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As the supporting structure of the wind turbine, the tower is important for the safety of the wind turbine. The accurate estimation of tower response is critical for the wind turbine tower design. In the preliminary design, lots of calculations are necessary to determine design parameters. The traditional time domain calculation suffers its low efficiency and hinders the design progress. To overcome this difficulty, the frequency domain analysis should be developed, especially for the large wind turbine which may be significantly affected by the aerodynamic damping. In this study, a semi-analytical formula for the variance of the tower base bending moment is developed from the frequency domain analysis at parked condition. First, based on the quasi-steady theory and the three-component (mean, background and resonant components) method commonly used in the wind-resistant design of structure, the analytical formula of the variance for the tower base bending moment is presented considering the three components of the wind velocity. Second, the analytical formula is corrected based on the comparison with the calculation result by FAST. In the correction, the empirical aerodynamic damping is adopted. Finally, the applicability of the developed semi-analytical formula is verified by 5 MW, 10 MW and 15 MW wind turbines. [ABSTRACT FROM AUTHOR]

To explore the load-bearing performance and the failure patterns of the lining structures, a full-scale loading test on the three-ring staggered assembled shield tunnel segments is carried out through a hydraulic loading system. In the experimental study, the segments’ internal force, convergence deformation, and displacement, and the bolts’ internal force, are analyzed. According to the experimental results, the relationship between internal force and deformation is obtained to determine the residual bearing capacity of the shield tunnel at each stage. Three stages are specified for the evolution of the segment’s maximum bending moment during the loading process, in which, the elastic stage is the main and longest stage, in which the bending moment of the segment increases the most. There are two stages for convergence deformation development and segment misalignment development. At the end of loading, the segment’s maximum positive and negative convergence values reach 61.22 and −57.69 mm, respectively. Besides, the maximum segment misalignment is 3.67 mm, which occurs in the direction of 90°. The segment cracks when its maximum convergence value reaches 25.03 mm. Moreover, there are signs of fracturing on the waist joint of the segment when its maximum convergence value reaches 32.73 mm. The concrete at the waist joint starts fracturing in pieces when the segment’s maximum convergence value reaches 38.93 mm, which is defined as the type of shear failure. Finally, the bearing capacity of shield tunnels during segment failure period can be evaluated by using the corresponding relationship between deformation and internal force. [ABSTRACT FROM AUTHOR]

High-speed craft typically utilizes hydroplane boat-type and large power engine to obtain high-speed in water. However, these designs result in significant hydrodynamic nonlinearities, including slamming, wetness, sliding, and dolphin effect. As a result, high-speed craft exhibits complex impact load characteristics and structural responses, which have garnered considerable attention from ship mechanics researchers. This paper studies impacting load and structural response of a high-speed craft by means of numerical approach that combines computational fluid dynamics (CFD) and finite element method (FEM). A model experiment of high-speed craft is selected to simulate impact load and structural response. The craft model consists of two ship bodies and a keel beam, and a number of pressure sensors and strain gaugesare arranged to capture the impacting pressure and vertical bending moment (VBM). A numerical fluid-structure interaction (FSI) approach is employed to investigate the model experiment of the high-speed craft by coupling CFD and FEM. CFD is utilized to solve the hydrodynamics of the high-speed craft. Dynamics of fluid-body interaction (DFBI) and overset grid algorithm are employed to accurately simulate the motion of the craft. Dynamic FEM is used to calculate structural response of high-speed craft, structural VBM is obtained. Two-way FSI is employed to realize coupling of CFD and FEM. This involves iterating the wave pressures and structural displacement to make progress. Ultimately, the numerical results and experimental results, which encompass impacting pressure, craft motion, and VBM, are compared and analyzed, demonstrating a high degree of agreement. Numerical methods can be employed to analyze the impacting load and structural response for high-speed craft. [ABSTRACT FROM AUTHOR]

The present study investigates the lateral response of piles on sandy slopes. PLAXIS 3D has been employed to perform three-dimensional finite element analysis. A number of numerical assessments have been conducted on the pile with a constant slope height, having different ground slope inclinations from 10° to 30° in sandy soil with different relative densities from 30% to 70%. The embedment length-to-diameter ratio is 30. Responses are compared with the results of horizontal ground conditions. The impact of pile position on the sloping ground has also been investigated by placing the pile at various positions from crest to toe of the sloping ground. The analysis has been done by providing the pile with lateral displacement in one case and a lateral load in the other. The current investigation will examine slope stability with and without pile reinforcement. Lateral pile capacity increases as relative density increases and it decreases as the slope of the ground increases. Maximum lateral displacement and maximum bending moment decrease as relative density increases and increase when the level ground is changed to sloping ground. The depth of the maximum bending moment is also reported. [ABSTRACT FROM AUTHOR]

In order to consider the comprehensive effects of steel casings in addition to the construction method in engineering projects, this study investigates the influence of steel casing length, thickness, mud skin, and shear rings on the horizontal load–bearing characteristics of composite steel piles. Based on the practical project of the Anluo Expressway Yellow River Bridge, nine sets of model pile experimental tests were conducted, with the aforementioned four influencing factors as variables. The test results were used to calibrate the variables of soil properties in the theoretical calculations used in the finite difference method and to obtain p−y curves and the initial modulus of soil resistance k that is applicable to this project. Using the calibrated parameters, the horizontal bearing characteristics of the piles were predicted. The results show that increasing the steel casing length can improve the horizontal bearing capacity and the soil resistance transfer depth of piles and can reduce displacement and cause a downward shift in the location of the bending moment peak. Furthermore, boundary effects were observed. It is recommended that the steel casing length below the mud surface may be set to be 0.4–0.5 times the critical pile length. It is for the first time that the critical pile length is used to estimate the length at the variable section to provide new insights for the study of variable-section piles. These results may have guiding significance for predicting the horizontal characteristics and engineering application of ultralong composite steel tube piles. [ABSTRACT FROM AUTHOR]

Subsea pipelines operate in harsh marine environments, and corrosion is the major cause threatening their operational safety. In this paper, the failure pressure of pipelines with multiple corrosion defects under combined loadings is investigated. A finite-element model of a pipeline with multiple corrosion defects is developed, and this model is verified with experiments. The effect of defect depth, axial, and circumferential spacings between corrosion defects on the pipeline's residual strength is estimated. Furthermore, the failure pressure of a pipeline with multiple corrosion defects under combined loadings, such as internal pressure, axial pressure, and bending moment, is examined. This study aims to support the integrity management of subsea pipelines with multiple corrosion defects. [ABSTRACT FROM AUTHOR]

The strength of cross section of different metals subjected to axial load and biaxial bending has been a problem of great interest for decades. Due to its complexity, this topic is addressed in short chapters in classical texts and codes. This research is the extension of a previously published work applied to concrete and metal cross sections. The M-P-φ curves are very useful to obtain the interaction diagrams of sections and to calculate the deflections and rotations of elements, but this second topic is not discussed in this paper; a simple numerical method to obtain theses curves for metal cross sections subjected to axial load and bending moment (axial or biaxial) is presented. The effects of bending residual stresses, strain hardening, and local buckling are included. Channel, box, tubular, I, and other shapes made of steel, aluminum, or other metals can be analyzed by dividing the cross section in discrete areas. The effects of shear or torsion stresses and strains are not taken into account. The sections can be subject to proportional or nonproportional loads producing biaxial bending. The model is presented in complete form with all the necessary equations to be programmed by readers. Three examples taken from the literature that show theoretical and experimental results are presented to verify the validity of the proposed model. [ABSTRACT FROM AUTHOR]

The study examines the performance of RC buildings subjected to underground blast–induced forces, evaluating the performance of X-plate dampers in mitigating blast loading conditions. Analyzing 11-story buildings with diverse plan geometries, the study evaluates damper placement strategies, namely, installing dampers at all locations and at alternate floors to enhance building performance. The primary goal is to optimize damper placement using fuzzy logic techniques. Additionally, the impact of various bracing systems (diagonal, X, V, inverted V, and K) on RC building performance is assessed. Strategic placement of X-plate dampers significantly improved building performance, offering a cost-effective solution against blast-induced loads. Unlike conventional methods that rely on predefined criteria for damper placement, this research integrates fuzzy logic parameters to determine optimal placement strategies. The study employs fuzzy logic to dynamically adjust damper positions based on real-time conditions, resulting in more efficient and effective blast resistance solutions. The study implements fuzzy logic models, namely Gaussian and sigmoidal membership functions, to optimize the number of dampers installed in square, rectangle, L-shaped, and C-shaped building models. It was observed that an X bracing pattern is the most efficient technique is obtaining maximum reduction in structural responses subjected to underground blast–induced vibrations. The structural responses such as displacement, shear force, and bending moment are reduced by 78%, 71%, 75%, and 86%, respectively, when subjected to far-end blast-induced vibrations. The study observed that implementing to lowest interstory drift ratio (S1) case fuzzy logic approach resulted in 75%, 63%, 63%, and 63% reductions in damper numbers for square, rectangular, L-shaped, and C-shaped buildings compared with dampers at all locations. [ABSTRACT FROM AUTHOR]

The use of permeable piles as an effective drainage method in liquefiable sites has become widely accepted. In this study, the seismic response of both the liquefiable soil and the pile was simulated using FLAC3D software to validate the anti-liquefaction performance of the permeable pile. A group of permeable piles designed according to the China foundation code were numerically modeled with various opening ratios (i.e. area of openings/total surficial area). The numerical results showed that the permeable pile is able to enhance liquefaction resistance by dissipating excess pore water through the drainage holes. The bending moments and axial force of the permeable pile decrease but the ultimate bearing capacity increases in the process of drainage. It is found that the excess pore water pressure ratio (EPWPR) of soil around permeable pile under seismic loading reduces rapidly with increasing opening ratio, but the excess pore water pressure tends to keep nearly a stable level once the opening ratio is beyond a critical value of 0.5%. As a result, the critical value of the opening ratio may be considered as the optimum parameter to design the permeable pile against liquefaction. [ABSTRACT FROM AUTHOR]

The construction of concrete-filled steel tube tied-arch bridges typically employs the "beam first and arch later" methodology. In this approach, tie beams are initially constructed on temporary supports, followed by the erection of the arch ribs. When post-construction loads—such as those from arch-rib supports and concrete-filled steel tubes—are applied, a synergistic force phenomenon occurs between the tie beam and temporary supports, which collectively bear these loads. To investigate the collaborative-force mechanism of the tie beam during construction, we developed a collaborative-force model based on Winkler's double-layer elastic foundation beam theory. We derived equations for displacement, rotation angle, bending moment, and shear force of the tie beam under concentrated loads. Using a 72-m concrete-filled steel tube arch bridge as our research subject, we conducted a comparative analysis utilizing finite element methods. The results indicated that our derived formulas were consistent with those obtained through finite element meta-computing techniques. Under concentrated loading conditions, it was observed that the load increment at the location of the steel pipe column in the Bailey beam was significantly larger than what traditional averaging methods would predict. Conversely, load increments at both mid-span and pier locations of the Bailey beam were relatively small. Furthermore, it was found that variations in concrete strength grade had minimal impact on displacement, bending moment, and bearing ratio for both tie beams and Bailey beams. However, factors such as cross-sectional height of the tie beam and arrangement of sandwich buckle frames exerted considerable influence on both displacement and load-bearing ratios for these structural elements. Additionally, while arrangements within Bailey beams significantly affected displacements in both types of beams (tie beam and Bailey beam), their impact on bending moments and bearing ratios was comparatively less pronounced. [ABSTRACT FROM AUTHOR]

The issues of numerous steel beam components and the tendency for deck cracking under negative bending moment zones have long been challenges faced by traditional composite I-beams with flat steel webs. This study introduces an optimized approach by modifying the structural design and material selection, specifically substituting flat steel webs with corrugated steel webs and using ultra-high-performance concrete for the deck in the negative bending moment zone. Three sets of model tests were conducted to compare and investigate the influence of deck material and web forms on the bending and crack resistance of steel–concrete composite I-beams under a negative bending moment zone. The findings indicate that, compared to a conventional steel–normal concrete composite I-beam, incorporating ultra-high performance concrete into the negative bending zone enhances the cracking load by 98%, resulting in finer and denser cracks, and improves the ultimate bearing capacity by approximately 10%. In comparison to the composite I-beam with flat steel webs, the longitudinal stiffness of the composite I-beam with corrugated steel webs is smaller, which can further enhance the bridge deck's resistance to cracking in the negative bending moment zone, and maximize the steel-strengthening effect of the lower flange of the steel I-beam. Based on the findings of this study, it is recommended to use steel ultra-high-performance concrete composite I-beams with corrugated steel webs due to their superior crack resistance, bending strength, and efficient material utilization. [ABSTRACT FROM AUTHOR]

The steel–Ultra-High-Performance concrete (UHPC) composite slab is a new type of structure made of steel and UHPC connected by pegs, and its flexural mechanical properties and related design methods need to be further investigated. Firstly, a detailed numerical model of the steel UHPC composite slab is established and validated based on previous flexural behavior experimental research. Secondly, the flexural failure mechanisms of steel–UHPC composite slabs are clarified through finite element analysis. Under positive bending moments, when the degree of shear connection is lower than 100%, the ultimate load capacity of the composite slabs is determined by the shear capacity of the pegs. On the contrary, there are no significant changes in the load-carrying capacity of all the specimens, but there is a slight increase in stiffness. Under negative bending moments, the load-bearing capacity, stiffness, and crack resistance of the composite slab are improved as the degree of shear connection and reinforcement ratio increase. Finally, the method used to calculate the flexural capacity of steel–UHPC composite plates under positive and negative bending moments with high accuracy is proposed based on the analytical results. This paper provides a theoretical basis for the design of flexural performance of steel–UHPC composite slab. [ABSTRACT FROM AUTHOR]

The increasing use of cable-stayed bridges with steel box girders necessitates more sophisticated design approaches, as the diverse environments of bridge locations place higher demands on the design process. Determining a reasonable finished state is a critical aspect of bridge design, yet the current methods are significantly constrained. A new approach to optimizing the finished state is proposed. This method's practicality and efficiency are verified through a case study, analyzing how constraints on vertical girder deflection, horizontal pylon displacement, cable forces, and cable force uniformity affect the optimization outcome. The results show that convergence of the mixed-constraint quadratic programming model is achieved within 30 iterations, yielding an optimized finished state that meets the design criteria. The chosen constraint ranges are deemed appropriate, and the optimization method for the construction stage is thus demonstrably feasible and efficient. The multiplier path following optimization algorithm is computationally efficient, exhibiting good convergence and insensitivity to the problem size. Being easy to program, it avoids the arbitrariness of manual cable adjustment, enabling straightforward determination of a reasonable finished state for the cable-stayed bridge with a steel box girder. The vertical displacement of the main girder, the positive and negative bending moments, and the normal stresses at the top and bottom edges, as well as the positive and negative bending moments in the towers, are significantly influenced by the constraint ranges. The horizontal displacement of the pylon roof is significantly affected by the constraint ranges of both the main girder's vertical displacement and the pylon's horizontal displacement, while the remaining constraint ranges have a limited impact. [ABSTRACT FROM AUTHOR]

This study examines the horizontal transient response of pipe piles in saturated soil, assuming a two-stage equivalent linear relationship between the bending moment and the rotation at the pile head. The potential function is introduced, and the three-dimensional wave equation for saturated soils is decoupled using operator decomposition and the method of separation of variables. By applying the appropriate initial and boundary conditions, the horizontal lateral forces on the pile from both the surrounding soil and the soil within the pile shaft are calculated. The pipe pile is modeled as a Timoshenko beam. Continuity conditions at the pile–-soil interface are applied, and a time-domain solution for horizontal transient vibrations is derived. This solution accounts for various pile top constraint conditions and is obtained through the inverse Laplace transform. Validation against existing results demonstrates the accuracy of the proposed model. Finally, a parametric study investigates the effects of factors such as impact load, permeability, pile diameter, and pile head constraints on pile displacement. [ABSTRACT FROM AUTHOR]

To investigate the excavation characteristics and mechanisms of a deep foundation under lateral confined water pressure, a model test was conducted with real-time monitoring of the stress and deformation of the foundation strut system. The results indicate that in stages 1 and 3 (the process of raising the lateral confined water level, O and F), the rise in lateral confined water levels caused the diaphragm wall to shift inward. However, the reduction in earth pressure due to the inward shift of the diaphragm wall exceeded the increase in water pressure from the raised confined water level, resulting in an overall decrease in lateral pressure on the diaphragm wall. During stage 2 (the excavation and supporting process, K1–Z4), as excavation and strut installation progressed, the lateral pressure on the diaphragm wall decreased, while both bending moment and horizontal displacement increased, with the most pronounced changes occurring when excavation reached the depth of the lateral confined aquifer. Upon reaching the soil layers within the depth of the lateral confined aquifer, the axial force of struts increased significantly, with the second level of strut experiencing the greatest axial force. In deep foundation design, it is essential to account for the maximum bending moment and horizontal displacement of the diaphragm wall within the depth range of the lateral confined aquifer, as well as the maximum vertical displacement in the range of 0.50%D–0.83%D outside the pit. Due to the rapid transmission of lateral confined water pressure changes in fine sand, and the delayed transmission in clay due to their low permeability, the diaphragm wall response is most pronounced within the depth range of the lateral confined aquifer. [ABSTRACT FROM AUTHOR]

The article in the Journal of Experimental Botany explores the complex mechanisms involved in the resupination of a lady's slipper orchid, highlighting both active and passive processes at play. The study delves into the biomechanics and developmental timing of the flower, emphasizing the importance of mass, timing, and functional traits in achieving the 180° inversion necessary for pollination. The research sheds light on the intricate interplay of active growth processes and passive structural traits in plant movements, offering insights into bio-inspired technologies and the potential applications of understanding living machines in nature. [Extracted from the article]

In order to study the factors that affect the crack width, cracking mechanism, and development laws of the U‐shaped steel concrete composite (USCC) beam, and to propose a crack width calculation formula suitable for this new type of composite beam, cracking tests were conducted on four simply supported beam specimens. These specimens, which featured different steel beam forms, shear connectors, and longitudinal reinforcement arrangements, were all subjected to negative bending moments. Research has shown that USCC beams and H‐shaped steel concrete composite (HSCC) beams exhibited basically consistent crack width‐load relationships. In the early stage of the experiment, the crack width of the specimen exhibits an approximately linear relationship with the load, while in the late stage of the experiment, the crack width rapidly increases. In addition, the crack width of the USCC beam specimen developed faster than that of the HSCC beam. The experimental phenomenon shows that whether it is an USCC beam or a HSCC beam, the distribution of crack width along the concrete slab width is uneven, and this non‐uniformity is more obvious outside the beam width range. The centralized arrangement of longitudinal bars will exacerbate the non‐uniformity of crack width distribution, and the overall crack width is greater than that of specimens with uniformly arranged longitudinal bars. In addition, the effectiveness of channel shear connectors in controlling crack propagation is better than that of shear studs, and the slip at the interface between the concrete slab and the steel beam of the specimen using shear studs is greater than that of the specimen using channel shear connectors when the load is large. Based on the experimental results and formulas in the “Design Standards for Steel Structures” and the “Design Specifications for Concrete Structures,” a formula for calculating the crack width of USCC beams is proposed, and the coefficients in the current specifications have been corrected. The calculated crack width is in good agreement with the experimental value, which can provide a reference for calculating the crack width of this type of composite beam. [ABSTRACT FROM AUTHOR]

AbstractDamping plays an important role in the design of offshore wind turbine structures. The hysteretic damping of the seabed soil represents the energy dissipation caused by the soil-particle interaction and the nonlinear behavior of the soil under cyclic loading. However, the effect of sand damping on the lateral response of the monopile foundation of an offshore wind turbine is still unclear. In this paper, the effect of soil hysteretic damping on the lateral dynamic response of a monopile foundation in a sandy seabed is investigated using a subplastic soil constitutive model. The constitutive model response at the foundation level is verified by comparing the monotonic and cyclic responses of the monopile with the results of the 1g model test. The results show that when soil hysteretic damping is present in the monopile-soil system, the energy dissipation in the soil reduces the stress accumulation in the soil, resulting in a reduction in the bending moment and horizontal displacement of the monopile, compared with the case without soil hysteretic damping. The results are crucial for optimizing the monolithic design of offshore wind turbine structures. [ABSTRACT FROM AUTHOR]

Recent research has shown that full mobilization of foundation bearing capacity may be beneficial in terms of structural integrity—especially in the case of seismic motions that exceed the design limits. Full mobilization of foundation bearing capacity may serve as seismic isolation because it limits the inertia loading transmitted to the superstructure. Although most research has focused on rocking shallow or embedded foundations, a rocking pile group has attracted much less attention. A potential reason is the probability of structural damage below the ground level (at the piles), which may be difficult to repair or even detect. To shed more light on the problem, the present study investigates the seismic performance of a rocking pile group in clay, aiming to assess its efficiency as a seismic isolation alternative. Employing the finite-element (FE) method, an idealized yet realistic example of a single bridge pier supported by a pile group foundation is analyzed. A carefully calibrated and thoroughly validated kinematic hardening constitutive model is employed for the soil, and the concrete damage plasticity model is applied for the structural members. Using a suite of records as seismic excitation, the response of an intentionally underdesigned rocking pile group is compared with that of a conventionally (capacity) designed system. Similarly to what has been shown for shallow foundations, the comparison reveals that the rocking pile group can be beneficial for the seismic performance of the bridge, reducing the flexural demand on the pier at the expense of increased settlement. Interestingly, the rocking pile group exhibits a genuinely ductile response, such that none of the studied ground motions could lead to full mobilization of the bending moment capacity of the piles. Thus, pile structural damage is avoided. The findings of the present study reveal the advantages of exploiting nonlinear soil–foundation response and indicate that there is a great potential to optimize the contemporary seismic foundation design, which conventionally culminates in massive pile group foundations. The rocking pile group concept may be of particular interest for the retrofit of existing bridges that do not meet the requirements of the current seismic design provision because it can reduce or even completely avoid strengthening the foundation. Ultimately the presented findings call for a shift toward performance-based design, with due consideration of geotechnical failure modes. [ABSTRACT FROM AUTHOR]

In contemporary sheet metal forming processes such as electromagnetic forming, the sheet is subjected to significant out-of-plane compression stress. This study focuses on predicting springback in isotropic sheet metal bending under through-thickness compressive normal stress. An analytical approach was employed to calculate the longitudinal stress distribution across the sheet thickness by utilizing equilibrium equations and applying the flow rule in incremental plasticity based on a power law hardening model. The reverse bending moment was then obtained from these calculations. During unloading, the springback was estimated by assuming linear elastic behavior and neglecting the Bauschinger effect through a superposition method. A case study was conducted on an aluminum alloy sheet with varying compressive stresses and bend curvatures. The comparison of springback angles with finite element modeling revealed that increasing compressive normal stress to 75% and 100% of yield stress resulted in a reduction in springback by 17.4% and 32%, respectively. At 75% yield stress, the numerical model exhibited only a 4.4% difference from the analytical model. Validation of the analytical model included a four-point bending test with varying initial bend curvatures and angles, demonstrating substantial agreement between experimental, numerical, and analytical outcomes. [ABSTRACT FROM AUTHOR]

The prediction of the design parameters of short to medium-span supported bridges in critical locations (such as canal/road crossings) under the action of high-speed trains has been investigated in this article. An artificial neural network (ANN)-based MIMO (multiple-input multiple-output) metamodels is proposed in conjunction with the semi-analytical framework of simply-supported bridges. Three cases, namely single moving load, series of moving loads at equal spacing (HSLM-B), and as per conventional train configuration (HSLM-A) recommended in Eurocode1: EN 1991-2 (2003), are considered. The prime novelty of the article is to develop a dimensionless semi-analytical framework to train and validate a MIMO metamodel implementing ANN for predicting the multiple dynamic responses of bridges under high-speed loads. The dependency of the maximum dynamic responses, that is, displacement, shear force, and bending moment, on the governing parameters (structural and loading) have been elucidated using Pearson's correlation matrix for the three different train configurations. Further, the robustness and efficiency of the best-fitted metamodels have been compared, and a user interface has been developed for ease of implementation. This platform evaluates the responses such as displacement, shear force, bending moment, and structural safety confirming the standards of Eurocode EN 1990:2002 + A1:2005 (E). [ABSTRACT FROM AUTHOR]

This paper presents a streamlined methodology to assess the horizontal response of an embedded pile subjected to combined horizontal dynamic and axial static loads in a nonhomogeneous Pasternak medium. The stiffness matrix equations for the pile elements are formulated using the modified finite beam element method (FBEM), enabling a comprehensive consideration of factors such as the axial second-order effect of the pile (P-Δ effect), soil shear effect, and side friction on the pile. Utilizing the FBEM, the solutions for the pile's lateral displacements and bending moments are derived while accounting for continuous pile–soil system boundary conditions. The accuracy of the FBEM is verified against existing solutions. Subsequently, a thorough parametric analysis is performed to investigate the influences of various properties of the pile, soil, and applied load on the pile's horizontal vibration response. This study underscores the significant role of the shear effect exerted by the surrounding soil in restraining the lateral deformations and internal forces of the pile. In stratified soils, the horizontal performance of the pile is notably impacted by the properties of the surface soil. Reducing the strength of the surface soil results in a substantial increase in the pile's bending moments and lateral displacements. Additionally, an increase in axial load at the pile head significantly affects the bending moments and lateral displacements due to the P-Δ effect. Moreover, the study reveals that the lateral displacements and bending moments of the pile exhibit an increase with the increases of the horizontal harmonic load amplitude H0 and a decrease with the increases in the dimensionless frequency a0 of the applied load. Practical Applications: The research work presented in this paper suggests a simplified approach to investigate the horizontal dynamic performance of an embedded pile subjected to combined horizontal dynamic and axial static loads in a nonhomogeneous Pasternak soil. The results of the parametric analysis indicate that the soil shear effect typically constrains the pile's internal forces and deformations, and ignoring the soil shear effect leads to overestimated lateral deformations and bending moments. This finding highlights the importance of accurately considering the soil shear effect during the design and analysis of a pile. Additionally, the study demonstrates that the Pasternak foundation model effectively simulates the continuity and stratification of the soil medium and provides high computational accuracy. The findings suggest the need to prioritize the effects of the surface soil's nature and high-amplitude horizontal harmonic load environments, as well as low-frequency vibration environments, on the pile's horizontal dynamic response during engineering design calculations. These practical implications of the study are beneficial to engineers and practitioners involved in the design and analysis of a pile in a nonhomogeneous soil environment. [ABSTRACT FROM AUTHOR]

The kinematic interaction between piles under seismic loading has been extensively studied from analytical, experimental, and numerical perspectives. Of note, within numerical modeling, the majority of the existing literature relies on simplified approaches for characterizing the soil–pile interaction, which leads to the requirement for more reliable and comprehensive research. In this paper, using FLAC3D, the seismic response of the soil–pile system was investigated with a set of fully nonlinear three-dimensional (3D) numerical analyses in the time domain. This model simulated the soil strength and stiffness dependency on the stress level and soil nonlinear behavior under cyclic loading. The Mohr–Coulomb (M–C) constitutive model described the soil's mechanical behavior, which was used with additional hysteretic damping to suit the dynamic behavior. In the framework of a parametric study, the effects of loading frequency on the response of a soil–pile system that was subjected to seismic loading were studied. The results showed that the pile response and soil characteristics, as well as the natural frequency mode of the system's dynamic behavior, are strongly affected by the frequency of the seismic loading. Therefore, the bending moment and lateral displacement along the length of a pile increase as the loading frequency approaches the natural frequency of the system. In addition, when the loading frequency reaches a threshold value far from the fundamental frequency of the system, the effect of loading frequency on the soil–pile system response becomes negligible. In addition, the relationship between the pile diameter and maximum pile bending moment at different loading frequencies is affected by the soil properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the application status and technical challenges of steel–wood composite joints in architecture, this paper proposes an innovative connection technology to solve issues such as susceptibility to pry-out at beam–column joints and low load-bearing capacity and to provide various reinforcement methods in order to meet the different structural requirements and economic benefits. By designing and manufacturing four groups of beam–column joint specimens with different reinforcement methods, including no reinforcement, structural adhesive and angle steel reinforcement, 4 mm thick steel sleeve reinforcement, and 6 mm thick steel sleeve reinforcement, monotonic loading tests and finite element simulations were carried out, respectively. This research found that unreinforced specimens and structural adhesive angle steel-reinforced joints exhibited obvious mortise and tenon compression deformation and, moreover, tenon pulling phenomena at load values of approximately 2 kN and 2.6 kN, respectively. However, the joint reinforced by a steel sleeve showed a significant improvement in the tenon pulling phenomenon and demonstrated excellent initial stiffness characteristics. The failure mode of the steel sleeve-reinforced joints is primarily characterized by the propagation of cracks at the edges of the steel plate and the tearing of the wood, but the overall structure remains intact. The initial rotational stiffness of the joints reinforced with angle steel and self-tapping screws, the joints reinforced with 4 mm thick steel sleeves, and the joints reinforced with 6 mm thick steel sleeves are 3.96, 6.99, and 13.62 times that of the pure wooden joints, while the ultimate bending moments are 1.97, 7.11, and 7.39 times, respectively. Using finite element software to simulate four groups of joints to observe their stress changes, the areas with high stress in the joints without sleeve reinforcement are mainly located at the upper and lower ends of the tenon, where the compressive stress at the upper edge of the tenon and the tensile stress at the lower flange are both distributed along the grain direction of the beam. The stress on the column sleeve of the joints reinforced with steel sleeves and bolts is relatively low, while the areas with high strain in the beam sleeve are mainly concentrated on the side with the welded stiffeners and its surroundings; the strain around the bolt holes is also quite noticeable. [ABSTRACT FROM AUTHOR]

This study puts forward a reliability analysis for the bearing performance of piles subjected to the coupled action of chloride corrosion and scouring. A chloride diffusion model was constructed based on the stiffness degradation factor and Fick's law. The Monte Carlo simulation method, along with the consideration of the scouring effect of water flow on the pile foundation, was employed to assess the impact of key factors on the failure probability, considering both the bending moment and lateral displacement damage criteria. The results show that for the same exposure period, the failure probability increases as the bending moment, lateral and vertical loads, and seawater velocity increase; furthermore for the same conditions, the failure probability increases with longer exposure times. According to a particular case study, the mean bending moment, mean lateral and vertical loads, and seawater velocity all have an impact on the lateral displacement failure criterion, making it more sensitive than the bending moment failure criterion. [ABSTRACT FROM AUTHOR]

Thousands of multi-span, simply supported beam bridges with short or medium spans have been built in China. They often suffer from problems of cracks in the link slabs over piers, and the deterioration and damage of deck expansion joints at abutments. To address these problems, one approach is to retrofit them by converting the simply supported box beams into continuous structures over the piers and jointless bridges over the abutments. This paper discusses the design methodology and details for retrofitting the Jinpu Bridge in Zhangzhou, Fujian, China, from a simply supported bridge into a semi-integral bridge, in which semi-fixed dowel joints are used to connect the superstructure and the substructure, including piers and abutments. Simultaneously, the finite element software is used to calculate the internal forces and displacements of the structure. The analysis reveals an 11.1% reduction in the maximum positive moment at the midspan of the main beam in the semi-integral bridge compared to the simply supported bridge. However, the shear forces at the interior pier increase by 6.4%. According to the response spectrum analysis, the maximum longitudinal displacement of the semi-integral bridge's main beam is 11.6 mm, reduced by 80.1% compared to the simply supported bridge under a dead load and earthquake effects. The maximum bending moment and shear force on the pier of the semi-integral bridge are 984.7 kN·m and 312.6 kN, respectively, both below their ultimate bearing capacities. The maximum displacement at the top of the pier is 7.7 mm, which is below the allowable 52.4 mm displacement. The calculated results conform to the design requirements specified by the code. [ABSTRACT FROM AUTHOR]

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Elliptical deep beams have a peculiarity: the compression paths (struts) are neither straight nor symmetrical within the same span. The asymmetrical horizontal curvature in one span leads to the formation of asymmetrical torsional moments. The strut-and-tie method (STM), approved by ACI 318-19 and most international codes, does not take into consideration the curvature of the strut and the consequent bending and torsional moments. Therefore, eight deep elliptical specimens were cast and reinforced with variable amounts of web and flexural reinforcement to study the role and importance of each one experimentally and theoretically from the STM point of view. Only the stress paths were cast and reinforced in two other specimens to study the STM in detail and to present alternative specimens to the reference ones with less weight and cost, in addition to providing openings for services. The STM has proven its effectiveness with asymmetrical, horizontally curved deep beams due to its ease and the high safety it provides. STM development has also been presented here by adding the effect of the horizontal curvature. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer (GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment zone. An experimental bending moment redistribution test was conducted on continuous GFRP-concrete composite slabs, and a calculation method based on the conjugate beam method was proposed. The composite slabs were formed by combining GFRP profiles with a concrete layer and supported on steel beams to create two-span continuous composite slab specimens. Two methods, epoxy resin bonding, and stud connection, were used to connect the composite slabs with the steel beams. The experimental findings showed that the specimen connected with epoxy resin exhibited two moments redistribution phenomena during the loading process: concrete cracking and steel bar yielding at the internal support. In contrast, the composite slab connected with steel beams by studs exhibited only one-moment redistribution phenomenon throughout the loading process. As the concrete at the internal support cracked, the bending moment decreased in the internal support section and increased in the mid-span section. When the steel bars yielded, the bending moment further decreased in the internal support section and increased in the mid-span section. Since GFRP profiles do not experience cracking, there was no significant decrease in the bending moment of the mid-span section. All test specimens experienced compressive failure of concrete at the mid-span section. Calculation results showed good agreement between the calculated and experimental values of bending moments in the mid-span section and internal support section. The proposed model can effectively predict the moment redistribution behavior of continuous GFRP-concrete composite slabs. [ABSTRACT FROM AUTHOR]

The onshore wind turbines are gradually developing with the aim of large single‐unit capacity, large impeller diameter, and higher towers. The steel–concrete hybrid tubular tower structure is the mainstream structure of high‐hub towers, whose lower part is a concrete tower tube and the upper part a steel tower tube. Also, there is no doubt that more and more wind turbines will work in harsh environments and seismic hazard zones. Based on the abovementioned two points, it is necessary to mitigate the dynamic responses of onshore wind turbines to ensure the safety of these structures. This paper studied the base‐isolated method, story‐isolation method, and three types of tuned mass dampers damping method: single tuned mass dampers (STMDs), multiple tuned mass dampers (MTMDs), and distributed‐tuned mass dampers (D‐MTMDs), to explore the response characteristics of the steel–concrete hybrid tubular tower under seismic loads. The results show that the base‐isolated structure can greatly reduce the bending moment and shear response of the upper steel tower tube, while the story‐isolated structure has a very good effect on reducing the structural displacement response. In the three tuned mass dampers damping method, D‐MTMDs have stable and effective control capacity, compared with STMD and MTMDs. [ABSTRACT FROM AUTHOR]

In this paper, the impact of the actuation sequence on the snap-through process of a composite multi-stable structure composed of regular triangular modules was investigated. Using ABAQUS finite element simulation software, a finite element (FE) model of laminated plates was established, actuation points was selected on its surface, and bending moment loads were applied in different actuation sequences to induce the snap-behaviors of the structure. Based on the minimum load value for driving structure deforms, the actuation sequence laws of multi-stable structures were obtained. The most efficient and feasible actuation path for transitioning between different steady states was also achieved. It's proved that the actuation paths are reasonable and feasible by the loading experiment. The research results of this paper can provide references for the design of multi-stable structures and the application modes of driving forces. [ABSTRACT FROM AUTHOR]

The fully mechanized tunnelling method using an earth pressure balance tunnel boring machine (EPB-TBM) with a horseshoe-shaped cross section was first developed and applied to a loess mountain tunnel, along with the application of a horseshoe-shaped segmental tunnel lining. The mechanical behavior of this novel type of segmental tunnel lining still contained uncertainties, and full-scale ring tests were conducted for further investigation. During the loading process, the ring deformation, joint opening, and concrete strain were measured, and the occurrence and progression of structural damage were observed and documented. The experimental results demonstrate that the structural failure of the horseshoe-shaped segmental ring mainly occurred in the arch area, while the invert did not prove to be a weak area. The deformation and failure mechanisms of the horseshoe-shaped segmental ring were found to be similar to those of circular ones. Significantly, the specific characteristics of the ring convergence deformation and bending moment distribution were significantly affected by the distribution positions of segment joints. In addition, during the initial stages of TBM advancement, frequent segment damage was observed at inferior joints, and the elaboration on the causes and corresponding measures was provided. This study provides significant evidence for the design and optimization of horseshoe-shaped segmental tunnel linings. [ABSTRACT FROM AUTHOR]

This paper presents an analytical solution derived with force method for the internal forces in the ring lining of maglev train tunnels, which are typically in a circular section and shallowly buried with low vacuum air pressure in the lining. The model incorporates the vacuum pressure induced by the differences in air pressures outside and inside the lining, and the vacuum pressure is assumed to be the active load exerting to the outside of the lining. The model assumes the vertical overburden acting on the lining is proportional to the soil depth at every particular point along the tunnel lining circumference. The lining-ground interaction, represented by tangential and normal resistance to the lining, is combined into the model and is comprehensively evaluated. The Mohr-Coulomb theory is used to estimate the interaction between tangential and normal resistance. The comparison with other models and case histories implies that the proposed model fits well for the field measurement data and results predicted with other models. Analyses based on the proposed model indicated that the vacuum pressure has a negligible effect on the bending moments acting on the lining, but its effect on the normal forces is significant. Parametric studies show that a higher cohesion and internal angle of friction of soils can induce a lower maximum bending moment and higher normal force, indicating that the better the soil conditions the thinner the lining. The cover-to-diameter ratio C/D impacts the maximum bending moment and the optimum C/D is approximately 0.20 in this study, a generally soft soil case. [ABSTRACT FROM AUTHOR]

The formulation of the hybrid‐Trefftz stress element for plate bending is extended to the modelling of concentrated forces and moments, either as prescribed loads or as reactions at point supports. As the bending, torsion and shear fields are hypersingular, the flexibility matrix of the element involves the use of the finite part integration concept. In addition, it requires the confirmation of the positive‐definiteness of the flexibility under gross shape distortion. The tests illustrate the modelling of applied concentrated forces and moments and also the combination of boundary layer and point reaction effects. The results obtained are validated using converged solutions obtained with a stress‐based hybrid‐mixed element (HMS) and a displacement‐based mixed element (MITC). [ABSTRACT FROM AUTHOR]

Given the various loading cases possible in tubular structures, cyclic bending moment is one of the frequent cases presented in bent structures attached by straight tubular parts, as in straight tubular structures or a connecting tubular element; their loading is under various cyclic modalities; analyzing these pressurized tubular structures or unlocking the difficulties of numerically predicting or approximating to possible and actual fatigue behavior is of interest to several researchers, this work opts to use 316LN stainless steel, also known as Z2CND18.12 N of an elbow attached by straight parts, the study of the cyclic response up to the damage of the pressurized bend is aimed at evaluating the behavior under the effects of the parameters analyzed, namely the amplitude and the pattern of the cyclic bending moment, The fatigue behavior of the steel is formulated as a combined isotropic and kinematic Ohno-Wang model introduced into the ABAQUS calculation code by parameters calibrated to the experimental, using the finite element method. The damage to the structure under a high cyclic bending moment is introduced into the structure mesh. Of the cyclic accumulation of stress, the damage will occur in the structure by crack initiation and propagation, hence using the XFEM technique. The non-linear behavior, independent of the strain rate, is based on the Von Mises equivalent stress flow theory by mode effect at high cyclic bending moment; the results presented by moment-rotation curves show a significant effect on the response, as well as the level of damage. That damage by crack initiation and propagation precedes excessive ovalization at the level of the elbow cross-section. The approach followed in this analysis and the reliability of the results obtained were previously based on a validation of experimental results, which showed good agreement with the numerical model used. [ABSTRACT FROM AUTHOR]

Fiber‐reinforced polymer (FRP) rebars have become an attractive alternative for replacing steel reinforcement due to their superior corrosion resistance. Columns reinforced with GFRP rebars can fail in a brittle manner than those reinforced with steel rebars. Adding discrete fibers in GFRP‐reinforced concrete (RC) columns can improve its ductility by bridging the cracks formed in concrete. Both steel and synthetic discrete fibers can be combined to form hybrid fiber‐reinforced concrete (HFRC) which synergizes the advantages of both fiber types. An analytical approach is presented here to estimate the axial compression (P) and bending moment (M) interaction behavior of FRC GFRP columns. Moment‐curvature analysis using suitable constitutive relations for concrete and GFRP bars under compression and tension is adopted. Bending moment capacity at different axial compression loads is established. Later, P–M interaction curves for square RC columns with GFRP rebars and discrete fibers are obtained and validated with test results. After that, a parametric study is carried out to understand the effect of concrete strength, amount of reinforcement, and different fiber dosages for GFRP RC columns. Results show that adding fibers can improve the bending and compression capacities at all combinations of axial and bending loads. The axial compression and bending capacity of the steel RC and GFRP columns with equal reinforcement ratios showed that GFRP HFRC had higher capacity than steel RC column sections under combined axial and bending loads. [ABSTRACT FROM AUTHOR]

Round-end hollow reinforced concrete (RC) tall piers have been widespreadly utilized for railway bridges in river valleys and mountainous regions. The post-earthquake damage state of such bridge piers differs significantly from that of traditional short-to-medium piers. To investigate the seismic performance and failure mode of RC round-end hollow tall piers, a finite element model was developed using the OpenSees platform and calibrated against previous test results. Subsequently, incremental dynamic analysis (IDA) and modal pushover analysis (MPA) were conducted to obtain bending moment and curvature distributions as well as damage ranges for piers subjected to different intensities of ground motion. The results indicate that: The RC round-end hollow tall piers subjected to strong ground motions can crack up to 75% and 80% of its height according to IDA and MPA, respectively. The MPA incorporating mode coupling up to the third order is capable of predicting crack distribution of the pier as demonstrated in this study. Furthermore, it is recommended that the damage range of the pier be considered as a primary control indicator in seismic design. [ABSTRACT FROM AUTHOR]

Buckling and springback defects are easily produced on the thin-walled aluminum alloy tubular components during the tube hydro-pressing process. In this paper, the cross-sectional buckling and springback behavior of the thin-walled 5A06 aluminum alloy tube blanks with D/t = 81.6 during the tube hydro-pressing process using a die with middle parting structure were researched by the experiment and numerical simulation. The effect of the internal pressure loading path on the cross-sectional shape and size of the tubular component was first discussed. Then, the buckling and springback mechanisms of the cross-section were revealed during the tube hydro-pressing process. The cross-sectional dimension deviation of the tubular components obtained under a constant internal pressure of 0.15ps (ps is the initial yield internal pressure of the tube blank) or a stepwise increasing internal pressure from 0 to 1.00ps with the upper die movement is lower than that under the constant internal pressures of 0.25ps and 0.50ps. The large bending deformation that occurs on the edge of the unsupported area will lead to buckling defect. Moreover, the deformation behavior of the straight wall is affected by the bending moment in the corner during the unloading process. On the one hand, a concave deformation happens on the straight wall during the unloading process of internal pressure. On the other hand, the concave cross-section will spring back outward in the process of die opening. [ABSTRACT FROM AUTHOR]

The kinematic discretisation technique of upper bound limit analysis is adopted in this study to evaluate the limit load of a strip footing located on the soils reinforced with different geosynthetic layers. The reinforcement is assumed to withstand the tension but not bending moment. The failure model of the reinforced foundation soil is generated using the discretisation method, a 'point by point' technique. Two failure modes of the reinforcement, the tensile rupture and sliding, are considered in the analysis. This article proposed the formulas for the first time to evaluate the effect of soil friction angle φ on the ultimate bearing capacity and on the failure mechanism of foundation. The calculation results are given considering different reinforcement layers, which describe the impact of different reinforcement depth and length on the ultimate bearing capacity. The optimum positions of different reinforcement layers and the optimum reinforcement length are obtained. The bearing capacity ratios are also presented in figures combing impact of reinforcement depths, soil cohesion and friction angle. The present method was verified by the results reported in literature. The present method can provide a reference for the footing design on the reinforced soils. [ABSTRACT FROM AUTHOR]

Combined opening girders with high stiffener webs used in the superstructure areas of passenger ships are prone to complex buckling phenomena under combined longitudinal and vertical loads caused by overall longitudinal bending and vertical forces from the deck cargo. In addition, the deformation and stress induced during structural assembly and welding make the buckling behaviour more difficult to predict. In response to this situation, thermal elastic–plastic and nonlinear finite element methods were used to simulate the welding and loading process and related experiments were conducted to provide a comparison. We further extended the investigation of the buckling behaviour of girders to the combined opening plate frame and investigated the buckling behaviour using experiments. This research on the buckling behaviour of combined opening girders and plate frames could provide a reference for the optimal design of these members in actual ship structures. [ABSTRACT FROM AUTHOR]

The multiscale model of building structures, as a balanced solution between accuracy and cost, has been widely used in the analysis of structural seismic performance. A reasonable interface connection method can accurately ensure load transfer and motion coordination between models of different scales. In this paper, a novel interface connection device and the corresponding design method for a multiscale test model of building structures were proposed, in which the upper structure with smaller sized components was replaced by a simplified story‐scale model, and the lower structure was adopted as a component‐scale model. The overall and local equations of motion for this multiscale model were established. For the interface connection between different scale models, a design method considering multiparametric similarity of shear force, axial force, and bending moment was proposed. In this method, the internal nodes at the interface of the component scale model were decomposed, and the coupling relationship of internal force between two adjacent nodes was established. The axial force of each node was decoupled into the interstory shear force and bending moment provided together. Additionally, the overturning moment is provided by adding the overlapping domain. According to the equilibrium relationships of the nodes at the interface, the corresponding transfer matrix was provided, and the design method of the interface connection device was proposed. The accuracy and feasibility of the method were validated by static and shaking table tests on a frame structure. [ABSTRACT FROM AUTHOR]