Pile Cap Research Articles

Rapid Assessment Method of Buckling Stability of Bridge Pier–Cap–Pile System Under Scour Effect

A novel analytical method for evaluating the buckling stability of the pier–cap–pile system under scour effect is proposed, and furthermore, the concept of rapid assessment of bridge buckling stability based on natural frequency is innovatively introduced in this paper. First, the total potential energy function of the bridge pier–cap–pile system is established, and the closed-form solution of structural system critical buckling load under scouring is solved according to the principle of stationary potential energy. Second, the sensitivity analyses of pier height, pier width, bending stiffness reduction in pier, pile slenderness ratio, pile bending stiffness reduction, m-value of soil and structural gravity to the buckling load are carried out. On this basis, 60 sets of sensitive parameter sample combinations are extracted by the Latin Hypercube Sampling algorithm, and a proxy model relating the critical buckling load to scour depth and the sensitive parameters are then developed using the McQuarter global optimization algorithm. Finally, the regression relationship model between the critical buckling load and the natural frequency is formed by combining the proxy model and the existing relationship between the scour depth and the first-order natural frequency. The feasibility of the proposed assessment method is demonstrated by the finite element method using a bridge case study, which provides an insight and a new means of quantitatively evaluating the safety of bridges under scour effect.

Numerical investigation on erosion characteristics of elevated pile cap in high concentration sediment flow environment

Numerical investigation on erosion characteristics of elevated pile cap in high concentration sediment flow environment

Experimental Investigations on the On-Site Crack Control of Pier Concrete in High-Altitude Environments

Concrete structures in high-altitude environments face many challenges. Establishing concrete crack control methods in high-altitude environments is crucial for enhancing the service capacity of concrete structures. In this study, a multi-field (hydration-temperature–humidity-constraint) coupling model was used to quantitatively assess the cracking risk of pier bodies at high altitude. On-site crack control tests were conducted on pier bodies using a micro-expansion anti-cracking agent to demonstrate the effectiveness of deformation shrinkage compensation in crack control at high altitudes. The results indicated that there was a risk of cracking in the pier body at high-altitude conditions, especially within 0.3 m from the pile cap and ±2.5 m from the center of the pier side surface. Compared with conventional piers, the micro-expansion anti-cracking agent approximately doubled the unit expansion deflection of piers at high temperatures while reducing the unit shrinkage deflection of piers by 11% to 12% at low temperatures. The concrete in conventional pier bodies was in a tension state after long-term hardening, while the concrete treated with the micro-expansive anti-cracking agent was in compression. Therefore, the deformation compensation effect of the micro-expansive anti-cracking agent was significant and reduced the risk of concrete cracking. In addition, early freezing had a significant impact on concrete strength, underscoring the importance of effective temperature control during the early stages of concrete placement in high-altitude environments.

Bearing Characteristics of Deep Cement Mixing Integrated Drilling, Mixing and Jetting Piles Based on Numerical Simulation

The Deep Cement Mixing Integrated Drilling, Mixing and Jetting (DMJ) technique has been developed through the installation of high-pressure spray holes at the mixing blades, with the objective of enhancing the bearing capacity of deep-mixed piles in the Yellow River floodplain. In order to enhance the bearing capacity of the foundation, variable-modulus piles and capped piles were incorporated within the DMJ piles. Engineering applications have demonstrated that DMJ piles can effectively address the issue of foundation reinforcement in the Yellow River floodplain region, minimize the wastage of cement, and reduce the environmental pollution associated with waste slurry. Nevertheless, a comprehensive study of the relevant factors is still lacking in the available literature. This study addresses this gap by conducting a numerical simulation of these two types of DMJ piles based on the preliminary field test data, with the objective of analyzing both the single-pile-bearing characteristics and the composite foundation-bearing characteristics. Furthermore, the study seeks to optimize the DMJ pile’s structure based on the simulation results. The findings demonstrate that the premature failure of a single pile during the bearing process can be averted if the modulus of the pile core reaches a minimum of 0.3 GPa or if the pile cap thickness exceeds 1 m. The utilization of large-diameter drilling, stirring and spraying piles can markedly enhance the bearing capacity of the composite foundation and mitigate the differential settlement of pile and soil. The spacing of the pile has been identified as a significant factor influencing the differential settlement of pile and soil. Consequently, this study also examines the impact of pile spacing on the differential settlement of piles and soil.

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.

Impact force-damage depth model for ship-bridge collision

The impact force-damage depth model, i.e., P-a model, provides a feasible approach to design and evaluate bridge resistance under ship collisions, which is inadequately addressed in the existing specifications and literature. In the present study, based on an 18500 DWT (deadweight tonnage) bulbous bow bulk carrier and the main tower of cable-stayed bridges, the P-a model for ship-bridge collision is established with consideration of pile cap, bridge pylon and striking ship. Firstly, the refined finite element (FE) model of prototype ship was established with detailed modeling of both the main and stiffening components. The material model parameters and FE analysis approach were validated through the existing tensile tests on marine steel coupons and crush tests on ship bow specimens. It is found that the modeling of stiffening components has rationality in predicting the impact force and asymmetrical folding collapse of ship bow. Then, concerning two collision scenarios with the main tower of cable-stayed bridges, i.e., only bulbous bow-pile cap collision and sequential bulbous bow-pile cap and bow overhang-bridge pylon collisions, the influences of nine critical parameters from pile cap (height, curvature and water level), bridge pylon (width, curvature, angle and bow overhang-bridge pylon distance) and striking ship (mass and velocity) on the impact forces and failure patterns of ship bow were comprehensively discussed. It indicates that: (i) the larger impact forces of bulbous bow and bow overhang appear with increased pile cap height, decreased bridge pylon curvature and inward inclined pylon angle; (ii) the loading paths of P-a relationships are approximately identical with different striking ship masses and velocities. Finally, the P-a model for ship-bridge collision was established by response surface methodology, and the corresponding calculation procedure was further given and validated.

Diseño estructural del edificio más alto de El Salvador

The Corporate Tower is a 33-story building with a total height of 139m and a floor area of 81x56m. The structural systems used were Dual Frame-wall and Special Moment Frame systems with Seismic Detailing, the foundations were of the deep type consisting of interconnected concrete piles through foundation beams and pile caps. This article outlines the guidelines followed for the superstructure and substructure’s structural design, as well as the challenges overcome due to the unique conditions of the project. Given the significance of this endeavor, site response studies were necessary to optimize the structure. Similarly, state of the art standards were implemented in accordance with the latest developments in structural design, such as ASCE7-10 and ACI318-14. ILIA: Investigaciones Latinoamericanas en Ingeniería y Arquitectura, No. 01, 2024: 115-121.

PELAKSANAAN PEKERJAAN STRUKTUR BAWAH BANGUNAN GEDUNG SERBAGUNA GELANGGANG GENERASI MUDA MAJALENGKA

The Majalengka Regency Youth Center Development Project is an important historical milestone for infrastructure development in the Majalengka Regency area. The concept of an oval-shaped building like a stadium gives uniqueness to the design of the foundation of this building. Basically, the substructure is a very vital component for the success of a building, so the author is interested in looking further into the substructure, especially in work methods or work implementation. This research uses a qualitative approach, which can be interpreted as directly describing the work of the lower structures in the project which is used as the research object. The implementation of the lower structure work starts with the piling work and then continues with the pile cap work, carried out in stages using a zone system. In the realization of the implementation of the lower structure work on the GGM project, namely the piling work starting from site preparation, mobilization and set up of HSPD piling tools, measuring pile points, driving piles using the hydraulic jack-in pile method, testing piles, and pile head treatment, continued with the implementation of pile cap work starting from preparation, measurement and bow plank, soil excavation, installation of formwork, reinforcement and casting.

Perencanaan Ulang Bangunan Gedung Dormitory Kawasan Sains dan Teknologi (KST) Nuklir Yogyakarta Berbasis Building Information Modelling (BIM) 5D

Building Information Modeling (BIM) is a method of processing data during the life cycle of a construction project that uses three-dimensional, real-time, and dynamic building modeling software, thereby creating a complete model related to project data from the planning to the construction phase of the project. In the re-planning of the Yogyakarta Nuclear Science and Technology (KST) Dormitory Building based on Building Information Modeling (BIM) 5D, a special moment resisting frame system (SRPMK) structure was used. The planned building consists of 7 floors, including the lower structure consisting of a 50x50 square pile foundation and five types of pile cap, the upper structure consisting of columns, beams, and floor plates. The quality of concrete in the structure used is fc' 40 Mpa and 35 Mpa with reinforcing steel quality fy 420B. In this planning, 2D and 3D modeling was carried out. Structural analysis was carried out using the SAP2000 application, which was then continued with 2D 3D modeling and Quantity take-off results using Revit and Scheduling using Ms. Projects. The Draft Budget (RAB) results for this planning are Rp. 37,691,368,000.00. The planned duration of work is 26 weeks. The results of the scheduling and RAB are then integrated using the Naviswork software so that the simulation results of the work to be planned can be seen.

Discrete element analysis of geosynthetic-reinforced pile-supported embankments

A discrete element trapdoor model was established using the MatDEM software, and the effects of different embankment and reinforcement heights on the soil arching effect of embankments under reinforced conditions were investigated by introducing a biaxial geogrid. The outcomes demonstrated that the inclusion of a geosynthetic reinforcement could enhance the load transfer efficacy of the embankment and thereby reduce the differential settlement of the embankment surface. The differential settlement could be reduced by approximately 50 % when the reinforcement height and the pile cap were close. The inclusion of the geosynthetic reinforcement helped reduce the development of the slip surface within the embankment above the reinforcement and prevented the vertical slip surface from continuing to move upwards, thus ensuring that the soil arching effect did not degrade too quickly and continued to play a role. In the case of a low embankment reinforcement, the soil arching effect was largely nonfunctional because of the rapid development of the vertical slip surface, and the load on the embankment in the soft soil was mainly transferred to the piles through the tensioned membrane effect of the geosynthetic reinforcement. For a high embankment with a low reinforcement height, the soil arch structure of the embankment was well maintained, the soil arching effect did not degrade, and the load on the embankment in the upper part of the soft soil was transferred to the piles via the soil arching effect along with the tensioned membrane effect. In the case of a high embankment with a high reinforcement, the reinforcement blocked the vertical slip surface only for the soil above the reinforcement height, whereas the vertical slip surface below the reinforcement height developed in line with that of the same height, when the tensioned membrane effect and soil arching effect worked together in the embankment above the reinforcement height, and the soil arching effect below the reinforcement height degraded and hardly played a role.

Spatial Variability of Sliding Plane on Volcanic Region. Case Study of Sta 21+200 Cisumdawu Toll Road

Landslide can be caused either by natural phenomenon or due to human intervention. Regardless of the triggering factor, once landslide occurs, sliding plane in the form of discontinuity or sometimes referred as sliding plane is formed. Identifying the location and geometry of the sliding plane is important in determining the location of the reinforcement to rehabilitate slope failure. However, it is often difficult to locate the location and geometry of the sliding plane as the sliding direction is also difficult to ascertain. In this paper, slope failure which occurred in STA 21+200 of Cisumdawu toll road is used as case study. Variability of the sliding planes are investigated based on the location of the concrete overbreak that occurred during the bored pile construction on Tuff (volcanic soils) in Sumedang Region. Sliding planes are also estimated based on the soil investigation and pile boring records. The proposed solution is to reinforce the bored piles that did not penetrate into the hard layer with ground anchors installed at the pile cap.

Analytical model of three-dimensional concentric ellipsoidal soil arching in geosynthetic-reinforced pile-supported embankments

The geosynthetic-reinforced pile-supported (GRPS) embankment is an effective method for improving soft ground, widely adopted in engineering applications. In this paper, a concentric ellipsoidal soil arching model was proposed to describe the stress distribution within the GRPS embankment. An analytical solution for soil arching efficacy was derived by solving the loads acting on the pile caps and geosynthetics under piles arranged in a squared pattern. Subsequently, finite difference models were established to verify the accuracy of the derived analytical solution. Meanwhile, four field tests were introduced to validate the analytical model. Finally, parametric studies were conducted on the concentric ellipsoidal soil arching model, considering parameters such as the embankment height, the pile spacing, the pile cap width, the unit weight, and the friction angle of fill soil.

Consolidation of unsaturated composite foundation reinforced by T-shaped deep cement mixing piles

T-shaped deep cement mixing piles are variable section piles designed to reinforce unsaturated composite foundation under the embankment loading, which can effectively reduce regional settlement and construction costs. However, how to calculate the consolidation settlement of the reinforced ground is unclear when considering the T-shaped deep cement mixing piles. To investigate the consolidation process, the governing equations for unsaturated composite foundation with T-shaped deep cement mixing piles are firstly derived under the equal strain assumption. Then, semi-analytical solutions for settlement and excess pore pressures are obtained using Laplace transform and transfer matrix methods, and Crump’s method is employed to get analytical solutions in the time domain. The accuracy of the proposed solutions is verified by comparing them with existing ones. Finally, the analysis of the parameters is conducted to explore the consolidation characteristics of unsaturated composite foundation with T-shaped deep cement mixing and deep cement mixing piles. The findings indicate that accounting for the enlarged pile cap leads to a quicker dissipation of excess pore pressures, resulting in a notable reduction in foundation settlement. As the height of the enlarged pile cap and the area replacement ratio increase, the settlement decreases markedly because the enlarged pile cap carries more load.

Dynamic Analysis of Force Redistribution in Small Pile Groups Foundation Subjected to Accidental Lateral Loads

Abstract Designing infrastructure always involves considering potential loads. Beyond anticipated loads, accidental ones can occur, as with the Pedamaran II bridge in Riau, where a ship collision damaged its foundation, breaking a pile and cracking the pile cap. However, this did not lead to structural failure, even though over 30% of the piles in the group were damaged. Initial hypotheses suggest that the use of bracing in the existing bridge might have helped redistribute forces. A numerical model was created using Opensees to simulate lateral loading on the shaft of an elevated pile cap, comparing the effects of bracing and no bracing using elastic elements in a simple 2x2 foundation model. The aim was to understand the correct modeling approach for bracing behavior and its impact on load response. Pushover analysis was performed on one of the shafts, with eccentric loading generating forces in both the x and y axes. Results showed that modeling bracing with elastic elements helped evenly distribute forces across rows of piles, with the greatest distribution occurring in the loaded row. The maximum moment occurred at the lowest bracing connection, highlighting the crucial role of bracing in load distribution, and significantly increasing lateral capacity by about 60%.

Analysis of the behavior of piled foundations in unconventional soil

Building foundations using pile groups generally assume that the piles absorb the entire load of the structure. However, it is known that pile caps rest not only on the piles but also on the surrounding soil. These foundations involve great complexity in the phenomenon of load sharing, especially when they are situated on unconventional soils, such as tropical climate soils. To study this behavior, static load tests were conducted on real foundations. These tests were also used to calibrate a three-dimensional finite element numerical model (FEA-3D) using Rocscience's RS3 software. The results showed that the settlement corresponding to the allowable load of the pile groups was significantly lower, ranging from 22 % to 73 %, compared to pile caps that exert contact pressure on the soil. For pile groups, the efficiency ranged between 92 % and 109 %, while for pile caps with contact, it ranged from 132 % to 178 %. In this sense, it becomes evident that estimating the settlement of the pile group based on the conventional design, which does not consider the contact between the cap and the soil, can significantly underestimate the settlement, and provide an overly optimistic analysis of the soil-structure interaction.

Design of E.R. Building At Ct Arsa Palu Hospital With Liquefaction Potential

This design hospital building is planned to be built in the city of Palu. Palu City has high earthquake potential, has history of liquefaction, tsunami and landslides disasters. Thorough design is needed so that this hospital building still become a place for health services after a disaster occurs. The building was designed using the Special Moment Resisting Frame Structure system based on the SNI. Earthquake load analysis uses the response spectrum method based on Earthquake Resistance Planning Procedures (SNI 1726:2019). This concept obtains structure design that meets SNI and still strong in strong earthquake and liquefaction. Analysis has been carried out and it was found that the potential for liquefaction to occur at a depth of 1.5 M to 4.5 M so that the foundation chosen was 4 piles with a diameter of 40 cm, a depth of 6 meters per pile cap. From the results of calculations, it shows that the structure of the emergency room building at CT Arsa Palu Hospital is safe from an analytical perspective.

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 investigation for shear behavior of pretensioned spun precast concrete pile

Pretensioned spun precast concrete (SPC) pile has emerged as a popular solution for deep foundation systems due to its ease of construction, enhanced bearing capacity, and overall cost-effectiveness. However, the hollowness of SPC piles, which reduces their sectional area, may become critical near the pile cap zone, especially in liquefaction scenarios during earthquake events. This study numerically investigates the shear behavior of hollow pre-tensioned SPC piles using the Finite Element (FE) technique. Primarily, the numerical results are validated with the test results of actual SPC piles where they were manufactured by high-strength concrete and high-tensioned steel strands for both with and without spirals. The numerical results show a good agreement with the experimental data in terms of strength, stiffness, and failure pattern for both types of spiral arrangements. The numerically obtained shear capacity is also found to be within close range of the code recommendations. A series of parametric studies have been conducted to understand the influence of essential pile parameters such as spiral’s spacing, effective prestress, number of strands, thickness-to-diameter ratio, concrete strength, and test orientation angle on the shear resistance of SPC pile. The study claimed that the addition of shear reinforcements to SPC piles boosts their shear capability, whereas the addition of strands and angle of test orientation have little effect on the piles' shear resistance. The optimum applied pre-stressing was found in a range of 4–8 MPa. The optimum values of t/d ratios in terms of material savings to shear resistance of the SPC pile fall in a range of 0.20 – 0.30. Morris Sensitivity Analysis (MSA) reveals that effective prestress and pile concrete strength are the most influential parameters of the shear capacity of SPC piles. This study provides important details for the SPC pile's shear design, illustrating its applicability in deep foundations in seismic areas.

Numerical Analysis of Flow Structure Evolution during Scour Hole Development: A Case Study of a Pile-Supported Pier with Partially Buried Pile Cap

This study numerically investigates a pile-supported pier, which comprises a column with a partially buried pile cap and a group of piles, recognizing that partially buried pile caps lead to the highest scour depth. Most research has focused on equilibrium scour conditions in laboratory settings, overlooking the detailed dynamics of horseshoe vortices around pile groups. This study aims to clarify the flow structure and vortex dynamics at a pile-supported pier during local scour hole development stages using an in-house developed numerical model. The model’s accuracy is validated against flat-channel and compound pier reference cases. For the pile-supported pier, fixed bed geometry was used in flow simulations at selected scouring stages. Results show significant changes in flow structure and vortex formation with scour hole time development, particularly as the bed surface moves away from the pile cap. The study reveals variations in vortex size, number, and positioning, alongside turbulent kinetic energy and Reynolds shear stress distributions over time. High positive Reynolds shear stress near the bed during intermediate scouring stages highlights the complex interactions within the flow field. This research provides the first detailed visualization of flow structure evolution within a scour hole at a pile-supported pier.

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.