Horizontal Bearing Research Articles

Study on seismic performance of narrow flange special-shaped column with herringbone center support

Abstract To solve the problems of convex beam, column and insufficient lateral stiffness of steel frame in residential buildings, a new type of steel special-shaped column with herringbone center support structure system is proposed by combining narrow flange special-shaped column with herringbone center support. The finite element model was established by ABAQUS to study the influence of parameters such as axial compression ratio and shear span ratio on the seismic performance of the structural system. The results show that the hysteresis curve of the structure is full, the lateral bearing capacity is high, and it has stable and reliable energy dissipation performance and plastic deformation ability. The structure has obvious yield and failure process under the action of horizontal reciprocating load, and the whole structure presents ductile failure. The plastic deformation of the structure is concentrated on the support, and the energy is consumed by the buckling of the herringbone central support, while the other structural members remain elastic. The increase of axial compression ratio will lead to a significant decrease in the horizontal bearing capacity and lateral stiffness of the structure. After the buckling of the brace, the structure also has good ductility. With the increase of shear span ratio, the lateral bearing capacity, lateral stiffness and ductility coefficient of the structure decrease.

Numerical Simulation Study of Bearing Characteristics of Large-Diameter Flexible Piles Under Complex Loads

The majority of the existing calculation methods for determining the ultimate bearing capacity of steel-pipe piles using Chinese criteria are designed for piles with diameters smaller than 2 m. To investigate the bearing capacity of flexible steel-pipe piles with diameters larger than 2 m under combined loading conditions, reveal nonlinear interactions between vertical and horizontal loads, and propose bearing capacity envelopes, in this paper, a numerical method was used to study the bearing capacity of a flexible pile with a diameter of 2.8 m and an embedment length of 72 m under vertical and horizontal loading conditions. First, a numerical model was developed and calibrated using field test results. Then, the effects of vertical pressure on horizontal capacity and lateral force on vertical capacity and uplift capacity of the pile were analyzed. The results indicate that vertical pressure at the top of the pile can nonlinearly reduce its horizontal capacity, but this pressure initially has a slight positive effect on the horizontal bearing capacity before causing a rapid decrease. Conversely, horizontal force negatively impacts both the compressive and uplift bearing capacities of the pile. Finally, depending on the above results, bearing capacity envelopes for piles subjected to vertical and horizontal loads were proposed.

An Analysis of the Flexural Stiffness and Horizontal Bearing Capacity of CFRP Composite Pipe Piles in Marine Environments

Carbon-fiber-reinforced polymer (CFRP) is a composite material consisting of a resin matrix reinforced with carbon fibers. This study focuses on CFRP composite pipe piles as the subject of investigation, exploring the impact of substituting steel bars with CFRP bars on the bending performance of pipe piles through rigorous three-point bending tests. The attenuation of flexural stiffness in CFRP pipe piles under a chloride salt environment was anticipated. The lateral bearing capacity of CFRP pipe piles was calculated by introducing a stiffness degradation coefficient for the piles and utilizing the finite difference method. The findings of the analysis suggest that as the CFRP reinforcement replacement rate increases, the initial bending stiffness of the composite pipe pile experiences a corresponding decrease. After serving for 28.15 years, the steel reinforcement within the pipe pile commences rusting, resulting in a nonlinear decline in the bending stiffness of the composite pipe pile. As the service time of pipe piles increases, a higher replacement rate of CFRP reinforcement results in a slower attenuation of pile stiffness. Consequently, both the horizontal displacement at the top of the pile and the bending moment along the body of the composite pipe pile gradually increase over time. During the same service period, the higher the rate of CFRP reinforcement, the less noticeable the attenuation in the horizontal bearing capacity of the pile shaft.

Investigation on the Bearing Performance of a Single Pile in Shallow Reinforced Soft Soil Foundation under Horizontal Load

The overall reinforcement of soft soil foundation has the disadvantages of large engineering quantity and high cost. When the pile foundation bears horizontal loads in the soil, the mechanical properties of the soil near the surface have a greater impact on it compared to the deep soil. Therefore, studying the influence of shallow soil reinforcement on the horizontal bearing capacity of pile foundations has important engineering significance. Studying the influence of shallow soft soil reinforcement around piles on the horizontal bearing performance of piles is of great significance for improving the economic efficiency of pile foundation reinforcement technology in soft soil areas. In this paper, seven pile-soil finite element models are established based on ABAQUS 2022 software to study the influence of shallow reinforcement on the horizontal bearing capacity of single pile. The models were established on the basis of a field test and its validity was verified. The influence of different reinforcement degrees on the horizontal bearing capacity of piles is analyzed by taking the reinforcement width and reinforcement depth as variables. The results indicate that shallow ground improvement significantly enhances the horizontal bearing capacity of the pile. The horizontal bearing capacity of the pile is increased by 83.0%, 104.3%, and 224.4%, respectively, corresponding to a reinforcement width of 2 times, 3 times, and 4 times the diameter of the pile, respectively. With the increase of the reinforcement width, the bending moment and deformation of the pile under the same horizontal load decrease significantly, while it has no significant effect on the location of the maximum bending moment of the pile. The bearing capacity of the pile foundation gradually increases with the increase of the reinforcement depth. Compared with the unreinforced situation, the horizontal bearing capacity of the pile body is increased by 224.4%, 361.3%, and 456.8%, respectively, corresponding to a reinforcement depth of 0.1 times, 0.2 times, and 0.3 times the pile length. As the reinforcement depth increases, the corresponding increase in bearing capacity does not increase linearly, but gradually decreases. This indicates that blindly carrying out deep soil reinforcement without comprehensive evaluation is not advisable.

Experimental and simulation study on seismic performance of seawater sea-sand PVA cementitious composite columns with GFRP bars

The seismic properties of seven seawater sea-sand (SWSS) PVA cementitious composite columns with Glass Fiber Reinforced Polymer (GFRP) bars were studied. The effects of four parameters, namely polyvinyl alcohol (PVA) fiber content, axial compression ratio, cementitious composite strength and stirrup spacing, on the seismic performance of composite columns were analyzed. The failure of the specimen was observed, and the hysteresis curve, skeleton curve, stiffness degradation, energy dissipation capacity, ductility and strain of the specimen were analyzed. The test results show that the large chip-based spalling will occur when the specimen without fiber incorporation is damaged, and the incorporation of PVA fiber, the reduction of stirrup spacing and the reduction of axial compression ratio will delay the rate of crack formation and development. In addition, through cross-section analysis and considering the reinforcement effect of PVA fibers, a proposed formula for calculating the horizontal bearing capacity of composite columns is proposed. Finally, the finite element model of SWSS PVA cementitious composite columns with GFRP bars is established, and it is found that increasing the strength grade of cementitious materials can greatly improve the seismic performance of composite columns. The conclusions could be references for the engineering application. In the context of the global emphasis on green development and environmental protection, seawater and sea-sand cementitious composites and components with fiber reinforcement will have a wide range of application prospects in the construction of coastal areas.

Bearing performance and failure mechanisms of HSCM piles in marine soft soil under lateral loads

Helix Stiffened Cement Mixing (HSCM) pile represents a novel type of grouted composite pile known for its excellent compressive and tensile performance. Based on field tests, this study introduces a laboratory-based test design methodology and piling technique for HSCM piles. A comprehensive analysis of their horizontal bearing capacity, pile-soil failure mode, optimal piling technique, and reinforcement mechanism is performed. SEM-EDS technology is utilized at a microscopic scale to examine the reinforcement mechanism of HSCM piles. Through ABAQUS finite element simulation, a full-scale model simulating the HSCM pile-soil interaction is developed. The analysis includes pile cross-sectional stress, displacement, and pile-soil failure mode. The p−y curve of the HSCM pile is then plotted, elucidating the reinforcement mechanism of cemented soil. The results indicate that compared to ordinary helical piles, the horizontal bearing capacity of HSCM piles increases by 125.9%. SEM-EDS images reveal that cement and kaolin form a mutual bond, enhancing the strength of the soil around the pile. Additionally, unlike other composite piles, the direction of soil flow around HSCM piles encircles the first helix of the pile core. This research offers a design basis for understanding the horizontal bearing performance and failure mechanisms of HSCM piles in marine soft soil.

Effect of soil spatial variability on the stability of pipelines under horizontal loading

Submarine pipeline has been utilized more and more widely in offshore oil and gas transportation engineering. Given that these pipelines frequently subject horizontal loading during operation, thus precise predicting their horizontal bearing capacity is essential. However, most previous studies employ deterministic analysis without considering soil spatialvariability. This article introduces a two-dimensional (2D) random finite element analysis to study the horizontal pullout behaviour and failure mechanisms of a pipeline in a spatial variability soil. It is observed that the effect of soil spatial variability on the horizontal bearing capacity factor and failure mechanisms is remarkably substantial, with the distribution of the former showing a close approximation to a log-normal distribution. Furthermore, the average horizontal bearing capacity typically falls below the corresponding deterministic value. Consequently, the deterministic estimation of the horizontal bearing capacity tends to be inflated. Eventually, a reliability-based approach is formulated, where a factor of safety is incorporated to account for the uncertainties arising from spatial variability and ensure a sufficient safety margin. This methodology enables engineers to determine appropriate factor of safety tailored to the specific requirements of each project.

Steel-concrete-steel sandwich composite cable-pylon anchorage of cable-stayed bridges: horizontal bearing capacity

Steel-concrete-steel sandwich composite cable-pylon is preliminarily applied to bridge engineering due to its excellent mechanical properties and high degree of assembly. However, the stress behavior of the steel-concrete-steel sandwich composite cable-pylon anchorage zone under the strong horizontal component force of the cable force is relatively unknown. In this paper, a 1:4 scaled-down steel-concrete-steel sandwich composite cable-pylon model test under horizontal force is designed and carried out to investigate the strain distribution in inner and outer steel plates, and the horizontal displacements in the pylon wall, and the crack development in the concrete pylon wall. Subsequently, a simplified analysis method is proposed for facilitating the calculation of the load distribution ratios of both steel plates and concrete, and the pylon wall stresses are obtained based on the force method. Furthermore, aiming to improve the problem of excessive stress in the anchorage region of the outer steel plate, the effects of various parameters on the mechanical properties of the anchorage region are investigated through parametric analysis, and the investigated parameters include the diameter of the reinforcement bar, area of the bearing plate, concrete strength, the thicknesses of the steel plate and perfobond ribs. The results indicate that increasing the diameter of the reinforcement bar is insignificant in improving the stress distribution and value of the outer steel plate, and appropriately increasing the bearing area, concrete strength, thicknesses of the steel plate and perfobond ribs can reduce the stress peak value of the outer steel plate, among which changing the thickness of the steel plate and bearing area is the most significant effect. The research results can provide experimental data and theoretical support for the design and optimization of steel-concrete-steel sandwich composite cable-pylon anchorage zones.

Horizontal bearing capacity of post-expanded arm grouting pile foundations

In order to effectively improve the horizontal bearing capacity of pile foundations, this study proposes post-expanded arm grouting technology and associated pile foundations. The horizontal bearing characteristic of the post-expanded arm grouting pile was explored through model tests. The test results indicate that the post-expanded arm grouting pile can increase the contact area between the pile and soil, and can improve the strength of the soil. The horizontal bearing capacity of the post-expanded arm grouting pile was approximately 3 times that of the conventional pile. It also shows that the larger the plate diameter ratio or grouting volume, the higher the horizontal bearing capacity of the post-expanded arm grouting pile. The maximum bending moment of the post-expanded arm grouting pile was located at the pile plate, and the displacement zero point of the new pile was higher than that of the conventional pile. The soil resistance at the pile plate was significantly higher than that of conventional piles, indicating that the pile plate effectively enhances the soil resistance. The improved p-y curve model and horizontal bearing capacity calculation method for the post-expanded arm grouting pile were proposed by considering the pile plate diameter factor. This method was finally verified by experimental results. The results of this study can provide a reference for calculating the horizontal bearing capacity of the post-expanded arm grouting pile.

Bearing capacity of modified suction caissons in clay overlying sand under monotonic horizontal loading

The modified suction caisson (MSC) is an innovative foundation for fixing offshore wind turbines, consisting of an internal caisson (IC) and an external skirt (ES). In this study, the Plaxis3D is conducted on the bearing capacity of the MSC in clay overlying sand under monotonic horizontal loading. The parameters of the aspect ratio of the IC, the size of the ES, the clay thickness, and the soil strength are considered. Results show that the horizontal ultimate bearing capacity of the MSC decreases as the length ratio of the ES to IC decreases. Moreover, the width of the ES enhances the horizontal bearing capacity of the MSC higher than the length of the ES. With the increase of the clay thickness, the rotation center of the TSC and MSC exhibits two and three stage change patterns, respectively. When the clay and sand are the inhomogeneous soils, the horizontal ultimate bearing capacity of the MSC is enhanced by 8.96% compared to the homogeneous soils. Additionally, the passive and active earth pressures around the MSC are mainly generated at the front and rear side of the loading direction, respectively. This study will provide theoretical guidance for the design of the MSC.

Influence of local scour on the evolution of the failure envelope for suction caisson foundation

Local scouring significantly undermines the load-bearing capacity of suction caisson foundations and poses a daunting challenge to the integrity of offshore structures. This study numerically addresses the impact that the size and shape of the local scour hole have on both the monotonic bearing capacities and failure envelopes of suction caisson embedded in sandy soil. Different loading conditions - individually and combined - by integrating local scour parameters such as scour depth (Sd), scour width (Sw) and scour angle (φ) while maintaining realistic scour proportions are carefully evaluated. The obtained results show that (1) scour depth has a stronger influence on the ultimate bearing capacity than the influences of scour width and angle; (2) the horizontal bearing capacity shows increased sensitivity to variations in scour depth; and (3) both the horizontal bearing capacity and the moment bearing capacity reach a plateau and a steady state manifest itself when the relative scour depth exceeds a threshold value of 0.9. An empirical formulation to characterize the failure envelope within the horizontal force-moment (H-M) plane is finally proposed, which properly considers the effect of scour depth. These findings provide a valuable reference for ensuring structural resilience to local scour phenomena.

Experimental Study on the Horizontal Bearing Characteristic of a Strip-Walled Underground Diaphragm Wall

Researching and developing a new type of diaphragm wall foundation can solve the probl em that the traditional diaphragm wall structure may not meet the high standards of safety and stability of underground structures in some specific engineering environments. This paper focuses on the horizontal bearing characteristic of a new form of foundation, a strip-walled underground diaphragm wall, through a series of model tests. In the tests, nine plexiglass models with different section sizes, wall spacings and wall heights, as well as loading strategies (horizontal loads along and against the wall in the model), were conducted. The influence of the above factors on the horizontal bearing performance of the foundation and the soil resistance distribution around the wall was studied. The results show that when the horizontal load applied along the wall is greater than 50 N, the growth rate of total displacement at the top of the wall gradually decreases; when a horizontal load is applied against the wall, with a uniform change in wall height, the optimal wall spacing is 11 cm. When the same displacement occurs, the bearing performance of the model under the former loading strategy is generally 10% higher than that under the later loading strategy. In addition, the depth where the maximum bending moment along the wall occurred gradually moves downward with the increase in horizontal load, and the increase in wall spacing and wall height has a positive effect on the horizontal bearing characteristic. With the application of load, the maximum bending moment of the wall will gradually decrease along the depth. The increase in wall spacing and wall height can improve the overall flexural stiffness and horizontal bearing performance of the foundation. Lastly, the group wall effect coefficient, β, is put forward, and a simplified formula for calculating the horizontal bearing capacity of a strip wall foundation is proposed. In the formula, β is negatively correlated with the buried depth of the wall and positively correlated with the distance between the walls, and its coefficient is greater than 1.

Influence of Length to Diameter Ratio of the Skirt on Horizontal Bearing Characteristics of Tripod Suction Jacket Foundation in Sandy Soil

Influence of Length to Diameter Ratio of the Skirt on Horizontal Bearing Characteristics of Tripod Suction Jacket Foundation in Sandy Soil

Horizontal Bearing Performance of the Four-Bucket Jacket Foundation

Horizontal Bearing Performance of the Four-Bucket Jacket Foundation

FDEM analysis of deep rock mass failure and its impact on horizontal bearing capacity in offshore wind turbine piles

Rock-socketed single piles are integral components of offshore wind turbine foundations in rock-based sea areas. Traditional numerical models have been employed to analyze the failure modes and lateral interactions between piles and the rock medium. However, these do not simulate the decline in the horizontal bearing capacity due to rock breakage, posing potential safety risks. In this study, the combined finite-discrete element method (FDEM) was used to simulate the deformation process of submarine rock masses transitioning from an intact to a fractured state. A notable innovation in the proposed approach is the consideration of the effects of the rock mass fracture and pile-rock cohesion on the load-bearing behavior of single-pile foundations. The FDEM model was validated through full-scale lateral load tests. The results showed a distinctive sequence in failure mechanisms, with the tensile failure of the rock mass around the pile at significant depths preceding the compression failure. Local failure at the contact interface significantly reduced the horizontal bearing capacity—a phenomenon that is inadequately represented by conventional finite element models. Furthermore, the cohesion element embedding method was introduced and used to simulate the influence of the tensile properties inherent in grouting materials on the failure strength and mode of the pile-rock interface. This study highlighted the importance of considering the nuanced effects of rock failure in the design of horizontally loaded piles. Failure to do so could lead to nonconservative designs and compromise the safety and efficacy of offshore wind turbine foundations. By pushing the boundaries of numerical modeling with the FDEM, the study aims to provide a more accurate and reliable framework for the design and assessment of rock-socketed single piles for offshore wind energy applications.

Numerical analysis of horizontal bearing capacity of pile in clay slope

In this study, a series of numerical calculations were performed to investigate the lateral behavior of piles in slopes and in horizontal ground. First, a numerical model is created and then verified by comparing the numerical results with the results of model tests. The numerical results agree well with the results of model tests. Second, numerical calculations of different slopes were conducted to explore the effect of slope angle on the horizontal displacement of pile and bending moment. Then, the effect of slope angle on the foundation stiffness proportional coefficient m is investigated. The stress distribution of soil around the pile and the deformation of pile at different slope angles are also compared. Finally, the p–y curves of the different slope angles are compared. An improved p–y method is proposed to consider the effect of slope angle based on the numerical results. The results show that the bearing capacity of piles decreases with an increase in slope angle. The horizontal displacement of pile nonlinearly decreases along the pile body with the depth of pile. The bending moment of piles increases along the pile body with an increase in pile depth, and until 0.5 times of the pile length, the bending moment reaches the maximum value. As the slope angle increases, the maximum of bending moment tends to decrease. The distance from the slope toe to the pile section has a little influence on the pile bending moment and horizontal displacement. With an increase in slope angle, the horizontal foundation coefficient m gradually decreases.

The Horizontal Bearing Characteristics and Microscopic Soil Deformation Mechanism of Pile-Bucket Composite Foundation in Sand

The pile-bucket composite foundation represents an innovative foundation form that surpasses the horizontal bearing performance of both single bucket-shaped foundations and pile foundations. The intricate interplay between piles and buckets introduces the complexity of the factors influencing the bearing performance of composite foundations under horizontal loads. In this paper, the indoor model tests were conducted to investigate the effects of relative density and pile-to-barrel diameter ratio on the horizontal bearing capacity and surrounding soil pressure of the pile-bucket composite foundation. A sensitivity analysis on the bearing characteristics of the pile-bucket foundation was performed using ABAQUS/CAE 2020 software. The results reveal a consistent variation in load–displacement curves across diverse diameter ratios of piles to buckets. The pile-bucket diameter ratio significantly impacts the horizontal bearing characteristics of the composite foundation. Reducing the pile-bucket diameter ratio improves the horizontal bearing capacity of the composite foundation. When the diameter ratio of piles to buckets diminishes to ≤0.317, the influence of this ratio on bearing performance becomes markedly pronounced. The displacement range of the surface soil decreases with an increase in relative density, while the influence depth of the surrounding soil of the composite foundation significantly decreases as the pile-to-barrel diameter ratio decreases.

Scour Impact on the Horizontal Bearing Capacity of Pier-Type Dolphin Structures

A study using numerical analysis techniques was conducted to examine the scour effect of pier-type dolphin structures installed in the domestic marine environment, and the effect of scour on horizontal bearing capacity was examined. In this study, we designed the berthing structures, taking into account the environmental and ground conditions of the target maritime area, and after calculating the predicted scour area, stability evaluation was performed by removing the ground elements of the area. The increase in scour depth was found to induce a direct decrease in horizontal bearing capacity due to soil loss in contact with the foundation, establishing a relationship that increases horizontal displacement. However, in the foundation designed to withstand the design load by reflecting the safety rate, the increase in horizontal displacement formed by possible scour is not large, which did not have a dominant effect on the horizontal bearing capacity of the foundation. In the future, research is required to analyze the impact of each factor and formalize evaluation and design techniques to evaluate the scour safety of marine foundations and pier-type structures installed in various ground conditions and structural formats.

Predicting the monotonic horizontal behavior of tripod bucket foundations in clay

The requirements for the foundation bearing characteristics become higher due to the evolution of offshore wind turbines in the abyssal sea. Tripod bucket foundations have good bearing performance and has gradually become a trend. To investigate the horizontal dynamic behavior of the tripod bucket foundation and the dynamic characteristics relationship between the tripod bucket and the single bucket under horizontal monotonic loadings, the predictive model of the dynamic characteristics of the tripod bucket is established through formula derivation, and extensive numerical analyses were conducted under horizontal monotonic loadings in clay. It was confirmed that the limit bearing moment of the tripod bucket enhances with increment of bucket spacing and length. The ultimate bearing moment has an exponential positive correlation with the ratio of length and diameter (L/D) for the single bucket and a linear positive correlation with the ratio of space and diameter (S/D) for the bucket. Predicting the dynamic characteristics of tripod bucket foundations under horizontal monotonic loadings based on the horizontal bearing capacity coefficient model and the single bucket foundations horizontal dynamic characteristics. Simplified prediction of the tripod bucket foundations' rotation angle and moment has been verified under horizontal monotonic loadings. That can provide a certain design reference of the multi-bucket foundation by studying the relationship between single and jacket foundation.

An innovative bionic offshore wind foundation: Scaled suction caisson

This paper presents an innovative scaled suction caisson (SSC) for fixing offshore wind turbines (OWTs) to enhance its anti-overturning bearing capacity. The outer wall of the SSC is constructed with a scaled bionic structure referring to snakeskin scales, reducing resistance to installation and increasing pullout capacity, which is verified by model tests that the SSC requires less applied suction and provides higher horizontal bearing capacity in sandy soil compared with the traditional suction caisson (TSC) under the same caisson diameter and height. Also, model test results reveal that the SSC can reduce the height of soil plug and the scaled structure can effectively limit the SSC inclination in comparison to the TSC. Additionally, numerical results show that the ultimate bearing capacity for the SSC increases rapidly when the friction factor λ between the caisson wall-soil interface ranges from 0 to 0.2. Moreover, the sidewall of the SSC dissipates less energy than that of the TSC due to the small displacement of soil near the sidewall. This study confirms that the SSC can eliminate grouting in the space between the top of the soil plug and the bottom of the cap, thus reducing the construction period, construction costs and avoiding marine pollution.