shape of the pier is smaller because of flow is bifurcated due to smooth curvature caused less intensity of development of horseshoe vortex. In the comparison of obtained results, it is reported that scour depth around a pier is exactly proportional to velocity of approach flow and exposed frontal area of the bridge pier. The result of this study can be likely used to help in selecting the best shape of the bridge piers as sharp nose shape of bridge piers is better among the other six bridge pier shapes for design purposes.

Finite Element Analysis of Bridge Deck Using MATLAB

Bridges are the most common types of structures generally adopted when there is a obstacle in the path such as water body, valley, road etc without closing the way underneath. Moving live load is one of the critical loading for which bridge superstructure need to be analysed by developing model as realistic as possible. Even though various conventional methods are present for the analysis of bridge superstructure but finite element analysis gives us more realistic behavior of structure. The objective of the thesis is to develop a finite element model of T-beam slab bridge ,bridge pier and pier footing and analyse to study behavior of bridge superstructure for moving live load as per Indian road congress standards given in IRC:6-2017 and IRC: 112-2011 and the dead load of the structure. In my work, bridge deck is modelled as Mindlin-Reissner plate element which is two dimensional plate in which shear deformations effect is considered whereas longitudinal girders ,cross girders and diaphragms are modelled using Euler-Bernoulli’s grid element which are a one dimensional element . A MATLAB code is developed to model T-beam slab composite action in which beam elements is modelled in plane of plate element so that the nodes of beams are coincide to the nodes of the plate by doing such center of gravity of the beam coincides with the plate element ignoring offset present between them. Moving live load analysis is performed using step by step method in which load moves in longitudinal as well as transverse direction giving the worst case for maximum bending moments, shear forces and deflections. Then Moving live load analysis for 2 lane T-beam bridge is carried out for IRC Class 70R wheeled vehicle and compare the result by modeled in sap2000,2016 of same dimension and the effect of the number of cross girders in the deck span on bending moments, shear forces and deflections of longitudinal girders is presented.

Seismic Behavior of Box Steel Bridge Pier with Built-In Energy Dissipation Steel Plates

Based on the design concept of earthquake-resilient structure, a new-type of box-shaped steel piers with embedded energy-dissipating steel plates was proposed. Quasi-static tests of 6 box-shaped steel pier specimens under variable axial pressure and cyclic horizontal loading were carried out. By analyzing the failure mode, load-displacement hysteretic curve, skeleton curve, displacement ductility coefficient, stiffness degradation characteristics, strength degradation coefficient, and cumulative hysteretic energy, the effects of setting energy-dissipating steel plate, axial compression ratio, and thickness of energy dissipation steel plates on the seismic performance of new-type steel piers were discussed. Finite element models of steel bridge piers were established and compared with the test results. The analysis results using FEM agree well with the test results. Results show that the setting of energy-dissipating steel plates can effectively improve the ductility, deformation capacity, and energy-dissipating capacity of box-shaped steel piers, and effectively delay buckling deformation and cracking of wall plates. The steel plate near the bolt hole of the wall plate at the root of the new-type of box-shaped steel piers is easy to crack due to stress concentration, resulting in a rapid reduction of the maximum bearing capacity of the specimens. With the increase of axial compression ratio, the bearing capacity, energy-dissipating capacity, and earthquake-resilient capacity of the specimens increase. The smaller the thickness of the replaceable energy-dissipating steel plates, the smaller the bearing capacity and faster the stiffness degradation of the specimens become, while the ductility and energy-dissipating capacity of the specimens are improved. The axial compression ratio and the thickness of the energy-dissipating steel plate have relatively little effect on the strength degradation of the specimens. In order to facilitate the popularization and application of the new-type steel piers, formulas were also established to calculate the bearing capacity and displacement ductility factor of the new-type of box-shaped steel piers.

Exploring the performance of experimentally benchmarked RC bridge pier models when subjected to sequential seismic shocks

In this paper we explore the performance of RC bridge piers to seismic ground motion sequences, using both experimental and numerical models. Four RC columns were tested on the University of Bristol’s shake table. These columns contained both well-confined and poor-confined cases. Spectrally matched by near-field without pulse (NFWP), near-field pulse-like (NFPL) and far-field (FF) ground motion records where employed in a sequential/progressive fashion ranging from (I) slight damage (II) extensive damage (III) complete damage and (IV) aftershock cases. These experimental test results are then used to develop a benchmarked OpenSees model of this bridge pier. The importance of the concrete tension constitutive model is highlighted. The differences between sequential (progressive damage) and neglecting sequential seismic events are discussed. The benchmarked model is then used for a heuristic case using incremental dynamic analyses. A comparison is made between drift and energy dissipation performance measures, that suggests drift cannot identify the increased system damage induced by sequential events.

Data-driven reliability assessment of dynamic structures based on power spectrum classification

The power spectral density function is a widely used tool to determine the frequency components and amplitudes of environmental processes, such as earthquakes or wind loads. It is an important technique especially in the engineering field of vibration analysis and in determining the response of structures. When using a large amount of data, a load model can be generated, which describes the characteristics of the underlying stochastic process. This load model enables artificially generated excitations to be created within the framework of Monte Carlo simulations. If multiple data records are utilised, a problem that can occur is that the individual records have a high variance in the frequency domain and are therefore too dissimilar from each other, even though they appear to be similar in the time domain. A load model derived from this data does not represent the entire data set, because not the whole spectral range is covered. Therefore, every attempt must be made to group the records according to their characteristics and thus combine similar data to derive two or more load models accordingly. In this work, an approach is proposed to classify real earthquake ground motion records using the k-means algorithm based on similarities within the data ensemble as determined by the Bhattacharyya distance. The silhouette method enables the identification of the optimal number of groups for the classification. The classified data thus form a subset of the entire data set from which load models can be generated and can be applied separately to the structure under investigation, leading to more accurate simulation results. The advantages of this classification approach are illustrated by means of an academic example and a seismic-isolated bridge pier model as a non-linear dynamic system.

Quasi-static test of the lattice-type railway bridge pier with replaceable connection component

Replaceable components are beneficial to functionality rapid restoration of structures after earthquakes, which is a good option for seismic design of resilient bridges. In this study, a lattice-type bridge pier with replaceable connection component was proposed for railway bridges. Large initial stiffness was provided by using steel truss connection system as replaceable connection component between two concrete columns. A 1/12-scaled bridge pier model was designed and fabricated to investigate its cyclic responses by quasi-static testing. It was proved that the replaceable connection component can be easily assembled between concrete columns and work well together with them. During testing, cracks occurred at the concrete columns and crack zone extended with the increase of loading displacement. At the later loading stage, some of steel rods of the connection component between the concrete columns began to yield, the hysteretic loop of the bridge pier showed obvious pinching effect. However, concrete columns were prevented to be severely damaged due to the sacrifice of replaceable connection components. There were differences in the strain distribution of the replaceable connection component and not all the replaceable components yielded during testing. Thus, steel rods with varied strength should be used in replaceable components for the lattice-type railway bridge pier. Otherwise, it should balance the stiffness and ductile in seismic design for the lattice-type railway bridge pier with replaceable connection component.

A comparative study on equilibrium scour volume around circular cylinders in clay–sand mixed cohesive beds, at near threshold velocity of sand – an experimental approach

Abstract Local scour around a bridge pier is a complex phenomenon resulting from the interaction of the three-dimensional turbulent flow field around hydraulic structures. An accurate estimation of scour depth below the stream-bed is important during design since it determines the foundation levels and the expansion of the bridge foundation structures. The present study reveals the results of flume experiments on equilibrium scour depth and scour volumes around circular bridge pier models in clay–sand sediment mixtures. The scouring process in a cohesive sediment mixture is a complex interaction between clay–sand network structure and bed shear stresses. The bed shear stress reduces inside the scour hole as scour depth increases, and this is related to the different modes of scouring in clay–sand mixtures. An exponential equation for the non-dimensional scour volume is proposed considering all the experimental runs to get a specific understanding of the surrounding volume of scour hole from maximum equilibrium scour depth in a clay–sand mixed cohesive bed, when the approach flow velocity is near to the critical velocity for mixed sand. The proposed equations are validated using the pre-existing data from the literature dealing with experimental investigations on bridge scour using clay–sand mixed cohesive sediment and show good agreement with observed data.

Study on seismic behavior of a self-centering railway bridge pier with sacrificial components

Railway bridge pier with large cross-section will vibrate significantly during strong earthquake events. Sacrificial components can be used to improve the lateral stiffness and control the initial uplift of the self-centering pier during earthquakes. This study investigated the seismic isolation mechanism and behavior of a self-centering railway bridge pier with sacrificial components by experimental and numerical methods. Based on an actual railway bridge, a 1/30 scaled bridge pier model was designed for pseudo-static test. Constant axial load and cyclic lateral load were applied for the scaled bridge pier model. Test results showed that sacrificial components were fractured when the loading displacement exceeded 25 mm. The hysteretic behaviors of the self-centering pier exhibited significant difference before and after the failure of sacrificial components. It was found that the bridge pier concrete cracked but steel bars did not yield during the test. This indicated that the failure of sacrificial components of the self-centering bridge pier can effectively protect the pier from severe damage during earthquakes. Furthermore, a Four-spring model was proposed with assistance of the Opensees software platform, and it was verified by pseudo-static test results. It is demonstrated that the proposed model can simulate the self-centering piers with sacrificial components under cyclic lateral loading.

Effects of Dynamical Change in Water Level on Local Scouring around Bridge Piers Based on In-Situ Experiments

To evaluate the stability of bridge piers affected by the local scouring, the existing formulas for estimating the maximum local scour depth have been developed based on the results of experiments conducted under a constant water level. However, the applicability of these formulas to the cases where the water level rises and falls, such as a water level change in a real river, is not clear. In this study, water flow experiments were conducted on cylindrical and oval bridge pier models to investigate the effect of iterated water level change on the progression of local scour around piers. Results of experiments with cylindrical and oval pier showed that the local scour depth and length increased by an iterated action of the water level change; however, these values converged after the number of iterated actions reached a certain time. The local scour length at upstream of the bridge pier was approximately 1.8 times larger than the theoretical value, which was calculated through the local scour depth and angle of repose in water. The local scour length is an important parameter for defining the streambed protection zone, which is one of the measures against local scour, and we showed that the streambed protection zone needs to be defined more widely.