Abutment Piles Research Articles

Assessment of the Impact of Construction of Reinforced Soil Retaining Walls on Abutment Pile Group Foundation

Assessment of the Impact of Construction of Reinforced Soil Retaining Walls on Abutment Pile Group Foundation

Numerical Evaluation of Drag Force on Integral Abutment Piles

Piles transmit structural loads through skin friction, end-bearing, or both to deeper and stronger soil layers. Surcharge loads, site grading, or dewatering activities induce downward movement in the soil that is adjacent to piles installed in a compressible soil layer. This movement causes negative skin friction stresses that act downward at the pile–soil interface, which causes an additional force denoted the drag force (Qn) that is applied to the pile, which results in a larger axial load in the pile shaft. The end-bearing force and positive skin friction that develops in the pile part within stable (incompressible) soil resist the applied loads [e.g., dead load (Qd) and Qn]. This paper aimed to evaluate Qn that was mobilized on driven H-piles that were installed in soft clay with three-dimensional (3D) nonlinear finite-element analysis. Two numerical models were validated against the field data from two instrumented H-piles, which were part of a three-span bridge (E-21) on Highway 418, Ontario, Canada. The calculated settlements and Qn agreed well with measured field data. The validated numerical models were employed to conduct a parametric analysis to investigate the location of the neutral plane (NP) at which the skin friction changed from negative to positive. In addition, the performance of the piles that were installed in small and large groups was investigated, which considered Qn and group effects. It was found that the group effect was negligible for piles that were installed in one row but were significant for piles that were installed in large groups. Finally, a group factor was proposed to calculate the drag force for piles in a group (Q(n)pile in group).

Effect of inclined pile on seismic response of bridge abutments undergoing liquefaction—Induced lateral displacement: Case study of Nishikawa bridge in the 2011 Great East Japan earthquake

It is reported that the inclined pile could be either beneficial or detrimental for the abutment they support in the condition of liquefaction—induced lateral displacement. To clarify the effect of inclined pile on seismic response of bridge abutments undergoing liquefaction—induced lateral displacement, numerical analyses were carried out on the damaged abutment that was supported by inclined piles and that was displaced riverwards 100 mm–150 mm due to soil liquefaction during 2011 Great East Japan earthquake. Accordingly, a fully coupled dynamic effective stress finite element model was developed for the soil—pile—superstructure system. It was found that the shear failure of the bridge abutment was initialized from the inclined piles and then followed by the middle vertical pile. Moreover, the earthquake—induced liquefaction caused substantial lateral displacement of soils around the piles and thus dominated the backward rotation of the abutments supported by inclined piles. Additionally, the exclusion of the deck pinning effect may lead to a marked increase in the lateral displacement and rotation of abutments. If the abutment were supported by vertical piles, a much larger lateral displacement was expected and the promotion of the earth pressure behind the abutment was the main cause of the forward rotation of the piled abutment.

Long-Term Monitoring of Drag Force on Integral Abutment Piles: Instrumentation and Data Analysis

Long-Term Monitoring of Drag Force on Integral Abutment Piles: Instrumentation and Data Analysis

Influence of Abutment Stiffness and Strength on the Seismic Response of Horizontally Curved RC Bridges in Comparison with Equivalent Straight Bridges at Different Seismic Intensity Levels

Seismic design codes have imposed some limitations on the maximum subtended angle of curved bridges and allow engineers to analyze and design them using an equivalent straight bridge. This paper investigates these limitations and evaluates the AASHTO code recommendations regarding the prediction of the seismic responses of curved bridges using an equivalent straight bridge for bridges with different abutment properties at different seismic hazard levels. In this regard, the seismic responses of 21 horizontally curved and straight RC four-span bridges with different abutment types are investigated. In 7 bridge models, soil-abutment-bridge interaction is neglected, while in the rest of the bridge models, the seat-type abutments with the participation of the nonlinear backfill soil, gap, and abutment piles are used in structural modeling. First, nonlinear static (pushover) analyses are carried out to evaluate the overall behavior of the bridges with different abutment configurations in the two perpendicular principal directions. Subsequently, nonlinear time history analyses are performed to predict the seismic response of bridge elements, including column drifts and deck displacements at the place of the abutments in the radial and tangential directions at different seismic intensity levels, including the design basis earthquake (DBE) and maximum credible earthquake (MCE) excitation levels. In addition, the actual maximum displacements of the components of the bridges (i.e., the total absolute displacements) were also predicted and evaluated for different cases. It was found that the abutment properties and boundary conditions had a significant effect on the seismic response assessment of curved bridges compared to straight bridges, while such parameters are not currently considered by the design codes. The results also indicated that by increasing the seismic intensity level, more limitations should be imposed on the use of the equivalent straight bridges.

Study on Calculation Method of Internal Force of Integral Abutment-Pile-Soil Interaction

Integral abutment jointless bridge (iajb) has the advantages of long service life, convenient construction and low construction and maintenance cost. At present, it has been widely used at home and abroad. Based on an actual iajb, an experimental model of integral abutment pile structure is designed and made. The quasi-static test is carried out under low cyclic displacement load, and the interaction between integral abutment, H-steel pile and soil is studied, with emphasis on the strain and bending moment of abutment and pile foundation. The test results show that the strain distribution of pile body is “Cup” shape when the abutment moves forward and “olive” shape when the abutment moves negatively. The maximum compressive stress and tensile stress under positive displacement load are greater than those under negative displacement load. Therefore, when the temperature increases, the internal force of pile foundation is greater than that when the temperature decreases, which means that H-shaped steel foundation pile is more unfavorable when the temperature increases in summer. In order to reduce the adverse effect of temperature on foundation piles, it is suggested that the overall closure temperature of the bridge should be slightly higher than the annual average temperature. In addition, the calculation also shows that when negative load is adopted, the pile bending moment calculated by these methods is not different from the test results, and the distribution law is similar to that of traditional foundation piles. However, under normal load, the pile bending moment calculated by classical theory or bridge code is quite different from the test results, and the distribution law is also different. In this paper, the moment of integral abutment pile-soil interaction is calculated accurately by polynomial fitting method and huanglin method, which can be used in practical engineering and provide reference for the design and application of iajbs.

Evaluation of Negative Skin Friction on Bridge Abutment Piles

Piles are used to transfer loads of structures to deeper and stronger soil layers through skin friction and/or end bearing. Surcharge loads, site grading, or dewatering may induce downward movement of soil adjacent to piles installed in a compressible medium. This movement creates negative skin friction stresses acting downward at the pile-soil interface, which applies additional loads “drag forces” to the pile causing a maximum axial load in the pile shaft at the “neutral plane”. To evaluate the development of drag forces, a comprehensive field monitoring program was conducted over four years for three instrumented abutment H-piles as part of a three-span bridge project. The soil settlement and changes in pore water pressure in the soil adjacent to the piles due to the construction of an approach embankment were monitored using multiple-point extensometers and vibrating wire piezometers. The piles’ elastic settlement and strains were measured using single-point extensometers and vibrating wire strain gauges. The field measurements are presented and discussed in terms of responses time histories and load distribution along one pile shaft. In addition, the calculated forces from vibrating wire strain gauges are compared with the unified design method prediction considering the total stress method (α-method) for cohesive soils. The results show that the maximum drag force was developed after the complete dissipation of excess pore water pressure and that the location of neutral plane varied during the embankment construction stages. Employing the total stress method in the unified design method provided a reasonable prediction of the drag force and the neutral plane’s location.

Soil-pile-structure interaction effects on seismic demands and fragility estimates of a typical Ontario highway bridge retrofitted with fiber reinforced elastomeric isolator

This study investigates the seismic performance of a seismically isolated soil-pile-structure system incorporating the effects of isolation system, soil layers of low stiffness and strength, pile inclination, pile-soil-pile interactions, and bridge-embankment interaction. A coupled three-dimensional nonlinear finite element model of an existing bridge in Ottawa, Ontario is developed as a representative of the 44% of the total bridges in Ontario that have been built prior to 1970. A seismic retrofit technique which involves isolating the bridge superstructure utilizing a novel type of elastomeric isolator called Fiber Reinforced Elastomeric Isolator (FREI) is adopted. Two bridge conditions, namely, monolithic (pre-retrofit) and isolated (retrofitted) are considered to investigate the effect of Soil-Structure Interaction (SSI) on the seismic performance of the bridge prior to and after the retrofit in its longitudinal and transverse directions, independently. Analytical fragility curves are developed for the bridge components based on the outputs of an Incremental Dynamic Analysis (IDA) using 45 synthetic ground motion records. It is shown that seismic isolation can effectively reduce the superstructure acceleration by allowing the deck to experience large lateral displacements. Therefore, the transferred shear forces to the columns and their supporting piles are decreased significantly. While seismic isolation of the bridge is found to be beneficial for bridge components, it has a detrimental effect on the extensive and collapse damage states of abutment piles in the longitudinal direction. This conclusion is limited to the conventional abutment models where the abutment backwall damage has not been taken into account. Using more complex physics-based abutment spring systems may reveal that using the seismic isolation systems can mitigate the probability of extensive damage and collapse to abutment piles by allowing the abutment to serve as a fuse and dissipate the imposed energy by its fracture mechanism.

Holistic Life‐Cycle Analysis of Bridge Solutions

AbstractSteel in bridge constructions is often associated with very large span bridges due to its favorable relationship between strength and weight. But even for bridges with small and medium spans of up to 60 m, steel combined with concrete as a composite bridge can lead to economically justifiable constructions, especially when the performance during the complete life‐cycle is integrated. In this paper, two life‐cycle oriented calculation methods (life‐cycle costs and external costs) are introduced and applied. As a result, comparisons between two abutment solutions (conventional reinforced concrete abutment and a permanent steel sheet pile abutment) and two superstructure variants (steel composite construction and in‐situ prestressed concrete superstructure) are presented. It is shown that accelerated construction processes, durable materials, and a smart bridge‐design considering actual technological developments lead to economically advantageous solution for traffic infrastructures.

A shake table investigation of dynamic behavior of pile supported bridges in liquefiable soil deposits

Bridges are a part of vital infrastructure, which should operate even after a disaster to keep emergency services running. There have been numerous bridge failures during major past earthquakes due to liquefaction. Among other categories of failures, mid span collapse (without the failure of abutments) of pile supported bridges founded in liquefiable deposits are still observed even in most recent earthquakes. This mechanism of collapse is attributed to the effects related to the differential elongation of natural period of the individual piers during liquefaction. A shake table investigation has been carried out in this study to verify mechanisms behind midspan collapse of pile supported bridges in liquefiable deposits. In this investigation, a typical pile supported bridge is scaled down, and its foundations pass through the liquefiable loose sandy soil and rest in a dense gravel layer. White noise motions of increasing acceleration magnitude have been applied to initiate progressive liquefaction and to characterize the dynamic features of the bridge. It has been found that as the liquefaction of the soil sets in, the natural frequency of individual bridge support is reduced, with the highest reduction occurring near the central spans. As a result, there is differential lateral displacement and bending moment demand on the piles. It has also been observed that for the central pile, the maximum bending moment in the pile will occur at a higher elevation, as compared to that of the interface of soils of varied stiffness, unlike the abutment piles. The practical implications of this research are also highlighted.

Effects of Partial Supporting Pile Removal from Deep Foundation Pits by Shallow Excavation Method in Loess Areas

Partial supporting piles removal from deep foundation pit may lead to large‐scale foundation pit collapse, resulting in severe consequences. Various studies have investigated the underpinning technology of cutting abutment piles by combining field monitoring and numerical simulation, but there are few studies on cutting supporting piles of foundation pit by the shallow excavation method. Taking an actual deep and large foundation pit as an example, the finite element method (FEM) was adopted to study the surface settlement and the changing trend of the force and displacement of the supporting pile caused by cutting piles during the shallow excavation of double tunnels. The FEM results were verified with the field monitoring data. The simulation results show that the surface settlement around the foundation pit mainly occurs at the pile cutting stage under different excavation sequences (0D, 1D, 2D), and the main distribution area is the one‐fold diameter area outside the double tunnel. After the supporting piles are partially cut, the bending moment and displacement of the lower part of the broken piles differ significantly due to different excavation sequences, but the bending moment and displacement of the upper part of the broken piles are basically similar. In the process of removing the supporting piles, the Earth pressure behind the piles is redistributed, and the load is mainly transferred to the adjacent supporting piles outside the tunnel within the radius of one time of the tunnel diameter. However, the load is not evenly transferred to the adjacent supporting piles. Some recommendations for the reinforcement scheme of the supporting structure during cutting supporting piles in deep foundation pit are also proposed. The research results can provide theoretical basis and practical guidance for the construction of similar projects in the future.

Performance of sheet pile as a seismic retrofit for old piled abutment subjected to liquefaction-induced lateral spreading

Liquefaction-induced lateral spreading causes severe damage to the pile foundation of structures. Old structures that are not properly designed for liquefaction are more vulnerable to a strong earthquake. Many old piled abutments require a remedial measure against lateral spreading. This paper examines the responses of an old piled abutment subjected to liquefaction-induced lateral spreading and efficacy of the sheet pile reinforcement technique to mitigate the associated damage through dynamic centrifuge experiments. The experiment on the old piled abutment reveals that the abutment moves together with the spreading soil and shows a significant channel-ward movement without pinning effect. The large bending moments are found to take place around the pile head and the interface of the loose and the dense layer as expected. The installation of sheet pile in front of the abutment considerably reduces the channel-ward movement of the abutment thus mitigate the bending moment demand of the piles.

Temperature‐driven fatigue life of reinforced concrete integral bridge pile considering nonlinear soil–structure interaction

AbstractIn this study, a five‐span fully integral reinforced concrete (RC) bridge has been investigated for fatigue life assessment of its RC piles considering the effects of environmental temperature variation and nonlinear soil characteristics. The effect of daily temperature variation on the abutment wall and pile foundation has been estimated. Multilayers of soil along the abutment pile depth have been considered in the formulations. The soil has been represented as 3D nonlinear springs. A new fatigue model has been used for crack initiation and propagation in the RC piles. In this model, a crack has been assumed to progress successively in three stages from the tension side of the pile. Finite element (FE)‐based modeling and analyses have been carried out to determine the longitudinal displacements and bending moment in piles, abutments, and piers. Furthermore, taking the bending moment as input crack mouth opening distance, crack propagation and fatigue life of pile have been assessed using the FE method‐based software. It is seen that the abutment piles suffer fatigue damage earlier as compared to the pier‐piles as a result of thermal and vehicular loads effects. Also, thermal fluctuation has shown little or no fluctuations in the longitudinal displacements of abutment and piles in the multispan fully integral bridge (FIB). It is expected that the proposed method will be helpful for the bridge engineers in designing the pile foundation passing through multiple soil layers against fatigue damage of a FIB in particular subjected to thermal and vehicular loading.

Semianalytical Solutions for Abutment Piles Under Combined Active and Passive Loading

Abstract Abutment piles in soft ground are always subjected to both active loads from upper structures and passive loads from horizontal soft ground displacements; however, theoretical solutions fo...

Experimental Study of Laterally Loaded Stub Abutment and Unburied Piles

In the integral bridge, the deck contraction makes the abutment move away from backfill and causes a failure wedge. To inhibit the failure wedge, a new method with connector from each abutment to the unburied piles outside the bridge has been proposed. The soil behavior around laterally loaded stub abutment and unburied piles was studied on laboratory models using the PIV (particle image velocimetry) method. The effects of unburied pile number and soil − pile interaction on the soil deformation pattern were investigated.

Influence of cement-fly ash-gravel pile-supported approach embankment on abutment piles in soft ground

Abutment piles in soft ground may be subjected to both vertical and horizontal soil movements resulting from approach embankment loads. To constrain the soil movements, the soft soil ground beneath the approach embankment is often improved using composite pile foundations, which aim at mitigating the bump induced by high-speed trains passing through the bridge. So far, there is limited literature on exploring the influence of the degree of ground improvement on abutment piles installed in soft soil grounds. In this paper, a series of three-dimensional (3D) centrifuge model tests was performed on an approach embankment over a silty clay deposit improved by cement-fly ash-gravel (CFG) piles combined with geogrid. Emphasis is placed on the effects of ground replacement ratio (m) on the responses of the abutment piles induced by embankment loads. Meanwhile, a numerical study was conducted with varying ground replacement ratio of the pile-reinforced grounds. Results show that the performance of the abutment piles is significantly improved when reinforcing the ground with CFG piles beneath the approach embankment. Interestingly, there is a threshold value of the replacement ratio of around 4.9% above which the effect of CFG pile foundations is limited. This implies that it is essential to optimize the ground improvement for having a cost-effective design while minimizing the risk of the bump at the end of bridge.

Fatigue in jointless bridge H-piles under axial load and thermal movements

The seasonal and short-term temperature variations produce cyclic horizontal displacements in the continuous superstructure of jointless bridges and hence in the abutment piles. Thorough study of the available field measurement data for jointless bridges showed that the thermal-induced cyclic flexural strains in steel H-piles (SHPs) at the abutments are composed of large, primary small and secondary small flexural strain cycles. While the SHPs at the abutments of jointless bridges laterally deform and experience these cyclic flexural strains due to thermal effects, they also carry axial loads transferred from the superstructure through the abutments. Review of the literature revealed that there is no specific study on the combined effects of axial load and thermal-induced/flexural strain cycles with various amplitudes on the low cycle fatigue (LCF) performance of jointless bridge SHPs. For this purpose, parametric experimental studies on full scale SHP specimens are conducted to simulate the cyclic behavior of SHPs under thermal effects in jointless bridges by considering the effect of axial load combined with large and small flexural strain cycles with various amplitudes. It is observed that at large flexural strain amplitudes, local buckling of the pile due to the effect of axial load adversely affects the LCF life of SHPs at the abutments of jointless bridges. Furthermore, it is observed that the effect of small flexural strain cycles on the LCF life of uncompact SHPs depends on the amplitude of large flexural strains and the amplitude ratio of the small and large flexural strains.

Seismic modeling of integral abutment bridges in Illinois

Integral abutment bridges (IABs) are a common bridge type used in modern design and construction to prevent damage at the abutment seat from water, dirt, or deicing chemicals penetrating through a compromised expansion joint. Elimination of expansion joints in IABs leads to complex soil-structure-interaction limit states involving the IAB abutment and surrounding soil, as well as unique overall bridge behavior in comparison to non-IABs. Despite this different behavior, there is a lack of studies investigating overall bridge performance of IABs when subjected to seismic loads. Existing seismic IAB studies have typically investigated individual components, such as the interaction between abutment piles and soil or the behavior of superstructure-abutment connections, but the comprehensive behavior of all IAB components when subjected to an earthquake has not been evaluated in an integrated fashion. This study details an IAB model developed for dynamic analysis that simultaneously considers contributions from all critical IAB components. The seismic response of two IABs, one with steel plate girders and another with precast prestressed concrete girders, is evaluated at the design-level shaking using the developed model. The design-level shaking is provided by 20 ground motions, for a 1000-year return period hazard-level, developed for the southern Illinois city of Cairo. Results demonstrate the ability of the IAB model to capture key features of bridge seismic behavior, and they provide a framework for bridge engineers to understand IAB earthquake response and limit states, as well as support recommendations for IAB seismic design in Illinois concerning side retainer anchor bolt size and pier column size.

FIELD PERFORMANCE OF TRANSITION RIGID PILED EMBANKMENT WITH SURCHARGED VERTICAL DRAIN OVER SOFT GROUND

Commonly, thick filling works over soft clay is aided with piled embankment at bridge approach to reduce differential settlement between the piled abutment and embankment over soft ground. However, long stretched thick filling works over soft ground requires substantial resources and time to construct rigid piled embankment. Generally for such long stretched and thick filling development over soft ground, other ground treatment such as prefabricated vertical drain (PVD) with surcharge is introduce to reduce the cost of construction. However, excessive total and differential settlement at the surcharged prefabricated vertical drain (SPVD) and rigid piled embankment intersection during post construction period may leads to rectification works over the time. This paper presents the field performance of an alternative design approach for long stretched thick filled embankment over soft clay at structure approach to control the differential settlement between the two conventional ground treatment approaches. With the introduction of the alternative ground treatment approach at the intersection of the two conventional ground treatment, post construction total settlement and differential settlement is reduced significantly.

The Analysis about Influence of Pile Foundation Construction on the Near Metro Tunnel

Based on the case of the construction of a bridge connecting engineering in Wuhan, this paper aims to make simulation analysis on the viaduct abutment pile foundation construction process which is close to the metro station, and find out the influence of deformation of pile foundation construction on existing metro stations. The results show that: Bridge piles near the subway station will have some distortion, but the deformation in each direction is within the safe range. Considering the situation that No.5 Base is close to No. 1 duct, it is recommended that No.5 Base Foundation should use the protection measure of steel sheet pile enclosure construction during excavation to ensure the safety of the viaduct and bridge construction on piles near the subway tunnel.