Lateral Load Research Articles

Numerical Study on the Lateral Load Response of Offshore Monopile Foundations in Clay: Effect of Slenderness Ratio

To meet growing energy demands, offshore wind turbines (OWTs) with higher energy outputs are being developed, presenting increased challenges for their foundation design. Over the past decade, extensive research on the design optimization of OWT support structures has significantly reduced the anticipated costs of offshore wind farm development. Various design methods have been developed and applied in practice, each with its own advantages and limitations. In this study, 3D finite element (FE) modeling, validated against the measured response of a large-scale test monopile, is used to investigate the lateral load response of monopiles with different geometries and slenderness ratios in smaall and large displacements. The results are compared to the standard p–y method, and specific behavioral and design aspects of large-diameter monopiles, such as the moment contribution ratio from different resisting components and the minimum embedment length criteria, are evaluated and discussed. The results showed that the maximum and minimum differences between the 3D FE modeling and one-dimensional (1D) DNV p–y method are 41% and 11% for large displacements, and 32.5% and 13.3% for small displacements, respectively. As the slenderness ratio increases, the discrepancy between the finite element (FE) modeling results and the 1D DNV p–y method decreases, with an average difference of about 13% across all monopile diameters at an L/D ratio of 10, in both small and large displacements, indicating the reasonable accuracy of the 1D method for slenderness ratios of 10 and above. Among the three minimum embedment length criteria examined, the DNV recommended and vertical-tangent criteria offered shorter embedment lengths. The primary resisting moment across all slenderness ratios comes from the distributed lateral load along the monopile shaft (MCRp−y), which increases as the L/D ratio increases.

Effect of Lateral Load to the Behavior of Single Piles Subjected to Earthquake Load in Sand

In fact, pile usually carry static and dynamic load in same time, the case of simulations lateral and dynamic load is possible occurred. This case is not cover enough by previous researches especially by laboratory model. Therefore, the purpose of this study is to determine the extent to which altering the horizontal lateral loads impacts the behavior of individual piles during seismic events. An experimental test was devised using a physical model with an advanced shaking table that using El Centro earthquake. Sandy soil with 65% relative density used raining technique. Lateral loads were applied at levels of 0%, 50% and 100% from allowable lateral load capacity. It was observed that when lateral load increased from 0% to 50% and 100%, the lateral displacement response decreased by 32.10% and 49.59% respectively. While the vertical displacement increased by 49.96% and 76.95%. Finally, the acceleration decreased by 34.39% and 41.03%. This is possibly due to the load acts at an angle opposite to the earthquake as a restraining factor for the pile. led to a decrease in lateral displacement, vertical displacement, and peak ground acceleration.

Analytical Model for the In-Plane Lateral Capacity of Unreinforced Masonry Walls Based on Effective Compression Zone Failure Mechanism

ABSTRACT This study proposes a simplified theoretical model to predict the in-plane lateral capacity of unreinforced masonry (URM) walls, addressing limitations in current design guidelines based on semi-empirical approaches. Masonry walls are conceptualized as macroscale units subjected to vertical and lateral loads, with failure mechanisms governed by the effective compression zone. The model applicability is evaluated against comprehensive URM datasets and compared with existing guidelines. The results indicated the outperformance of the proposed model compared to existing guidelines. Additionally, a parametric study explores the influence of primary design parameters on the in-plane lateral capacities of URM walls, offering valuable predictive insights.

Experimental and Numerical Characterization of the In-Plane Shear Behavior of a Load-Bearing Hollow Clay Brick Masonry System with High Thermal Performance

Modern masonry systems are generally built with hollow clay bricks with high thermal insulating properties, fulfilling the latest sustainability and environmental criteria for constructions. Despite the growing use of sustainable masonries in seismic-prone countries, there is a notable lack of experimental and numerical data on their structural behavior under lateral in-plane loads. The present study investigates the in-plane shear behavior of load-bearing masonry walls with thin bed joints and thermal insulating hollow clay blocks. Shear-compression tests were performed on three specimens to obtain information about their shear strength, displacement capacity and failure modes. The experimental characterization was supplemented by three shear tests on triplets, along with flexural and compression tests on the mortar for the thin joints. Furthermore, two Finite Element (FE) models were built to simulate the shear-compression tests, considering different constitutive laws and brick-to-brick contact types. The numerical simulations were able to describe both the shear failure modes and the shear strength values. The results showed that the experimental shear strength was 53% higher than the one obtained through Eurocode 6. The maximum shear load was found to be up to 75% greater compared to similar masonry specimens from the literature. These findings contribute to a better understanding of the potential structural applications of sustainable hollow clay block masonry in earthquake-prone areas.

Bearing capacity of large-diameter pile foundation under combined VHM loadings in soft clay

ABSTRACT The large-diameter pile foundation is with an intermediate depth, widely used in engineering fields such as ports, breakwaters and rapid construction of artificial islands as a supporting structure to resist lateral loads. However, there is limited research on the bearing performance of such large-diameter, intermediate-depth pile foundations. In this paper, the finite element method is used to investigate the bearing capacity of the large-diameter pile foundation with different embedment ratios in homogeneous soil and normally consolidated soil and the prediction formulas for uniaxial and combined bearing capacity are developed. This study also sets up three different skirt wall–soil interface properties to discuss their influence on the bearing performance of the large-diameter pile foundation. The research is systematic, and relevant analysis can provide practical suggestions for engineering design.

Accuracy of stochastic finite element analyses for the safety assessment of unreinforced masonry shear walls

ABSTRACT To examine structural safety and reliability, an accurate prediction of the variability of structural resistance must first be determined. This may be achieved through extensive physical testing or, more commonly in modern research, synthetic data generation, such as stochastic finite element analyses (SFEAs). Due to the prevalence and versatility of such techniques, and the need for a high level of confidence when performing a safety assessment, an understanding of the accuracy of data derived from SFEAs is essential. In this paper, SFEA models have been developed to predict the responses of 16 unreinforced masonry walls tested in a laboratory under cyclic in-plane lateral loading. Each SFEA has been developed to reflect the as-built conditions of these experimental specimens and focus on predicting the shear capacity of the failure mechanisms that unreinforced masonry shear walls are susceptible to. From the results of these SFEAs, the accuracy (quantified as model error) of this modelling strategy has been estimated by comparing the peak in-plane shear resistances of the laboratory and numerical models.

Evaluation of retrofitting effect of concrete filling in hollow RC columns using XFEM

Hollow RC columns are widely utilized in the construction of high piers in mountainous regions. Recently, precast hollow RC columns have been increasingly used to enhance transportability and ease of handling, aiding Accelerated Bridge Construction. This paper evaluated the effectiveness of concrete-filling retrofitting measures for hollow RC columns using eXtended Finite Element Method (X-FEM). Our focus was particularly on instances where original hollow sections and post-filled concrete sections don't behave as unified structures. The proposed X-FEM model's reliability was validated through simulations replicating compressive strength tests on molded concrete specimens and previous static loading tests on hollow RC columns conducted to evaluate the efficacy of concrete-filling retrofitting for hollow RC columns. The proposed X-FEM model successfully represents the compressive softening and fracture behavior of concrete under uniaxial compression. It also successfully replicated the lateral load capacity and the crack patterns of hollow RC columns observed in the previous experiments. When comparing the component ratios of bending and shear deformation of the columns, the shear deformation component of the hollow RC column retrofitted with the concrete filling was about 1.5 times larger than that of the solid RC column at each displacement. This result indicates that concrete-filling retrofitting might not enhance the shear capacity of hollow RC columns to the anticipated level in scenarios where the pre-existing hollow portion and the post-filled concrete portion fail to function as unified structures. Based on these findings, this study investigated the efficacy of anchor reinforcement in hollow RC columns filled with concrete to enhance the structural unity of existing and filled portions. The results indicate that anchor reinforcement improved the shear resistance properties by enhancing the structural unity between the pre-existing hollow portion and the post-filled concrete portion.

Experiment and analysis on seismic performance of a self-centering Y-eccentrically braced frames structure

Conventional eccentrically braced frames (EBFs) exhibit significant residual deformations following major earthquakes, necessitating costly repairs for the damaged structures. This study proposed a novel self-centering Y-eccentrically braced frames (SC-YEBFs) system to enhance the seismic resilience. A theoretical mechanical model which takes into account its components is formulated to predict the lateral load behavior of SC-YEBFs. The pseudo-static experiments were conducted on four specimens, and the resulting observations and analyses demonstrate that the shear links effectively function as ductile fuses, dissipating a significant portion of the input energy to safeguard the main frame from damage. Furthermore, the self-centering joint exhibits a hinge-like behavior with remarkable self-centering characteristics. The structural reparability of all specimens was found to be exceptional during major seismic events. By increasing the initial prestress and sectional area of steel strands, the self-centering performance can be further enhanced. The damaged shear links could be easily detached by loosening bolts, and the consideration of prestress loss is nonnegligible to ensure an exceptional self-centering performance. The proposed theoretical model predicted the mechanical properties of SC-YEBFs, including lateral stiffness, energy dissipation, and self-centering mechanism, through a comparison with experimental results. Moreover, the theoretical model was utilized to propose an equivalent simulation method for simulating self-centering joint and shear link using Connector function in ABAQUS software, while establishing a simplified frame finite element model for further analysis.

Geotechnical performance of X-section cast-in-place concrete piles under torsion loads in clay soil – numerical study

ABSTRACT Deep foundations are inexorably subjected to torsional load due to eccentric lateral loads. The conventional piles face shortcoming under torsional loads due to its fair face. So, this study employed an innovative X-section cast in place concrete pile to improvement the torsional capacity of piles. PLAXIS 3D V20 Software was used to study the performance of XCC pile under torsional load, and combined torsional, and vertical loads in clay soil. The numerical results reflect that at the ratio of pile length to pile diameter (Lp/Dp) = 15, and the ratio of the open arc spacing to pile diameter (ap/Dp) = 0.14, open arc degrees (θ°) = 90, the torsional capacity can be improved by 3.96, 5.06, and 5.71 times of torsional capacity of conventional pile with the same cross-sectional area at clay cohesions of 70 KN/m2, 40 KN/m2, and 30 KN/m2, respectively. Also, The XCC pile recorded an increase ratio of 35% in the vertical capacity of piles compared to conventional pile with the same cross-sectional area. It can be concluded that XCC piles exhibit significant resistance to torsional forces due to their cross-sectional geometry which enhances soil-pile interaction.

Experimental study on the flexural performance of concrete hollow composite slabs with tightly connected panel sides

The performance of joint connections in composite slabs is crucial for ensuring their bidirectional load-bearing capacity and overall structural integrity. To effectively address the challenge of protruding rebar in precast components, a new structural form of a tightly connected hollow concrete composite slab without protruding rebar on the slab side is proposed. To investigate the mechanical performance and failure modes of this slab-side tight-joint connected hollow concrete composite slab, bending performance tests under monotonic load were conducted on three tightly connected hollow composite slabs and one seamless hollow composite slab. The analysis focused on the failure modes, crack distribution, bending capacity, and bending stiffness of additional steel bars at the joints of the slabs. The results indicate that, under normal operating conditions, the flexural performance development of concrete hollow composite slabs with tightly connected slab sides is generally consistent with that of the non-spliced cast hollow composite slab. Under ultimate conditions, tearing or brittle fracture failure at the joint interface is likely to occur in the composite slabs, leading to a reduction in flexural bearing capacity. With an increase in joints, the bending capacity of the hollow composite slab decreases by 17.1%, Conversely, when joints are positioned away from the most stressed section, the flexural stiffness of the section increases by 13.5%. A comparison of experimental data and theoretical calculations indicates that the additional rebar at the joints effectively contributes to the lateral load transfer in the hollow composite slab, achieving bidirectional load-bearing capacity. This further validates that the design of the single-joint, tight-joint connected hollow concrete composite slab without protruding rebar meets the requirements for bidirectional load-bearing performance.

Development of improved finite element formulations for pile group behavior analysis under cyclic loading

AbstractThe effect of cyclic loading is an essential factor leading to progressive soil strength degradation. Therefore, a comprehensive analysis of the pile‐soil system behavior under cyclic loading is required to ensure the stability of pile group. There is room for improvement in the inherent constraint of the conventional numerical model in terms of approximating the soil resistance distribution along the pile by point loads at element nodes, necessitating a specific element that integrates considerations of pile group effect and cyclic loading within a unified framework. This study aims to develop a newly specific type of element for efficiently predicting nonlinear behavior within the pile‐soil system, addressing simulations involving nonlinear pile‐soil interaction, pile group effect, and cyclic loading. Modified element formulations based on soil stiffness matrices and soil resistance vectors specifically address pile group effect and consider parameters that influence pile behavior under cyclic lateral loading. The numerical solution procedure with Newton‐Raphson iteration allows the calculation of pile responses in geometric and material nonlinear analyses. The validation of the proposed method includes several examples, comparing it with existing numerical solutions and experimental tests of single piles and pile groups under cyclic loading. These comparisons further support the consistency of the proposed method with measured data and validate its accuracy in considering group effect and cyclic loading. The parametric study illustrates the ability of the proposed method to capture cyclic loading parameters while considering the influence of the number and magnitude of load cycles, the cyclic load direction, and the installation methods.

Research on the Pile–Soil Interaction Mechanism of Micropile Groups in Transparent Soil Model Experiments

Micropile groups (MPGs) are typical landslide resistant structures. To investigate the effects of these two factors on the micropile–soil interaction mechanism, seven sets of transparent soil model experiments were conducted on miniature cluster piles. The soil was scanned and photographed, and the particle image velocimetry (PIV) technique was used to obtain the deformation characteristics of the pile and soil during lateral loading. The spatial distribution information of the soil behind the pile was obtained by a 3D reconstruction program. The results showed that a sufficient roughness of the pile surface was a necessary condition for the formation of a soil arch. If the surface of the pile was smooth, stable arch foundation formation was difficult. When the roughness of the pile surface increases, the soil arch range behind the pile and the load-sharing ratio of the pile and soil will increase. After the roughness reaches a certain level, the above indicators hardly change. Pile spacing within the range of 5–7 d (pile diameters) was suitable. The support effect was poor when the pile spacing was too large. No stable soil arch can be formed, and the soil slips out from between the piles.

Shear strengthening and damage control effects of CFRP and self-prestressing iron-based SMA for concrete columns

Although prestressed shape memory alloy (SMA) has shown a great performance in flexural retrofitting of slender RC columns, its shear strengthening effect for squat RC columns has been barely studied. This study explores the shear strengthening and damage control effects of iron-based SMA (Fe SMA) for squat RC columns. The heat-activated prestressing of Fe SMA was evaluated first at material level, then applied to component level structural testing of RC columns. The four circular RC columns with different retrofitting schemes were tested under quasi-static lateral cyclic loading. The specimens strengthened with carbon fiber-reinforced polymer (CFRP) sheet and Fe SMA strip exhibited satisfactory global responses without showing significant shear failure. From the visual inspection and non-destructive damage assessment, the prestressed Fe SMA was found to be superior in delaying damage accumulation in concrete compared to CFRP.

Behavior of Beam-Column Joint Self-Compacting Concrete (SCC) Using Steel Fiber 5D under Lateral Cyclic Loading

Behavior of Beam-Column Joint Self-Compacting Concrete (SCC) Using Steel Fiber 5D under Lateral Cyclic Loading

Failure behaviors of anisotropic shale with a circular cavity subjected to uniaxial compression

Layered rock formations are frequently encountered during the excavation of underground structures. The stability of such structures is influenced not only by the stress concentration caused by the cavities in the strata but also by the anisotropy of the layered rock mass. The interaction between them can lead to critical structural failure, such as rupture, collapse, or significant deformation within the adjacent rock mass, thereby jeopardizing operational safety. However, the coupling law and mechanism between the stress concentration resulting from the cavities and the anisotropy of a layered rock mass remain unclear. In this study, a uniaxial compression test was performed on shale specimens containing a circular hole to investigate the effects of layer inclination and circular holes on the mechanical properties, elastic energy storage, and failure behaviors of these specimens. The failure mechanism of the rock surrounding the hole was analyzed on the basis of the single plane of weakness theory and the Kirsch solution. The test results indicated pronounced anisotropy in the compressive strength, elastic modulus, and elastic strain energy of the specimens, with distinct “V”, “M” and “U”-shaped patterns correlated with varying layer inclination angles. In addition, the combined effect of stress concentration and layer inclination resulted in different failure types, which were classified into four groups according to their failure behavior. Theoretical analysis revealed that failure around circular holes in layered rock is affected by a range of variables, such as layer inclination, layer strength, lateral pressure coefficient, azimuth, and loading stress.

Seismic response assessment of tapered piles in sandy soils: A numerical investigation

For the same volume, tapered (non-prismatic) piles have premium advantages over conventional (prismatic) cylindrical piles with respect to the axial and lateral load resistance and, thereby, are considered an economical alternative to prismatic piles. While previous investigations have studied the behavior of tapered piles subjected to different dynamic loading conditions, their seismic response has not yet received a comprehensive examination. This study aims to investigate the seismic response of tapered piles in sandy soils using non-linear three-dimensional (3D) finite element analyses. A total of 3084 cases were studied using MIDAS software to consider a wide range of parameters, including variations in soil density (Dr), taper angle (θ°), slenderness ratio (L/DAvg), and different earthquake recorded data. A parametric analysis was also undertaken to investigate the behavior of the pile lateral displacement, pile bending moment, and frictional resistance. The findings of the study reveal that tapering enhances the lateral stiffness of the pile, resulting in reduced lateral deflections and decreased sensitivity to changes in L/DAvg and ground motion intensity. Furthermore, under higher ground motion intensity, improved pile stiffness through tapering contribute to an increase in bending moments experienced by the pile. Another significant observation is the substantial improvement in frictional resistance due to soil densification. This emphasizes the critical importance of considering the soil behavior and its density in the design of pile foundations, particularly when aiming to withstand seismic loads effectively. These insights offer valuable guidance for designing pile foundations that can reliably endure the dynamic forces present during seismic events.

A Review on Analysis of Seismic Impact of Improvements with Rigid and Semi Rigid RC Structure with having Podium

Abstract: The growing population and limited land in urban areas are driving up demand for towering buildings on a daily basis. India and other emerging countries are seeing an increase in the use of tall buildings. Land becomes unavailable for further expansion in any city, particularly in major cities, beyond a certain point of horizontal development. Consequently, multi-story skyscrapers gained popularity as a means of optimising land use. The design principles used for low- and mediumrise structures are not applicable to high-rise skyscrapers. Tall structures demand the most advanced design techniques since they are intricate engineering tasks. Architects and engineers proposed/put forward the new idea of Podium sort constructions in order to meet the demands of both the growing population and the present bye-laws requiring a minimum parking space for such types of buildings. These days, tower-podium style structures are quite common since they provide for the best possible use of available space on the property and the financial leverage to meet the need for more commercial space. A portion of a structure known as a podium has lateral load resistance greater than that of a tower.

Evaluating the Feasibility of Short Dental Implants as Alternatives to Long Dental Implants in Mandibular Bone: A Finite Element Study.

This study uses finite element analysis to investigate the potential application of shorter dental implants as a substitute for longer implants in the lower jaw (mandible). FEA allows the evaluation of the stress patterns around the implant-bone interface, a critical factor for successful osseointegration. Ten models were generated, encompassing five long (L1-L5) and five short implant models (S1-S5) with variations in diameter and length. Hypermesh software was utilized to meticulously prepare the FEA models, ensuring accurate mesh generation. The FEA simulations were conducted under four distinct loading scenarios (100 N occlusal load, 40 N lateral load, 100 N oblique at 30°, and 100 N oblique at 45°) to realistically mimic the forces exerted during biting, using an ABAQUS CAE solver. The results revealed that the von Mises stress generated within the short implant models was demonstrably lower compared to their long implants. Additionally, a significant drop in stress was observed with increasing the diameter of the short implants, to a certain diameter range. These findings suggest the potential for successful substitution of long implant model L4 with short implant model S4 due to the demonstrably lower stress values achieved. Furthermore, the data indicates the possibility of utilizing short implant models S3 and S5 as alternatives to long implant models L3 and L5, respectively. These observations hold significant promise for evaluating the feasibility of replacing long implants with shorter variants, potentially leading to a reduction in implant-related failures.

Analytical Study of the Structural Behavior of Hollow-Hole Anchors for Replacement of Bridge Bearings under Static Lateral Loads

Analytical Study of the Structural Behavior of Hollow-Hole Anchors for Replacement of Bridge Bearings under Static Lateral Loads

In-Plane Cyclic Behaviour Comparison of Adobe Wall Retrofitted by Mortar Enhanced by Physical and Chemical Methods

ABSTRACT A mortar overlay on damaged adobe masonry is employed for its load carrying capacity improvement and low skill requirement. Nevertheless, delamination between the adobe wall and mortar has been commonly observed due to bonding failure. Physical enhancement (groove, shear dowel, and wire mesh) and chemical enhancement (a novel biological and traditional Chinese binder, sticky rice pulp, SRP) are carried out to enhance the bonding between mortar and adobe. The high-moisture adsorption mortar is also utilized to alleviate water accumulation resulting from the application of mortar on earthen buildings. Four adobe walls with different retrofitting methods are subjected to in-plane lateral cyclic loading tests to analyse the failure mode, hysteretic load-displacement response, skeleton curve, ductility behaviour, energy dissipation and stiffness degradation. It indicates that the retrofitting effectiveness of adobe walls coated only with mortars is limited, as their peak load increases are comparatively modest compared to other retrofit wall systems. However, employing additional bonding enhancement methods significantly enhances the peak load capacity. Specifically, a combination of physical and chemical enhancements results in a remarkable 114% increase on the positive side and an astonishing 500.1% increase on the negative side.