Pile Cap Research Articles

Study on seismic response of liquefiable soil-pile group considering pile cap and soil contact

In this paper, based on the centrifuge test of liquefied soil-pile foundation system, a numerical model of liquefied soil-pile foundation-structure system is modelled by using OpenSees platform. In the simulation model, the friction effect between liquefied ground and low pile cap is considered, and the method of establishing virtual nodes is used to deal with the non-linear contact between liquefiable soil and low pile cap. The rationality and effectiveness of the numerical simulation method adopted in this paper has been verified and evaluated by comparing with the results of centrifuge experiments. A typical liquefaction soil-pile integrated finite element model is modelled using validated numerical simulation methods. The law of seismic response of the pile foundation system with different embedding depths of pile cap, different contact modes between the pile cap and saturated sand, and the thickness of the overlying saturated loose sand layer are discussed. The results show that the pile cap and pile foundation in the high pile cap system show higher seismic response characteristics than the other three low pile cap system conditions; Under the condition of different contact modes between the pile cap and the surrounding saturated sand, the peak bending moment and residual displacement of the pile foundation calculated by the bond contact are larger than calculated by the friction contact, and the deformation of pile is more significant. By comparing the working conditions of different thicknesses of overlying saturated loose sand layer, it is found that the degree of liquefaction in shallow soils is less affected by thickness of the saturated loose sand. As the thickness of saturated loose sand layer increases, the peak bending moment and residual displacement at the top of the pile also gradually increase. The change of peak bending moment at the soil interface is more obvious.

Field test on thermal control for bridge piers on plateau through energy pile

This study presents a sustainable thermal control method (energy pile technology) for bridge piers in high-altitude regions, addressing the challenges posed by temperature variations in mass concrete structures. The proposed method involves integrating various heat exchange tubes within the pile foundation, pile cap, and bridge pier concrete to harness shallow geothermal energy. This paper summarizes failure cases of bridge structures due to the impact of thermal loads. Through three field tests on a plateau, the feasibility and practicality of the energy pile technology are verified. The system exhibits promising results, achieving a maximum temperature difference reduction of 3.9°C and a reduction of 53.4%. Furthermore, the method has effectively reduced the expansion strain on the sunny side of the bridge piers, with a maximum reduction of up to 44.4%. Importantly, the energy pile technology has minimal impact on the pile foundation, with negligible constrained stress variation. The study evaluates the heat exchange efficiency and energy efficiency of the energy pile-based system, reporting stable heat exchange rates and a comprehensive Coefficient of Performance (COP) reaching up to 4.0. The findings highlight the potential of this sustainable temperature control methodology to enhance the resilience and longevity of critical infrastructure in challenging climates.

Experimental study on wave-induced loads and nonlinear effects for pier-pile group foundations of sea-crossing bridges: Wave slamming and suction effect

Strong nonlinear effects, such as wave slamming, suction effects, and wave overtopping, may be induced during wave-bridge interaction. However, an accurate understanding of these nonlinear effects is still insufficient. This study comprehensively investigates the wave slamming and suction effects on pier-pile group foundations of sea-crossing bridges in a 1:50 scale laboratory experiment. Random and regular waves with different strengths are generated based on wave conditions at the bridge site. Five water depths with a 2 cm spacing are designed to simulate varying pile cap clearances. Various pile arrangements are also set up to explore the influence of piles. Results show that wave slamming is low-aeration and is triggered mainly on the cap bottom wall, whereas the wave action on the vertical wall of the pile cap is quasi-static. The suction effect is generally recorded in the quasi-static phase of pressures and depends on the water exit process and the wave crest height. Moreover, the pressure oscillation after the impact phase results from the flow separation and rotation at structure corners. The wave slamming enhances with the increasing wave frequency when the impact area is constant, otherwise, it depends on the impact area. On the cap bottom wall, the wave slamming on inter-pile areas is enhanced, but the suction effect is less affected by pile arrangements. The increase in pile cap clearances reduces vertical forces but has less effect on horizontal forces. Additionally, a sustained increase in the wave crest height may reduce the slamming force. An empirical method for predicting wave forces is finally proposed based on the water entry theory and experimental findings. This work enhances the physical understanding of nonlinear effects during wave-bridge interaction and aims to support the design of substructures for sea-crossing bridges.

Inspection of Foundation Structures with Pile Integrity Test (PIT) of Steel Tower Building

Pile Integrity Test (PIT) is a tool from Pile Dynamic Inc. (PDI), consisting of a mini-computer, accelerometer, and hammer. Integrity testing on piles using PIT equipment is carried out by analyzing one-dimensional wave propagation provided by hammer blows on the pile head. An accelerometer sensor installed on the pole will read the reflection that occurs during wave propagation on the pole head. The wave propagation speed that occurs in concrete will range from 3,500 m/s to 4,200 m/s. The PIT test results indicate the reduction in impedance in the pole by the BTA value, which compares the theoretical impedance value to the residual impedance. From the results of the Pile Integrity Test carried out at three pile points, it was found that all samples experienced a reduction in impedance around a depth of ± 3.0 meters below the sensor with BTA values of 75%, 78%, and 72% and fell into the damaged category. The reduction in impedance at a depth of 3 meters is most likely part of the connection between piles because one pile point uses 2–3 spun piles, with the length of 1 spun pile being 9 meters. From the results of visual observations, it can be seen that the condition of the existing spun pile and pile cap is still quite good.

Analysis of Pile Foundation for Hospital Buildings

Pile foundations are widely employed to provide support for bridges and various structures, ensuring the safe transfer of structural loads to the ground while preventing excessive settlement or lateral movement. They excel in transferring structural loads from weaker or compressible soil layers to the stronger, more stable soils and rocks beneath. Pile foundations constitute an integral component of a structure.  In this research work the foundation of the hospital (G+6) was design by the pile foundation. We have used M25 grade of concrete for the preparation of design mix. The characteristic strength and load bearing of soil was tested by Plate load test and other materials tested by slump cone test , aggregate Impact Value test cement compressive strength test (cement fineness test construction water PH value . The expected result of SBC is 20000kg approximate.  Project reports typically encompass introductions and problem definitions, along with literature reviews pertinent to the project. They detail the study area's location and the project site, as well as providing concise information about the equipment utilized on- site.  Additionally, it covers crucial tasks such as centerline marking, boring, reinforcement placement, concrete pouring, excavation, and chipping of pile caps.

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.

Dynamic soil arching effect in pile-supported embankment due to train passages at high speeds

Pile-supported embankment has been widely adopted for high-speed railways constructed over soft soils to reduce post-construction settlement. The role of soil arching effect in stress distribution inside pile-supported embankment under static weight load has been extensively studied, while the dynamic soil arching effect due to train moving loads has been paid little attention. In this paper, a sophisticated three-dimensional (3D) track-embankment-pile-subsoil finite element model (FEM) has been developed to analyze dynamic stress responses due to train passages at high speeds. The numerical model has been validated by experimental results on a full-scale pile-supported railway embankment model. The numerical analyses reveal that the dynamic soil stress distribution in the embankment near the track is almost consistent with the Boussinesq solution, but the presence of piles underneath the embankment leads to the redistribution of dynamic soil stresses inside the embankment due to the dynamic soil arching effect. The soil arch height under train load is 2 m (2.5 times of the clear space of piles), higher than the height 1.6 m (2 times of the clear space of piles) under embankment self-weight. Besides, the pile efficacy (ratio of load borne by the pile cap to the total applied load) caused by moving train load at 100 m/s is 0.6, which also is higher than the pile efficacy 0.57 caused by embankment weight. Train passage at high speeds significantly amplifies the dynamic stress intensity in the embankment but barely changes the pile efficacy.

Dynamics Responses of a Block Machine Foundation and a Pile Group Foundation Systems on Stratified Residual Soils in Indonesia by Lumped Mass and Finite Element Methods

This paper presents a comprehensive study of the dynamic responses of machine foundations, both block and pile foundations, on stratified residual soils in Duri and Ulubelu, Indonesia. The evaluation was conducted using two widely recognized methods: the lumped mass method (LMM) and the finite element method (FEM). LMM and FEM were performed by utilizing DYNA and ABAQUS, respectively. The analysis results showed that LMM generally predicted more conservative displacements compared to FEM. This conservatism in predicted displacement was more pronounced for pile group foundations, which are inherently more flexible than block foundations. Additionally, this study found that the resonance frequencies obtained through both analysis methods were not the same. Furthermore, this paper includes a parametric study and presents its results to assess the influence of key factors, i.e., pile cap thickness, pile diameter, number of piles, and vertical dynamic loads, on displacement.

Effect of the pile cap length and the soil relative density on the pile cap – pile – dense soil interaction: Experimental investigation

In the present study, the RC pile cap-pile-soil interaction was experimentally investigated by testing twelve half-scale RC pile caps. Two main parameters were considered within the experimental program; the first factor was the relative density of the supporting sandy soil. Four models were tested without being rested on soil, while the other eight models were rested on sandy soil with a relative density of 80% or 90%. The second studied factor was the ratio between the spacing between the RC piles and the width of the pile (S/D), which varied within the range of 2.25, 2.5, 2.75, and 3.0. In comparison to the reference models (without underneath soil), the impacts of the examined parameters on the load-midspan deflection responses, cracking, and ultimate loads were investigated. Additionally, the associated settlements, stiffness, ductility, and energy dissipation capacity were also examined. The findings revealed that all RC pile caps exhibited a punching failure mode accompanied by shear cracks, irrespective of whether they were resting on sandy soil or not. On the contrary, the ultimate load of RC pile caps resting on sandy soil, especially with a higher relative density, was incredibly enhanced with respect to models loaded without supporting soil. The gain in the ultimate load of RC pile caps with S/D ratios of 2.25, 2.5, 2.75, and 3.0 was in the range of 5.4–6.7%, 12–16%, 15–21%, and 24–35%, respectively.

Load transfer mechanisms for capped and uncapped non-displacement piles above tunnels: a centrifuge modelling study

This paper presents results from geotechnical centrifuge tests of tunnelling in dry dense sand beneath loaded non-displacement piles, focusing on the effect of a pile cap (representative also of a raft or grade beam) in contact with the soil surface on load transfer mechanisms. Experiments included loading tests to ascertain the foundation capacity and load-displacement response in the presence/absence of an underlying model tunnel. Individual ‘reference’ pile response is compared for cases with and without a pile cap, including pile displacements and load distributions between the head, shaft, and base; the case of ‘friction’ piles with a compressible base are also considered. Results show that uncapped piles with relatively large service loads experience ‘geotechnical failure’ (i.e. large settlements or a significant increase in settlement rate with tunnel volume loss) in order to mobilise base or shaft resistance. Pile caps are shown to reduce settlements and prevent geotechnical failure of both reference and friction piles; they also improve the post-tunnelling foundation performance under loading. The paper provides evidence to enable engineers to consider the beneficial role of shallow elements in contact with the surface on the performance of pile foundations both during and subsequent to tunnelling.

ANALISIS MANAJEMEN WAKTU KONSTRUKSI PEMBANGUNAN GEDUNG KLINIK UNIBA DENGAN MENGGUNAKAN METODE CPM DAN APLIKASI QM FOR WINDOWS V5

Factors that influence the delay in the construction of the UNIBA clinic building is a lack of communication between labor and supervisor, delay shiping material, quality of job control, the intensity of rainfall. This research is to determine the analysis of the management planning of the construction. To find out the urgency of the use of barchart in the process of managing the construction of the UNIBA clinic building. Conclution in this problem the author uses the CPM method, barchart. In this CPM analysis there are several jobs that belong to the criticalpath, namely the critical path of the work of the UNIBA clinic building structure there are 10 jobs, namely preparatory work (A-7 days). Bored pilee (B-21 days) work. Pile cap (C-21 days). Floor plate work (H-14 days). Ladderwork (-3 days). Beam wor (N-21 days). Floor plate work (S-0-14 daays). Sanitair work (W-35). Ceiling work (S-42). Paint work (X-42). Conclution of the use of barchart in the process of managing the construction of th UNIBA clinic building timeliness, data objectivity, submitting information on time, to provide standards that can be used to measure or compare progress with status, to identify and isolate the most important information

Testing of equipment for removing reinforced concrete pile caps

Testing of equipment for removing reinforced concrete pile caps

Dynamic Response of Pile Foundation Subjected to Different Frequencies in Sandy Soil

This research presents an experimental study of the dynamic response of pile foundation as a result of the vibration of a nearby foundation as a source of dynamic load in sandy soil with relative density of 85%. The experiments were conducted on dry and soaked state of soil. The pile raft consisted of a pile cap with dimensions of (100 x 100 x 10) mm, connected with four solid steel piles with a slenderness ratio of 30 and pile diameter is 8 mm, and the machine foundation (vibration source) with dimensions (80 x 80 x 40) mm. After having completed the soil layers preparation inside a steel container with suitable dimensions is used, the machine that generated vibration was operated by the rotating mass, as this vibration reached the pile raft. The results showed that the displacement amplitude, acceleration, velocity and settlement of the pile raft decreased with increasing distance with the vibration source (from 0.5B to 2B) for the three frequencies (10,15 and 20) Hz, while the decrease for displacement was (48%,23.83% and 42.48%) respectively in the dry state of soil. On the other hand, the decrease for displacement was (37%, 23.16% and 46.27%) in the soaked state of soil. Regarding acceleration, it was decreased to (29.66%, 45.79% and 40.38%) respectively in the dry and (100%, 21.88% and 34.04%) in the soaked state of soil. Furthermore, the velocity reached (45.38%, 42.96% and 38.18%) respectively in the dry and (54.05%, 11% and 28%) in the soaked state of soil, the settlement was (63.82%, 52.1% and 38.18%) respectively.

Influence of Soil Excavation on Bearing Behavior of Pile Group Foundation Composed of Underpinning Piles and Existing Piles

Abstract The behavior of underpinning piles during the soil excavation is critical for constructing new basements under the existing structures in urban areas; however, none of the existing studies has systematically evaluated their performance and interaction with existing piles under loading. This study aims to experimentally evaluate the impact of soil excavation on the bearing capacity of pile group foundation composed of underpinning piles and existing piles under loading. A model pile foundation with four model piles, one pile cap, and retaining structures was first constructed in our laboratory. Different soil excavation depths at 10 cm, 20 cm, and 30 cm (soil type: clayey silt) were used to explore their influence on the pile side friction, the axial force of the pile shaft, and pile settlement. The results were compared with the bearing behavior of the pile group foundation composed of four model piles and five underpinning piles at different pile lengths (500, 600, and 700 mm) and diameters (5, 10, and 15 mm). The results showed that soil excavation activity could immediately activate the different interaction responses between piles and soils and cause foundation settlements. The underpinning piles with sufficient length (more than 67 % of the existing model pile length) and diameter (more than 25 % of the existing model pile diameter) as well as proper pile’s embedded depth significantly reduced the foundation settlement, particularly at high soil exaction depth. The pile-soil interaction mechanism caused by soil excavation is revealed. The work could bring insights to the underpinning pile design for basement excavation beneath existing buildings.

Optimum design of pile cap considering minimization of environmental impacts

Optimum design of pile cap considering minimization of environmental impacts

Perencanaan Gedung Bertingkat 5 Lantai Asrama Putri Pondok Pesantren Hasyim Asy’ari Bangsri Jepara

The development of the world of Islamic education in Indonesia also includes Islamic boarding schools, Hasyim Asy'ari Bangsri Jepara Islamic boarding school is one of the best Islamic boarding schools, to support the smooth teaching and learning, it is necessary to have adequate student facilities and facilities. This research aims to help fulfill the capacity of santri facilities and infrastructure at the Hasyim Asy'ari Bangsri Jepara Islamic boarding school. The building structure calculations were reviewed for dead loads, live loads and earthquake loads using the SAP 2000 program. The structural calculations carried out included roofs, floor plates, beams, columns, stairs, sloofs and foundations. The building planning location is Jl. Jepara-Bangsri No. 9, Krasak Bangsri, District. Bangsri, Kab. Jepara, Central Java 59452. From the structural planning, the roof structure is obtained with 2L steel trusses 50.50.7, floor plate 130 mm ∅ 12-100, beam B1 500x300 mm 10 D19, beam B2 400x250 mm 10 D19, column K1 500x500 mm 18 D19, column K2 400x400 mm 12 D19, ladder plate thickness 150 mm ∅ 12-150, sloof 500x300 mm 9 D19, pile cap foundation 160x160x60 mm, pile D30 cm 6 m long, with concrete quality (f'c) = 30 MPa, reinforcement quality (fy) = 400 MPa and (fy) = 240 MPa. The programs used are Microsoft Office, Microsoft Excel, Autocad, SAP 2000, and SketchUp.

Evaluation of Pile Cap Reinforcement Design Using Conventional and Finite Element with Strut and The Method Based on SNI 2847-2019

The Strut and Tie Method (STM) is one effective method for predicting the ultimate strength, failure modes, and behavior of reinforced concrete pile caps. However, the use of the strut and tie method in pile cap design in Indonesia is not as popular as the use of conventional methods. This study aims to evaluate the reinforcement design of pile caps using conventional methods and the finite element method (FEM) approach, utilizing the strut and tie method specified in SNI 2847 2019. The analysis results show that the required area of longitudinal reinforcement in the conventional method does not meet the criteria when evaluated using the STM method. The deficiency in the longitudinal reinforcement area amounts to 40.13% compared to the design results obtained using the STM method. Meanwhile, the use of the FEM method results in a required reinforcement area that exceeds the required area for the STM method. The difference in reinforcement is even greater, reaching up to 7.85% for the FEM method.

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.

Case Study on Instrumenting and Monitoring Geosynthetic-Reinforced Pile-Supported Mechanically Stabilized Earth Wall Built over Soft Soil

This paper presents a case study on instrumenting, monitoring, and finite element modeling (FEM) of geosynthetic-reinforced pile-supported (GRPS) mechanically stabilized earth (MSE) walls. The GRPS-MSE wall was monitored using various instruments such as piezometers, earth pressure cells, shape-acceleration arrays (SAAs), and strain gauges. The performance criteria included efficacy, stress concentration ratio (SCR), differential settlement, and reinforcement tension. Collected data, such as excess pore-water pressures, contact pressures on pile and soft soil, differential settlements, and lateral displacement of MSE wall, were analyzed thoroughly. A 3D FEM was also developed to simulate the GRPS MSE wall, and the results are in good agreement with field data. The results demonstrated significant load transfer from soil to piles as a result of soil arching, yielding 30–32 SCR. The field efficacy was measured at 37.69 %, while the FEM efficacy was estimated as 42.4. Strains in geogrids within the geosynthetic-reinforced load transfer platform (GLTP) system were under 1%, less than the 5% maximum recommended by FHWA. The maximum differential settlement measured between pile cap and soft soil from SAAs is 7.1 mm, while it is estimated to be 8.3 mm from FEM. The MSE wall exhibited low lateral displacement (<25 mm), indicating enhanced stability because of GLTP. The comparison between five analytical GLTP design methods showed that the CUR226 methods gave the closest results to field measurements and FEM results. This study offers crucial insights into leveraging GLTP and MSE walls in highway construction.

Buffeting Characteristics of a Long-Span Cable-Stayed Bridge Crossing a Deep Canyon during Erection: Response Evaluation and Vibration Control

The stiffness of a long-span cable-stayed bridge under construction may be much lower than that observed in service, making it more susceptible to wind effects, especially for a bridge designed using high piers crossing a deep canyon. To study the buffeting characteristics of such cable-stayed bridges under construction, a long-span cable-stayed bridge (the main span is 575 m) is taken as the engineering background. In this study, the buffeting responses and vibration countermeasures at three different construction states were systematically studied using time-domain analysis. It was found that the buffeting response enlarges with an increase in the wind attack angle. The RMS values of the vertical buffeting of the bridge deck end are relatively greater at the maximum double cantilever construction state and maximum single cantilever state. At maximum double cantilever construction state, the traditional wind-resistant cable connecting the bridge deck end to the bridge pile cap significantly reduces the vertical buffeting response, while the suppression effect on lateral and torsional buffeting is limited. When the bridge deck nears completion, wind-resistant cables installed at both cantilever ending in the ‘soft connection’ method would effectively suppress the vertical, lateral, and torsional buffeting. The suppression effect of cross-arranged wind-resistant cables is superior to that of the parallel arrangement. It is recommended that a reasonable wind-resistant cable layout scheme according to different construction conditions is selected.