Pile Cap Research Articles

Analysis methodology and design verification for strengthening moment-resisting caisson foundations

Many existing monopole towers rely on caisson foundations to resist the effects of large overturning moments. Increased loading on these towers, coupled with material deterioration and more stringent code requirements, often results in the overloading of the existing caissons. The strengthening of these caissons for additional overturning resistance presents many challenges and typically requires the installation of new piles. A pile cap is commonly used to connect the existing caisson to the new piles. The proper design of the pile cap has a critical importance in ensuring an effective stress transfer and creating a resilient foundation system. While a number of strengthening design approaches are repeatedly used in industry, there is a dearth of guidance and proven analysis methods to verify the performance achieved with these approaches. This study proposes a well-defined analysis methodology for the system-level structural design verification of the strengthened foundation systems. The methodology provides two routes, using either the strut-and-tie or nonlinear finite element analysis methods, to quantify the load, deformation, cracking, and failure responses. The methodology helps expose and address the weak aspects of the design using an iterative design improvement process. A common strengthening design approach from industry, involving a moment-resisting caisson strengthened with four concrete piles and a pile cap, is used as a case study to demonstrate the application of the methodology. The results demonstrate that the methodology provides significant insight into the system-level behavior both at the serviceability and ultimate limit states. The analysis results are found useful in identifying the locations where modified bar detailing could significantly improve the system performance. The improved design from the methodology provided a 56 % increase in the load capacity for the case-study foundation while still using the same amounts of reinforcing steel and concrete as compared to the initial design before the application of the proposed methodology. This paper presents the studies undertaken, conclusions reached, and recommendations made for developing resilient pile cap designs for strengthening moment-resisting caisson foundations.

Perencanaan Pondasi Borepile Pada Jembatan, Studi Kasus : Jembatan Utama Cisadane

The most important part in a bridge construction is the foundation. Bore pile foundation is planned for 2 abutments and 5 piers. The entire foundation uses a diameter of 1 meter with a depth of 20-30 meters. Calculation of axial bearing capacity using the reese and wright method produces a single pile axial bearing capacity of 268.090 - 470.697 tons. The efficiency of the pile group using the Converse-Labarre method and the axial bearing capacity of the pile group is 5870,246 - 33176,233 tons. Single pile settlement using a semi-empirical method and resulted in a decrease of 50,100 - 59,490 mm. The settlement of the pile group used the vesic method and resulted in a decrease of 6,627 - 13,302 cm. consolidation decrease using the coefficient of volume change and resulted in a decrease of 104,024-576.047 mm with a time of 5,694-26,731 years. The calculation of lateral bearing capacity and pile deflection using the Broms method resulted in the lateral bearing capacity of the pile group of 3024-20580 tons and deflection of 1.485-5.888 mm. foundation reinforcement using the reference of SNI 2847-2019. Longitudinal reinforcement using 10D32 and stirrup reinforcement D16-50 and D16-75. Pile cap planning refers to SNI 2847-2019, resulting in a pile cap thickness of 1.5-4 meters. The X direction and Y direction reinforcement used are D32-150 for the pier and D32-150 and D25-150 for the abutment. The calculation of the cost budget plan uses the unit price analysis method and the resulting total cost is 73.574.031.053.

Control of Reinforcement Concrete in Pile Caps over Steel Piles – Case Study

This paper presents a case study about the challenges and good building practices involved in the execution of structural reinforced concrete pile caps over steel piles. The structural reinforcements were carried out in a project with 3 residential towers of approximately 30 floors each, located on the seafront. As a result, it was observed that mix design to define the type and characteristics of concrete, prototype event, particularities of the construction site, executive procedures employed, as well as the systematic monitoring and control of concreting events and other constructive stages were determining factors to promote the safety and quality of reinforcement services in accordance with the assumptions and design requirements.

Construction technologies and mechanical effects of the pipe-jacking crossing anchor-cable group in soft stratum

In this study, an open-cut approach using steel-sheet piles and jet grouting piles for waterproofing was proposed to resolve the problem that ordinary pipe-jacking equipment cannot cross areas with existing anchor cables in soft stratum. The case history of a pipe-jacking project of a sewage treatment plant in the Jinan East Railway Station area was investigated. The mechanical properties of steel-sheet piles, horizontal displacement of piles, and ground surface settlement in the anchor-cable crossing area were investigated based on in situ observations. Numerical investigations were performed using the finite element method (FEM). The effects of existing anchor cables on the mechanical behaviors of retaining structures, deformation variation of the ground, and stability of the excavation were studied. The results indicate that the composite supporting structures of steel-sheet piles and jet grouting piles have a positive effect on waterproofing and deformation control in areas with existing anchor cables. When the steel-sheet pile touched the anchor cable during pile jacking, the compressive stress at the pile cap increased rapidly until it reached 62.8 MPa (the maximum pressure provided by the pile-pressing machine), which is twice the pressure under ordinary conditions. The maximum horizontal displacement of the retaining pile, δv, increased linearly with the excavation depth He. Existing anchor structures behind the excavation can restrain the deformation of the ground and retain the structure to a certain extent. The δv value of the pile with existing anchor structures behind is 6.5 mm or approximately 0.01% of the He value, which is 70% of that of the retaining pile without existing anchor structures. “Groove type” ground surface settlements are found on both sides of the excavation. The maximum ground settlements δh are 0.29% He and 0.05% He, respectively. The plastic zone at both sides of the excavation bottom extends to the ground surface with an angle of about 45°. When an excavation fails, the plastic zone range in the ground with existing anchor cables is significantly larger than it is in the ground without anchor cables. The key contribution of this research is to provide an effective and low-budget treatment for pipe-jacking crossing through an anchor-cable group region. The findings from this study also provide industry practitioners with a comprehensive guide regarding the specific applications and mechanical performance of the crossing excavation for obstacle treatment.

Numerical study on pile group efficiency for piles embedded in cohesive and cohesionless soils

This paper aims to study the efficiency of pile groups with various numbers of piles and pile spacing. Axial loading tests on pile groups and also single piles were simulated using a three-dimensional finite element program to obtain the load-settlement curve and the ultimate bearing capacity of the piles which was later used to estimate the pile group efficiency. In this study, the piles were embedded in cohesive and cohesionless soils. The stress-strain responses of the soils and the concrete pile and pile cap were simulated using the Mohr-Coulomb and the linear elastic models, respectively. The numerical-based pile group efficiencies were then compared to those computed using the published formulas. To verify the findings, a series of parametric studies on pile groups embedded in stratified soil was performed where the parameters of the soils were derived based on a back analysis on a case study of a single pile axial loading test in South Jakarta. The results show that the axial pile group efficiency in cohesive soil would be less than or equal to one, whereas in cohesionless soil would be more than or equal to one, especially at pile spacing more than three times the pile diameter. Meanwhile, similar results as found in cohesionless soil were obtained for the stratified soil case.

Hydro-Structural Response of Complex Elevated Pile Cap Substructures to Strom Surge Impact by Smoothed Particle Hydrodynamics: Part 2: Model Results

Hydro-Structural Response of Complex Elevated Pile Cap Substructures to Strom Surge Impact by Smoothed Particle Hydrodynamics: Part 2: Model Results

Research on the Force of Steel Column in Tower Crane High Pile Cap System

Research on the Force of Steel Column in Tower Crane High Pile Cap System

Random wave action on pile group foundations with complex geometry for sea-crossing bridges

To explore the mechanical properties of pile group foundations (PGFs) with complex geometry in sea-crossing bridges under ocean wave action, this study develops a numerical model for predicting wave loads on PGFs under multidirectional random wave action. Furthermore, an experimental model of the PGF composed of a quasi-elliptical pile cap and 13 tilted piles is designed and made based on the gravity similarity criterion. By performing model experiments and numerical analysis, the mechanical characteristics of the PGF model under random wave action, the effect of principal wave direction angle and random wave directionality, and the influence of the pile cap on wave loads of tilted piles are systematically investigated. The results show that the calculated results of the presented numerical model match well with the experimental data. The frequency characteristics of wave loads on the PGF model are mainly determined by the wave spectrum. The increase of the significant period improves the contribution of the pile group to the horizontal wave loads on the PGF. The effect of the principal wave direction on the vertical wave loads on the PGF is not obvious under the experimental wave conditions. Neglecting the wave directionality will overestimate the wave loads in the principal wave direction and vertical direction on the PGF. Under the influence of diffraction waves from the pile cap, the wave loads on the pile group and the piles where the wave finally acts are easily amplified when the wave number is small, but in the large wave number case, the wave loads on the pile group and the piles below the middle of the pile cap may be weakened.

Numerical Investigation on Effect of Opening Ratio on Structural Performance of Reinforced Concrete Deep Beam Reinforced with CFRP Enhancements

Reinforced concrete deep beams are a vital member of infrastructures such as bridges, shear walls, and foundation pile caps. Thousands of dollars and human lives are seriously threatened due to shear failure, which have developed in deep beams containing web openings. This paper investigates numerically the overall behavior of simply supported concrete deep beams reinforced with carbon fiber-reinforced polymer (CFRP) sheets through forty specimens grouped in four groups. The numerical analysis results agreed well with the experimental results in the literature, particularly the visual failure initiation with a failure load difference of nearly 7%. Finite element analyses indicated that the presence of an opening with considerable width reduced the failure load by about 71% compared to the corresponding solid specimens. In addition, the reinforced concrete deep beam samples started to behave differently when the (b/h) ratio increased more than (2.0). The findings showed that the compression stress strut pathway had been disrupted by the web opening leading to stress redistribution, and the structure will behave as two separate members. Thus, the upper web-opening part sustained the most stress, while the part under the web-opening did not show any stress concentration. The numerical stress distribution results showed that the attributed reason is that rebars and openings helped redirect the stresses to the compression strut. Using CFRP sheets with a width of more than 160 mm significantly improved the reinforced concrete deep beam with web-opening due to the increasing confinement to the upper part of the reinforced concrete deep beams with the opening.

Study of the Causative Factors of El-Ghandouri Landslides and their Stabilization Methods

Tangier landslides are considered a common engineering problem throughout the construction of different roads or other engineering works in the north of Morocco. This research paper aims to identify the main causes of landslides in an area with an important tourist site to search for the most appropriate engineering solutions. Several geotechnical studies were carried out through boreholes up to 30 meters deep to determine the main causes of the landslides. These studies exhibit that the main reason for landslides is the presence of Layers of soil with weak mechanical properties, which are highly affected by rainfall. The limit equilibrium (LE) analysis method and finite element (FE) method was utilized to analyze the stabilities of the EL Ghandowri slopes before excavation, after excavation, and after stabilization treatment of the slopes for construction. The analysis results indicated that the EL Ghandowri slopes, before any excavation, were unstable in their natural state. The reinforced concrete piles' row with anchors and concrete piles cap were the stabilization methods, which give the best safety factor and horizontal deformation results. The soil-structure interaction method (SSIM) and finite element (FE) method were used to calculate the horizontal deformation of piles. The occurrence of EL Ghandouri landslides can be reduced if the main reason is addressed; thus, the problem of Tangier Province landslides, especially EL Ghandouri, should be given big attention throughout the survey and design of the engineering works, not only during the construction.

Response of soil–pile–superstructure–quay wall system to lateral displacement under horizontal and vertical earthquake excitations

The excess pore water pressure generated under the combined vertical and horizontal earthquake excitations is generally greater than that under the unidirectional excitation, which may further affect the dynamic response of soil-pile-superstructure-quay wall (SPSQ) system. This study conducted a coupled effective-stress analysis for the response of SPSQ system to liquefaction-induced lateral displacement under horizontal and vertical earthquake excitations. To accurately describe the lateral displacement behind the quay wall, the liquefaction behavior of soils was described by a modified generalized plasticity model with parameters properly determined from laboratory tests. The numerical model of the SPSQ system was validated against the previously reported centrifuge model tests. The results show that the earthquake excitation with abundant low-frequency component causes greater residual lateral displacements of pile cap (ux,RC) and quay wall (ux,RQ) than that with abundant high-frequency component. The ux,RC and ux,RQ tend to increase as the peak vertical acceleration increases for both vertical and inclined piles. Increasing the fixity of the quay wall significantly reduces the influence of vertical ground motion on the ux,RC and ux,RQ. The polarity reversal of the vertical ground motion also has a significant effect on the ux,RC and ux,RQ and should be considered in the analyses. In addition, the lateral displacement of liquefied ground causes an amount of rotation of the cap of the inclined pile, probably leading to the potential shear failure at the head of piles. Special consideration should be given to the earthquake-induced shear force at deeper location because the shear force could be significantly greater than that at the head of both inclined and vertical piles in certain cases.

Analysis of Load Transfer and the Law of Deformation within a Pile-Supported Reinforced Embankment

In this paper, the load-transfer mechanism and settlement behaviors of the pile-supported reinforced embankment are reviewed by laboratory model tests, and a series of finite element method (FEM) modellings are conducted to analyze the soil-arching geometry and embankment deformation patterns of the pile-supported reinforced embankment. The results show that: the embankment load distribution is significantly impacted by the filling cohesion because of the effect of cohesion on the interaction between particles. The soil pressure difference between the center and corner of the pile caps decreases with the increase of filling cohesion. The pile-subsoil stress ratio decreases with the increase of filling cohesion. The embankment deformation behavior and soil-arching geometry are less affected by the change in filling cohesion compared with the influence of pile spacing. That may because of the fact that although the cohesion of the embankment filling has been increased, the granular material’s properties have not been fundamentally changed. Pile-subsoil different settlement decreases with the increase of embankment filling cohesion, and the different settlement at the mid-span between four piles decreases by 4.09% and 6.34%, respectively, as filling cohesion increases from 0 kPa to 11 kPa and 25 kPa. The height of the soil-arching crown decreases with the increase of filling cohesion, and the height of the soil-arching crown between horizontal adjacent piles decreases by 3.85%, 7.69%, and 9.62%, as filling cohesion increases from 5 kPa to 15 kPa, 25 kPa and 45 kPa. The rate of decrease in soil-arching height gradually decreases with increasing cohesion. The height of the soil-arching between the horizontal adjacent piles is about 1.0 (s−a). The height of soil arching between the diagonal adjacent piles is about 1.02 (s−a). The differential settlement at the same height inside the embankment decreases with the increase of filling cohesion, and the height of the equal settlement plane is basically the same as the height of soil arching.

Key Technology for Construction of Steel-concrete Composite Suspending Cofferdam without Bottom Cover for Platform of Coastal Intercommunication Project

<p>Many bridge piers were built in the Coastal Interconnection Project of the Ningbo Section of the Hangzhou-Ningbo Expressway Double Line. Affected by the tides at the bridge site, the high pile caps are constructed using a suspending cofferdam without a bottom cover. Based on the consideration of various factors such as construction difficulty, safety, cost and construction period, etc. A cement structure is generally adopted as the floor of the suspended box cofferdam. The steel-concrete combined hanging box cofferdam without bottom cover adopts the structure of steel wall plate and prefabricated cement floor, and the partition wall plates are connected by bolts. The steel-concrete composite suspending cofferdam adopts the prefabricated bottom plate and wall plate. The construction sequence is listed as follows: First, weld the load-bearing corbel on the steel casing, and then hoist the prefabricated bottom plate to the steel casing corbel in blocks. Pour the wet joint between the prefabricated bottom plate and install the side plate. After that, pour the cushion after welding the shear plate. Finally, carry out the construction of the cap. During the construction of the project, the connection method between the wall plate and the bottom plate was optimized. The connection of the fine-rolled rebar hanger rod was changed to the steel bar pair pulling, which improved the construction efficiency significantly.</p>

Theoretical investigation on characteristics of field reactions of saturated ground subjected to vibrations of inclined pile groups

Inclined pile groups have been adopted in engineering practice (e.g. offshore wind turbines) to withstand strong horizontal environmental loads that are repetitive in nature. Field reactions including the additional stresses and excess pore water pressures are responsible for the cyclic degradation of foundation soil, which may induce the accumulative deformation and fundamental frequency shifting of the marine structure. In this study, a theoretical model incorporating an inclined pile group and a saturated half-space was established, wherein the pile and saturated soil were described by the E–B beam and Biot poroelasticity theories, respectively. The pile and soil were coupled through the receptance matrix, which was established at the pile–soil interaction points in the transform domain. The dynamic impedances of the inclined pile group are first obtained, and then the field responses, including stresses and excess pore water pressure in the saturated ground, are evaluated for different types of loads applied to the pile cap. The frequency response function and spatial distributions of the field responses were obtained for varying rake angle of pile and permeability of soil. It was found that the horizontal force induces the largest responses in the ground when compared to the vertical force and the overturning moment applied to the inclined pile group. It is beneficial to employ an inclined pile group to withstand the horizontal force and overturning moment because the foundation stiffness increases, and the additional stresses in the ground decrease with increasing rake angle.

LESSON LEARNED: BEST PRACTICE IMPLEMENTASI BUILDING INFORMATION MODELING (BIM)

In the past few decades, Building Information Modeling (BIM) has been widely used worldwide in industry of architecture, engineering dan construction (AEC). This scope is started from construction material manufacturing to construction project. So, this industry, which is one of the most complex industries, requires improvements in time and cost efficiency.. The purpose of this paper is to provide best practice of using BIM in buildings and infrastructure. The research method used in this research is project based evaluation. Project based evaluation is carried out on construction projects, namely building structures which include bored piles, pile cap, plates, shear walls, columns, and beams. The second project based evaluation is the bridge which focuses on structural work in single and double pillars. The results of research on building structures used as project based evaluations show that the difference in volume for each element ranges from 0.03% to 1.13%. with the total difference between conventional recalculation and modeling is around 0.358%. While the modeling in the second project based evaluation showed a volume difference of 12,965.66 kg for single pillar structures and 48,233.51 kg for double pillars. While the conventional method produces a larger estimated volume of 13,482.72 kg for single pillar structures and 49,827.70 kg for double pillars

Laterally loaded piles and pile groups partially embedded in transversely isotropic fractional viscoelastic saturated soils

This paper investigates the time-dependent behaviour of laterally loaded piles and pile groups partially embedded in stratified transversely isotropic (TI) saturated soils. The partially embedded single pile in stratified soils is regarded as a Timoshenko beam, and its total stiffness matrix can be assembled by using the finite element method (FEM). Based on the fractional viscoelastic model for solving non-axisymmetric consolidation of stratified cross-anisotropic media developed before, the solution for a partially embedded single pile is obtained by combining the boundary element method (BEM) and the extended precise integration solution of the media. Considering the interaction between piles in a pile group and the load distribution from the pile cap to pile tops, the solution for the partially embedded pile group is derived by extending the solution of single piles. The accuracy and efficiency of the proposed solution is verified with existing literatures, and some examples are designed to investigate the effects of the embedment ratio, the transverse isotropy, the slenderness ratio, the fractional derivative order, the flexibility coefficient and the pile spacing. Numerical results show that the embedment ratio and fractional derivative order are essential parameters that significantly affect the rate of the time-dependent response of the partially embedded lateral loaded piles.

Integrated Approach for Estimating Extreme Hydrodynamic Loads on Elevated Pile Cap Foundation Using Environmental Contour of Simulated Typhoon Wave, Current, and Surge Conditions

Abstract Typhoon is a disastrous weather system, which usually induces strong waves, currents, and surges along the coastal area, and causes severe hydrodynamic loads on the elevated pile cap foundation, which is widely used to support the sea-crossing bridge. Estimating the hydrodynamic loads under typhoons is essential to ensure the bridge's safety. This paper develops an environmental contour-based framework that can estimate the extreme hydrodynamic loads induced by typhoons while considering the correlation among environmental conditions. The elevated pile cap foundation of the Xihoumen Rail-cum-road Bridge was used to illustrate the framework. The SWAN + ADCIRC model was employed to simulate the environmental conditions under typhoons. The pair-copulas were adopted to construct joint probability distributions, and the environmental contours with a given return period were then established by the inverse first-order reliability method. Given the hydrodynamic model and short-term peak value of the structural response, the AK-LHS method was then used to find the maximum hydrodynamic loads based on the environmental contours. The environmental contour constructing methods and selection methods of short-term peak values were compared and discussed. The main findings include: (1) ignoring correlations of the environmental conditions overestimates the extreme hydrodynamic loads and results in a conservative design; (2) the estimation of extreme hydrodynamic loads is affected by the selection and fitting of short-term peak values significantly; and (3) the extreme hydrodynamic loads estimated by either Rosenblatt transformation or Nataf transformation shows similar results.

Ultimate Bearing Capacity Analysis of Pile Caps with New Socket Connections

Socket connection need a groove reserved in the cap to accommodate a bridge pier, which greatly weaken the vertical bearing capacity of the cap. The conventional treatment measure is to increase the thickness of the cap, and the corresponding cost will increase. The measures to enhance the vertical bearing capacity of socket caps without increasing the thickness of the cap were discussed in this paper, including a rough interface at the bottom of the pier, additional hanging bars, high-strength grouting material in the seam, and large-diameter metal corrugated pipes, etc. Based on a previous test, the finite element analysis of the vertical bearing capacity of pile caps with new socket connections was carried out. The analysis parameters included the construction method, steel bar diameter in the bottom of the cap, socket depth, thickness of the bottom plate, pile length, and friction coefficient, etc. The bearing capacity M–N relation of the full-scale model was also analyzed. Research indicated the vertical bearing capacity of the cap is mainly provided by rough interfaces, the bottom plate, and the additional hanging bars, and the contribution of the three parts was about 40%, 34%, and 26%; the vertical bearing capacity was proportional to the areas of steel bars on the cap and the thickness of the bottom plate, and was inversely proportional to the length of the pile. To obtain the vertical bearing capacity of the overall cast-in-place plan for the socket cap, the thickness of the cap needs to be increased by 27%. At last, a design formula for the calculation of the vertical bearing capacity was proposed.

Integrating the foundation component into seismic fragility analysis of bridges

A component-based seismic fragility analysis method for bridges recently developed by the authors is extended here to include the foundation component. In line with the treatment of other components like the piers or abutments, the foundation system is analysed separately, and its capacity and limit state thresholds are described in terms of the displacement of a monitoring point, which in the usual case of pile foundations is the pile cap; in this way all sources of strength and stiffness degradation are accounted for. The influence of the way the pile cap is loaded in the foundation component analysis is estimated by exploring various ‘scenarios’ of increasing complexity. Components of two typical overpass bridges are analysed; one with single column piers and one with wall-type piers, to evaluate the effect of foundation on bridge fragility in the case that energy dissipation occurs primarily in the plastic hinges of the piers and the case that part of the dissipation takes place in the foundation system. It is concluded that in the case of hinging piers the pile foundation is not critical for the bridge fragility and may be ignored for simplicity, whereas this is no more the case when piers remain elastic and damage in the piles and/or the soil occurs.

Lem Beton Pengaruh Penggunan Lem Beton Pada Sambungan Pengecoran Antara Beton Lama dan Baru

In carrying out concrete work, if the casting work is not completed, then the casting must be stopped at places that do not endanger the construction according to the instructions of experts in accordance with the plan drawings. Casting of joints between old and new concrete with an overview of inclination angles of 0⁰, 45⁰, and 90⁰. Joints are part of the concrete construction to provide a safe stop for the casting for the stage of construction. The casting is carried out in several steps, in the first step filling the concrete in the cylinder mold up to half of the total, after the concrete has reached the age of 7 days, then the next concrete as connection concrete fills half of the old concrete by coating the old concrete connection using glue which is a mixture of additon addibond glue + water and without concrete only a mixture of cement + water. This research was conducted so that the implementation in the field knows the function of each slope angle at 0⁰ is used in casting column connections, 45⁰ is carried out on casting plate and beam connections, and 90⁰ is carried out on casting pile cap foundation connections. The test results of the compressive strenght & split tensile strength of concrete showed that the variation of the joint slope using glue was greater than the variation of the connection without. For the results of the greatest compressive strength test in intact concrete with an average strength value of 35,29 Mpa, while in the split tensile strength test the concrete got an average strength value of 2,37 Mpa.