Deformation Of Piers Research Articles

Study on Deformation Control of Road-Deep Foundation Pit Passing under Elevated Subway Bridge

This paper focuses on the application of pile foundation underpinning technology in a deep foundation pit of a subway Viaduct Project in Beijing. The study aims to address the engineering characteristics of the project, including a large number of new piles, a wide span of underpinning abutment, a long length of deep foundation pit, and a wide range of influences. This research utilizes field monitoring and numerical simulation methods to investigate the pile foundation underpinnings. The impact and management of road-deep foundation pit construction are considered, as well as their combined effect on subway viaducts and track structures. The primary accomplishments are as follows: (1) By analyzing the data from on-site deformation monitoring, it is evident that the pier exhibits maximum vertical deformation and maximum transverse deformation at the same location. The measuring locations are specifically situated on Pier 7# at the pile foundation underpinning. The maximum vertical and transverse deformations of the track are directly proportional to the maximum deformation of the pier. (2) By comparing the numerical simulation results with the field monitoring data, it is observed that although there is some discrepancy between the two, the deformation trend is largely consistent. This suggests that the numerical simulation analysis method is effective in reflecting the deformation of the bridge and track. (3) Through the numerical model and changing the values of the retaining structure parameters, the sensitivity of the pier deformation near the road foundation pit to the retaining structure parameters is systematically analyzed. The sensitivity of the pier deformation to the foundation pit parameters is as follows: the embedded depth insertion ratio of the retaining pile > the diameter of the retaining pile > the pile spacing.

Impact analysis of repeated improper treatment of bridge site slopes to bridge across

The bridge site slope in Zhengjiawan has been renovated several times in response to the adverse geological conditions of the Zhengjiawan ancient landslide (ZAL) in China. However, improper control and treatment measures have caused the structural failure of the Zhengjiawan bridge (ZB). Based on long-term field monitoring data of rainfall, temperature, bridge deformation, and bridge site slope displacements, this paper analyses the impact of repeated improper treatment on bridge site slopes to bridge across. Furthermore, it summarized the interrelationship between bridge deformation and bridge site slopes under natural rainfall and improper treatment measure conditions, and proposed a set of solutions for bridge site slope control and treatment. The results show that the destruction of ZB is primarily attributed to the deformation of ZAL, natural rainfall is the main trigger controlling the intermittent creep of the ZAL, while the construction of anti-slide pile and deviation rectification of bridge abutment result in significant deformation of ZAL. The deformation of ZB and ZAL were synchronous, and the monthly displacement difference ranged from 0.18 to 5.19 mm. The failure of the ZB structure resulting from the ZAL is attributed to the insufficient shear strength of the weak loose soil comprising the landslide, which fails to withstand the sliding force induced by continuous heavy rainfall. Additionally, the original anti-slide pile inadequately controls the deformation of the landslide. By setting the second-row anti-slide pile, adding the cross-sectional area of the bridge pier foundation, and installing drainage pipes, the safety of the bridge is effectively guaranteed. The control and treatment of ZAL show that preventing bridge pier deformation should be prioritized followed by controlling and treating bridge site slopes, and this study provides insights into interactions between unstable landslide treatments and bridge structures which may serve as a reference for similar projects.

Cyclic test evaluation of double skin composite hybrid coupled wall with frictional steel truss coupling beams

The seismic performance of double skin composite shear walls (DSCSWs) has significant superior to conventional reinforce concrete (RC) shear walls. Previous studies have neglected the changes of axial compressive forces and bending moments actting on the top of wall piers. In addition, behaviors hybrid coupled wall (HCW) under real boundary condition have not been fully investigated. Thus, in this study, a novel quasi-static test which incorporates the boundary conditions of substructures in a prototype building was preformed. And a cyclic test was carried out on a 2/3-scaled double skin composite (DSC) HCW with frictional steel truss coupling beams (FSTCBs) using the proposed method. The seismic behavior of specimen under reversed lateral cyclic loads was investigated. The failure modes of the wall piers mainly included local buckling of the steel faceplate, fracture of the side plate, and concrete crushing at the corners of walls. The force-displacement hysteresis curve of FSTCBs was obtainable from the attached instruments as the force transmission path of the steel truss could be clearly observed. DSCSW pier deformation was evaluated based on the deformative relationship between the wall pier and FSTCB. The FSTCB primarily dissipated 80% of the total energy input prior to damage occurring in the DSCSW. Strain distribution curves along the DSCSW showed that the pre-peak-resistance plane section assumption was still valid.

Comparison of Damage Indexes for Assessing Seismic Fragility of Bearings in an Offshore Bridge

This study analyzes the applicability of different damage indexes for bearings, focusing on the time-dependent deterioration of materials and the time-dependent bond-slip behavior between steel and concrete caused by chloride erosion. First, the methodology is proposed, encompassing the time-dependent deterioration of materials, the time-dependent bond-slip behavior, the quantification of different damage indexes of the bearing, and the fragility analysis for the bearings. Next, an offshore bridge is used as an example to investigate the detailed elements of the components and the time-varying effects. Thereafter, based on incremental dynamic analysis and fragility analysis, the discussion focuses on the comparison of damage indexes for assessing the seismic fragility of bearings in an offshore bridge. This study indicates that if the relative displacement ductility ratio is adopted as the criterion, the coverage of PGA obtained by the theoretical method is 167% greater than that obtained using the empirical method, and the relative displacement ductility ratio, which incorporates the shear deformation of piers, is better aligned with the performance-based ductility design concept and offers better economy. Safety-based damage indexes are recommended for the bridge in seismic zones, while economy-based indexes can be used in favorable bridge environments.

Novel fiber-based seismic response modelling and design method of partially CFST bridge piers considering local buckling effect

Considering the prohibitive computation time and convergence problems of shell-solid models in seismic analysis of partially concrete-filled steel tubular (CFST) bridge piers, a simple fiber-based nonlinear modelling method is proposed and calibrated in this study intended for large-scale seismic analyses. The local buckling effect of the outer steel tube is considered in the proposed method. By comparing the results of the numerical modelling with those from the experiments, the proposed fiber models are demonstrated to capture the hysteretic behavior of CFST piers with a comparable effectiveness but an enhanced efficiency and analysis time and effort over the shell-solid models. Based on the proposed fiber models, extensive cyclic pushover and time-history analyses are conducted to investigate the effect of critical design parameters on seismic performance of partially CFST piers. The analysis results indicate that the parameters of steel tube and infilled concrete should be properly designed in a combined way to mitigate the local buckling of the steel tube and thus improve the overall seismic performance of partially CFST piers. A novel design method using layered concrete filling is proposed for partially CFST piers, which can achieve an improved structural seismic performance. Furthermore, this method is validated to be especially efficient for seismic retrofit of existing hollow steel piers, which can significantly enhance the pier deformation capacity without imposing much extra force demands on pier foundations.

Theoretical Investigation on Multiple Separation of Bridge under Near-Fault Vertical Ground Motion

In order to consider the effect of near-field vertical earthquake, a model of a two-span continuous beam bridge is established. On the basis of superposition of longitudinal and vertical seismic actions, the possible separation of vertical earthquake is considered, and the influence of separation on structural failure is calculated. The transient wave characteristic function method and the indirect mode superposition method are used to solve the response theory of the bridge structure during the earthquake. When the vertical seismic excitation period is close to the vertical natural vibration period of the bridge, structure may separate. For the high-pier-type bridge, the separation enlarges the deformation of the pier and even causes the pier failure. The external conditions such as the time difference of arrival of seismic wave and the stiffness of support will affect the deformation of bridge piers. In addition, the number of separations will also change the seismic response of the pier.

Study on Influence of Shield Side-piercing Construction on Pile Foundation of Nearby High-speed Railway Bridge

Taking the pile foundation of Suzhou Metro Line 3 passing through viaduct as the engineering background, the driving process of shield tunnel is simulated by finite element software. Through the analysis of surface settlement, bridge pier deformation and bridge pile foundation deformation in shield construction, the following conclusions are drawn: The foundation reinforcement “scheme of root pile + sleeve valve pipe grouting” has an obvious effect on reducing the ground settlement, the deformation of bridge piers and the deformation of pile foundation structure. The deformation and stress of the pile foundation of the bridge and the horizontal displacement of the pier above it are related to its distance from the tunnel, and the nearer it is, the greater its influence is. Whether the foundation is strengthened or not has little influence on the change law of axial force of bridge pile foundation, and the maximum axial force appears at the inflection point of horizontal displacement. Due to the excavation of shield tunnel, the bending moment of pile foundation changes in three sections along the depth direction, and the change of bending moment in the middle section is opposite to that on both sides.

Safety analysis for bridge pier under nearby road construction and operation

A temporary road underneath a riverine expressway was constructed to accommodate the need of transporting soil for land reclamation. One of the most outstanding characteristics of the new temporary road was that it passed underneath the piers of a continuous reinforced concrete bridge. The additional loads caused by the road construction and later on operation with heavy trucks potentially jeopardized the safety of bridges. The objective of this study was to examine the influence of the road construction and operation on the behavior of bridge piers and foundation piles. In addition, the effectiveness of a retrofit countermeasure of using steel sheet walls for improving the stability of the bridge was studied. A detailed three-dimensional finite element (FE) model, capable of addressing the interactions between pier columns, pile foundations, surrounding soils, and heavy truckloads, was developed to facilitate the analyses. After validating the model with the common analytical M method, the developed model was employed to investigate the behavior of bridge under the combined effects from temporary road loads (i.e., soil excavation load, pavement weight, and heavy truckloads). Field measured data from a tilt health monitoring system were utilized to verify the performance of FE analyses and confirm the performance of the retrofit countermeasure for pier deformation control. The steel sheet walls were found to be effective in increasing the safety of existing bridge piers.

Model of Reinforced-Concrete Structure Deformation Under Combined Effect Carbonation and Chloride Corrosion

The present paper is devoted to creating a model of deformation and destruction of reinforced-concrete bridge structures subject to combined effect of load and carbonation (caused by presence of carbon dioxide), and chloride corrosion triggered by salts used for bridge road deicing. The model is a hybrid of several models such as loading model; structural element model (pier, beam, roadway slab, span structure); impact models of two corrosive environment triggering carbonation and chloride corrosion; concrete deformation models (considering transformations caused by impact of various corrosive environments); reinforcement corrosive wear model. Concrete deformation model is created with due regard to nonlinearity of its operation and variable tension and compression resistance. Impact functions are the tool that demonstrates the influence carbonation and chloride corrosion have on the structure. Corrosive wear model is built as a piecewise function with a zero value at the incubation period, and as a power function after the end of the incubation period. Due to combined effect of carbonation and chloride corrosion, critical content of chlorides (which triggers reinforcement corrosion) drops twofold at a critical value of the carbonation process parameter, and this significantly shortens the incubation period. The paper describes the generalized model bridge pier deformation due to combined effect of load, carbonation, and chloride corrosion. The model shows the stages of how pier operates during ingression of the chloride-containing environment and carbon dioxide to the cross-section from the outside. The pier calculation methodology has three phases: loading, pier submerging into a corrosive environment (which causes chloride corrosion and carbonation), and pier deformation over time with due regard to change of mechanical qualities of concrete (caused by carbonation and chloride corrosion), and to reinforcement corrosion. When calculating pier deformation over time, time steps are used; step duration is set to ensure that changes of all step-sensitive parameters (chloride content, stress) would not exceed the preset limits. Following the methodology, a software package was developed, which enabled to calculate the values of the vertically loaded pier under combined effect of a chloride-containing environment and carbonation. As a result, it was found that under the combined effect of chlorides and carbon dioxide, the incubation period of reinforcement corrosion shortens significantly, corrosion intensity grows, and pier durability turns out to be shorter than when impacted by each factor separately.

Measurement of Pier Deformation Patterns by Ground-Based SAR Interferometry: Application to a Bollard Pull Trial

In this paper, we describe a new methodology for the nondestructive measurement of absolute displacements of a pier during a bollard pull trial by ground-based synthetic aperture radar (GBSAR) interferometry. This technique measures displacement patterns with a submillimeter precision in any weather conditions, operating at a distance up to $\text{4 km}$ from the target area. Bollard pull trials are performed to study the deformation response of a pier when a static pull is applied by a tug to a bollard on the pier edge. The precise measurement of the pulling force and the corresponding displacement pattern of the pier around the bollard is a useful piece of information for the back-analysis studies during the assessment phases of recently built piers. An experiment is carried out to measure pier's displacements at 12 co-located corner reflectors (CRs) and surveying prisms, by SAR interferometry and topographic techniques during a bollard pull trial. The GBSAR results have been validated at the CR locations using the displacement measurements provided by topographic survey. The pulling force applied to the bollard is measured by a load cell specifically customized to precisely measure the pulling force during the trial. Results demonstrate that GBSAR systems can provide a useful tool for the assessment of harbor infrastructures, such as piers, measuring absolute displacements with near-real time capabilities.

Effects of Pier Deformation on Train Operations within High-Speed Railway Ballastless Track–Bridge Systems

The deformation of a bridge foundation (i.e. pier) for a ballastless track of a high-speed railway may cause additional irregularities within the track, thereby affecting train operation. By using a unit slab ballastless track bridge system as the research object, this study built a finite element model and a train–track dynamic interaction model. The additional rail deformation caused by the vertical or lateral deformation of a bridge pier was calculated by the finite element model, and then the effects on train operation due to the additional rail deformation were analyzed by the train–track dynamic model. It was found that the lateral deformation of a single pier should be of the most concern for the management and control of a high-speed railway. Specifically, when a pier suffered settlement and lateral deformation concurrently, the evaluation indices of train operation were primarily affected by the magnitude of the lateral deformation, and were only slightly affected by the settlement.

Subsidence Displacement Analysis of Bridge Pier under Approaching Excavation Load

Based on the finite element model of approaching excavation of foundation pit, the influence laws of excavation depth and distance on the bridge pier deformation are studied. The results show that subsidence displacement of the bridge pier increases with the increasing of the approaching excavation depth. The axial force of the steel pipe near the bridge pier is greater than that far away from the bridge pier. The influence of approaching excavation distance on foundation pit decreases with the approaching excavation distance increasing. The maximum sedimentation deformation appears at the location of 0.5B (B is the lateral width of the pier). When the approaching excavation distance is less than 1B, sedimentation deformation of the pier is dangerous. When the approaching excavation distance is greater than 1B, sedimentation deformation of the pier is safe.

The Inclination of Bridge Pier due to Neighboring Embankment Construction and its Rectification Technique

In case of highway road construction often beneath existing overpass project, the filling of neighboring embankment may cause lateral displacement of bridge piers, which seriously threaten the safety of bridge. One case history, for inclination disease of overpass bridge piers in soft soil area, was presented. Aiming at the deformation of piers caused by the neighboring embankment construction, the displacement feature of bridge bearings were tracked and measured by site monitoring, and the damaged position of piles were clarified with low strain dynamic test. For these geological traits, the reasons of the inclination were analyzed. And the rectification method of applying surcharge load for smaller deviation (50mm) and the rectification method of pushing combined traction for serious deviation (>50mm) were respectively put forward on the basis of the lateral displacement statistics of bearings and the analytical standard set by Bozozuk. Site observation indicates these rectification methods can achieve the desired results.

Numerical analysis of vertically loaded rammed aggregate piers and pier groups

Predicting the effects of piers in settlement control and capacity enhancement of foundations supported by rammed aggregate piers (RAPs) is an important aspect in design of these foundations. To quantify these effects, employing the finite-element approach, a series of three-dimensional elasto-plastic numerical models of RAP foundations were developed. To take into account the influence of radial stress development in the matrix soil during the ramming process, which forces aggregate downwards and outwards into the borehole wall, the cavity was expanded both in radial direction and downward at the base of the pier. Using a parametric study, the effects of some parameters such as piers slenderness, the ratio of piers area to the foundation area and soil properties on static behaviour of such a foundation system were investigated. Using the results of the parametric study conducted on single piers, the research aimed also to provide new insights into the group behaviour of piers when they are subjected to vertical loads. The results demonstrated that the dominant deformation of piers in group is a tendency to tip-stress behaviour. Based on the results provided in this study, which were focused on the load–settlement behaviour of RAPs-supported foundations, a settlement-based design procedure was presented for RAP systems in which the values of slenderness and the area ratios are determined.

Monitoring and Analysis of Railway Bridge Pier Deformation of Municipal Engineering Crossing underneath Beijing-Shanghai High Speed Railway

Taking the bridge pier monitoring when a municipal engineering was passing through Beijing-Shanghai High Speed Railway (BSHR) as a example, monitoring plan, its implementation of automatic monitoring combined with manual control and comprehensive analysis of monitoring data are introduced ,to provide theoretical reference for similar engineering monitoring plan design .

Monitoring and Analysis of Railway Bridge Pier Deformation of Municipal Engineering Crossing underneath Beijing-Shanghai High Speed Railway

Taking the bridge pier monitoring when a municipal engineering was passing through Beijing-Shanghai High Speed Railway (BSHR) as a example, monitoring plan, its implementation of automatic monitoring combined with manual control and comprehensive analysis of monitoring data are introduced ,to provide theoretical reference for similar engineering monitoring plan design .

Numerical Modeling and Simulation on Seismic Performance of High-Speed Railway Bridge System

In this paper, the responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation. Elastic deformation will occur in the bridge system under low-level earthquake; however, the bridge system may enter a nonlinear stage under high-level earthquake. The whole finite element model of the bridge system was set up by means of ANSYS software and self-compiled moment-curvature relationship program, the elastic seismic responses of bridge system and the elastic-plastic deformation of piers considering different vehicle speeds are calculated respectively. The calculation results show that, the earthquake responses of bridge system are increase in general with the increase of vehicle speed and earthquake intensity, and the bottom of piers step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred at the pier bottom, the pier bottom step into the plastic stage, some measures such as lateral reinforced steel encryption should be taken into account to ensure safety.

Numerical Seismic Analysis of Simply-Supported Girder Railway Bridge under High-Speed Train Load

Along with rapid development of high-speed railway in many countries, recently research on seismic response of high-speed railway bridge under train load has raised much concern among researchers. The whole bridge finite element model is establish to analysis the seismic responses of simply-supported girder railway bridge subjected to high-speed train in this paper, ICE series high speed vehicle is employed as train live load, the vehicle is simulated by moving spring-mass system, The track irregularities can be obtained by Simpack software, the birdge incluing superstructure and substructure is three-dimensional space beam element, the bottom of piers is proposed consolidated. elastic seismic responses of bridge system and elastic-plastic deformation of piers considering different train speeds are calculated. The calculation results indicate that, seismic responses of bridge system are increase with the increase of train speed and earthquake intensity, and the bottom of piers will step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred within 1.4 meters of bottom of pier. The numerical results can provide some references for design of high-speed railway bridge.

Effect of Pier Vertical Deformations on Deflections of Main Girders for High Pier and Long-Span Continuous Rigid-Frame Bridges

In some long-span prestressed concrete box girder bridges, excessive deflections of main girders are often observed. These unacceptable deflections have detrimental influence on the serviceability and safety of the structures. To better understand and estimate short term and long term deflections for prestressed concrete box girder bridges, pier vertical deformation and its effect on deflections of main girders of Jinghe Bridg is investigated in this paper. Piers in Jinghe Bridge are tall and the difference in height between piers up to 22 m. Analysis indicates that although the short term deformations of piers are small, the long term deformations of piers can be 3 times as large as that of short-term ones. The maximum short-term downward deflection of Jinghe Bridge caused by pier deformation for main girders is 7.7 mm and the maximum long-term downward deflection is 33.3 mm. These values are relatively small compared with the span length of the bridge. But when the deflection of the main girder itself is also included, the final total deflection of the main girder may exceed the design code limit.