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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 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.)

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]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe 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.)

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]

ABSTRACT The p‐y curve method provides a relatively simple and efficient means for analyzing the cyclic response of horizontally loaded piles. This study proposes a p‐y spring element based on a bounding surface p‐y model, which can be readily implemented in Abaqus software using the user‐defined element (UEL) interface. The performance of these p‐y spring elements is validated by simulating field tests of laterally loaded piles documented in the literature. The developed spring element effectively replicates the nonlinear hysteresis, displacement accumulation, and stiffness degradation observed in soft clay. Subsequently, a finite element model of a large‐diameter monopile is established using the proposed spring element. A comprehensive numerical investigation is conducted to explore both the monotonic and cyclic responses of large‐diameter monopiles in soft clays. The results are presented and discussed in terms of pile head load–displacement curves, the evolution of rotation angles at the mud surface, and cyclic p‐y curves. Additionally, empirical formulas are proposed to predict the evolution of cumulative rotation angles and peak bending moments under both one‐way and two‐way cyclic loading conditions. The results provide valuable insights into the mechanism of pile–soil interaction under lateral cyclic loading. [ABSTRACT FROM AUTHOR]

The article delves into the spanwise wake instability characteristics behind oscillating foils at different Strouhal numbers, focusing on the growth of secondary hairpin-like vortical structures in the wake of an oscillating foil at Reynolds number 8000. It discusses the transition from primary leading edge vortex cores to secondary hairpin-like structures, shedding light on vortex dynamics and their impact on propulsive performance in swimming and flying applications. The study highlights the transformation of primary LEVs into hairpin-like structures with increasing Strouhal numbers, leading to changes in force generation from drag-dominated to low thrust performance. [Extracted from the article]

When laying pipelines using concrete supports and frames in the overhead laying scheme, the pipes may experience deformation and tension due to the height at which they are installed, typically between 1.0-1.5m from the ground surface. The installation of overhead pipeline on hard or collapsible foundations causes bending due to the combined weight of the pipes and the transported product. This text discusses the use of three moment equations to solve this problem. [ABSTRACT FROM AUTHOR]

Calculation model for thermal pre‐stressing of subsequently added reinforcement Key technical limitation of many strengthening measures is that they are not effective for the structure's self‐weight. As a solution, a targeted tempering of reinforcing bars put into respective slots is proposed for statically determinate load‐bearing structures. The aim is to thermally pre‐stress the bars, which are embedded in a grouting material, and to balance their strain to that of the initial reinforcement. The bond with the grout prevents the bars from re‐forming when cooling after heating is stopped. This creates pre‐stress that neutralizes the bending moment from the self‐weight and relieves the tensile zone of the cross‐section. In the paper, an analytical calculation model for the strengthening approach is presented and derived. This is verified through numerical calculations and a first experimental realization. The main factors influencing the effectiveness of the strengthening measure are analyzed in parameter studies. The results show that the thermal pre‐stressing of subsequently added reinforcing bars is effectively possible. Depending on the actual boundary conditions, the calculation predicts the strengthening effect with an accuracy of 80–97 %. The accuracy increases with the height and a lower initial temperature and a lower thermal conductivity of the concrete in the initial cross‐section. [ABSTRACT FROM AUTHOR]

The article discusses the innovative engineering solution implemented at the Loko Oweto Bridges in Nigeria to address the challenges posed by the 1835‐m‐long bridge spanning the Benue River. The construction method involved balanced cantilever techniques and strategically placed midspan expansion joints to allow for movement without compromising structural integrity. Specially designed steel girders were used in the expansion joints to provide continuity for bending moment, shear, and torsion, effectively resolving the challenges faced during the construction of the bridges. The successful implementation of this solution showcased the prowess of creative engineering in overcoming monumental construction challenges. [Extracted from the article]

In order to improve the design level of pre-stressed hollow slab bridge beams, the airport 1# bridge was taken as the research object to study on the influence of guardrails on the mechanical properties of pre-stressed hollow plate beam bridges. On the basis of conducting overall structural verification, a solid model was established to analyze the influence of bridge deck guardrails on the mechanical behavior of cast-in-place joints in hollow slab bridges. Research shows that the maximum deflection and the maximum bending moment internal force decreases by 40 % and 14.5 %, respectively when taking into account the stiffness of the guardrail. However, the maximum shear force of the hollow slab edge joint and middle joint increases by 75 % and 14.5 %, respectively. The maximum shear force increases by 35.62 % when the height of the guardrail increases from 0.5 m to 2 m. The results indicate that the influence of bridge deck guardrails on the shear performance of slab hinge joints should be considered during the preliminary design stage of such bridges. The research results can provide reference for such structures. [ABSTRACT FROM AUTHOR]

Scouring leads to soil loss around piles, which, in turn, changes the ground-vibration characteristics and influences the seismic performance of bridges. In this study, the Xiang'an Bridge was used as a reference for constructing a large shaking-table test model to investigate the dynamic characteristics of the pore-pressure ratio of saturated sandy soils, accelerations, and bending moments of the piles, as well as the horizontal displacements of the pile-top at scouring depths of 10, 20, and 32 cm, with ground-vibration intensities ranging from 0.10-0.45 g. The results indicated that as the scour depth increased, the pile acceleration of the group piles increased and changed abruptly at the variable cross-section and soil-stratum interface. The peak values of the horizontal displacement of the pile-top and bending moment of the pile exhibited an increasing trend. As the ground-shaking intensity increased, the pore-pressure ratio of the saturated sandy soil, pile acceleration of the group piles, horizontal displacement of the pile-top, and bending moment of the pile body gradually increased, whereas the base frequency of the pile foundation gradually decreased. This study can serve as a reference for the seismic design and reinforcement of scour bridges in areas prone to seismic activity. [ABSTRACT FROM AUTHOR]

This work explores earthquake-induced kinematic bending in the so far unresolved case of a pile embedded in a two-layer soil with a thin surface layer. The problem is treated analytically by means of a generalised Winkler model, which in addition considers the effect of boundary conditions at the pile head over earlier contributions on the subject. Novel analytical closed-form expressions of the kinematic bending moment at the pile head and at the interface between the two soil layers are provided for both fixed- and free-head piles. The analytical solutions are validated through a rigorous finite-element model, which proves a remarkable accuracy in the static regime. While for interface bending the past literature indications for the dynamic coefficient make the proposed formula accurate for both shallow and deep interface, a novel dynamic interaction factor, describing dynamic effects for pile-head bending, is introduced. A numerical example provides guidance on application of the formulae in real design scenarios. [ABSTRACT FROM AUTHOR]

This study investigates the seismic behavior of long-span prestressed concrete box-girder bridges subjected to long-duration (LD) ground motions and spectrally equivalent near-fault (NF) and far-fault (FF) short-duration ground motions. For this purpose, the Kömürhan and Gülburnu Highway Bridges built with the balanced cantilever method using prestressed concrete box-girder were selected. This paper consists of two main sections. First, ambient vibration tests were conducted to identify the modal parameters of the bridges and calibrate the finite element models. Second, using three ground motion sets consisting of 42 acceleration records applied to the orthogonal and vertical directions of the bridges, the structural responses were evaluated and compared. In order to determine the type of ground motion that is critical for this type of bridge, these sets consist of 14 long-duration ground motions, 14 spectrally equivalent near-fault short-duration ground records, and 14 spectrally equivalent far-fault short-duration records. The comparison parameters considered for this study were displacements and internal forces in the piers and decks. The results strive to highlight the extent to which the duration and characteristics of the ground motion sets affect the structural behavior. Results indicate that the mean deck displacements of selected bridges obtained from FF short-duration records were nearly 10.70% and 7.44% less than those obtained from the LD and NF short-duration ground motions. These trends were also observed in the bridge piers. Moreover, increases of up to 17.54% and 26.65% in the mean shear forces of the piers under LD and NF short-duration ground motions were observed compared to those determined from the FF short-duration counterparts. Similar trends were observed in the bending moment values. It was also observed that far-fault short-duration records may have substantial consequences on such structures. [ABSTRACT FROM AUTHOR]

Shaft design assumes that the end supports of the shaft are simply supported that is not entirely correct. This article investigates the effects of simply supported ends and fixed-fixed supported ends on the bending moment developed in shafts. The bending moments and hence bending stress are life limiting parameters of shafts. Moreover, the effects of transverse loading inclination, loading spacing, and loading variation on the bending moment developed in shafts are studied. Analytical, numerical, and experimental approaches were adopted. Notched steel rods were used in fatigue experiments. The fatigue lives of those rods were measured and recorded. The bending moment applied to the rod specimen was calculated and compared to those obtained from the analytical and numerical approaches. The studies revealed that the simply supported end conditions will result in a shaft diameter that is 88% larger. However, the fixed-fixed end condition will result in a shaft diameter that is 67% smaller. The average bending moments of the simply supported and the fixed-fixed end conditions will result in the most accurate shaft diameter. Moreover, the maximum bending moment occurred when the load inclination angle θ = 0.0. It also increased with increasing the load ratio P1/P2 and the load spacing ratio l1/L, where P1, P2, l1, and L are respectively the left-hand load, the right-hand load, the position of P1 from the left-hand support, and the total length of the shaft. [ABSTRACT FROM AUTHOR]

The large-span flexible photovoltaic support array is a new wind sensitive structure system, and its vertical and horizontal flow field interference is more significant than that of the single-row photovoltaic. The complexities make it difficult to accurately predict the extreme wind load of photovoltaic array. Taking a typical flexible photovoltaic demonstration project as the object, this paper analyzes the wind pressure characteristics of the single-row flexible photovoltaic surface based on the large eddy simulation method and verities the effectiveness by comparing it with the wind tunnel test. Based on the Davenport method and the Sadek-Simiu algorithm, the peak factor of non-Gaussian wind load is determined and the distribution law of the extreme wind load of photovoltaic array is revealed. Finally, the interrow interference of the array wind load is discussed systematically and the mechanism of the array wind load interference is discussed from the perspectives of spectrum analysis and flow field driving. Results show that the extreme wind load of the largespan flexible photovoltaic bracket array reaches the minimum value at the second windward row, and the interrow interference effect of the array presents a decreasing static wind load and an increasing fluctuating wind load. At 0° and 180° wind direction angles, the wind pressure interference coefficients of the flexible photovoltaic array are 1.09 and 1.14, respectively, and the bending moment interference coefficients are 1.49 and 1.21, respectively. [ABSTRACT FROM AUTHOR]

To adapt to complex underwater geological conditions, immersed tunnel projects have gone through the development from rigid and flexible to semirigid immersed tunnels. The stiffness of segment joints and the element joint could reflect the differences in structural characteristics of the three types of immersed tunnels. This paper presents a theoretical model using segment joints, the element joint, and 16 segments for the longitudinal seismic response analysis of the three types of immersed tunnels. Based on the matrix transfer principle, the end boundary conditions and the continuity conditions for the forces and deformations at the segment joints and element joint were considered. Analytical solutions were validated by verifying the established laws. Results indicate that the semirigid immersed tunnel, in contrast to the rigid immersed tunnel, can reduce shear forces and bending moments along the longitudinal direction by using segment joints and the element joint. In addition, compared with the flexible immersed tunnel, the semirigid immersed tunnel has higher overall stiffness and better continuity of deformation between the adjacent soil regions through the prestressed tendons inside the tube element. The semirigid immersed tunnel is a viable solution for complex geological conditions where the strata change every few tens of meters. [ABSTRACT FROM AUTHOR]

The current study on free bending focuses on traditional macroscopic tubes and profile components. Nevertheless, as the geometric size of the tube decreases, the resulting size effect affects the free bending deformation behavior of the microtube in the less constrained state. In this investigation, a constitutive model of microtubes considering the surface layer model was established. The corresponding model parameters were determined by fitting the flow curves of surface single crystals and internal polycrystals. According to the principle of free bending, the springback internal bending moment of the microtube was derived to explain the phenomenon whereby the bending radius of the microtube decreases with decreasing size factor. With decreasing size factor, the influence of the surface layer grains on the bending behavior of the microtube becomes more intense. Furthermore, by comparing the results of the microscale free bending experiment and simulation, it can be concluded that the material properties of microtubes in the finite element (FE) simulation should be defined based on the surface layer and inner layer. With decreasing microtubule size factor, the bending radius of the tube decreases, and the wall thickness changes more significantly. The cross-sectional distortion of the microtubes decreases with increasing grain size and wall thickness. This study explored the feasibility of the free bending process to achieve bending of microtubes and revealed that the size effect on the deformation behavior of microtubes should be considered in the microscale free bending process. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency 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.)

Due to the development of communication routes (metro, railways), it is frequently necessary to build underground structures in order to improve traffic flow, which is a key factor in the metropolitan areas' regeneration. Taking in account of the interaction between tunnel-soil-piles is a significant topic and a vital factor in the analysis the total solutions of these underground projects. The significance of the impacts communicated depends on a number of factors, including the genre of structure, and the soil type. The main purpose of the present paper is to study numerically the immediate influences that will result from the new tunnels construction near existed piles (micropiles), this model will be employed to an existent case of an Algerian East-West highway tunnel section, while using the code of calculation Plaxis3D tunnel. A detailed parametric survey that will be made to put in evidence influences it of the different parameters geometric and mechanical on the interaction between shallow tunnel and an existing piles and security objectives. And for understand furthermore the problem of interaction mechanism between micropiles and tunnel, principally when piles are positioned in close proximity to tunnels. The obtained findings show that the tunneling may affect in nearby piles a considerable bending moments, lateral deflection, compressive forces, and axial forces. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University 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.)