Experimental study on the behaviour of pile caps subjected to combined column loads

ABSTRACT High-speed rail (HSR) development in India, with trains operating at ~320 km/h on elevated viaducts, demands reliable and indigenous foundation design solutions. Pile groups are widely adopted to enhance bearing capacity and control settlement; however, post-construction settlement under repeated train loading remains insufficiently explored. This study presents a methodology to predict cumulative settlement of pile groups subjected to high-frequency cyclic loading from HSR. A three-dimensional finite element model of the pile group is developed in Abaqus using suitable constitutive model. The influence of train speed, spcing of the pile (S) soil stifness (Es), length of pile (L) and pile cap thickness is investigated. Results indicate that train velocity has minimal impact on ultimate settlement, while increased pile length and stiffness significantly reduce it. The study proposes optimal pile group configurations and provides practical nomograms for efficient settlement prediction of a pile group from single pile settlement for HSR.

Combined effects of altered hydrodynamics and skew angles on scour around a complex cap pile group foundation

The main aim of this research is to investigate and analyse the non-linear behaviour of a single pile and pile groups with rigid pile caps subjected to torsional loading in clay soil. Plaxis 3D software is utilised, considering pile groups (1 × 2, 2 × 2, 3 × 2 and 3 × 3), different L/d ratios (L/d = 20, 30 and 50), spacing (S/d = 3, 4 and 6), depth of embedment (f/t = 1, 0.5 and 0), diameter (d = 0.76 m, 1.5 m and 2 m) and clay soil consistency (soft and stiff). The applied torque is found to be mainly resisted by the lateral and torsional resistances of each pile in a pile group, and quantitative evaluation of their contributions is conducted. From the numerical results, it is found that the failure torque of a single pile increases with pile length (57–257%), pile diameter (198–388%) and the depth of embedment of piles (6–206%). The torsional resistance of the groups increases with the pile length (7–22.5%), pile spacing (68–228%), pile diameter (176–281%), the depth of the embedment of piles (10–43%) and soil consistency (soft to stiff), but the torsional contribution decreases as the group size and spacing increases.

To investigate the mechanical response of surrounding rocks and existing bridges during shield tunnel construction, this study relied on the Guangzhou Electric Power Shield Tunnel Project. The 1g scaling test and numerical analysis method are employed to examine the variation patterns of surface settlement, surrounding rock pressure, pile displacement, and internal force during the shield tunnel construction, considering the two key factors: the longitudinal slope angle of the tunnel axis and the horizontal distance between the pile and the tunnel. The results signify that the width of the surface settlement trough on the pile side decreases under the influence of the existing pile foundation. The relationship between the maximum surface settlement caused by construction and the tunnel's longitudinal slope angle follows an approximately exponential function. The primary area affected by the construction extends from −2 to 4 times the diameter of the tunnel excavation on both sides of the pile cap. Additionally, the displacement of the pile cap caused by tunnel construction increases. As the shield tunneling transitions from uphill to downhill excavation, the settlement displacement of the pile cap induced by the tunnel construction also increases.

Rapid and accurate prediction of seismic response and fragility for bridge pile-group foundations (PGFs) is crucial for assessing seismic resilience. However, the high computational cost of traditional high-fidelity nonlinear analysis limits the application of probabilistic seismic risk analysis. To address this, an integrated deep learning framework is proposed that employs a unidirectional, multi-layer LSTM network for end-to-end prediction of structural responses directly from ground motions. The proposed model features two innovations. First, its multi-output capability enables simultaneous prediction of complete response time histories and peak values for key engineering demand parameters—bending moment, curvature, and pile cap displacement. Second, the network incorporates sliding time windows and residual connections to capture complex nonlinear soil–structure interaction. These predictions are integrated into a probabilistic seismic demand model to generate fragility curves. The framework is validated using a high-fidelity OpenSees model of a real bridge PGF subjected to 1000 ground motions. Results demonstrate the model’s excellent predictive accuracy: for peak bending moment, the mean predicted-to-actual ratio ranges from 0.97 to 1.03, with standard deviation below 0.12; the derived fragility curves show excellent agreement with benchmarks, achieving an average R2 of 0.985 across four damage states. More importantly, the framework reduces the time for a complete fragility assessment (200 incremental dynamic analyses) from approximately 12 h to about 1 s—a 40,000× speed-up—making data-driven rapid and large-scale seismic risk assessment a reality. The proposed framework provides engineers with a practical design tool for rapidly evaluating alternative foundation configurations and informing seismic design decisions, thereby integrating advanced data-driven methods directly into the engineering design workflow.

To address the stability issues of bridge piers on high expansive soil slopes in the Yangtze-Huaihe River Water Transfer Project and reveal the slope-bridge structure interaction mechanism, this study performed 100 g geotechnical centrifuge model tests. Slope failure modes under rainfall-bridge load coupling are investigated, with bridge pier deformation, earth pressure, and pile bending moment evolution analyzed. Results show that rainfall-induced failure causes shallow slope sliding with negligible pier displacement, keeping the structure safe. Conversely, under bridge working and ultimate loads, the slope will experience a mid-deep landslide with a sliding depth of 13–20 m, leading to slope instability and bridge overturning. The influence range of shallow landslides is 1–2 m, and the earth pressure at the pile cap is 132 kPa, which is a critical factor affecting bridge stability. In contrast, the bearing performance of pile foundations plays a dominant controlling role in deep-seated landslides. With the increase in landslide depth, the inflection point of the pile gradually moves downward. Numerical simulations further indicate that shallow landslides feature superficial slip–shear failure, and deep-seated landslides follow a progressive slip tensile cracking mechanism.

Pile foundations play an important role in ensuring the stability of multi storey buildings subjected to axial loads, lateral loads, and moments. In the Batang III Industrial Worker Housing Project (JTGRSN21-03), the original foundation system used bored piles. This study redesigns the foundation into spun piles with a diameter of 0.80 m and a length of 12 m under the same soil conditions and loads. The research methodology was conducted through analysis of three foundation joints. Axial bearing capacity was evaluated using the Meyerhof method, resulting in a tip resistance of 946.00 kN, skin friction resistance of 2,970.37 kN, ultimate bearing capacity of 3,916.37 kN, and allowable bearing capacity of 1,305.46 kN. Lateral bearing capacity was analyzed using the Broms method with an allowable capacity of 162.0 kN. Group pile bearing capacity was determined using the Converse Labarre method. Settlement analysis using the Vesic method showed a single pile settlement of 22.69 mm and group settlements of 50.2 mm at joint 599, 41.8 mm at joint 628, and 21.0 mm at joint 371. Plaxis analysis produced smaller settlements of 13.94 mm, 13.44 mm, and 9.19 mm. The pile cap and shear wall design is considered safe.

We conducted bending shear experiments on five test specimens to apply precast pile caps to the steel foundation beam construction method and to verify our previous proposed formulas. In each specimen, we confirmed that there was no rapid loss of horizontal resistance after the yielding of each rebar and maximum load, and we organized the effects of various parameters on the maximum load. Additionally, we presented the characteristic strain distribution of the main reinforcement. In the comparison of experimental results and calculated values, we were able to demonstrate the validity of the proposed formulas.

This study presents the redesign and structural verification of a 60,000 DWT dry bulk jetty in the coastal area of Gresik, East Java, where the project site is characterized by soft ground (Site Class SE) and requires earthquake-resistant performance. The original structural concept is reconfigured from a precast system to a cast-in-situ reinforced concrete system to improve continuity, connection robustness, and constructability in a seismic port environment. A three-dimensional numerical model was developed in SAP2000 to represent the interaction between deck slab, beams, pile caps, and steel pipe piles (SPP Ø1016 mm, t = 15.9 mm). Design actions include dead and operational live loads (3.0 t/m²), crane wheel loads under critical transverse positions, vessel berthing and mooring loads (fender reaction and bollard demand), and response-spectrum earthquake loading based on Indonesian provisions. The redesigned superstructure adopts a 350 mm deck slab with D16–150 reinforcement, and beam detailing is provided for longitudinal, transverse, and crane beams. Foundation checks confirm that axial reactions remain below the pile bearing capacity, pile utilization ratios are below unity, maximum vertical settlement is 0.63 cm (within the allowable limit), and maximum lateral deflection is 85.14 mm (below the serviceability threshold). The lump-sum construction cost implication for the redesigned system is USD 11.062 million.

A simplified approximate method to analyze the rocking response of pile groups subjected to seismic loading is introduced. The proposed method accounts for the nonlinear response of the soil and reinforced concrete (RC) piles, including the axial load dependency of RC bending moment capacity, and gapping effects at the soil–pile interface. The piles are replaced by an assembly of hysteretic (kinematic hardening) elements, combined with springs, sliders, and gap elements. Viscous damping is added to the springs and the hysteretic elements for the elastic range of the response. The proposed simplified method is verified against nonlinear three-dimensional (3D) finite-element (FE) analyses of a rocking 2×1 pile group in a stiff overconsolidated clay of uniform undrained shear strength. Two uniform shear strength profiles, Su=100 kPa (pile shaft adhesion factor α=0.75) and 220 kPa (α=0.25), and four cases of vertical loading are examined, ranging from vertical factor of safety FSV=10 (very lightly loaded), FSV=5 (lightly loaded), to FSV=3 (normally loaded), and to FSV=2 (heavily loaded). The moment-to-shear ratio is also explored, considering two different pier heights HP=6 and 12 m. The simplified method is shown to capture the seismic response of rocking pile groups remarkably well. The prediction errors of maximum foundation rocking and permanent settlement did not exceed 20% in most cases; the predictions of residual foundation rotations were less reliable. The proposed method neglects the contribution of the pile cap, cannot account for kinematic soil–pile interaction effects, and its applicability is limited to pile groups exhibiting rocking-dominated response. Furthermore, the method is intended for the seismic analysis of pile groups that fully mobilize their bearing capacity, and may not be equally efficient for pile groups that do not exhibit strongly nonlinear response. Focusing on cohesive soil, detailed calibration guidelines are proposed, well aligned with the existing literature and supplemented with a parametric FE study of a single pile in a soil of uniform shear strength. Although the proposed method offers considerable flexibility, further verification across different soil conditions and pile group typologies is needed. Additionally, extending the calibration guidelines to noncohesive soils would enhance the method’s applicability.

The foundation of turbine machines in industrial buildings must be able to withstand static and dynamic loads caused by operational vibrations. Generally, reinforced concrete block foundations are used due to their good stability. However, under certain conditions such as limited land, decreased soil bearing capacity, and the need for structural rehabilitation, their application becomes less effective. Therefore, this study aims to analyze the use of Micropile foundations as an alternative for turbine machine foundations at Candi Baru Sugar Factory, Sidoarjo.The research method includes literature studies, soil data collection through Cone Penetration Test (CPT), machine technical data analysis, and the design and analysis of Micropile foundations. The analysis covers bearing capacity, settlement, dynamic response, pile cap design, and cost estimation.The results indicate that Micropiles with a diameter of 0.20 m, a length of 2 m, five piles, and a pile cap size of 2 m × 2 m × 4.5 m are able to safely and stably support the machine load. In addition, this system is considered more efficient in terms of construction time and implementation. Therefore, Micropile foundations are recommended as an effective and economical alternative for turbine machine foundations.

Pontianak City has experienced a steady increase in tourist arrivals, which has resulted in a higher demand for temporary accommodation facilities. In response to this development, this study presents the structural design of an eight-story reinforced concrete hotel building located on Sepakat II Street in Pontianak City. The structure is designed using an Intermediate Moment-Resisting Frame (IMRF) system to ensure adequate performance under seismic loading conditions. The structural design process was carried out in accordance with the applicable Indonesian National Standards (SNI). Structural analysis was conducted using ETABS software to evaluate the building’s behavior under gravity and earthquake loads, while technical drawings were prepared using AutoCAD and SketchUp. The building utilizes concrete with a compressive strength of f’c = 30 MPa and reinforcing steel with a yield strength of fy = 420 MPa. The seismic performance of the structure was evaluated through several parameters, including mass participation ratios, inter story drift limits, natural period verification, and P-Delta effects. The analysis results show that the structural system satisfies all required performance criteria, indicating that the building is capable of resisting seismic forces safely and efficiently. The slab system consists of D10 main reinforcement bars and Ø8 shrinkage reinforcement bars, with slab thicknesses of 150 mm for the roof, 130 mm for typical floors (Levels 1–8), and 160 mm for stair landings. The primary beams (B1) have cross-sectional dimensions of 300 × 600 mm and are reinforced with D19 longitudinal bars, D13 shear reinforcement, and D19 torsional reinforcement. Secondary beams (B2) measure 200 × 400 mm and use D16 longitudinal bars, D13 shear reinforcement, and D16 torsional reinforcement. Columns have a uniform cross-section of 700 × 700 mm and are reinforced with 20D22 longitudinal bars and D13 transverse reinforcement. The foundation system consists of three types of pile foundations using 200 × 200 mm precast concrete piles with reinforced pile caps designed to accommodate varying structural loads.

This study aims to analyze the construction management of the 80-meter Cikeruh Steel Box Girder Bridge Project on the Cirebon-Bandung Highway in Majalengka Regency, which is a replacement for the old bridge due to the age of the structure and increased vehicle load intensity. This construction management analysis includes calculating the volume of work, estimating the budget plan (RAB), and scheduling project implementation. The research method used is qualitative with direct observation, interviews, and literature study techniques. The data collected includes primary data (field technical data, working drawings) and secondary data (location maps, unit price analysis, and unit prices). The AHSP used in this study is the 2024 Majalengka Regency AHSP. The results of the analysis of the main work volume calculations show a bore pile volume of 89.49 m3, a pile cap volume of 134.4 m3, a column volume of 50.2656 m3, and a pier head volume of 56000 m3. Based on the RAB calculations, the total cost required to complete the project is IDR 31,149,328,054.56. The work schedule was analyzed using a Bar Chart and S-Curve. This study provides a comprehensive overview of the essential aspects of volume, cost, and time in bridge construction project management.

Pile foundations are critical load-bearing components in bridge structures, particularly in soft, high-moisture soils susceptible to external disturbances. This study investigated the impact of large-scale soil excavation on the stability of adjacent pile foundations through comprehensive field monitoring of a newly constructed bridge during both the bridge construction and channel excavation phases. The close proximity of the excavation site to the pile caps facilitated a detailed assessment of soil–structure interaction. The results indicate that the pile axial force peaked at the pile head and decreased progressively with depth, consistent with the load transfer mechanism of friction piles. Notably, a distinct variation in axial force was observed at the bedrock interface, attributed to reduced relative displacement between the pile and the surrounding soil. Furthermore, channel water filling raised the local groundwater table, which increased the buoyancy and reduced negative skin friction, thereby decreasing the pile axial force. The study also highlighted the sensitivity of pile deformation in soft soil to unbalanced earth pressure. Asymmetric excavation and surface surcharge loading were identified as critical factors compromising pile stability and overall structural safety. These findings provide valuable insights for construction practices and offer effective strategies to mitigate adverse excavation effects, ensuring long-term structural stability.

Seismic action significantly affects the mechanical properties and failure characteristics of bridge pile foundations, soft rocks, and sediments. This study, by integrating shaking table tests, numerical simulations, and on-site monitoring, systematically analyzed the influence mechanisms of seismic intensity, sediment characteristics, and pile foundation layout on structural responses. Tests show that the 2.5-layer rock–sand pile exhibits nonlinear bearing degradation under seismic force: when the seismic acceleration increases from 0 to 100 m/s2, the bearing capacity of the pile foundation decreases by 55.3%, and the settlement increases from 3.2 mm to 18.5 mm. When the acceleration is ≥2 m/s2, the cohesion of the sand layer is destroyed, causing a semi-liquefied state. When it is ≥10 m/s2, the resistance loss reaches 80%. The increase in pore water pressure leads to dynamic settlement. When the seismic acceleration is greater than 50 m/s2, the shear modulus of the sand layer drops below 15% of its original value. The thickness of the sediment has a nearly linear relationship with the reduction rate of the bearing capacity. When the thickness increases from 0 to 1.4 cm, the reduction rate rises from 0% to 55.3%. When the thickness exceeds 0.8 cm, it enters the “danger zone”, and the bearing capacity decreases nonlinearly with the increase in thickness. The particle size is positively correlated with the reduction rate. The liquefaction risk of fine particles (<0.1 mm) is significantly higher than that of coarse particles (>0.2 mm). The load analysis of the pile cap shows that when the sediment depth is 140 cm, the final bearing capacity is 156,187.2 kN (reduction coefficient 0.898), and the maximum settlement is concentrated at the top point of the pile cap. Under the longitudinal seismic load of the pile group, the settlement growth rate of the piles containing sediment reached 67.16%, triggering the dual effect of “sediment–earthquake”. The lateral load leads to a combined effect of “torsional inclination”, and the stress at the top of the non-sediment pile reaches 6.41MPa. The seismic intensity (PGA) is positively correlated with the safety factor (FS) (FS increases from 1.209 to 37.654 when 10 m/s2→100 m/s2), while sediment thickness (h) is negatively correlated with FS (FS decreases from 2.510 to 1.209 when 0.05 m→0.20 m). The research results reveal the coupled control mechanism of sediment characteristics, seismic parameters, and pile foundation layout on seismic performance, providing key parameters and an optimization basis for bridge design in high-intensity areas.

The position of foundation pile caps of monument constructed on coastline changed from below to above the soil surface. Therefore, the piles were driven in a free-standing condition and then covered with beach sand soil. This research aims to analyze the frictional resistance of buried pile, then compare it with the frictional resistance of ordinary piles. Practical analysis methods and finite element methods using RS Pile software are compared to obtain a representative method. The comparison results show that the Meyerhof method has the closest soil bearing capacity behavior to the field test results. Based on the results, the skin friction of buried piles is 52% - 57% lower than ordinary piles. This decrease occurred because the assumed value of the angle of friction in the soil was lower because the soil around the pile was not as dense as in ordinary conditions which compacted during the driving process.

The calculation of work volume and construction costs is a fundamental aspect of project management, as errors in the estimation process can directly affect the preparation of the project budget. Many projects still use conventional methods for estimation, which are based on 2D working drawings with the assistance of Microsoft Excel, as seen in the Sungai Raya Religious Court Building project. This method is considered prone to calculation errors and less efficient due to the considerable amount of time required. With the advancement of technology, Building Information Modeling (BIM) has emerged, enabling automatic and integrated calculation of work volumes and construction costs through a three-dimensional digital model. This study aims to examine the implementation of BIM in the Sungai Raya Religious Court Building project and to compare the results of work volume and construction cost calculations between the BIM method using Autodesk Revit and the conventional method based on the project’s Bill of Quantity (BoQ). The research method was conducted by modeling the structural elements of the building, including pile caps, tie beams, columns, beams, floor slabs, and reinforcements. The results of work volume and construction cost calculations obtained from Autodesk Revit were then compared with the project’s BoQ as the conventional method. Based on the analysis, an average difference of 6.3% in work volume and 5.6% in construction cost was found, with the Autodesk Revit calculations showing slightly lower values compared to the project’s BoQ.

Behaviour of pile caps with socket connections and different embedment depths under vertical loads

Vertical load transfer of pile caps with plain socket connections