Pile-cap Connection Research Articles

Bearing Performance of Prestressed High-Strength Concrete Pipe Pile Cap Connections under Truncated Pile Conditions

To investigate the load-carrying performance of the nodes between tubular piles and bearing platforms, low circumferential reciprocating load foot-scale tests were performed on two truncated PHC B 600 130 tubular piles. The development law of node destruction was explored. The test results revealed that under the action of tensile–bending–shear loading, the bearing concrete in the node area buckled and was damaged, and an articulation point was formed. When the embedment depth increased from 200 mm to 300 mm, the ultimate bearing capacities of the positive and negative nodes increased by 57.60% and 54.60%, respectively. Numerical simulation was used to analyze the bearing capacities of nodes with different types and embedment depths. Formulas for the bearing capacity of the nodes were proposed. Furthermore, two preferred node types were proposed as follows: pipe pile core-filled longitudinal reinforcement anchored to the bearing node and pipe pile body longitudinal reinforcement anchored to the bearing node + pipe pile core-filled longitudinal reinforcement anchored to the bearing node, with preferred embedment depths of 350 mm and 200 mm, respectively.

Numerical Study of Strengthened Spun Pile with Concrete Infill and Steel Jacket

The confinements in a spun pile in Indonesia are below the minimum requirement mentioned in ASCE 7-16. Since Indonesia still adopts the linear elastic concept for foundation design, where the pile should be designed strongly without damage, the deficiency does not matter. However, enormous piles are required to keep it elastically under severe earthquakes. Hence, a transition to performance-based design (PBD) should be prepared since the seismic acceleration tends to increase. PBD requires sufficient transverse reinforcement to ensure flexural failure. Steel jacket is proposed to overcome the lack of confinements, particularly on the pile cap connection where the largest curvature occurs. Experimental and numerical studies have been conducted on a full-scale spun pile-to-pile cap connection with a steel jacket under cyclic loading. A monotonic pushover analysis with Opensees Navigator open-source software was performed for further study.

Study of Spun Pile to Pile Cap Connection with Steel Jacket Strengthening

Spun piles in Indonesia are designed to behave as an elastic structure according to SNI8460:2017. The piles are designed with low confinement where the amount does not meet ASCE 7-16 requirements. Indonesia should apply a performance-based design for the bottom structure someday since the seismic demand tends to increase based on the current seismic risk map. Steel jackets are proposed to fulfill the need for transverse reinforcement, particularly at the connection region where the curvature demand is higher. The steel jacket was made from high-quality zincalume steel, a high-quality rolled steel that is customizable following the size of the spun pile and has a low cost. Experimental and numerical studies were conducted. A 500mm diameter spun pile was retrofitted with a steel jacket loaded vertically and horizontally. The experimental study applied the cyclic loading according to ACI374.2r, and 0.1fc'Ag vertical load was applied. The experimental study applied the cyclic loading according to ACI374.2r, and 0.1fc'Ag vertical load was applied. The experimental study found that the spun pile and grouted concrete interaction was not perfectly bonded. A further finite element study was conducted to understand the connection's performance thoroughly. Two parameters were investigated, the steel jacket's height and thickness. A numerical study performed pushover analysis on the 3D model using the ABAQUS software to see the effect of the height and moment-curvature analysis obtained from fiber section element from SAP software to study the impact of the thickness. The results were presented in terms of its strength and ductility.

Analysis Methods for the Design of Pile–to–Pile Cap Connections Concerning Plain Pile Embedment

Analysis Methods for the Design of Pile–to–Pile Cap Connections Concerning Plain Pile Embedment

The Evaluation of Displacement Ductility of Low Confinement Spun Pile to Pile Cap Connections

The Evaluation of Displacement Ductility of Low Confinement Spun Pile to Pile Cap Connections

Numerical study of spun pile with steel jacket

The confinement ratio of spun piles manufactured in Indonesia has been a matter of concern since it does not meet the applicable requirements. Additional steel jacketing retrofitting was used to cope with the problem as well as improve the strength of spun pile to pile cap connection. A numerical study was performed to study the effect of steel jacketing on a spun pile with concrete infill reinforcement. Furthermore, a parametric study was conducted to study the effect of steel jacketing length to spun pile behaviour. Pushover analysis using the Opensees software will be performed with a monotonic loading approach. The results were compared in terms of load – displacement curve, shear and bending capacity, and displacement ductility. It is found that the presence of steel jacketing provides a better behaviour and significantly increases the ductility of specimens. The study also found that a minimum length 1.5D of steel jacketing retrofitting was necessary for better results and remain easily repairable for future concerns.

Behavior, Performance, and Evaluation of Prestressed Concrete/Steel Pipe/Steel H-Pile to Pile Cap Connections

Better understanding of the connection between piles and pile caps/footings is needed so that future designs and design reviews can be adequately performed. This review paper presented discussions on the published experimental and analytical studies on prestressed concrete piles, steel H-piles, or steel pipe piles with cast-in-place (CIP) or precast footings, and/or pile cap connections with a focus on (1) pile embedment to achieve a fully fixed or pinned moment connection; (2) behavior of the pile embedment length when not treated by a special connection detail; and (3) reinforcement details to decrease the embedment length and develop fixity with a plain pile. The length of the pile embedment contributing to achieving a full fixity condition has a critical impact on substructure cost involving pile-to-pile cap (PTPC) connections. The design procedures involving piles subjected to lateral loading require a proper understanding of the fixity and ductility levels provided by the PTPC connections. Discussions on finite-element analyses (FEAs) were presented, including behavior predictions of the connections at both global and local levels. The study points to the need for modifications to the design of the PTPC connections in the existing standard codes/specifications.

Pseudostatic Behavior of Precast Piers with Composite Pier–Pile Cap Connections: Experimental Investigation

Pseudostatic Behavior of Precast Piers with Composite Pier–Pile Cap Connections: Experimental Investigation

Numerical study of low confinement spun pile to pile cap connection

The numerical study has been conducted to investigate the behaviour of spun pile – pile cap connection based on the common practice in Indonesia. The piles manufactured in Indonesia have low confinement where the amount of transverse reinforcement is less than 20% than the minimum requirement set by ACI 318-19. The research objectives are to study the parameters that affect the behaviour of that connection. Three parameters investigated are: the connection details, the effect of concrete infill and the amount of transverse reinforcement. The typical connection of spun pile and pile cap in Indonesia is considered adequate and can perform as fixed connection since slip at connection region was not detected in the FE analysis. The embedment length is adequate to develop yield strength of the prestressed wire. By filling the hollow with the concrete it increases the connection strength by 15% whereas the strength improves more than 50% by adding 6D19 reinforced bar. Adequate confinement improves the performance of the connection at peak post-stage that affects ductility.

Simulation of pile cap contribution to the lateral pile performance due to adjacent excavation

Laboratory and field test data on the lateral pile response with caps due to adjacent excavation are rather limited. The current practice for design of capped piles is to consider the cap resistance and the pile capacity independent of each other. This paper presents some results from three-dimensional finite-difference analyses that couple the constrain effect of pile cap on the lateral pile performance adjacent to an excavation. The analyses were performed in saturated homogeneous clays, and 38 cases of various pile head conditions restrained by caps including embedded depths of the pile into the cap, relative pile cap–pile modulus and pile cap–pile interface stiffness were carried out. The results have shown that the pile–pile cap connections can significantly affect the distribution of lateral pile deflections and bending moments and change the lateral pile performance, especially with a deep-buried and completely fixed cap. To combine the effects of the pile head embedded depths and the cap material properties, a convenient design method based on statistical analysis for estimating the pile–pile cap connections was presented. The proposed constraint coefficient method can be used to assess the lateral performance of the capped pile and simplify the design procedure of the pile cap due to excavations.

Experimental behaviour of prefabricated pile-cap foundation under seismic loading

Precast building has attracted more and more interest of both researchers and engineers due to fast constructional speed and lower labour cost. In the past, the precast structure was generally used in the superstructure, such as load bearing frame, however, it is seldom applied in the substructure such as foundation. The paper thus proposed a type of pile-cap connection to fabricate the foundation of a substation. A series of tests on the prefabricated pile-cap connection using these connections were carried out under seismic loading. The failure mode and lateral load versus lateral displacement response of the tested specimens were experimentally investigated. The seismic behaviour of the precast foundation was compared with the behaviour of the corresponding cast-in-place foundation.

Study on Seismic Performance of Improved High‐Strength Concrete Pipe‐Pile Cap Connection

Four prestressed high‐strength concrete pile‐ (PHC pile‐) pile cap connections under low‐cycle loading were tested to study the test phenomena, failure modes, hysteretic performance, ductility, and bearing capacity. The PHC piles were reinforced with steel fiber and deformed bars and CFRP. The tests results showed that the connections were damaged by bending. The concrete of the caps were squeezed to be crushed. The concrete of connection was crushed and formed a hinge joint that resulted in the connection rotating unrestricted, and the rotation capacity of connection increased. The PHC pile reinforced with steel fiber and deformed bars can improve the displacement ductility of the connections. The finite element software ABAQUS was used to simulate the nonlinear behavior of pile‐cap connections. The prediction agreed relatively well with the experimental results. The stress and strain of specimens were studied. The connections should be designed with enough rotating capacity and make sure the cap will not be damaged by squeezing or prying due to the rotation of pile end.

Pile-cap Connection Behavior between Hollow-Head Precast Reinforced Concrete Pile and Foundation

Pile-cap Connection Behavior between Hollow-Head Precast Reinforced Concrete Pile and Foundation

Seismic Performance of Pile-Cap Connections of Prestressed High-Strength Concrete Pile with Different Details

This study investigated analytically and experimentally the pile-cap connection of a full-scale prestressed high-strength concrete pile considering three different connection details: the common connection (specimen CT-1), a strengthened connection (specimen CT-2) and an internal T-shape steel connection (specimen CT-3). Specifically, the failure modes, hysteretic performance, ductility and bearing capacity were studied. The test results show that the three connections experience different failure patterns. Specimen CT-1 was severely damaged primarily at the pile-cap connection due to the rupture of anchor plates and the formation of a plastic hinge, but no damage to the pile was observed. This connection consists of a relatively large node angle and behaves like a hinge, resulting in poor energy dissipation due to small moment resistance. Specimens CT-2 and CT-3 were damaged at lesser degree and in more sparse areas. These two types of connections have smaller node angles and behave as a rigid joint with greater moment resistance, leading to a higher energy dissipation. Bond slippage failure of anchor bars was not observed in the cap, and the anchor bar length was found to meet the design requirements. A non-linear finite element model (FEM) was established to analyse the mechanical properties of the three connections using ABAQUS. The moment–displacement curves obtained from the numerical analyses compare well with the experimental results. The degree of effects of influencing parameters on the behaviour of the connections was evaluated using the FEM.

PHC말뚝과 확대기초 연결방법에 따른 접합부 거동

Abstract: The pile-cap connection part which transfers foundation loads through pile body is critical element regarding flexural and shea r force because the change of area, stress, and stiffness occurs in the this region suddenly. The purpose of this study is to investigate the s tructural behavior of pile-cap connection dependent on fabrication methods using conventional PHC pile and composite PHC pile. A series of test under cyclic lateral load was performed and the connection behavior was discussed. From the test results, it was found that the initial rotational stiffness of pile-cap connection was affected by the length of pile-head inserted in footing and the location of longitudinal reinforcing bars. The types of pile an d location of longitudinal reinforcing bars governed the behavior of pile-cap connection regarding load-carrying capacity, ductility, and energy dissipati on.Keywords: Pile-cap connection, Cyclic lateral load, PHC pile, Composite PHC pile 1 정회원, 충남대학교 건설방재연구소 박사후 연구원

Testing of pile to pile-cap connection on steel pipe piles subject to axial and uplift loads

Testing of pile to pile-cap connection on steel pipe piles subject to axial and uplift loads

Flexible Pile Head in Jointless Bridges: Design Provisions for H-Piles in Cohesive Soils

AbstractSeveral methods are used to increase the lateral displacement capacity of the piles supporting jointless bridges, the most effective of which are predrilled holes and a flexible pile-cap connection. Depending on soil type and required displacement capacity, these two methods can be combined. This paper discusses a simple study carried out to demonstrate the efficiency of the flexible-head condition, and a finite-element analysis conducted on a prestressed pile. The model was first calibrated with the test results, and then a flexible detail was applied to the model. The results of this part of the study show that a flexible connection can increase the displacement capacity of embedded piles. Finally, nonlinear analyses were conducted using simulation software for compact HP piles. The results of these analyses revealed that strong axis bending results in larger displacement capacity compared to weak axis bending, although the stiffness is smaller in the latter case. Provisions are also developed t...

Experimental and numerical investigation on the behaviour of prestressed high strength concrete pile-to-pile cap connections

Six Prestressed High Strength Concrete (PHC) pile-to-pile cap connections were tested to evaluate their damage process and failure modes under low cyclic loading. The hysteretic behaviour, rotation angle, ductility and bearing capacity were observed and analyzed. In addition, the effect of connecting forms and cutting-off piles on seismic performance of pile-cap connections was considered and investigated. The experimental results showed that flexural bending failure occurred in all connections. There were two main failure modes. One was tensile rupturing of prestressed bars and headings, resulting in loss of bearing capacity of the connections. The other type was more severe damage due to anchor bar yield and appearance of plastic hinge. Moreover, bond-slip failure of anchor bars was not observed in the cap, and the length of anchor bars met requirements. The analysis indicated that the bearing capacity and energy dissipation capacity increased along with the rotation capacity of the pile connections. Nonlinear finite element models were established to analyze the mechanical properties of these connections using OpenSees. The load-displacement curves obtained from the numerical analysis agreed with the experimental results. The effects of various parameters on the behaviour of the connections were conducted based on the numerical model.

A Study of Pile Group Geometry on Soil Bed Response, under Dynamic Loads, Using Finite-Element Method

Abstract. Without a doubt, using piles in construction industry, considering various conditions of sites in different locations, especially in problem soils, seems unavoidable. High-priced laboratories unavailable for most designers, on one hand and well-proven capability of the finite-element method to get the job of obtaining acceptable results done, and pass the red face test of the concordance contest with experimental results, on the other hand, drags the trade-off trend of study methods to the latter. In this paper, with the use of finite-element method dynamic analysis, executed in Abaqus software, the effects of piles' geometry on soil bed response have been investigated. The results indicate that using piles with larger diameters is much more effective than using more piles with smaller ones. Furthermore, under dynamic stimulations, the uttermost displacement occurs at pile caps, and with a well-designed pile cap connection to the foundation, seismic failures, which are one of the most probable damages at connection points, can be prevented.

Seismic Performance of Prestressed High Strength Concrete Pile to Pile Cap Connections

Six pile-cap connections were tested to evaluate performance of prestressed high-strength concrete piles (PHC pile)-cap connection under cyclic loading. The failure modes, hysteretic performance, ductility and bearing capacity were observed and analyzed. In addition, the seismic performance of pile-cap connection with different connections and cutting-off pile was studied. The test results showed that the connections appear to be bending damage. The two flexural modes were tensile rupturing of prestressed bar and yielding of anchor bars. The connections were severely damaged because of the yielding of anchor bars and appearing of the plastic hinge. The bond slippage failure of anchor bars was not observed in the cap, and the length of anchor bars meet requirements. It shows that the bearing capacity and energy dissipation capacity increased with the rotation capacity of pile connection. Nonlinear finite element models were established to analyze the mechanical properties of these connections using ABAQUS. The moment-displacement curves obtained from the numerical analysis compared well with the experimental results. The effects of parameters on the behavior of the connections were conducted based on the numerical model.