Pile Cap Research Articles

Study of spun pile connection with steel jacket strengthening

The amount of spiral reinforcement in the spun pile manufactured in Indonesia is below the minimum requirement. Additional shear reinforcement is needed, particularly on a pile at the adjacent pile cap. To cope with the deficiency, steel jacket is initiated to strengthen the pile. A numerical study was performed to study the effect of steel jacket addition to spun pile behavior. Two different software, SAP and Abaqus were employed. Pushover analysis was performed with a monotonic loading approach. The parameters studied were the steel jacket’s thickness and the existence of adhesive between the steel and the concrete surface. Brittle behavior was detected with the presence of steel jacket which was indicated by the force displacement curve. The steel improves the strength of the spun pile connection but decreases the ductility. It seems that pile is in over reinforced condition. To get a thorough understanding, a 3D model with Abaqus software was performed. Steel jacket is applied on the spun pile without rebar inside concrete fill and thinner steel was selected to prevent over reinforce. Hence, different results were found where spun pile connections behave in a ductile manner. Steel jacket improves not only the strength of spun pile connection but also the ductility.

Load-displacement behaviour of tapered piles: Theoretical modelling and analysis

This paper presents a simplified analytical approach for evaluating the load-displacement response of single tapered pile and pile groups under static axial compressive loads. The response of the tapered pile shaft is considered elastically in the initial stage, whereas the increase in stresses due to slippage along the pile-soil interface is obtained from a developed undrained cylindrical cavity expansion solution based on the K0-based anisotropic modified Cam-clay (K0-AMCC) model. An effective iterative computer program is developed to calculate the load-displacement behaviour of a single tapered pile. Regarding the response analysis of tapered pile groups, a finite-difference method is employed to calculate the interaction between tapered pile shaft, and the linear elastic model to simulate the interaction developed at the pile base. A reduction coefficient is introduced into the analysis of pile shaft interaction to clarify the reinforcing effect between tapered piles. Therefore, the settlement calculation methods of pile groups are proposed for different pile cap stiffness. The calculation methods of single tapered pile and pile groups are validated using two 3D Finite Element (FE) programs, and the comparison results show that reasonable predictions can be made using the method proposed in this paper. Parametric studies are conducted to investigate the effects of taper angle, soil anisotropy, pile spacing, and pile number on the load-displacement behaviour of single tapered pile and tapered pile groups.

Numerical analyses of two-pile caps considering lateral friction between the piles and soil

abstract: Pile caps are structural elements used to transfer loads from the superstructure to a group of piles. The design of caps is normally based on analytical formulations, considering the strut and tie method. Through the advance of computational technology, the use of an integrated soil and foundation model may suggest a behavioral trend to obtain a more realistic modeling for the structural element being studied. This work aimed at analyzing, in numerical fashion, the structural behavior of reinforced concrete two-pile caps considering the lateral friction between the piles and the ground through a continuous modeling, as well as to analyze the portion of the load that is transferred to the ground directly by the cap. The lateral friction was modeled considering node coupling and through contact elements. Simulations were performed considering three soil types (sandy, clayish, and soilless), three cap heights, and three pile lengths. Soil parameters were obtained through semi-empirical correlations. Through these analyses, the conclusion was reached that, on average, 4.50% of the force applied to the pillar is transferred directly to the ground by cap. In terms of the principal compression stresses, in the superior nodal region, the strut tends to form beyond the section of the column. Alternatively, increasing cap stiffness provided, on average, an increase in the load carrying capacity of the models.

Influence of foundation flexibility on seismic fragility of reinforced concrete high-rise buildings

This study investigated the effect of foundation type and layout on the seismic vulnerability of tall reinforced concrete buildings using fragility curves. To this end, the seismic fragility of 12-, 18-, and 24-story buildings sitting on shallow and pile foundations (i.e., with rigid and flexible pile caps) were evaluated. The uncertainty in the structural and soil properties was assessed by using the Latin Hypercube Sampling method and the seismic uncertainty was incorporated using several near- and far-field earthquakes. The results showed that the use of flexible pile caps reduced the seismic fragility and base shear of superstructures compared to the piled structures with rigid pile caps. Furthermore, the flexible pile caps improved the seismic performance of pile foundations by reducing the earthquake-induced pile head forces and deflection. The findings of this study can help the engineers to select the appropriate foundation layout to optimize the seismic performance of buildings.

Influence of higher-order modes of slender tall pier bridge columns on the seismic performance of pile foundations

Numerous highway bridges have been constructed with slender tall piers over 40 m in Southwest China, due to the mountainous topography. Current researches on this type of bridges mainly focus on the higher mode effects on the seismic behavior of pier columns, while the responses of group pile foundations are generally neglected. The objective of this paper is to investigate how the dynamic demand of group piles are influenced by the higher-order modes of slender tall pier columns. To better understand the influence of higher order modes, two analysis scenarios, representing (1) the equivalent single-degree-of-freedom (SDOF) system neglecting higher mode effects of piers, and (2) the multi-degree-of-freedom (MDOF) system of the original bridge, are developed and analyzed. Fiber elements are utilized considering the potential nonlinear behavior of pier columns and piles, while nonlinear p-y, t-z and q-z springs are employed simulating the properties of soil layers in these numerical models. Using displacement of pile cap as damage index, the effects of higher-order modes on pile foundations are investigated through both incremental dynamic analysis (IDA) and fragility analysis procedures. The results show that the seismic demands of pile foundations could be significantly underestimated when the contribution of higher-order modes of columns are neglected. The damage of piles is observed prior to that of the pier columns, indicating that damage state of pile foundations should be carefully considered during seismic design, and only focusing on the pier columns would lead to unconservative results. Furthermore, p-y springs are shown to perform nonlinearly under strong excitations, which implies that modeling the soil layers with linear springs is insufficient and should be better considered with these nonlinear springs.

Monitoring of the Response of the Sagamore Parkway Bridge and its Foundations During a Live Load Test

In this paper, we report the results of a live load test performed on the Sagamore Parkway bridge over the Wabash River, Indiana. The seven-span concrete bridge was constructed from 2016 to 2018 to replace the old, east-bound bridge. The main goals of the live load test were: (i) to study the transfer of the live loads from the bridge pier to the foundation elements and the distribution of live loads among the individual piles supporting the bridge pier; and (ii) to verify the assumptions (e.g., regarding the pile cap resistance) made in bridge foundation design. For these purposes, one of the interior piers (Pier 7) of the bridge and the fifteen pipe piles supporting it were instrumented with vibrating-wire strain gauges. With the bridge temporarily closed to traffic, the live load test was performed by parking twelve loaded triaxle trucks at specific locations on the bridge deck near Pier 7 in March 2019. The truck loads were applied in seven stages, simulating the driving of several trucks over the bridge pier. The settlement of the pier was measured using a digital level during the live load test. The data from the strain gauge readings were processed to produce the history of load distribution within the cross section of the pier and among the piles in the pile group during the seven stages of the live load test. The soil in contact with the pile cap carried about half of the total live load.

A three-dimensional investigation on performance of batter pile groups in laterally spreading ground

The performance of batter pile groups in laterally spreading ground has rarely been investigated. The present study evaluates the performance of 2 × 1 batter pile groups with four different configurations subjected to lateral spreading displacement through three-dimensional, fully coupled numerical investigations. Pressure dependent multi-yield model for the soil medium complemented with variation in permeability of liquefiable soil for excess pore pressure generation is considered. The nonlinear behaviour of the reinforced concrete pile is also incorporated. The behaviour of batter pile groups is evaluated for various earthquake time histories. The study indicates that the bending moment developed in the pile sections of both upstream and downstream sides of the ground displacement is observed to reduce under combined (kinematic + inertial) loading conditions for batter pile group configurations considered. However, shear and axial forces show increasing trends for batter pile groups, especially with higher batter angles for both kinematic and combined loading conditions. It is also observed that the presence of batter piles reduces both pile cap and superstructure displacements. However, significant pile cap rotations are recorded for pile groups with higher batter angles. The performances of the pile groups are confirmed for earthquake motions with a wide range of peak ground accelerations.

Dynamic Response of Single Pile Subjected to Different Frequencies in Gypseous Soil

This paper exhibits an experimental study on dynamic response of a single pile under dynamic load which comes from motor placed on cap pile called a vibration source. This study used the effect of the dynamic movement of vibration on one pile, collapsible soil (gypseous soil) used in this study with 30% gypsum content. The experiment is performed in a dry and soak state. A solid steel pile with a slenderness ratio of 27 was inserted into the soil after preparing it in layers in a steel container (30 * 30 * 60) cm. The test was performed under a dynamic response to the different frequencies 10, 15, 20, and 25 Hz. The results showed that the speed, acceleration and displacement increase with increasing frequency of the vibration source in addition to that the values of speed, acceleration and displacement amplitude are less in the case of soaking compared to their values in the dry state.

Dynamic Response of Machine Foundation Resting on End Bearing Piles

Herein, a finite element software (ANSYS. 11) is adopted which provides an effective tool for dynamic analysis and structural design of machine-foundations. As a case study, machine foundation on piles in sandy soil is investigated. Machine foundations supported by end-bearing piles are introduced. Sinusoidal dynamic load is applied. A study of parameters is conducted to investigate the influence of a number of parameters that include: geometry of the piles below the foundation, the dynamic load amplitude, damping ratio and frequency of the load. Linear elastic model is adopted for modeling the piles and their cap for machine foundation using eight node isoparametric (solid 65) element, while elastic model is adopted to model the soil behavior and eight node isoparametric elements are used to model the soil through (solid 45) element. It is concluded that the frequency ratio decreases with increase of spacing between piles values due to increase in natural frequency, except in the case of 3 m spacing where it increases due to decrease in natural frequency as the mass was increased obviously. The increase in spacing caused the increase of natural frequency by about 6% in the model having 1.5 m spacing more than the 1.25 m case and by about 3% for the 1.75 m spacing more than the 1.5 m reference case. The increase in pile cap length caused the natural frequency to decrease by about 18% for the 3.75 m pile cap length as compared with the reference case and by 29% in the case of 5 m less than the reference case. In the case of increasing pile cap thickness, there was only a slight difference in the values of natural frequency.

KAJIAN METODA PELAKSANAAN PEKERJAAN PONDASI BORED PILE PADA TAHAP PERENCANAAN PELAKSANAAN

Pondasi bored pile adalah pondasi tiang yang pemasangannya dilakukan dengan mengebor tanah lebih dahulu. Jenis pondasi bored pile banyak digunakan pada proyek konstruksi. Pelaksanaan pondasi bored pile yang dipilih disesuaikan dengan jenis tanah, kondisi medan serta metode konstruksi yang terpilih. Metode konstruksi merupakan penjabaran tata cara dan teknik-teknik pelaksanaan pekerjaan yang merupakan inti dari seluruh kegiatan dalam sistem manajemen konstruksi. Untuk itu menarik dilakukan kajian bagaimanakah metode pelaksanaan pondasi bored pile pada tahap perencanaan pelaksanaan pada proyek Pembangunan GOR di Abiansemal,Badung. Tahap perencanaan pelaksanaan merupakan kegiatan yang penting guna memberikan gambaran lebih rinci tentang strategi dan teknik pengerjaan secara efisien dan efektip baik dari segi waktu,mutu dan biaya. Adapun tujuan yang ingin dicapai dalam penelitian ini adalah melakukan kajian mengenai metode pelaksanaan pondasi pada tahap perencanaan pelaksanaan. Sehingga dapat memberikan sumbangan dalam pengembangan ilmu pengetahuan tentang penerapan teori metode pelaksanaan pondasi bored pile dan merupakan informasi bagi mereka yang tertarik dengan penelitian selanjutnya. Berdasarkan hasil kajian bahwa pada pekerjaan persiapan diawali dengan penentuan titik pusat pile dan penempatan alat bored pile. Pada pekerjaan pengeboran menggunakan metode wet drilling volume 1105 m dengan durasi 8 hari. Untuk pekerjaan pembesian volume 9309.61 kg dan durasi 13 hari didahului dengan proses fabrikasi dan dilanjutkan dengan pemasangan tulangan ke dalam lubang bor. Pengecoran dilakukan menggunakan pipa tremi, volume 74.394 m³ dengan durasi 11 hari. Selanjutnya dilakukan penentuan as pile cap dan pekerjaan galian,dilanjutkan dengan pekerjaan lantai pile cap dengan pasir urugan beton, volume 136.708 m³ selama 6 hari. Sebagai bekisting menggunakan batako dengan volume 237.474 m² dikerjakan selama 14 hari, dilanjutkan dengan pembentukan tulangan dan perakitan tulangan volume 5454.21 kg dengan durasi 9 hari serta metode pengecoran dilakukan dengan cara manual dengan volume 117.632 m³ dan durasi 14 hari.

Seismic behavior of a dolphin-type berth subjected to liquefaction induced lateral spreading: 1g large scale shake table testing and numerical simulations

The effects of liquefaction induced lateral spreading on the piles of a dolphin-type berth were investigated using 1 g large scale shake table testing accompanied by numerical simulations. For this purpose, various aspects of the response of the soil and the pile group to lateral spreading were considered. The results indicated that large bending moments were induced in the piles during lateral spreading and the downslope piles of the group received greater bending moments than the upslope one. The monotonic components of bending moments in the piles were reasonably predicted by the displacement based numerical approach using p-y springs when they were properly tuned for strength reduction in liquefied soil and the pile position in the group. A three dimensional hydro-mechanical finite element analysis was also undertaken in OpenSees which appropriately reproduced the physical model behavior. Lastly, a comprehensive parametric study on the verified finite element model revealed that the relative density of soil and the amplitude of base excitation can profoundly affect the induced bending moments in piles as well as the pile cap displacements while the effect of pile flexibility was comparably smaller in this regard.

Analisis Pondasi Tiang Pancang Berdasarkan Hasil Perhitungan dan Loadding Test

Pile foundation is one of the solutions of high-rise buildings not in the area of restrict area. When the pile foundation reached until the hard ground reaches, a small settlement is expected and different setlement are not occur. The objective: analyze the results of loading tests compared carryng capacity calculations, pile cap thick required secure.The research method used in this research is the case study of pile foundation twelve floors building in Batam island. The reaction on the pile is analyzed using software program of non-linear structure version 9.5 which is supported by primary data, namely loading test and secondary data of soil investigation and the largest column force taken on the pole 1.618,854 ton, Mx -7,936 ton meter, My -75,531 ton meter.Carrying capacity analysis is based on friction and end bearing and calculated pole efficiency. The axial load of the plan is supported by 16 (sixteen) piles, based on the loading test (P) the ultimate pile foundation reaches 200% (two hundred percent) in the amount of 411.52 tons. Single pile carrying capacity is 205.76 tons .Settlement in the loading test results 10mm is smaller than from the setlement in calculation results. The stress acting on the pile cap of 12.453 kg/cm2 is smaller than the permit strees of 13 kg/cm2.

Development of high performance sustainable optimized fiber reinforced geopolymer concrete and prediction of compressive strength

Geopolymer concrete is the sustainable building material that can be used as an alternative for cement concrete. There are several factors that affect the property of geopolymer concrete such as type of binder material used, molarity of activator solution and curing condition. The frailty of practical application of geopolymer concrete lies in its brittle nature. The main objective of this work focuses towards the synthesis of high impact strength fiber reinforced geopolymer concrete by optimizing various factors that affect its strength and reduce its brittleness. The novelty of the work lies in the approach of augmentation of high modulus glass fibers over the optimized Geopolymer concrete. In the current investigation, extensive experimental works were conducted to optimize the molarity of alkaline solution, utilization of Ground Granulated Blast Furnace Slag and glass fiber in geopolymer concrete under different curing condition. Further Microstructural investigation through Scanning Electron Microscopic analysis and Energy Dispersive Spectroscopy analysis was carried over to understand the microstructure of the geopolymer matrix. An exhaustive and meticulous discussion part is included to elaborate the influence of molarity, curing condition, Ground Granulated Blast Furnace Slag utilization and incorporation of fibers in to the geopolymer matrix. Analytical Investigation though Artificial Neural Network has been performed to predict the compressive strength of the fiber reinforced geopolymer concrete based on three different input conditions. This study reported the optimum molarity of sodium hydroxide as 13M and optimum utilization of GGBS slag as 100 percent under ambient curing and 20 percent under heat curing. Further the work reported significant increase of about ten times in the energy absorption capacity and considerable decrease over the brittleness of the geopolymer concrete with the utilization of glass fiber. This research work could pave way for the development of high performance sustainable geopolymer concrete under ambient curing condition enabling the application of application of geopolymer concrete in industry that demand high impact strength materials such as machine foundations, pile caps, spill ways. This concrete could pave way for replacing conventional concrete in all its existing applications.

Study on Underpinning Scheme of Viaduct Pile Foundation Crossed by Shield Tunnel

Rapid developments in domestic metro construction could inevitably result in cross-engineering conflicts between metro lines and existing bridge pile foundations. Pile underpinning technology has been successfully applied to such projects to ensure the operating safety of viaducts and synchronous construction of metro lines. One section tunnel of Jinan Metro Line R2 is selected as the research object in this study. First, the processes of pile underpinning and tunnel crossing construction are numerically simulated using finite element software. Next, the deformation law of underpinning structures is studied and the engineering risk points are determined. Finally, the design scheme of pile underpinning is proven to be correct and reasonable. The results are as follows: (1) The underpinning structure presents a trend of overall settlement. The horizontal displacement of the pile body occurs in the form of a bow. Maximum deformation occurs at the underpinning beam and top of the pile. (2) The influence area of the soil surface is approximately 4 m outside the underpinning beam, and the deformation values of the underpinning system meet construction requirements. (3) The following construction steps are recommended. Step 1: Pre-jacking constructing. Step 2: Pile cutting. Step 3: Jack removal and underpinning beam and pile cap construction. Step 4: Road surface backfilling and repair. The shield machine should then be allowed to pass. (4) This paper provides targeted risk management measures. For example, isolation piles should be set on both sides of the tunnel.

Analysis methods for pile foundation: a critical review of the literature and recommended suggestions

Pile cap foundation is a type of deep foundation. These types of foundations are used when soil, constructional or economical condition makes it necessary to transfer load of structure to the soil strata which are beyond the reach of shallow foundation. Foundation of any structures transfers the total super-structural load to soil. In case of deep foundation, the process of rehabilitation or repair is quite difficult. Hence, it should be designed properly to satisfy strength, serviceability, economic and constructability requirement. Investigation on all parameters related to these requirements is now in process, under order to develop an effective and simple approach for design of such foundations. In the present paper various methods for analysis of pile foundation are discussed in comprehensive manner. Moreover, suggestions are recommended on the basis of existing analysis methods.

Behaviour of pile foundation of G+5 buildings on various soil types of Guwahati at regional scale

The paper presents the results of a parametric study of static and dynamic response of pile groups of G+5 buildings of Guwahati, the capital city of Assam situated in India. Based on a preliminary survey conducted on 500 buildings of the city, it is observed that most of the buildings under survey are G+5 buildings. Guwahati, being a hub of erratic topography, consists of varied soil types. These soil types are grouped into various geo-units on the basis of their grain size distribution obtained from the geotechnical investigations at around 600 boreholes within the city. The study is conducted by modelling a representative G+5 building with piles, grouped in five, fixed at the head by pile caps and embedded in a homogeneous soil stratum in a finite element formulating software, PLAXIS 3D. The results are presented in the form of comprehensive plots, and a comparative study is made to obtain the pattern of pile behaviour, in terms of deflection, bending moment and shear force, in various geo-units of Guwahati. The paper gives an insight to the pile designers of the region, an estimation of the maximum seismically induced deflection, bending moment and shear strength of the pile to maintain the structural integrity of the pile, when the pile is embedded in different types of soil of Guwahati.

Influence of phase difference between kinematic and inertial loads on seismic behaviour of pile foundations in layered soils

A series of dynamic centrifuge experiments was conducted on model pile foundations embedded in a two-layered soil profile consisting of soft-clay layer underlain by dense sand. These experiments were specifically designed to investigate the individual effect of kinematic and inertial loads on a single pile and a 3 × 1 row pile group during model earthquakes. It was observed that the ratio of free-field soil natural frequency to the natural frequency of structure might not govern the phase relationship between the kinematic and inertial loads for pile foundations as reported in some previous research. The phase relationship obtained in this study agrees well with the conventional phase variation between the force and displacement of a viscously damped simple oscillator subjected to a harmonic force. Further, as expected, the pile accelerations and bending moments can be smaller when the kinematic and inertial loads act against each other compared to the case when they act together on the pile foundations. This study also revealed that the peak kinematic pile bending moment will be at the interface of soil layers for both single pile and pile group. However, in the presence of both kinematic and inertial loads, the peak pile bending moment can occur either at the shallower depths or at the interface of soil layers depending on the pile cap rotational constraint.

Time-dependent response of laterally loaded piles and pile groups embedded in transversely isotropic saturated viscoelastic soils

This paper investigates the time-dependent response of laterally loaded single piles and pile groups embedded in transversely isotropic saturated viscoelastic soils. The solution for single piles subjected to lateral loads is solved by the coupling of the boundary element method and the Timoshenko beam theory. In the analysis of the pile group, the interaction between piles is taken into account and the generalized displacements caused by all piles are obtained by superimposing the influences of boundary forces on the soil-pile interfaces. The load distribution from the pile cap to pile tops is involved in the analysis. The presented method of laterally loaded piles and pile groups is verified through several examples, and the influences of some key parameters including transverse isotropy, the viscoelastic parameters, the flexibility coefficient, the slenderness ratio and the pile spacing are investigated by numerical examples.

Effect of Free Vibration Frequency on Modeling of Bridge Pier

Pile groups are a widely used foundation system to support structures placed over soft soil or when the shallow foundation is not appropriate due to excessive settlement especially for bridges, flyovers, or metro piers. Estimation of appropriate free vibration frequency for a bridge pier in design procedure gives appropriate and more optimized design. The frequencies obtained by considering soil pile interaction are more realistic than considering bridge pier as single degree of freedom (SDOF) system fixed at top of a pile cap. In the present study, the frequency is calculated by modeling the pier as SDOF system as well as by considering the soil-pile interaction effect. It is observed that to evaluate free vibration frequency, pile-soil interaction effect including distributed mass system for pier should be accounted.

Numerical stability analysis of piled embankments reinforced with ground beams

Rigid piles are extensively used to support high-speed railway embankments resting on soft ground, and ground beams are structural elements at ground level to connect adjacent pile caps to improve the stability of pile-supported embankments. In this study, a validated three-dimensional numerical model of piled embankment was developed based on a well-documented centrifuge test, where the Mohr–Coulomb tension crack model was adopted for capturing the brittle failure behavior of concrete piles. The results showed that concrete piles are subject to a serious bending failure within the clay layer when the overlying embankment collapses. By introducing the ground beams in conjunction with rigid piles, the resultant displacement of the improved area was markedly decreased and the pile failure mode was changed. The combination of concrete piles and ground beams results in a synergistic effect. According to the mechanical response of individual piles, the foundation soil was divided into the extension-bending, bending, bending-compression, and compression zones to elucidate the reinforcement mechanism related to ground beams. A proper arrangement of ground beams was ultimately obtained based on the localized slip resistance performance of the improved ground. Overall, this research contributes to the knowledge of piled embankment performance evaluation and may further extend the practical application of ground beams.