Vertical Pier Research Articles

Effects of pier inclination angle and direction on local scour at rectangular and circular piers

Effects of pier inclination angle and direction on local scour at rectangular and circular piers

Investigation of the Mechanical Features of Steel–Concrete Composite Girder Rigid Frame Bridges with V-Shaped Piers during Construction Stages

Steel–concrete composite girder rigid frame bridges with V-shaped piers are a new type of bridge structure. Based on the traditional composite continuous beam bridge, part or all of the vertical piers are changed into V-shaped piers. This special structure makes them have the mechanical characteristics of both composite continuous beams and V-shaped piers. In this paper, the finite element model of the first steel–concrete composite continuous beam V-pier rigid frame bridge in China is established by simulation software, the construction process of the bridge is simulated, and the stress and deflection of the bridge in each construction stage are studied. At the same time, the stress of the completed bridge model considering the construction stage is compared with that of the completed bridge model without considering the construction stage. It is found that the stress difference between the two concrete slabs is as high as 2.7 MPa. The results show that the stress state of the bridge is greatly affected by the construction process. This study can provide guidance for the design and construction of such bridges, which is of great significance.

Spatio-temporal characterisation of local scour around a circular bridge pier in cohesive soil with different clay/silt ratio

This paper presents new data on scour around a vertical pier in cohesive soils. It specifically focuses on the temporal evolution of local scour hole around the pier with increasing the clay/silt ratio content. Series of flume tests were performed using soil mixtures made with 85% fine sand and 15% fines. The fines fraction used in the soil mixtures includes silt, kaolinite clay, and various combinations of both with different proportions. The water velocity during the tests was kept constant and slightly above the erosion critical velocity of the fine sand used in the mixtures. A 3D laser scanner was employed to continuously record the geometry of the scour hole. Results show that increasing the Kaolinite clay in the fine fraction reduces significantly the scour. The mixture with a range around 7.5–10% of kaolinite clay fines content provides the threshold composition for cohesive soil behaviour effect in scouring process, recognized through scour pattern change. As the clay content increases, notable reductions are observed in the dimensions of the scour hole. Furthermore, the temporal evolution of maximum scour depth measured in flume was in agreement with the results from SRICOS-EFA (Scour Rate in COhesive Soil - Erosion Function Apparatus) method.

Hydrodynamic and morphologic investigating of the discrepancy in flow performance between inclined rectangular and oblong piers

Accurate estimation of local scour is crucial for designers and stakeholders that involved in bridge pier construction. Understanding the scour mechanisms at different cross sections is essential. This study aims to re-evaluate how the inclined rectangular and oblong piers influence the local scour. The flow behaviour around two rectangular and oblong shaped piers with vertical and inclination angles (10⁰,21⁰ and 30⁰ downstream flow direction) under steady-current, shallow flow and clear water conditions was numerically investigated. To achieve this, a hydrodynamic coupled with morphological model are created and tested using experimental data sets on flow and scour. The reliability of flow velocity predictions was verified with high accuracy. The maximum scour depth around inclined rectangular and vertical oblong pier was reduced by 19 and 21% respectively compared with vertical rectangular pier. The simulation results reveal that although oblong piers play a significant impact in minimizing scour development in comparison to rectangular piers, inclined rectangular piers may experience significantly less scour. However inclined oblong piers, regardless of their round nose shape (low intensity of the downward flow), demonstrate a less reduction in eroding the bed around the pier compared to the vertical oblong piers.

A macroblock 2D finite element model for assessing the roots of failure of Huaca de la Luna’s main pyramid (Peru) under seismic action

This study contributes to the seismic structural failure analysis of the main pyramid of the archaeological complex Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850C.E.), the monument is one of the largest adobe structures in the world. The monument shows signs of severe natural and anthropogenic damage due to its position along the Pacific Ring of Fire and extensive looting since Spanish colonial times. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear finite element (FE) model is introduced for assessing the contribution of this pier architecture to the structural response of the pyramid. The time-evolution of elastic strain and plastic dissipation energies is used to quantitatively track structural failure. The instant of structural collapse and attendant lateral capacity can be extracted from the point at which these energies match. Critical regions of a representative cross-section are modelled with individual piers represented by macroblocks and separated by frictional interfaces. A continuous description is adopted for the remaining part of the model. A nonlinear, two-dimensional (2D) plane strain analysis is conducted in Abaqus/CAE Explicit using concrete damaged plasticity and Mohr-Coulomb formulations for adobe construction and soft soil, respectively. A two-stage assessment procedure begins with a quasi-static analysis to predict the stress state due to gravitational load. A dynamic analysis follows to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. The development of local damage conditions up to structural collapse is visualized by the nucleation and propagation of maximum principal plastic strains throughout the model. A sensitivity analysis was conducted to evaluate the effect on lateral capacity of the contact friction coefficient between macroblocks and the number of macroblocks used to discretize the critical area. Introducing macroblocks to the model produces lateral capacities that are lower than analogous, purely-continuum models. These results are shown to be critically affected by the frictional coefficient that governs contact between the macroblocks. The results of this study offer critical insights on the consolidation strategy for the northwest corner of the pyramid and may find application to similarly-built historical earthen structures in northern Peru.

Assessment the local scour around vertical and inclined oblong piers under shallow flow condition

Scour around abutment and piers of water structures cause a failure for these structures in most developing countries. Most of the existing scour prediction equations are mainly produced for circular and square piers. However, in reality, many bridge piers behave as oblong piers (round noses). The dimensionless maximum scours depths (ys/D) were extensively investigated for ten pier configurations under shallow flow operating conditions. The length-to-width (L/D) ratio was optimized for the development of the scour hole around inclined and vertical oblong piers. The ys/D depths around vertical and inclined oblong piers are slightly affected by the L/D ratios in contrast to rectangular piers. However, the ys/D value was reduced by values of 5.9–11.6% around the oblong piers compared to the circular one. Furthermore, the appropriate prediction equations were assessed for determining the maximum ys/D for different pier configurations. CSU and Vagfhi equations are modified to give an accurate prediction for the maximum ys/D around vertical and inclined oblong piers, respectively.

Assessment of Modal Characteristics of Steel–Concrete Composite Girder Bridge with V-Shaped Piers

As the standards of bridge design and construction continue to improve, more and more combination bridges are being put into use. The public’s demand for aesthetically pleasing bridges is also increasing, making it necessary to use the special structure of steel–concrete combinations, continuous V-shaped piers, and continuously stiffened bridges. This structure has the structural and mechanical characteristics of both a continuous girder and a V-shaped pier bridge. The span can be reduced to a certain extent because the support of the V-shaped piers can be applied directly to the main girder. The spanning capacity of the bridge is generally greater than that of a combined steel–concrete girder bridge with vertical piers. The whole bridge is continuous, without expansion joints, making it more stable and safe for traffic. At present, research on this structural bridge type is not yet complete. In this paper, the structural system and dynamic characteristics of this bridge are investigated in the context of real-life engineering. Firstly, the self-vibration characteristics of the three structures were analyzed, and their effects on the self-vibration characteristics were studied by varying the height of the crossbeam at the V-shaped piers’ support, the main beam stiffness, and the V-shaped piers’ stiffness in the three structures. The results show that the increase in main beam stiffness can effectively improve the vertical stiffness of the three structures, with the most obvious effect on structure one and the least effect on structure two; the increase in V-shaped pier stiffness causes a huge improvement in the transverse stiffness of the three structures. Subsequently, a two-unit rod system model of the background bridge was established using the finite element method, and the original model was improved by calculating the equivalent shear stiffness of the shear nail group so that it could simulate the shear joints more accurately. The effects of the shear connectors on the self-vibration characteristics of the steel–concrete combined continuous beam–V-shaped piers and continuous rigid-frame bridge were investigated through theoretical analysis and finite element simulation. It was found that due to the existence of flexible shear connectors, the interface between the steel beam and concrete slab in the combined beam has a slippage effect which causes the deformation to become unsynchronized, and there is a certain difference between vibration patterns. The stiffness of the shear connectors has a certain effect on the self-vibration frequency of the bridge. The damage to the local shear connectors does not have a large effect on the self-vibration frequency of the overall structure, but the damage to the shear connectors at the beginning of the connection between the V-shaped piers and the main beam is greater than that of the other areas. Damage to shear joints should be given special consideration in comparison to other areas.

Effects of hooked-collar on the local scour around a lenticular bridge pier

This paper presents the results of comprehensive laboratory experiments to investigate the effects of hooked-collar on the scour development around a vertical pier with a lenticular cross section. The flow around the pier was uniform, steady, and under the clear-water condition. The axial scour profiles for cases without and with a lenticular hooked-collar were measured and the effects of hooked-collar dimensions and elevation from the bed were examined. To compute the efficiency of hooked-collar for scour prevention, the results of local scour for a bridge pier without a collar and a bridge pier with a plain collar, without a hooked wall, were used as benchmark data sets. A wide range of hooked-collar geometries such as the ratio of collar width to the pier width, Wc/Wp, ranging from 1.5 to 3.5, the ratio of hooked-collar wall height to the pier width, Hc/Wp, ranging from 0.15 to 0.6, and the ratio of collar elevation to the pier width, Ec/Wp, of −0.5, 0, and 0.5 were tested. The experimental results indicated that the equilibrium scour depth decreased with the ratio of hooked-collar to the pier width when Wc is twice the pier width, Wp. For Wc/Wp > 2, the scour depth was similar to the tests with an infinitely large pier width. In addition, the scour depth consistently reduced as the hooked-collar wall height, Hc, to the pier width, Wp, approached 0.3. The highest scour reduction efficiency was achieved when the hooked-collar being placed on the bed surface. Empirical models were developed for prediction of maximum scour depth near the lenticular bridge pier with a modified collar. The results showed that the volume of scour hole around a lenticular pier increased non-linearly with the maximum scour depth and it was independent of the hooked-collar geometry.

Analysis of Mechanical Performance of Steel‐Concrete Composite Girder Bridge with V‐Shaped Piers

The steel‐concrete composite girder bridge with V‐shaped piers is a new type of bridge structure. It has both the unique mechanical performance of a combined continuous girder and that of a V‐shaped pier bridge. At present, studies on the mechanical properties of steel main girders combined with concrete deck slabs are mainly focused on the substructure for vertical piers, but piers and girders are not solidified. However, if the V‐shaped piers are cemented to the main girder, the performance of the V‐shaped piers will directly affect the performance of the total superstructure. The steel main girder and concrete deck slab of a steel‐composite girder are considered to be different parts of the same section. The joint section is used to simulate the changes in section stiffness of each section during the different stages of construction. In this paper, the first steel‐concrete composite girder bridge with V‐shaped piers is studied in detail. The effects of different influencing factors on the structural forces are investigated using finite element analysis. The results show that the force performance of this bridge type is strongly influenced by the structure. These can provide guidance for the design and construction of this bridge type, which is of great significance.

Prediction of Flow around a Vertical Circular Pier in a Discordant Bed Channel Confluence

Prediction of Flow around a Vertical Circular Pier in a Discordant Bed Channel Confluence

The Variation of Scour Depth near Vertical and Inclined Cylindrical Bridge Piers: An Experimental Study

The stability of bridge piers against scouring phenomena require to estimate the scour depth carefully at different hydraulic condition to ensure safe design. In this study, laboratory experiments were carried out to examine and compare the scour depth for vertical and inclined cylindrical piers with downstream direction under clear water scour conditions. The measured scour depth in front of three inclined configurations (ϴ = 10°, 16° and 22°) for single cylindrical pier was compared to that observed at vertical cylindrical pier (ϴ = 0°). The experiments were conducted at four flow intensities (V/VC=0.495, 0.714, 0.824 and 0.989) for sand bed material of d50=0.72 mm. The obtained results revealed and confirmed the inverse relationship between the measured scour depth and the angle of inclination of pier, whereas the maximum and the minimum scour depth was observed at ϴ = 0°, and ϴ = 22° respectively. The results of this study showed that the scour depth near threshold conditions (V/VC=0.989) can be reduced approximately by (5%, 10%, and 15%) for inclined piers with (ϴ = 10°, 16° and 22°) respectively. Furthermore, by assessment of five existing formulas, new modified empirical formula has been proposed for scour depth estimation of inclined piers with ± 9% error margins.

A Multi-Pier-Macro MPM method for the progressive failure analysis of perforated masonry walls in-plane loaded

The aim of this paper is to present and put at disposal a reliable numerical procedure called MPM (Multi-Pier-Macro) method that can be used by unexperienced practitioners by means of a software equipped only with non-linear truss elements with softening for the progressive failure analysis of large scale perforated masonry walls in-plane loaded. The authors have a previous successful experience in the field, with a procedure proposed called MP Multi-Pier approach that relies into the substitution of a masonry wall in plane loaded with a composition of trusses, typically two vertical piers and braces. The intrinsic drawbacks of the MP method (mainly the large number of elements needed for the analyses) is here overcome, modeling each pier, spandrel and cross-joint belonging to a large and perforated wall with the minimum number of truss elements (piers and braces), having in mind to carry out very fast but reliable progressive failure analyses for large existing structures subjected to horizontal loads. To achieve such goal, for each single element used, suitable equivalent geometric and mechanical properties are assigned, assuring the equivalence element by element of the 1D mesh with the continuum in terms of elastic energy, behavior at peak and softening branch.MPM is benchmarked on two large scale perforated walls, where the results of several previous models are available from the literature, showing satisfactory accuracy in the reproduction of the global behavior and the activation of the mechanisms inducing the collapse.

Prediction of scour around single vertical piers with different cross-section shapes

In the present work, a 3D numerical model is proposed to study local scouring around single vertical piers with different cross-section shapes under steady-current flow. The model solves the flow field and sediment transport processes using a coupled approach. The flow field is obtained by solving the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations in combination with the k-w SST turbulence closure model and the sediment transport is considered using both bedload and suspended load models. The proposed model is validated against the empirical measurements of local scour around single vertical piers with circular, square, and diamond cross-section shapes obtained from the literature. The measurement of scour depth in equilibrium condition for the simulations reveal the differences of 4.6%, 6.7% and 13.1% from the experimental measurements for the circular, square, and diamond pier cases, respectively. The model displayed a remarkable performance in the prediction of scour around circular and square piers where horseshoe vortices (HSVs) have a leading impact on scour progression. On the other hand, the maximum deviation was found in the case of the diamond pier where HSVs are weak and have minimum impact on the formation of local scour. Overall, the results confirm that the prediction capability of the present model is almost independent of the strength of the formed HSVs and pier cross-section shapes.

Numerical Study of Bed Topography Variations Owing to Placement of Triad Series of Vertical Bridge Piers Installed in a 180-degree Bend with Different Relative Radii Using SSIIM Numerical Model

In this paper, the scouring around a triad series of vertical bridge piers located in a bend is investigated using SSIIM software. To this end, some of the most essential parameters such as the relative radius and the bridge pier position in both transverse and longitudinal directions to the flow have been examined. Then the bed topography variations have been detected within a flume. It is worth mentioning that the experiments have been conducted in a 180-degree sharp bend in the presence of the bridge piers. The available experimental results were used to ensure correctness of the simulated output data. Accordingly, it is evident that the simulated model not only is capable of estimating the amount of the maximum scour and sedimentation but also can effectively predict their position using an experimental model. Based on the results, it is indicated that the maximum scour depth is reported in the case of the bridge pier transverse to the flow installed at the 60-degree position of the bend with a relative radius of 5. Under these circumstances, the maximum depth of scour is evaluated to be 1.14 times the depth of flow at the beginning of the bend. Also, the maximum volume of scour around bridge piers has been detected in this case.

Optimal Octagonal Hooked Collar Countermeasure to Reduce Scour Around a Single Bridge Pier

Pier modification countermeasures are essential as they play a vital role in protecting pier against local scour action. Current study investigates experimentally the scour around vertical pier of octagonal cross section with pier modification such as newly proposed octagonal hooked collar is explored, in steady uniform state, under clear water condition. The results of pier scour without any modification were used as a reference to compute the efficiency of hooked collar provision around octagonal pier. The results show that by increasing the hooked collar width up to 2.5 Wp reduced maximum scour depth significantly. However, the experimental investigation revealed that the best combination to be with a hooked collar width of 2.5 Wp, having sidewall height 0.45 Wp. The best combination minimized around 73.3 % of scour hole depth, compared to octagonal pier without any modification. Using experimental results, a new equation is proposed to predict the scour depth around a bridge pier fitted with hooked collar. Moreover, a relation was developed for maximum scour depth and scour hole volume. Results indicate that the scour hole volume around a bridge pier increases quadratically with maximum scour depth.

Mitigation of the amplitude and celerity of dam break shock wave using combination of groyne and vertical pier

This paper aims to numerically investigate the impact of the combination of groynes and vertical piers on mitigating the amplitude and celerity of dam break wave-front. First, a robust numerical model based on the Finite Volume Method (FVM) with the Harten, Lax and van Leer (HLL) approximate Reimann’s solver’s technique is developed and validated with other research studies. Then many different scenarios including group of piers, group of groynes with different shapes and combination of groynes and piers are considered for dam break flow modeling. The final results showed that group of piers alone or group of groynes alone have no significant effects on the wave-front depth and celerity but, combination of L-head groyne with piers can decrease the amplitude and celerity of the dam break wavefront or flood wave. In this case, a blockage zone between the groynes and intensive backwater effects behind them were observed.

Spatial Stress of the Pier–Girder Rigid Region of a Continuous Rigid-Frame Bridge with V-Shaped Piers in Two Directions

The pier-girder rigid region of continuous rigid-frame bridges with V-shaped piers has a complex spatial stress state because of its special structure and complex boundary condition. However, using the beam-column element model for mechanical analysis in design induces large errors. Therefore, this study analyzes the spatial stress and structural optimization of the pier-girder rigid region of a continuous rigid-frame bridge with V-shaped piers. A solid model of the pier-girder rigid region is established by photoelastic stress experiment and numerical analysis. The stress distribution characteristics of the pier-girder rigid region in the longest cantilevered stage and operational stage are revealed in view of tri-directional normal stress and boundary tangential normal stress, and the stress distribution curve of slice boundary at key positions is drawn. Results show that (1) the experimental values are consistent with the finite element analysis values, and the compressive stress is dominant in the main girder structure, which meets the design requirements of fully prestressed concrete structures; (2) the tensile stress concentration appears around the hole of the diaphragm in the bridge transverse direction, whereas the compressive stress concentration appears at the joints between the top/bottom plates of the box girder and the diaphragm in the bridge longitudinal direction; (3) the consolidation zone between the V-shaped bracing and the vertical pier is the most dangerous area of the structure, where the structural measurements of increasing the reinforcement or using steel fiber reinforced concrete are proposed. An optimization measure for increasing the height of the vertical pier is introduced to present the property of a flexible pier and optimize the mechanical characteristics of the bridge. As the height of the pier increases, the stress gradient of each section of the V-shaped bracing decreases, and the distribution of cross-section stress becomes uniform. When the height of the pier is greater than five times of the girder height at the pier top, the stress gradient of each section of the V-shaped pier is less than 0.6. Herein, the force is reasonable with large safety reserve, which can adapt to the longitudinal displacement of the main girder caused by concrete shrinkage, creep, and temperature change in the later stage.

Three-dimensional numerical modelling of the flow around a circular bridge pier: a scaling analysis

Three-dimensional numerical simulations of water flow around a vertical circular pier using the 'large Eddy simulation' method are presented. All simulations were performed using the solver 'interFOAM' supplied with OpenFOAM. The objective of this paper is to provide a better understanding of the influence of the free-surface on the velocity and pressure fields. The influence of three parameters, the Froude number (Fr), the Reynolds number (Re) and the geometrical parameter G (ratio between the water depth and the pier diameter), on the behaviour of free-surface is investigated. Qualitative observations and quantitative results are reported. It is shown that downstream the pier, the flow depends on Fr and G. Indeed, a dimensionless number combination of Fr and G describes all the phenomena related with the free-surface deformation (the wavelength size, the free-surface deformation). On the contrary, for estimating the drag coefficient or for describing dynamic phenomena such as the separation of boundary layers in front of the pier a dimensionless number combination of Fr and Re must be used.

Application of SVM Algorithm in Predicting Vertical Pier Scour Depth

Application of SVM Algorithm in Predicting Vertical Pier Scour Depth

Experimental study of the local scouring around sloped piers and its estimation using statistical tools

Local scouring around sloped bridge piers in steady currents was studied both experimentally and mathematically. The effects of different inclination angles, flow intensities, flow depths, and pier size on local scouring were investigated. The experimental results show that the scouring depth increases with an increase in the values of discharge and pier width. The scouring depth for the sloped piers is smaller than the vertical piers one and the maximum scouring depth continuously decreases as the pier inclination angle increases. Prediction of the scouring depth around bridge piers using analytical models can be utilized in the feasibility studies of different models, and evaluations of the parametric analytical. Therefore, it was tried to model the scouring depth as a function of Froude number, flow intensity, and relative roughness parameters using non-dimensional analysis. The regression analysis based models were introduced to determine the scouring depth at upstream side of the pier using experimental tests data. Step-wise linear regression showed that the value of relative scouring depth has considerably good correlation only with two non-dimensionless parameters of inclination angle and normalized approaching flow depth. In this regard, some linear and nonlinear regression tools were utilized to establish functional relationships between these variables. Statistical indices and residual analyses of the models revealed the suitability of the models. Comparison of the experimental and predicted value of relative scouring depth illustrates that the suggested models can reasonably predict this parameter.