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In this article, the performance of transversely loaded glass fiber reinforced epoxy (GFRE) tubular components containing carbon nanopowder (CNP) in terms of crashworthiness was investigated. The wet‐wrapping by hand lay‐up procedures were used to make GFRE tubes that included 0, 0.25, 0.50, 1, 2, 3, and 4 wt% of CNP. For the laterally loaded tubes, the crashing load and total absorbed energy (TAE) versus displacement responses were displayed. The histories of deformation were tracked in addition. As part of the crashworthiness analysis, the TAE and specific absorbed energy (SEA) were evaluated. Overall results demonstrated that CNP enhances both TAE and SEA up to 0.50 wt% of CNP; after that, a significant deterioration was noticed. CNP, at very low wt%, is considered a great choice for enhancing the crashworthiness performance of composite structures. Highlights: The designed tubes, that is, GFRE tubes filled with 0, 0.25, 0.50, 1, 2, 3, and 4 wt% of CNP, were created using wet‐wrapping by hand lay‐up techniques.The fabricated tubes were subjected to lateral compression loads to investigate their crashworthiness behavior.The crashing load and absorbed energy versus displacement responses for the laterally loaded tubes were exposed. The history of deformation for each specimen was also examined.The experimental results were analyzed and discussed. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) is a recently emerged material with exceptional durability and ductility. While widely used in bridge retrofitting, particularly to replace expansion joints and deck overlays, UHPC has seen limited use in jacketing piers for the improvement of lateral load resistance. It presents superior mechanical properties and deformation resilience, enabled by the distributed fibers and the dense microstructure, providing corrosion resistance and a maintenance-free service life. The significant tensile strength and ductility establish UHPC as an attractive resilient jacketing system for structural members. The experimental literature documents the effectiveness of this solution in enhancing the strength and ductility of the retrofitted member, whereas premature modes of failure (i.e., lap splices and shear failure in lightly reinforced piers) are moderated. A comprehensive database of tests on UHPC-jacketed piers under lateral loads was compiled for the development of practical guidelines. Various UHPC jacket configurations were evaluated, and detailed procedures were developed for their implementation in bridge pier retrofitting. These procedures include constitutive models for UHPC, confined concrete, and the strengthening of lap splices, flexure, and shear resistance. The results are supported by the database, providing a solid foundation for the broader application of UHPC in improving the lateral load resistance of bridge piers. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) is a recently emerged material with exceptional durability and ductility. While widely used in bridge retrofitting, particularly to replace expansion joints and deck overlays, UHPC has seen limited use in jacketing piers for the improvement of lateral load resistance. It presents superior mechanical properties and deformation resilience, enabled by the distributed fibers and the dense microstructure, providing corrosion resistance and a maintenance-free service life. The significant tensile strength and ductility establish UHPC as an attractive resilient jacketing system for structural members. The experimental literature documents the effectiveness of this solution in enhancing the strength and ductility of the retrofitted member, whereas premature modes of failure (i.e., lap splices and shear failure in lightly reinforced piers) are moderated. A comprehensive database of tests on UHPC-jacketed piers under lateral loads was compiled for the development of practical guidelines. Various UHPC jacket configurations were evaluated, and detailed procedures were developed for their implementation in bridge pier retrofitting. These procedures include constitutive models for UHPC, confined concrete, and the strengthening of lap splices, flexure, and shear resistance. The results are supported by the database, providing a solid foundation for the broader application of UHPC in improving the lateral load resistance of bridge piers.

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 ( M C R p − y ), which increases as the L/D ratio increases. [ABSTRACT FROM AUTHOR]

Abstract In this study, ten shear walls were experimentally tested to examine behaviour of ferrocement hollow shear walls subjected to axial and lateral loads. Ferrocement mortar (FM) was used to build eight walls, while normal concrete (NC) was used to build two controls. Walls were lateral reinforced using conventional stirrups, two layers of welded wire mesh (WWM), and expanded steel mesh (ESM). Two specimens lacked lateral reinforcement except for one transverse web in the center of the inner hole. Two symmetric groups of five walls each were created by dividing the walls. While the other group was loaded laterally, one group was loaded axially. In each group, the load–displacement relationship, maximum load and associated displacement, stiffness, ductility, and failure mechanism of FM and NC walls were compared. The results showed that FM walls provided with ESM and WWM had ultimate axial loads that were, respectively, 36% and 19% higher than NC control walls. Ultimate lateral loads and related ultimate drifts of FM walls reinforced with two layers of WWM and ESM were, respectively, 68% and 39%, 96% and 43.5%, larger than control NC wall. For lateral loads greater than those applied to the NC control wall, stiffness increase ratios for FM walls ranged from 2.5% to 89.5%, and for axial loads, they ranged from 20% to 150.5%. The ductility of FM walls increased when compared to NC walls by 58.5% and 158.8% for axial and lateral loading, respectively, when two layers of WWM were utilized to lateral reinforce FM walls. When two layers of ESM were applied to laterally reinforce FM walls in comparison to an NC wall, this increased the walls' ductility under axial and lateral loads by 110.5% and 214.7%, respectively.

Nowadays, thin-walled cylindrical tubes with stiffeners have been rapidly considered in crashworthiness applications owing to their outstanding energy absorption characteristics and comparatively light weight. This research article deals with the influence of the internal linear stiffeners with varying numbers on the lateral crushing characteristics and impact energy absorbing response of cylindrical tubes subjected to quasi-static loading through experimental approaches. Five different configurations were proposed and all the tubes were additively manufactured through Fusion Deposition Modeling (FDM)-based 3 D printing method. Eventually, the fabricated tubes were tested under quasi‐static lateral crushing force and their crashworthiness characteristics were determined. The obtained results revealed that the PLA-CF-based C6S tube exhibited Specific Energy Absorption of 4.99 kJ/g and attained Crush Force Efficiency is 98.68%. Overall outcomes reported that both the carbon fiber reinforced polymer composite tube structures presented better crushing behavior and enhanced energy absorbing capability. Therefore, the proposed linear stiffener induced cylindrical tubes could be employed as a crash box for absorbing energy under lateral impact. [ABSTRACT FROM AUTHOR]

This paper presents a novel mathematical model for the analysis of laterally loaded floating piles embedded in a homogeneous soil layer of finite thickness. The governing equations of the soil surrounding the pile are established by treating soil as a Tajimi‐type continuum, and their solution yields a closed‐form expression that provides the lateral force developing to resist pile deflection. Accordingly, analytical expressions are obtained for the swaying, swaying‐rocking and rocking pile head stiffness, as well as for pile displacement and rotation along its length. The derived expressions are functions of parameters that have direct physical meaning, such as pile and soil elastic stiffness. As such, they pose as an attractive alternative to numerical methods for the low‐cost calibration of Winkler‐based model empirical parameters associated with small pile deflections. The presentation concludes with a parametric study focused on exploring the sensitivity of pile stiffness and deformations to the main problem parameters, and on highlighting differences in the lateral response of floating and end‐bearing piles. [ABSTRACT FROM AUTHOR]

Helical piles are integral to support resilient infrastructures subjected to axial and lateral loads. This study explored model-scale testing of group helical piles in cohesionless soil in a rigid box. Initially, a total load of 5000 N is applied to the pile raft model, followed by a lateral load of 1600 N. Nine model tests are performed with a configuration of four, six, and nine, having conventional, single helical, and double helical piles. The data logger facilitated data collection using MATLAB software, and the load was increased at rate of approximately 4.9N/sec. The computed average reduction in the displacement of Single and Double Helical Pile Rafts is observed as 36.43% and 55.71%, respectively, compared to Conventional Pile Rafts. The addition of a second helix further reduced lateral displacement by 19.27%. Numerical analysis on Plaxis-3d showed that the experimental and numerical results are in good agreement. [ABSTRACT FROM AUTHOR]

In this study, ten shear walls were experimentally tested to examine behaviour of ferrocement hollow shear walls subjected to axial and lateral loads. Ferrocement mortar (FM) was used to build eight walls, while normal concrete (NC) was used to build two controls. Walls were lateral reinforced using conventional stirrups, two layers of welded wire mesh (WWM), and expanded steel mesh (ESM). Two specimens lacked lateral reinforcement except for one transverse web in the center of the inner hole. Two symmetric groups of five walls each were created by dividing the walls. While the other group was loaded laterally, one group was loaded axially. In each group, the load–displacement relationship, maximum load and associated displacement, stiffness, ductility, and failure mechanism of FM and NC walls were compared. The results showed that FM walls provided with ESM and WWM had ultimate axial loads that were, respectively, 36% and 19% higher than NC control walls. Ultimate lateral loads and related ultimate drifts of FM walls reinforced with two layers of WWM and ESM were, respectively, 68% and 39%, 96% and 43.5%, larger than control NC wall. For lateral loads greater than those applied to the NC control wall, stiffness increase ratios for FM walls ranged from 2.5% to 89.5%, and for axial loads, they ranged from 20% to 150.5%. The ductility of FM walls increased when compared to NC walls by 58.5% and 158.8% for axial and lateral loading, respectively, when two layers of WWM were utilized to lateral reinforce FM walls. When two layers of ESM were applied to laterally reinforce FM walls in comparison to an NC wall, this increased the walls' ductility under axial and lateral loads by 110.5% and 214.7%, respectively. [ABSTRACT FROM AUTHOR]

A screw micropile is a multi-sectional pile typically consisting of a smooth segment at the top, a threaded segment in the middle and a tapered segment at the bottom. Although the axial behavior of this pile type has lately been studied, response to lateral loading and contribution of the threads to lateral capacities are yet to be investigated. To facilitate the design of this pile type for applications where wind or seismic loads are concerned, there is a necessity to examine the lateral behavior and capacities of screw micropiles and effect of the threads on the lateral capacities. Hence, lateral load field test programs were carried out on six types of screw micropiles at two cohesive soil sites and a cohesionless soil site. Selected piles were instrumented with bending moment strain gauges along the pile shaft. A geotechnical site investigation was carried out at each site to obtain soil profiles and properties. The lateral load versus displacement curves and the bending moment distribution were obtained. The lateral capacity and failure mode of the piles were determined from existing methods and analysis of the field test results. The lateral capacities of the piles were estimated using the Broms method without considering the effects of the thread. The estimated and measured lateral capacities were in a good agreement. This suggested that the effects of the threads on the lateral capacities were minimal. In addition, the effects of the tapered segments on the lateral response of the piles were negligible. This research was the first one for screw micropiles subjected to lateral loading and the outcome may support the engineering of the piles and further studies on soil-screw micropile interaction. [ABSTRACT FROM AUTHOR]

Piles supporting large structures are often subjected to cyclic lateral loads due to natural phenomena, including earthquakes, winds, and waves. Such loads are main causes of progressive deterioration in the stiffness and reduce the lateral capacity of piles. However, the effects of unsaturated soil conditions on the lateral cyclic response of piles are not yet fully understood, and the p–y curves used in engineering practice are merely based on the assumption of full saturation or complete dry conditions. This study is aimed to investigate the pile performance under unsaturated soil conditions by performing monotonic, cyclic, and post-cyclic loading tests on piles installed in sand with a varying water table. A loading system was designed and constructed to carry out different types of cyclic loadings. It was observed that the lateral capacity of the pile is influenced by the average suction stress along the pile which increases with the depth of the water table. During the cyclic loading, gap formation is noticed around the pile head for tests conducted in unsaturated conditions, which results in significant stiffness degradation compared to the saturated state. However, post-cyclic loading tests showed that the ultimate lateral capacity of the pile is not affected by the cyclic loading history. Finally, a modified p–y curve is proposed for the piles embedded in unsaturated sandy soils, and a comparison of its performance with the observed results is promising. [ABSTRACT FROM AUTHOR]

The paper analyses the behavior of a rigid passive pile embedded in a soil profile consisting of a stable layer underlying an unstable layer subjected to a uniform soil displacement. Pile-soil interaction is considered by modeling the soil by a series of elastic–plastic springs along the pile shaft. The modulus of horizontal subgrade reaction is assumed to linearly increase with depth in the unstable layer and constant in the stable one. The ultimate soil resistance is assumed increasing with depth in both layers. The results of analysis are presented in dimensionless form in terms of shear force developed at the slip surface as a function of the pile embedment into the stable layer and the distribution of soil characteristics over depth. The method allows capturing pile response not only at the soil ultimate state but also at the intermediate states. Specifically, the governing equations for the elastic, elastic–plastic and plastic cases are discussed and, whenever possible, a set of closed-form expressions is provided to estimate the maximum bending moment along the shaft and the pile head deflection, so that for an assigned value of the required stabilizing force both ultimate and serviceability limit state of the pile can be checked. A numerical example is given to illustrate the application of the proposed procedure. [ABSTRACT FROM AUTHOR]

Hollow bar micropiles (HBMP) offer high structural capacity through the hollow steel bar and the grout and are increasingly used to support a variety of structures subjected to lateral loads. However, their performance under lateral loading is largely unexplored. Therefore, there is a need to evaluate the lateral capacity and performance of single and groups of HBMPs. In this study, six 6 single micropiles were constructed in cohesionless soil utilizing hollow bars with 51 mm OD and 33 mm ID and were subjected to monotonic and cyclic lateral load tests. Four 4 micropiles were installed with a 152 mm diameter drill bit and two micropiles were installed with a 115 mm diameter drill bit to examine the effect of drill bit size on HBMP lateral capacity. In addition, a square group of four micropiles was installed and subjected to monotonic lateral loading. The total length of the micropiles was 6 m with an embedded length of 5.75 m. The load test results are presented and discussed. In addition, the lateral response of the micropiles was analyzed utilizing the commercially available program LPile and the results were compared to the experimental results. The results indicated that increasing the drill bit diameter improved the lateral capacity by about 32% resulted in substantially stiffer performance. The cyclic load test results were used to establish the degradation behavior of the HBMP as the number of load cycles increased. The results on the numerical modeling indicated that the properties of the soil along the top eight to nine micropile diameters govern the HBMP performance under lateral loading. [ABSTRACT FROM AUTHOR]

This paper investigates the response of finned piles in sand subjected to static lateral load through laboratory tests and full-scale field tests. Firstly, model tests were carried out on free headed single piles of different shaft diameters with and without fins in sand to explore the performance of the piles under lateral loading. The results obtained from monotonic loading tests on three series of piles of three different combination of fins and pile shaft diameters were presented. The effect of fins on improving the stiffness and ultimate lateral capacity of the piles was discussed. An equivalent diameter was proposed for a finned pile, which enabled the experimental results to be back calculated using an available elasto-plastic solution for laterally loaded piles in sand. Secondly, field tests were conducted on laterally loaded Starfin screw piles in loose to medium dense sand. The proposed approach was then used for the analysis of the measured response of Starfin screw piles and further validated against measured test results from fully instrumented finned piles in overconsolidated dense sand. The results show that the proposed equivalent diameter and approach for the analysis of finned piles provided the most satisfactory match to the measured data, ranging from the initial elastic state to the ultimate limit state. [ABSTRACT FROM AUTHOR]

Featured Application: The findings of this study hold significant implications for the field of geotechnical engineering, particularly in the design and construction of foundation systems for structures subjected to large lateral loads. The Innovative Post (IP) system presents a promising solution for enhancing the lateral load resistance of sound wall systems in layered cohesionless soils. Under environmental loads such as wind and earthquakes, piles are subjected to large lateral loads. A foundation system denoted Innovative Post (IP) that is composed of an H-pile shaft and one or two steel plates (paddles) welded to its flanges, has been developed to resist large lateral loads on sound wall systems. The present study evaluates the performance of IP installed in layered cohesionless soils through a comprehensive full-scale lateral load testing program and finite element (FE) analysis considering various pile and plate configurations. The developed FE model was validated employing the field test data and was then employed to conduct a parametric study to evaluate the performance of IP considering different paddles geometry (i.e., number of paddles, single or double, width, and length). The results demonstrated that adding the plates significantly increased the lateral capacity of H-piles. A positive relationship was identified between paddle's width and length and the load efficiency. Optimal parameter values for paddles are established based on the experimental and numerical results proposed. [ABSTRACT FROM AUTHOR]

In this paper, the structural performance of exterior fly-ash based concrete beam-column joints reinforced with hybrid glass fiber reinforced polymer (GFRP) and steel bars was studied, to inspect the hybrid concept efficiency under lateral loads. This paper studied two mixes of concrete, normal strength concrete (NC) and fly-ash based concrete (FC), a 20% replacement ratio of the cement weight with superplasticizer is considered in FC mix, which is considered as an environmental-friendly and cost-effective alternative to ordinary Portland cement. Ten joints were tested under the effect of monotonic lateral load experimentally. The studied joints were divided into two groups based on their concrete type, in each group, five joints with different GFRP to steel ratios “from 0% to 100% with an increment of 25%” were tested. The obtained results showed that the fly ash presence in concrete resulted in an average increase in both ductility and load capacity of 18% and 28.3%, respectively. Also, the average total energy absorption increased by 35%, and the average initial and post-yield stiffness increased by 34% and 41%, respectively. Moreover, the ductility index for each model was obtained, the FC model with 75% GFRP to steel ratio achieved the maximum ductility index, so it was considered as the optimum one. After that, the finite element analysis FEA was utilized to study the performance of the tested beam-column joints. The FEA showed identical results compared to the experimental ones concerning energy absorption, load capacity, and model stiffness. Finally, using FEA, a deep parametric study on FC models reinforced with GFRP to steel bars ranging from 60% to 90% was performed to obtain the optimum GFRP to steel reinforcement ratio. Through the performed parametric study, it was found that the optimum range of the reinforcement ratio was 68% to 82%. According to this research, the usage of fly ash in concrete increased RC beam-column joints' efficiency especially when provided with hybrid GFRP and steel reinforcement, in addition to the important environmental impact achieved through the recycling process. It was recommended to utilize the composite reinforcement ranging between 60% to 75% GFRP to steel bars in the presence of fly ash-based concrete for the beam-column joints.

An efficient foundation system of single- or double-paddled H-piles (PHPs), which comprises steel H-piles fitted with specially configured steel plates (paddles), is proposed to support sound walls subjected to wind loading. The lateral responses of single-paddled (SPHPs) and double-paddled H-piles (DPHPs) installed in clay is evaluated using a comprehensive assessment of the foundation performance via a full-scale lateral load testing program, alongside extensive three-dimensional (3D) nonlinear finite element (FE) analysis. The comparison between the calculated and measured responses of the PHPs demonstrates that the developed numerical model accurately depicts the response of the PHPs under lateral load. The validated numerical model is then used to evaluate the effect of the soil consistency on the lateral response and capacity of the PHPs. The influence of the paddles’ configuration on the lateral response and capacity of the PHPs is also evaluated. Furthermore, the change in the PHP lateral stiffness due to adding a second paddle is also examined. Finally, the influence of the plates on the surrounding soil is investigated by analyzing the formation of the strain field around the pile and evaluating the extent of the soil influence zone at different plate-width-to-pile-flange-width ratios (Wp/Wf). The result of this study indicates that adding plates contributes significantly to the lateral capacity of PHPs in clay and reduces the maximum bending moment. The parametric study reveals that the top 5–6 Wp of the soil have a significant effect on the lateral response of the proposed H-pile. Based on the outcomes of the field tests and numerical analysis, optimal geometrical parameters for paddles are proposed.

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.

This article proposes a biomimetic multilayer foam-filled structure (BMFS) that mimics the microstructural characteristics of biological structures such as human bone and whale baleen. The lateral compression performance of such structures is investigated using experimental and numerical analyses. The proposed structure consists of three layers of aluminum foam with different densities filled in several concentric circular aluminum tubes. The test includes a solid design (Design-1) and a hollow design (Design-2). A series of quasi-static compression tests and finite element simulations are conducted, and the results show that BMFS exhibits a more advantageous sequential collapse deformation pattern for practical use. An energy absorption analysis of each layer shows that the energy absorption ratio of the foam layer reaches 85%. Comparing Models 1–3 of the two designs shows that the energy efficiency decreases, and the work efficiency increases, as the foam density increases. In addition, the interaction between the tubes and foams enhances the energy absorption properties of the structure. The parameter study shows that the energy absorption characteristics of Design-2 are insensitive to the diameter of the tube. The SEA of Design-1 increases with the thickness of Tube-1. [ABSTRACT FROM AUTHOR]

An efficient foundation system of single- or double-paddled H-piles (PHPs), which comprises steel H-piles fitted with specially configured steel plates (paddles), is proposed to support sound walls subjected to wind loading. The lateral responses of single-paddled (SPHPs) and double-paddled H-piles (DPHPs) installed in clay is evaluated using a comprehensive assessment of the foundation performance via a full-scale lateral load testing program, alongside extensive three-dimensional (3D) nonlinear finite element (FE) analysis. The comparison between the calculated and measured responses of the PHPs demonstrates that the developed numerical model accurately depicts the response of the PHPs under lateral load. The validated numerical model is then used to evaluate the effect of the soil consistency on the lateral response and capacity of the PHPs. The influence of the paddles' configuration on the lateral response and capacity of the PHPs is also evaluated. Furthermore, the change in the PHP lateral stiffness due to adding a second paddle is also examined. Finally, the influence of the plates on the surrounding soil is investigated by analyzing the formation of the strain field around the pile and evaluating the extent of the soil influence zone at different plate-width-to-pile-flange-width ratios (Wp/Wf). The result of this study indicates that adding plates contributes significantly to the lateral capacity of PHPs in clay and reduces the maximum bending moment. The parametric study reveals that the top 5–6 Wp of the soil have a significant effect on the lateral response of the proposed H-pile. Based on the outcomes of the field tests and numerical analysis, optimal geometrical parameters for paddles are proposed. [ABSTRACT FROM AUTHOR]

A new practical formulation of the load-transfer P-Y curves to analyze the load–deflection response of a single pile under lateral loads is proposed in this paper. Parameters of the P-Y curves, namely the lateral reaction modulus and the lateral soil resistance, were correlated to the pre-bored pressuremeter (PMT) data as well as to the pile/soil stiffness ratio. A total of 16 full-scale monotonic lateral loading tests carried out in six experimental sites in France, representing a variety of soil conditions, were interpreted focused on the construction of the experimental P-Y curves along the test pile. For practical purposes, a methodology of construction of the P-Y curves was proposed. Moreover, the paper highlights the new concept of the critical deflection, which is the threshold of the nonlinear pile/soil response, as well as a classification of piles based on the pile/soil stiffness ratio. The process of validation of the proposed P-Y curve-based method was undertaken by comparing the predicted load–deflection curves to the experimental curves of several test piles within a medium-sized database, and a very good predictive capability was noticed. At last, the concept of the normalized load–deflection curve was introduced to estimate the pile deflection during a preliminary stage of pile design. [ABSTRACT FROM AUTHOR]

Natural hazards such as strong winds, typhoons, and earthquakes have caused massive economic losses in the form of damage to residential and life-line structures. Electric transmission infrastructures are life-line structures susceptible to severe damage under lateral loads like wind and earthquakes. This study focused on vulnerability assessment and measures to reduce the expected damage to the prestressed electric transmission poles under lateral loads. The Glass Fiber Reinforced Polymer (GFRP) sheet is selected as a strengthening material because the fiber cost is affordable but still has acceptable high tensile strength. A full-scale 12-meter-long prestressed transmission pole was tested under reversed cyclic lateral loading. Furthermore, another specimen strengthened with the GFRP sheet was tested to quantify the effectiveness of this technique. The experimental results show significant improvement in the lateral response behavior of prestressed poles in terms of lateral drift capacity, ductility, and energy dissipation characteristics. The GFRP-strengthened specimen exhibited a significantly enhanced lateral drift capacity (more than 100 %) compared to the control specimen. The performance of GFRP in preventing the collapse of a full-scale transmission pole is proved experimentally in this study. Finally, a numerical model based on the fiber modeling concept was also implemented in the open-source platform OpenSees to simulate the observed hysteretic behavior for strengthened and unstrengthened prestressed electric transmission poles. The application of this strengthening method is shown to be very practical for collapse prevention of existing PC poles both in terms of performance and budget.

This paper presents a numerical study of the lateral load-carrying capacity of hemp concrete as infill material in timber frame walls. The parameters that significantly affect the lateral resistance of hemp walls were investigated. For this purpose, vertical stud timber frame walls measuring 2.5 m in height and 1.2 m in length were used as the benchmark to validate earlier experimental work. A numerical study of three timber walls filled with hemp concrete was conducted to assess the effect of wall length on the lateral load-carrying capacity of hemp concrete. Three vertical stud timber frame walls with a standard height 2.5 m and different lengths (1.2 m, 1.6 m and 2.4 m) were investigated using Abaqus software. This study confirms, firstly, that the length of a timber wall plays a significant role in the lateral load-carrying capacity of hemp concrete. Secondly, the contact and bonding between the hemp concrete and timber wall have a significant effect on the lateral load-carrying capacity of hemp concrete as infill material in timber frame walls. It was clear, from the numerical results, that increasing the length of the wall significantly increases the contribution of hemp concrete to lateral resistance. Good contact and bonding between the hemp concrete and the timber elements also increase the lateral strength of the hemp wall. [ABSTRACT FROM AUTHOR]

The P-Y curves-based methods are nowadays powerful tools of design of laterally loaded piles. Semi-empirical methods based on correlation of the P-Y curves parameters with the in situ tests data are increasingly gaining interest among the geotechnical engineers. The aim of this paper is to present a new method of construction of the P-Y curves for a single pile embedded in a clayey soil, based on the pre-bored pressuremeter test (PBPMT) data. Detailed interpretation of full-scale lateral loading tests on 10 instrumented piles driven into 2 saturated clays served as a framework to develop this method. It was shown that the lateral reaction modulus and the lateral soil resistance may be formulated respectively as power and linear functions of the lateral pile/soil stiffness ratio. The predictive capability of the proposed method was demonstrated through a validation process by comparing the predicted load–deflection curves to the ones obtained from a database of full-scale piles. It was found the proposed method slightly overpredicts the pile deflections, which is in the safe side. [ABSTRACT FROM AUTHOR]

For the consideration of required elevation, pile shafts are partially buried in the soil stratum and partially exposed above the ground surface, known as high-rise pile group (HRPG). The HRPG is extensively used in the construction of infrastructures and is usually adjacent the slope. It is frequently subjected to high lateral loads from the superstructure, leading to considerable displacement and bending moment. To alleviate the deformation and internal force of HRPG, a batter pile is employed, forming the high-rise batter pile group (HRBPG). A numerical simulation is conducted to observe the response of HRPG foundation subjected to downwards lateral load adjacent slope. The effects of slope angle, cap elevation, and lateral loading magnitude are determined. Results of HRBPG are compared with traditional high-rise vertical pile group (HRVPG). Conclusions can be drawn as follows. (1) The slope has significant effect on the displacement and bending moment of HRPG, so it should be considered in the design process. The displacement and bending moment of pile shaft increase gradually with the slope angle (0°–30°) and then they have a sharp growth (45°–60°). (2) With the rise of cap elevation, the displacement increases dramatically, whereas the bending moment rises and then falls. The displacement is highly sensitive under lateral loading with a high cap elevation; the higher the elevation is, the greater the displacement will be. Special attention should be paid when a high pile cap is adopted under large lateral loading. The displacement and bending moment of HRBPG are considerably smaller than those of HRVPG at a high pile cap elevation. (3) The displacement and bending moment are relatively small when a diminutive lateral loading is performed; however, they have a sharp growth under large lateral loading. The larger the load is, the greater the bending moment and displacement will be. (4) The displacement of the leading pile is slightly larger than that of the trailing pile, whereas the bending moment of the rear pile is larger than that of the leading pile. The pile shaft displacement above the ground surface is considerably larger than that below. The maximum bending moment occurs at the pile head, and the pile toe has minuscule bending moment. (5) The use of batter pile is beneficial for reducing the displacement and bending moment, whereas the slope and lateral loading are detrimental. [ABSTRACT FROM AUTHOR]

Shear failures are one of the most brittle modes of response in rein-forced concrete columns subjected to earthquake-induced lateral drifts, notably if the failure occurs before the flexural strength is reached. Columns exhibiting this failure mode are termed shear-critical and are associated with the loss of the column s axial load-carrying capacity. Using a database of tests on 38 large-sized rectangular and square columns that exhibited this mode of failure, this paper reviews 10 methods published in the literature and compares their predictive capabilities. This paper shows significant differences between the methods, with the methods in Pan and Li (2013) and ASCE/SEI41-13 being assessed as the most accurate. [ABSTRACT FROM AUTHOR]

The p–y method as a simplified analysis tool has been widely used to analyze the behavior of laterally loaded piles. This paper develops a novel cyclic p–y elastoplastic model within the framework of the single-surface bounding surface theory. The model can capture the soil stiffness degradation during cyclic loading by incorporating the cumulative plastic displacement to an interpolation function of the elastoplastic resistance coefficient. The model is relatively simple with only four parameters that can be determined from standard soil properties and stress–strain responses measured in direct simple shear tests. The performance of developed model is validated by predicting the cyclic lateral response of piles installed in soft clay during field and centrifuge tests published in the literature. The model can reliably simulate monotonic and cyclic responses of piles under different lateral loading patterns, and capture main characteristics of the pile-head load–displacement curve, such as nonlinearity, hysteresis, displacement accumulation, and stiffness degradation. It can also predict the evolution of the lateral deflection and sectional bending moment along the pile during cyclic loading. [ABSTRACT FROM AUTHOR]

In this article, a mathematical derivation is made to develop a nonlinear static model for the thermal post-buckling characteristics of an annular system reinforced with graphene nanoplatelets (GPLs) and coupled with the piezoelectric actuator (PA) and shape memory alloy (SMA) under lateral loading. The matrix material is reinforced with GPLs at the nanoscale. The displacement-strain of postbuckling analysis of the functionally graded-graphene nanoplatelets reinforced composite (FG-GPLRC) annular system via higher-order shear deformation theory (HSDT) and using Von Karman nonlinearity is obtained. The governing equations and boundary conditions are formulated via the minimum total potential energy principle, and they are solved with the generalized differential quadrature method (GDQM). The direct iterative approach is presented for solving the set of equations that include highly nonlinear parameters. Finally, the results show that SMA fiber, radius ratio of outer to the inner, geometrical parameter of GPLs, applied voltage, piezoelectric thickness, and large amplitude play an essential impact on the thermal postbuckling response of the annular sandwich system. Another important consequence is that the highest thermal postbuckling to thermal buckling ratio is for the GPL-O pattern for all ranges of the large amplitude while considering the GPL-X pattern leads to the lowest thermal postbuckling to thermal buckling ratio for the smart annular system. This study's more general conclusion is that designing the FG-GPLRC annular system should be more attention to the nonlinearity parameter. [ABSTRACT FROM AUTHOR]

Under environmental loads such as wind and earthquakes, piles are subjected to large lateral loads. A foundation system denoted Innovative Post (IP) that is composed of an H-pile shaft and one or two steel plates (paddles) welded to its flanges, has been developed to resist large lateral loads on sound wall systems. The present study evaluates the performance of IP installed in layered cohesionless soils through a comprehensive full-scale lateral load testing program and finite element (FE) analysis considering various pile and plate configurations. The developed FE model was validated employing the field test data and was then employed to conduct a parametric study to evaluate the performance of IP considering different paddles geometry (i.e., number of paddles, single or double, width, and length). The results demonstrated that adding the plates significantly increased the lateral capacity of H-piles. A positive relationship was identified between paddle’s width and length and the load efficiency. Optimal parameter values for paddles are established based on the experimental and numerical results proposed.

Hollow bar micropiles are increasingly used to support a variety of civil structures due to their several practical advantages such as fast installation, small installation equipment requirements and efficient load transfer mechanisms. The main objective of this paper is to investigate the performance of hollow bar micropiles utilizing nonlinear three-dimensional finite element analysis. The cavity expansion theory was used to simulate the installation effect and radial stress changes due to the micropiles installation. Displacement- controlled cavity expansion analysis was conducted and a surface prescribed displacement was applied to a cylindrical cavity to replicate the increase in radial stresses during the micropile installation. The results obtained from the cavity expansion analysis were compared with those obtained from the more common method of simulating pile installations by increasing the lateral earth pressure coefficient (K0) values to those back calculated from pile load tests. Finite element models were verified by simulating the field loading experiments of full scale single and grouped micropiles. The verified finite element models were then employed to investigate the effect of micropile installation in cohesionless soils and the group effect. The numerical model results confirmed that the micropile group efficiency is equal to unity for micropiles in a 2 × 2 and 3 × 3 arrangement. [ABSTRACT FROM AUTHOR]

This study aims to investigate the response of flexible piles in the course of cyclic and post-cyclic lateral loadings for different loading scenarios including cyclic loading pattern, loading frequency, and also amplitude. For this purpose, an experimental program has been organized and a series of tests were conducted on a model pile embedded in dry sand. Experimental p–y curves derived from bending moment profiles for different loading patterns, namely symmetric two-way, asymmetric two-way, full one-way, and one-way patterns without complete unloading were studied. The results indicate that the stiffness is highly dependent on the cyclic loading pattern, and the two-way cyclic loading was found to increase the lateral force and soil stiffness more than any other factor. Also, compared to the monotonic loading, the residual force induced by one-way loading and one-way loading without complete unloading causes the lateral bearing capacity to decrease significantly. In addition, the post-cyclic load–displacement response of the pile was found to be influenced by the number of cycles, loading amplitude, and soil density index. Finally, a comparative study revealed that predictions made by the API code for the lateral resistance of flexible piles embedded in dry sand underestimate the p–y curves obtained from experimental observation. [ABSTRACT FROM AUTHOR]

Large-diameter steel pipe pile foundations, typically known as monopiles, are currently the dominant foundation solution for supporting offshore wind turbines. The design of monopiles in sandy seabed is typically based on p-y curves derived for fully drained conditions. However, in reality, the drainage condition around a monopile under cyclic loading, at least during each single loading cycle, is generally undrained. To verify the applicability of the design methods based on fully drained condition, this study conducted a series of finite element analyses examining the effect of drainage condition on the monopile soil-pile interaction in sandy seabed. Based on the analyses in four sands which are of different relative densities and particle size distributions, it is found that, for medium dense to very dense sands that exhibit dilative response upon shearing, the effect of drainage conditions can be practically ignored within the range of load relevant for practical engineering. For loose sands or sands with considerable fines that exhibit contractive response upon shearing, the drainage conditions have negligible effect on the soil-pile interaction stiffness at low to modest load levels; however, the undrained conditions can lead to lower capacities. This implies that the current design approach which assumes fully drained soil response is still acceptable for the FLS design in such soil conditions. However, for the ULS design, assumption of drained soil response may lead to overestimation of the lateral bearing capacity and assessment of the actual drainage condition and its influence on soil-pile interaction on a project-specific basis is warranted for such cases. • Effect of drainage condition on soil-pile interaction in four types of representative sands is examined systematically. [ABSTRACT FROM AUTHOR]

Prolonged lateral cyclic loading leads to soil stiffness degradation around offshore wind turbine (OWT) foundations, which reduces the system's natural frequency and increases the accumulation of foundation rotation angle. Proper evaluation of natural frequency and rotation angle is crucial for the design of OWT foundations. This study develops a two-stages numerical approach to calculate the fundamental frequency of OWT systems considering the foundation stiffness degradation by integrating a stiffness degradation model of soft clays with a simplified three-spring model. Subsequently, it investigates the evolution of accumulated rotation and natural frequency for three foundation types—monopile, monopod bucket, and hybrid monopile-bucket—throughout their service life. It is observed that the hybrid foundation shows the smallest rotation in the first cycle, attributable to its relatively high initial stiffness compared to the other two foundations with the same steel consumption. However, it also exhibits the highest rate of cumulative rotation growth. At the same load level, the monopod bucket foundation exhibits the largest cumulative rotation angle due to its lower bearing capacity, and the degradation of natural frequency is most pronounced for monopod bucket OWT. For all three foundation configurations, increasing either the pile diameter or the bucket diameter is the most effective approach to reduce the cumulative rotation angle and improve natural frequency degradation, while maintaining the same steel consumption. These findings should be considered in the design of OWT foundations. • A two-stages method is developed to calculate the fundamental frequency of OWT considering foundation stiffness degradation. • Evolution of accumulated rotation and natural frequency for three OWT types throughout their service life is investigated. • Influence of foundation dimensions on the rotation angle and natural frequency of OWTs is investigated. [ABSTRACT FROM AUTHOR]

In this paper, the flexural strength and buckling of the partially concrete-filled steel tubes (PCFST) under laterally repeated loads was investigated through three-point bending test configuration. Three-dimensional Finite Element (FE) models of the bending tests of the PCFST were developed, in which the concrete filling was modelled using elastic-plastic-fracture model capturing crack development and the tube steel was modelled using elastic-plasticity model. The bond between concrete and tube was considered as frictional touching contact. The validation showed the FE results including the ultimate flexural load and buckling failure mode of the steel tube were in excellent agreement with the experimental ones. A parametric study was then conducted using the verified FE models to investigate the effects of the tube diameter-to-thickness ratio, the concrete filling length ratio, the compressive strength of concrete, and the tube steel's yield and tensile strengths on the PCFST's ultimate flexural strength. Based on this study, buckling modes, the optimal concrete filling lengths, and the confined compressive strengths of concrete were determined considering the effects of all these parameters. The confined compressive stresses and strains in concrete predicted by the FE models were evaluated against those determined by theoretical models. The results revealed that the effects of concrete compressive strength to the PCFST's flexural capacity was insignificant while increasing the tube diameter-to-thickness ratio or the tube steel's yield and tensile strengths could significantly increase the PCFST's flexural capacity and the confined compressive strength of concrete; and there was an optimal length of concrete filling at about 66% of the tube length. It demonstrated that the Finite Element analysis can therefore be used as a powerful method to the analysis and design the PCFST columns under lateral loads. [ABSTRACT FROM AUTHOR]

In harsh offshore environmental conditions, the monopile foundations supporting offshore wind turbines must be designed for lateral loads such as winds, waves, and currents. The Beam on Nonlinear Winkler Foundation (BNWF) method has been widely used because of its clear concept and lower calculation cost. The selection of a reasonable p–y curve is critical to the calculation accuracy of this method. This paper clarified the defects of widely used API p–y curves for soft clays and then proposed a new p–y curve with better versatility and applicability. The suitability of the proposed p–y curve was validated by comparing it with the calculation results from the three-dimensional finite element method (3D FEM). Compared with the API p–y curve, the proposed p–y curve can better predict the lateral behavior of large-diameter piles in soft clays, such as the load–displacement curve of the pile head, lateral deflection profile, and bending moment profile. The research findings can provide guidance for the design of monopile foundations supporting offshore wind turbines in soft clays. [ABSTRACT FROM AUTHOR]

An analytical method is proposed to characterize the stress distribution of the soil around a caisson foundation under lateral load in an elastic half-space. A series of model-scale tests is performed to delineate the characteristics of lateral resistance stress along the foundation periphery. Accordingly, the mathematical expression of circumferential resistance stress is established based on the elastic-beam theory. Thereafter, the stress increment in the surrounding soil is derived by numerically integrating the Mindlin's stress solution. The analytical solution for the stress variation in different directions can be solved by a numerical calculation program, the effectiveness of which is further evaluated by comparing with the experimental results. It is found that the stress increment of the soil around the caisson foundation decreases exponentially with the increase of the distance from the foundation side. The vertical additional stress is approximately saddle-shaped and anti-symmetric with respect to the x-axis and the y-axis of the foundation. A bridge project with caisson foundation is further analyzed using the proposed method to demonstrate the influence of caisson foundation geometry, including the embedment and the diameter, on the additional stress distribution. [ABSTRACT FROM AUTHOR]