Concrete Pile Caps Research Articles

Inversion Analysis for Thermal Parameters of Mass Concrete Based on the Sparrow Search Algorithm Improved by Mixed Strategies

In the traditional mass concrete temperature field calculation, the accuracy of the thermal parameters is extremely important. However, the actual thermal parameters of mass concrete may have some errors with the laboratory-measured values or specification values due to the site ambient temperature, concrete surface insulation measures, cooling water flow, etc. Therefore, it can be combined with the measured temperature of the field temperature sensors using the sparrow search algorithm (SSA) for the inverse analysis of thermal parameters. Firstly, to address the problem that SSA has low convergence accuracy and easily falls into local optimum, a mixed strategy was adopted to improve the algorithm, including Logistic Chaos mapping initialization of the population, the introduction of adaptive weighting factors, and the use of the Cauchy mutation strategy. Then, the performance test was carried out to compare the performance of the algorithm with three different intelligent algorithms and reflect the superiority of the SSA that was improved by mixed strategies (SSAIMSs). Finally, the proposed method was applied to the thermal parameter inversion of a mass concrete pile cap. The inversion results demonstrated that SSAIMSs can improve the accuracy and speed of thermal parameter inversion, and the calculated results of the thermal parameters and temperatures obtained using the SSAIMSs matched well with the measured results in the field, which can meet the accuracy requirements of the actual engineering.

Study on the Hydration Heat Effect and Pipe Cooling System of a Mass Concrete Pile Cap

Under the action of cement hydration heat, the construction environment, thermal insulation measures, and pipe cooling systems, a mass concrete pile cap is subject to a complex internal temperature field, which makes it difficult to control its internal surface temperature difference (TISTD), the internal adiabatic temperature rise (TIATR), and the surface temperature (TST). In this study, a mass concrete pile cap of a very large bridge (the length, width, and height were 26.40 m, 20.90 m, and 5.00 m, respectively, and the central-pier pile cap was constructed with C40 concrete) was taken as the research object. The control factors affecting the temperature field of the pile cap were determined by comparing the field temperature measurements with the values calculated with finite element software simulation analysis. By using Midas Civil (2022 v1.2) and Midas FEA (NX 2022) finite element software, these factors (the concrete mold temperature, the concrete surface convection coefficient, the ambient temperature, the pipe cooling system parameters, etc.) were numerically analyzed, and their influence laws and degrees were determined.

Numerical Modeling of Four-Pile Caps Using the Concrete Damaged Plasticity Model

Four-pile caps made from concrete are essential elements for the force transfer from the superstructure to piles or pipes. Due to the difficulties in carrying out full-scale tests and all the instrumentation involved, the use of numerical models as a way to study the mechanical behavior of these elements presents itself as a good alternative. Such numerical studies usually provide useful information for the update and improvement of normative standards and codes. The concrete damaged plasticity (CDP) constitutive model, which combines damage and plasticity with smeared-crack propagation, stands out in the simulation of reinforced concrete. This model is composed of five parameters: dilatation angle (ψ), eccentricity (ϵ), ratio between biaxial and uniaxial compressive strength (σbo/σco), failure surface in the deviator plane normal to the hydrostatic axis (Kc), and viscosity (μ). For unidimensional elements, the values of the CDP parameters are well defined, but for volumetric elements, such as concrete pile caps, there is a gap in the literature regarding the definition of these values. This fact ends up limiting the use of the CDP on these structural elements due to the uncertainties involved. Therefore, the aim of this research was to calibrate two numerical models of concrete four-pile caps with different failure modes for the evaluation of the sensitivity of the CDP parameters, except for ϵ, which remained constant. As a result, the parameters σbo/σco and Kc did not significantly influence the calibration of the force × displacement curves of the simulated structures. Values of ψ and μ equal to 36° and 1 × 10−4, respectively, are recommended for “static” analysis, while for “quasi-static” analysis, ψ values ranging between 45° and 50° are suggested according to the failure mode. The results also showed to be sensitive to the constitutive relation of concrete tensile behavior in both modes of analysis. For geometric parameterization, the “static” analysis is recommended due to the lower coefficient of variation (3.29%) compared to the “quasi-static” analysis (19.18%). This conclusion is supported by the evaluation of the ultimate load of the numerical models from the geometrically parametric study compared to the results estimated by an analytical model.

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.

Testing of equipment for removing reinforced concrete pile caps

Testing of equipment for removing reinforced concrete pile caps

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.

Experimental Investigation of Size Effect on Shear Strength of Reinforced Concrete Pile Caps

Experimental Investigation of Size Effect on Shear Strength of Reinforced Concrete Pile Caps

Fundamentals of Construction Materials and Types of Building Using WPM Method

Building materials are construction materials. Natural resources such as branches, wood, clay, pebbles, and sand can all be used to build. Many naturally occurring compounds and some more and some less artificial man-made items are in use. Building materials are called from a range of sites and quarried and mined as jio goods. Must find new resources because the demand to cling to what is now available is expanding along with the world's population. Concrete has a long and illustrious history, but adobe bricks, stone, and clay were the primary building materials used throughout history. These products are still in demand, and any more quarry for their specific extractive industries in the same area causes issues. this is a list of construction supplies. Buildings and structures produce several types of building materials that are employed in the construction sector. Construction is used for projects to specify materials and processes, and project managers' materials and goods are utilized in this category by architects and construction. Blockwork, typically wood building materials, and cold, rolled steel frame are all considered modern construction techniques as opposed to slow ones. There are several applications for various building materials; as a result, you should always check with the manufacturer to be sure a product is good for your needs. Around the world, almost 11,000 new structures are constructed each day. Buildings, sidewalks, and skyscrapers the first being undersea constructions, mines, and bridges for building products, numerous structures up to various construction are used. This page discusses the various types of construction materials used in construction. A hotel and residential complex in midrice the trust is now in motion. Supported by types and earth steel wallers around the excavation the pile also holds the steel sheet. The equipment enters, and the image travels down the earth's curve before leaving the spot. On the right, is a large backhoe from the previous structure there following the ancient mounds around digging continues but pressure-painted setting up the concrete pile legs what is happening, in the movie, better-completed piles are visible in the nearby center and the far corners. Piledrivers in large groups work. Strengthening of columns and concrete pile caps construction is underway on an excavation in the middle of the center. A well-liked technique for multi-criteria decision analysis (MCDA) and multi-criteria decision making (MCDM) is the weighted product model (WPM). The weighted sum model is comparable to this (WSM). The primary distinction is that multiplication is used as the primary mathematical operation rather than addition. The decision-making model by multiplication in linking an attribute rating includes the Weighted Product (WP) technique. When attributes are multiplied, weight for attributes acts as a positive rank, whereas attribute rating acts as a negative rank for the cost attribute. Materials, Construction equipment, Labor, Finance, Enabling Expenses, Admin Expenses, Surplus Building, Roads, Bridges, Dams, Power, Railway, Mineral Plant, Transmission the result it is seen that Dams is got the first rank where as is the building is having the lowest rank. Dams is ranked first and industrial Building is ranked lowest.

Numerical analysis of load-transfer mechanism of stiffened deep cement mixing pile foundation

ABSTRACT To reveal the load-transfer mechanism of stiffened deep cement mixing (SDCM) piles, the three-dimensional numerical analysis of a pilot pile was first conducted using the finite element software Diana, which can simulate the Mohr-Coulomb friction interface. Comparisons show that the computed load-settlement curve and distribution law of the skin frictions agreed well with the measurements. Then, the numerical method was employed to model the group pile foundations with four SDCM piles. It shows that the bearing capacity increased with increasing pile spacing and core lengths. And most loading was shared by the stiffened cores. It indicates that negative skin frictions may arise at the bottom of a reinforced concrete pile cap or the end of a stiffened core. And there is a hysteresis effect for the peak frictions on the two interfaces to mobilize. Meanwhile, plastic shear zones in soil and DCM pile may sequentially arise with increasing load.

Feasibility of improving shear performance of RC pile caps using various internal reinforcement configurations: Tests and finite element modelling

The loads from columns and bridge piers are transferred to the pile foundation by reinforced concrete (RC) pile caps, which are important structural components whose behavior is significantly affected by the internal reinforcement configuration. Therefore, the current study experimentally investigates the shear response of RC pile caps by testing nine specimens have identical dimensions and various reinforcement configurations. The experimental matrix is designed to study (i) the influence of using a closed transversal reinforcement along with the presence of an upper reinforcement only or an upper and side reinforcement together. (ii) Behavior of RC pile caps internally reinforced with various closed-side bars’ area and (iii) the impact of the interaction between the longitudinal reinforcement of the piles and the column in the presence of upper reinforcement only or side closed bars solely. RC pile cap specimen internally reinforced with closed transversal reinforcement with upper reinforcement and 12 mm-diameter closed side bars can be considered the optimal reinforcement form due to the fact that this specimen achieved the highest ultimate load and toughness of 1286 kN and 1089 kN.mm, respectively. Moreover, the current research involves the development of a three-dimensional (3D) non-linear finite element model to evaluate the response of RC pile caps while taking into account concrete's tensile strength and softening behavior in either tension or compression. Results of the numerical model well agreed with the experimental data. Additionally, a parametric study is conducted using the verified model to examine the impact of utilizing bent bars positioned perpendicular to the shear crack's direction on the ultimate load, failure pattern, and toughness of the RC pile caps.

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.

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.

Flexible support of a pile embedded in unsaturated soil under Rayleigh waves

AbstractUnder the action of Rayleigh waves, pile head is easy to rotate with a concrete pile cap, and pure fixed‐head condition is rarely achieved, which is a common phenomenon for it usually occurs on the precast piles with insufficient anchorage. In addition, the propagation characteristics of Rayleigh wave have been changed significantly due to the existence of capillary pressure and the coupling between phases in unsaturated soil, which significantly affects the pile‐soil interaction. In order to study the above problems, a coupled vibration model of unsaturated soil–pile system subjected to Rayleigh waves is established on the basis that the pile cap is equivalent to a rigid mass block. Meanwhile, the soil constitution is simplified to linear‐elastic and small deformations are assumed to occur during the vibration phase of soil–pile system. Then, the horizontal dynamic response of a homogeneous free‐field unsaturated soil caused by propagating Rayleigh waves is obtained by using operator decomposition theory and variable separation method. The dynamic equilibrium equation of a pile is established by using the dynamic Winkler model and the Timoshenko beam theory, and the analytical solutions of the horizontal displacement, rotation angle, bending moment and shear force of pile body are derived according to the boundary conditions of flexible constraint of pile top. Based on the present solutions, the rationality of the proposed model is verified by comparing with the previous research results. Through parametric study, the influence of rotational stiffness and yield bending moment of pile top on the horizontal dynamic characteristics of Rayleigh waves induced pile is investigated in detailed. The analysis results can be utilized for the seismic design of pile foundation under Rayleigh waves.

Shear behavior of RC pile cap beams strengthened using ultra-high performance concrete reinforced with steel mesh fabric

Although pile cap bases of structures are the most significant element in the construction and one of the most difficult parts in strengthening applications, previous studies on this element, particularly strengthening, are quite limited. The most extensively utilized, highly efficient, and simple to implement solution is ultra-high performance concrete (UHPC). In this study, six-half scaled pile cap beams were prepared and experimentally tested. Three of them were strengthened with UHPC (one in shear with connectors only, one in shear with connectors and steel mesh fabric (SMF), and one in shear and punching with connectors and SMF), while the other three were not strengthened to explore the influence of side bars. The bottom bars of the all six beams were identical, consisting of main longitudinal tensile and secondary lateral reinforcement. The load-displacement response, ultimate carrying load, failure mechanisms, energy dissipation capacity, and shear ductility of pile cap beams were all thoroughly investigated. The results revealed that using side bar reinforcement and UHPC with various techniques significantly enhanced the shear strength and ductility of pile cap beams. Except for the specimen including additional internal side bars, there were no appreciable differences in the peak load of un-strengthened reinforced concrete (RC) pile cap beams. The gain in peak load was 59% due to use of side bars. The RC pile cap beam strengthened in shear and punching with connectors and SMF exhibited the highest peak load and the highest energy dissipation capacity among all tested specimens.

Compression Tests of Very Large Reinforced Concrete Pile Caps and Comparison with Predicted Strength

Compression Tests of Very Large Reinforced Concrete Pile Caps and Comparison with Predicted Strength

Dynamic response of driven end-bearing piles and a pile group in soft clay: an experimental validation study

This paper presents novel measurement data on the dynamic soil–structure interaction of an end-bearing pile foundation. The purpose is to assess the ability to predict the foundation impedances based on the small-strain properties of the soil obtained from site investigations. Measurements were performed in two stages of construction, allowing to assess interaction between the piles through the soil. First, single pile impedances and interaction factors between the piles were experimentally obtained for the four piles when they were free to move at the surface. Second, the impedances of the square pile group were measured after casting a concrete pile cap. The piles were additionally instrumented with accelerometers at depth along the centerline of each pile, allowing to illustrate the global behaviour of the piles within the soil. Numerical predictions based solely on information of the small-strain soil properties obtained from extensive site investigations are compared to the experimental results. The impedances of the individual piles are overestimated compared to the measurements, while the interaction factors show a better agreement. The pile group impedances are better captured than the individual ones, using the same soil model. The pile–soil–pile interaction is clearly manifested in the experimental results by pronounced peaks in the pile group vertical impedance, validating results from previous numerical studies.

Pile caps with inclined shear reinforcement and steel fibers

This experimental investigation presents results and a discussion on a series of four reinforced concrete pile caps with and without steel fibers, measuring 400 × 400 × 1000 mm3, which were tested under concentric loading. The study set the steel fiber and the inclined shear reinforcement as variables. The fiber volume fraction was 1.5%, and the concrete compressive strength was 25 MPa. The results showed a tendency to increase ductility and ultimate strength with the use of inclined shear reinforcement; the same behavior was observed with the addition of steel fibers, improving the performance of the tested pile caps. This study opens the possibility of designing slender pile caps, especially when associated with both analyzed parameters.

Strength reduction design method for reinforced concrete structures: Generalization

This work presents a generalization and enhancement of a previously developed computational strength reduction design method (SRDM) for the design of complex reinforced concrete structures. The enhanced method SRDM-3D presented in this work extends the applicability of the original method to a more general 3D state of stresses and to different possible input tension stiffening and incompatibility laws, via a new calibration procedure. It also addresses the limitations of the strut-and-tie method initially developed and often applied to 2D geometries. Application of the developed method for simple 3D configurations allowed to obtain important results regarding the shape of nodal zones, incompatibility between concrete struts and reinforcement ties and conditions for the development of bottle-shaped struts for the general 3D framework of reinforced concrete structural elements. Validation examples presented at the end of the study on reinforced concrete pile caps demonstrate the robustness of the developed method, and its ability to provide a safe lower-bound design solution to different geometry configurations and different failure mechanisms. The developed method has the advantage of using a simple constitutive law and input parameters that are standard parameters required for design of RC structures.

Numerical analysis of hollow steel pile subjected to a combination of horizontal and vertical loads

This paper presents an analysis for investigating the nonlinear behaviour of a single hollow steel pile with a concrete pile cap subjected to different combinations of axial and lateral loads. The finite element based software ABAQUS/Explicit was used for the analysis. A number of load combinations were applied to understand the dynamic behaviour of hollow steel piles inserted in soil with different layers. Response of hollow steel pile in terms of vertical displacement, horizontal deflection and stresses developed in soil and pile was observed. The analysis results showed the pile's vertical downward settlement and horizontal deflection under different load combinations and the maximum amount of load the pile can carry before it fails. It further showed the stresses developed in the soil surrounding the pile.

Ultimate loads for reinforced concrete square pile caps

This paper reports the test results for eight high-strength concrete square pile caps. The main variables are the area of flexural steel bars and the configuration patterns of flexural steel bars. The test results show that the ultimate load on the pile cap increases as the total area of the flexural steel bars increases. The load–displacement curves are not significantly affected by an increase in the total area of the flexural steel bars. For a specific area of flexural steel bar, the ultimate load on the pile caps in a bunched square reinforcement pattern is no greater than that for pile caps in a grid reinforcement pattern. Pile caps in a bunched square reinforcement pattern exhibit no significant mechanical advantage over pile caps in a grid reinforcement pattern. Square pile caps in a grid reinforcement pattern perform better because this pattern is more conducive to concrete casting than a bunched square reinforcement pattern. The softened strut-and-tie model more accurately predicts the ultimate load for pile caps than the ACI sectional method for various shear span-to-depth ratios and compressive strengths of concrete. The ACI sectional method overestimates the flexural strength of the square pile cap.