Horizontal Loads Research Articles

Analysis of the screw pile group subjected to combined V–H loading for energy application

ABSTRACT The present study investigates the behaviour of screw piles in very stiff clay under the combined vertical and horizontal loads using a three-dimensional finite element analysis. The soil is modelled using the Mohr–Coulomb elastic, perfectly plastic material, whereas the pile shaft and helices are modelled as a linear elastic material. This study examines the effect of the number of helices, helix diameter, inter-helix spacing, and pile spacing on the performance of screw piles under both vertical compression and lateral loads. The study shows that the effect of the number of helices is negligible under the combined load. The increase in the helix diameter (D h) improves the pile performance. The results also reveal that the optimum interhelix spacing is 3D h, and the optimum pile spacing is 2D h. Thus, the present study demonstrates that optimizing the geometry of the screw pile enhances its performance, making it suitable for offshore wind turbines.

An Evaluation of the Structural Behaviour of Historic Buildings Under Seismic Action: A Multidisciplinary Approach Using Two Case Studies

The evaluation of the structural behaviour of iconic historic buildings represents one of the most current structural engineering research topics. However, despite the various research works carried out during recent decades, several issues still remain open. One of the most important aspects is related to the correct reconstruction of the complex geometries that characterise this type of construction and that influence structural behaviour, especially in the presence of the horizontal loads caused by seismic action. For these reasons, different techniques have been proposed based on the use of laser scanners, Unmanned Aerial Vehicles (UAVs), and terrestrial photogrammetry. At the same time, several analysis methods have been developed that include the use of linear and non-linear approaches. In this present paper, the seismic performance of the Santa Maria Novella basilica and Santa Maria di Collemaggio basilica (before the partial collapse due to the 2009 L’Aquila earthquake) were investigated in detail by means of several numerical analyses. In particular, a series of non-linear time history analyses (NTHAs) were carried out, as reported in the Italian Building Code. To represent the non-linear behaviour of the main structural elements, smeared cracking (CSC) constitutive law was adopted. The geometry of the structures was reconstructed from a complete laser scanner survey of the churches, in order to consider all the intrinsic irregularities that characterise the heritage buildings. Finally, a comparison between the structural behaviour of the two case studies was carried out, highlighting the differences and similar aspects, focusing on possible collapse mechanisms and the identification of the most critical structural elements represented, in both cases analysed, by the main pillars of the transept.

Test-Based Assessment of the Seismic Response of Bracing Systems for Concealed Grid Suspended Ceilings

ABSTRACT Despite not directly contributing to a structure’s load-bearing capacity, non-structural elements like partitions, cladding, ceilings, floor finishes, and facades play a pivotal role in the overall building design and occupant safety. Their susceptibility to damage during seismic events, however, can lead to substantial economic losses, business interruptions, and potential risks to occupants. Focusing on concealed grid suspended ceiling systems, this study focuses on enhancing their seismic resilience introducing and experimentally evaluating two innovative bracing systems (Typology N and Typology W) that utilize steel members, already used in non-seismic application, as braces. Unlike prior research using shake tables, this study employs a specially designed set-up on a universal testing machine, offering a cost-effective and efficient approach for cyclic testing and considering the spatial variability of seismic loads. As a complementary task, component-level tests were conducted on the compressed strut to extend the results for suspended ceiling systems having suspension height up to 2 meters. The results show that Typology N performs better than Typology W, with 1.7 times greater resistance and 2.5 times greater stiffness on average, demonstrating the importance of considering different directions of horizontal seismic loading in the performance assessment. The study provides valuable insights, including design resistance values and a step-by-step procedure for determining the maximum ceiling area that a single bracing system can cover, aiding in optimizing bracing system selection and mitigating seismic vulnerability in concealed grid suspended ceilings for seismic-prone regions.

A SPECIALIZED SYSTEM FOR IN VITRO TEST OF ANATOMIC GLENOIDS BASED ON ASTM F2028-14

Glenoid loosening, primarily induced by the “rocking horse” phenomenon from humeral head load on the glenoid rim, is the foremost complication and cause of failure in anatomic total shoulder arthroplasty. The dynamic load exerted by universal fatigue testing machines significantly deviates from the standard ASTM F2028-14 in the rocking test. To accurately conduct the in vitro loosening test on anatomic glenoids, a specialized system and customized test methods are developed to achieve anatomic glenoid rocking and subluxation tests. The horizontal and vertical loading can be achieved synchronously or asynchronously by two self-developed high-performance electromagnetic linear motors. In addition, the subluxation tests on anatomic glenoids are verified by finite element simulation. The results show that the subluxation load and translation of anatomic glenoids in the subluxation tests are consistent with those in numerical simulations. The error of the applied axial force in the rocking tests is only 5[Formula: see text]N, strictly meeting the standard of ASTM F2028-14. During the rocking tests, the system runs smoothly and the software works well, indicating the feasibility of the in vitro shoulder joint test system. This study provides an approach to accurate dynamic evaluation of glenoid loosening or disassociation.

Numerical study of internal solitary wave loads on a submerged slender body with multi-parameter coupling

This study investigates the destabilizing loads exerted on submarines by large-amplitude internal solitary waves (ISWs), which significantly increase the risk of a phenomenon known as “falling deep.” Using numerical simulations and theoretical analysis, the research explores the multi-parameter coupling effects of ISWs on a slender body in a two-layer fluid system. A numerical wave generation method for large-amplitude ISWs, based on the strongly nonlinear adjusted high-order unidirectional (aHOU) model, is proposed. A corresponding numerical model is also developed to simulate the interaction between ISWs and a submerged slender body, with validation against experimental data confirming its accuracy and reliability. The study further examines how wave amplitude, submergence depth, and wave incidence angle affect the load characteristics induced by ISWs. Theoretical analysis identifies the components of ISW-induced loads, revealing a linear relationship between horizontal load and wave amplitude, as well as the influence of submergence depth on the duration of vertical forces. The primary contributor to the horizontal force is identified as the pressure-gradient force generated by the ISW's flow field, while the vertical force is primarily driven by the reduced gravity force due to density stratification and wave forces, which are well-approximated by Morison's formula. Additionally, the peak values of horizontal and vertical forces are significantly affected by wave incidence angle and wave amplitude, respectively. These findings provide a theoretical foundation for understanding the “falling deep” phenomenon encountered by submarines under the influence of ISWs.

Numerical Simulations of Abutment PRB Structures with Post-Tensioned Unbonded Prestressing Tendons for Highway Bridges under Horizontal Seismic Loads

Numerical Simulations of Abutment PRB Structures with Post-Tensioned Unbonded Prestressing Tendons for Highway Bridges under Horizontal Seismic Loads

Seismic performance of precast concrete shear wall with treatments of connecting reinforcement defects in grouted sleeves under combined axial tension and cyclic horizontal load

With the purpose of investigating the influence of connecting reinforcement defect in grouted sleeves and corresponding strengthening schemes on the seismic performance of precast concrete shear walls under combined in-plane axial tension and cyclic horizontal load, four full-scale precast concrete shear wall specimens and one monolithically cast-in-place concrete shear wall specimen as a reference, were designed and tested. The seismic performance, including failure mode, seismic load bearing capacity, ductility, stiffness degradation and energy dissipation capacity, of all specimens were selectively emphasized. The test results revealed that under combined axial tension and cyclic horizontal load, the precast shear wall with reliable connecting via grouted sleeves technology would achieve the satisfactory seismic performance, approximately parallel to that of monolithically cast-in-place shear wall. However, the ultimate seismic load bearing capacity and ultimate deformation of precast shear wall with reinforcement connection defect in grouted sleeves decreased by around 44.1%, 171.6% respectively, compared with that of precast shear wall with reliable connecting via grouted sleeves. In terms of strengthening specimens, the seismic load bearing capacity, peak deformation, flexural stiffness and energy dissipation basically recovered to the identical level of seismic performance with monolithical shear wall under coupling action of axial tension and cyclic horizontal load. Differently, the post-peak deformation ability of strengthening specimens severely decreased due to the stress concentration and further premature fracture of steel rebars resulting from the presence of UHPC in strengthening region. Finally, the portion of shear deformation and failure mechanism of precast concrete shear walls with reinforcement defect in grouted sleeves, and those employing different strengthening schemes were well discussed and analyzed under coupling action of axial tension and cyclic horizontal load as well.

A New Method for Predicting Dynamic Pile Head Stiffness Considering Pile–Soil Relative Stiffness Under Long-Term Cyclic Loading Conditions

Under long-term horizontal cyclic loading, the evolution characteristics of the loading and unloading stiffness of piles are an important representation of pile–soil interaction. However, research in this area is limited, particularly regarding the impact of factors like pile–soil relative stiffness. In this study, laboratory tests with a long-term horizontal cyclic loading strategy were conducted to study various factors, including different cyclic amplitude ratios (ζb), cyclic load ratios (ζc), and pile–soil relative stiffness (T/L) in sandy soil, on dynamic pile head stiffness. The results show that the normalized cumulative displacement increases with the number of cycles and the ratio of T/L but tends to decrease as ζc increases. As ζb increases, the normalized cyclic loading stiffness also rises, while it has little effect on the normalized cyclic unloading stiffness. On the other hand, as ζc or T/L increases, the cyclic loading stiffness increases while the unloading stiffness decreases. Based on these observations, prediction formulas for normalized cumulative displacement and cyclic loading and unloading stiffness were established and confirmed with test results. The findings of this study provide methodological references for establishing models of pile–soil interaction under cyclic loading and for predicting loading and unloading stiffness under different influencing factors.

A Review on Determination of Efficiency of Soil Parameters Below Multi-Storied Building

Abstract: The construction of high-rise structures is widely utilized in urban and semi-urban areas of developed and developing countries. These tall structures, including residential apartments, commercial, and semi-commercial spaces, are characterized by their efficient use of construction area relative to their footprint. During the structural analysis stage, significant characteristics such as vertical load, horizontal load, superstructure design, and foundation design are considered. However, prior to this stage, the larger construction area is planned by architecture. It is essential that this preliminary selection not only considers structural design configurations but also incorporates soil parameters, which should be assessed beforehand. This paper presents a review of past research on the aforementioned topics and draws conclusions based on the reviews. It is concluded that the location parameter, determined based on soil investigation reports, should be prioritized for the selection of the construction area's optimal Soil Bearing Capacity (SBC), ensuring the suitability of the soil for structural performance.

Study on the Ratio and Model Test of Similar Materials of Heavily Weathered Granite.

To study the bearing characteristics of rock-socketed single piles on the southeast coast of Fujian Province, we conducted similar material ratio tests and single pile model tests. Initially, based on the mechanical parameters of strongly weathered granite, 10 groups of similar material samples were prepared using iron concentrate powder, barite powder, and quartz sand as aggregates, with rosin and alcohol as the cementing agents and gypsum as the modulating agent. Through triaxial testing and range and variance analysis, it was determined that the binder concentration has the most significant impact on the material properties. Consequently, Specimen 1 was selected as the simulation material. In the model test, the strongly weathered granite stratum was simulated using the ratio of Specimen 1. A horizontal load was applied using a pulley weight system, and the displacement at the top of the pile was measured with a laser displacement meter, resulting in a horizontal load-displacement curve. The results indicated that the pile foundation remained in an elastic state until a displacement of 2.5 mm. Measurements of the horizontal displacement and bending moment of the pile revealed that the model pile behaves as a flexible pile; the bending moment initially increases along the pile length and then decreases, approaching zero at the pile's bottom. The vertical load test analyzed the relationship between vertical load and settlement of the single pile, as well as its variation patterns. This study provides an experimental basis for the design of single pile foundations in weathered granite formations on the southeast coast of Fujian Province and aids in optimizing offshore wind power engineering practices.

Investigating the Response Mechanism of Vertical Concrete Structures to Alternating Horizontal and Lateral Loads

The improper performance of columns in concrete buildings designed and built in the past years has caused concern and attention to their vulnerability to collapse. The investigation of the damages caused to the structures after various earthquakes and the research conducted during these years have caused changes in the design practices to achieve ductile behavior in the columns. Most of the efforts have been made in these years to improve the design criteria, but the effect of the axial force or the loss of the axial capacity of the columns in the existing buildings built in the past years is still unknown. Most of these columns have transverse reinforcements with large distances, which provide little lateral resistance for the longitudinal reinforcements and also little confinement for the concrete in seismic loads. Many of these columns are not accepted according to the rules of today's regulations. In these columns, not only determining the shear capacity but also the ability of the column to withstand the axial force after the shearing is of great importance. The failure of such columns is due to shear deformations that lead to shear failure and then axial failure. At first, a comprehensive review is done of the studies of other researchers. In this review, we try to collect the analytical and laboratory studies available in the technical literature. These studies are related to the testing of concrete columns until the time of gravitational collapse and the behavior models of the columns until this limit state. Then, according to the collected information and their analysis, several columns will be designed and built for laboratory study. These columns are designed to represent the condition of columns in old concrete buildings. The comparison between the analytical and laboratory results of the 6 tested column samples shows a good agreement between them. As a result, the proposed method has sufficient accuracy and efficiency to determine the effective stiffness of columns.

Large scale analogue experiments in rock mechanics : new experimental facility, 3D-printed material and insertion of force transducers for stresses measurement.

Abstract The aim of this paper is to present a new experimental device that was designed to perform analogue rock mechanics experiments with 3D-printed material. The device consists in the creation of two rectangular excavations (mining tunnels) in slices of 3D sand printed material. This is a true-triaxial test device that allows us to study the mechanical behaviour of reduced scale models of underground structures. The experimental protocol entails the horizontal loading of the specimen, followed by the excavation of two galleries while the specimen is maintained under a constant load. The results of the test carried out in DiMiTri show a generally logical evolution of the sensors with an increase in vertical stresses induced by the presence of excavations. This paper discusses the upcoming challenges in terms of instrumentation that will be encountered, together with the new opportunities for future research.

Experimental study and numerical analysis of a novel serrated-and-plate truss structure

High-speed rail station has extensive span and height, making daylighting a challenge. This paper proposes the serrated-and-plate truss structure (SPTS) to improve station daylighting. SPTS combines a serrated truss structure (STS) for daylighting and a plate truss structure (PTS) for lateral stability and deformation resistance. A downscaled SPTS with support-loading system is designed and built to test mechanical properties. It has 264 stress and 19 displacement measuring points, tested under four vertical and two horizontal load cases. Maximal stress and displacement are 150.7 MPa and 5.07 mm, with peak chord axial force and column base bending moment of 13.5 kN and 663.7 kN mm. Simulated and measured results match well, confirming the numerical method's accuracy. Thermal effects of SPTS are studied via conventical and extreme thermal analyses, with stress and displacement well below limits. Seismic spectrum and time-history analyses indicate SPTS stress and deformation at 63.9 % and 68.3 % of limits. Comparative analysis across 64 load cases reveal that STS is significantly less stable and resistant to deformation than SPTS, validating PTS's boundary constraint effects. Experimental and numerical studies confirm SPTS's engineering applicability and provide valuable references for similar truss structure research.

A 3-D modelling of monopile behaviour under laterally applied loading

Deploying higher-capacity offshore wind turbines to meet the growing energy demand poses a significant challenge in designing their foundations. Monopiles currently constitute 80% of the foundation installations for these turbines. This study utilizes a nonlinear three-dimensional (3D) finite element model to explore the behavior of monopiles underpinning a five megawatt wind turbine under horizontal loads. The findings reveal that the performance of monopiles is influenced by the strength of the soil and the ratio of pile depth of embedment to diameter (L/D). Examination of flexural bending profiles at/close to failure loads demonstrates the flexible behavior of monopiles, even with a low L/D ratio. The L/D ratio exhibits varying degrees of impact on the normalized ultimate lateral capacity of monopiles, with a notable effect observed in soft clays, resulting in an increase of up to five times for L/D ratios ranging from 3.33 to 13.33. Stiff clays show comparatively lesser effects. Under serviceability loading, an increase in the L/D ratio leads to a 3–6% rise in the maximum flexural moment of monopiles, while the maximum shear force experiences a decrease of 20–30%. Furthermore, a significant reduction, up to five-fold, in the maximum tower tip displacements and rotations at the mudline is observed with an increasing L/D ratio. However, this reduction is more pronounced for higher foundation rigidity.

Bearing Performance of a Helical Pile for Offshore Photovoltaic under Horizontal Cyclic Loading

For an offshore photovoltaic helical pile foundation, significant horizontal cyclic loading is imposed by wind and waves. To study a fixed offshore PV helical pile’s horizontal cyclic bearing performance, a numerical model of the helical pile under horizontal cyclic loading was established using an elastic–plastic boundary interface constitutive model of the clay soil. This model was compared with a monopile of the same diameter under similar conditions. The study examined the effects of horizontal cyclic loading amplitude, period, and vertical loads on the horizontal cyclic bearing performance. The results show that under horizontal monotonic loading, the bearing capacities of a helical pile and monopile in a serviceability limit state are quite similar. However, as the amplitude of horizontal cyclic loading increases, soil stiffness deteriorates significantly, leading to greater horizontal displacement accumulation for both types of piles. The helical pile’s bearing capacity under horizontal cyclic loadings is approximately 60% of that under monotonic loading. With shorter cyclic loading periods, horizontal displacement accumulates rapidly in the initial stage and stabilizes over a shorter duration. In contrast, longer cyclic loading periods lead to slower initial displacement accumulation, but the total accumulated displacement at stabilization is greater. When vertical loads are applied, the helical pile exhibits more stable horizontal cyclic bearing performance than the monopile.

In situ tests of building structures isolated by innovative three‐dimensional vibration isolation bearings

AbstractAn innovative three‐dimensional vibration isolation bearing (3D‐VIB) was proposed in past studies to mitigate rail‐induced vibration and improve the seismic performance of buildings. The 3D‐VIB was composed of a thick laminated rubber bearing as the vertical vibration isolation element and a friction pendulum system as the horizontal seismic isolation element. In this study, in situ tests were carried out on a subway over‐track structure with 3D‐VIBs. The in situ tests included the subway‐induced vibration excitation test and the horizontal loading test on the same structure. In the subway‐induced vibration excitation test, the vertical isolation performance of the test structure was changed by transforming the isolation layer from a normal vibration‐isolation‐state to a non‐isolation‐state. The comparison between the two states proved that the installation of 3D‐VIBs significantly changed the vertical vibration mode and reduced the subway‐induced vibration of the superstructure. The shear performances of the isolated structure were examined by the horizontal loading test, which subjected the superstructure to a large horizontal movement under external load. The shear performances of the structure with 3D‐VIBs were consistent with that of the 3D‐VIB specimens measured in the laboratory. The in situ tests confirmed the effectiveness and stability of the 3D‐VIBs when applied to practical engineering.

Study on fatigue performance and topology optimization of cast steel bifurcation joint under alternating load

Abstract The numerical simulation analysis of a typical cast steel bifurcation joint under the alternating load was performed to comprehend its mechanical properties. The MSC Fatigue is used to explore and analyze the fatigue behavior of joints, and the control variable approach is used to examine the impact of various geometric parameters on fatigue life. Then, the load spectrum and fatigue life were invertedly calculated and transformed into maximum stress constraints by converting fatigue limitations into stress constraints. Finally, the optimal shape of cast steel bifurcation joint under fatigue limitations was studied using topology optimization methods, intending to solve the lightweight problem while still fulfilling fatigue design requirements. The research results show that the intersection of the main and branch pipes is the fatigue weakest part of the whole joint, and the geometric parameters significantly affect the joint's fatigue performance. The topology optimization shapes of cast steel bifurcated joints are different under vertical and horizontal loads, indicating that different load conditions significantly impact topology optimization shapes. The topology optimization method can reduce the self-weight while maintaining fatigue performance.

In-Plane Mechanical Properties Test of Prefabricated Composite Wall with Light Steel and Tailings Microcrystalline Foamed Plate

The tailings microcrystalline foamed plate (TMF plate), produced from industrial waste tailings, has limited research regarding its use in high-performance building walls. Its brittleness under stress poses challenges. To improve its mechanical properties, a prefabricated light steel-tailings microcrystalline foamed plate composite wall (LS-TMF composite wall) has been proposed. This LS-TMF composite wall system integrates assembly, sustainability, insulation, and decorative functions, making it a promising market option. To study the in-plane performance of the composite wall, compression and seismic performance tests were conducted. The findings indicate that the light steel keel, steel bar, and TMF plate in the composite wall demonstrated good working performance. Strengthening the TMF plate enhanced the restraint on the light steel keel and improved the composite wall’s compressive performance. Increasing the thickness of the light steel keel further improved the compressive stability. Under horizontal cyclic loading, failure occurred at the light steel keel embedding location. Increasing the strength of the TMF plate was beneficial for the seismic performance of the composite wall. This structural configuration—incorporating light steel keels, TMF plates, and fly ash blocks—enhanced thermal insulation and significantly improved in-plane stress performance. However, the splicing plate structure adversely affected the seismic performance of the composite wall.

Bearing Behavior of Large-Diameter Monopile Foundations of Offshore Wind Turbines in Weathered Residual Soil Seabeds

The southeastern rock base sea area is the most abundant wind resource area, and it is also the mainstream construction site of offshore wind farms (OWFs) in China. The weathered residual soil is the main seabed component in the rock base area, which is the important bearing stratum of the offshore wind turbine foundation. Previous studies on the mechanical properties of seabed materials and bearing characteristics of the pile foundations in OWFs have mainly focused on the submarine soil-based seabed, resulting in a lack of direct reference for the construction of offshore wind power in the rocky seabed. Therefore, the mechanical properties of weathered residual soil and the bearing behaviors of monopile foundations are mainly investigated in this study. Firstly, dynamic triaxial tests are conducted on the weathered residual soil, and experiments analyze insight into the evolution law of the hysteresis curve, cumulative strain, and stiffness attenuation. Then, the horizontal loading behaviors of monopile foundations in residual soil are analyzed by numerical simulations; more critically, the service performances under wind and wave coupling loads are evaluated, which provide a direct theoretical basis for the construction and design of offshore wind turbine foundations in rock base seabeds.

Experimental insights into the seismic behaviour of flanged URM walls

Considerable attention has been given to understanding and modelling the seismic response of unreinforced masonry piers with rectangular cross-sections. However, the seismic performance of load-bearing masonry walls with flanges, commonly found in actual building configurations, remains less explored. This study investigates the behaviour of flanged walls through cyclic quasi-static tests on four full-scale C-shaped specimens comprising two primary seismic-resistant walls (webs) interconnected by a single flange. The construction of the specimens varied: two were built using standard solid calcium-silicate bricks with general-purpose mortar, while the other two utilised large-sized calcium-silicate blocks with tongue-and-groove interlocks and a thin layer of cement-based adhesive mortar. All specimens were subjected to cyclic horizontal loading parallel to the webs under consistent overburden load and double-fixed boundary conditions. The primary variable in testing the two walls of each type was the number of cyclic loading repetitions. This paper initially describes the key characteristics of the wall specimens, including geometry, construction details, and mechanical properties. Subsequently, it details the instrumentation plan and test protocol, and summarises the major observations from the tests, illustrating damage evolution and hysteretic force-displacement response. The results highlight the effect of the flange on initial stiffness and lateral force resistance, as well as the influence of block type and loading repetitions on failure mode, displacement capacity, and energy dissipation. Additionally, the study demonstrates the impact of floor slab uplift due to in-plane rocking of the webs on the top boundary conditions and the out-of-plane stability of the flange.