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In this study, the seismic behavior of a recycled aggregate concrete-filled square steel tube (S-RACFST) frame under different design conditions was investigated. Based on previous studies, a finite element model for the seismic behavior of the S-RACFST frame was developed. Moreover, the axial compression ratio, beam–column line stiffness ratio, and yield bending moment ratio of the beam–column were regarded as the variation parameters. It was through these parameters that the seismic behavior of eight S-RACFST frame finite element specimens was discussed. The seismic behavior indexes, such as the hysteretic curve, ductility coefficient, energy dissipation coefficient, and stiffness degradation were obtained—which, in turn, revealed the influence law and the degree of the design parameters regarding seismic behavior. Moreover, the sensitivity of the various parameters with respect to the seismic behavior of the S-RACFST frame was evaluated via grey correlation analysis. The results show that the hysteretic curves of the specimens were fusiform and full with respect to the different parameters. Firstly, with the axial compression ratio increasing from 0.2 to 0.4, the ductility coefficient increased by 28.5%. In addition, the equivalent viscous damping coefficient of the specimen with the axial compression ratio of 0.4 was 17.9% higher than that of the specimen with the axial compression ratio of 0.2, which was 11.5% as well as that with an axial compression ratio of 0.3. Second, when the line stiffness ratio rises from 0.31 to 0.41, the specimens' bearing capacity and displacement ductility coefficient both get better. However, the displacement ductility coefficient gradually decreases when the line stiffness ratio is greater than 0.41. As a result, an optimal line stiffness ratio (0.41) thus exhibits good energy dissipation capacity. Thirdly, with the increase in the yield bending moment ratio from 0.10 to 0.31, the bearing capacity of the specimens improves. In addition, the positive and negative peak loads increased by 16.4% and 22.8%, respectively. Moreover, the ductility coefficients were all close to three, thus demonstrating good seismic behavior. The stiffness curve of the specimen with a large yield bending moment ratio with respect to the beam–column, is higher than those that possess a small beam–column yield moment ratio. In addition, the yield bending moment ratio of the beam–column possesses a significant influence on the seismic behavior of the S-RACFST frame. Furthermore, the yield bending moment ratio of the beam–column should be considered first in order to ensure the seismic behavior of the S-RACFST frame. [ABSTRACT FROM AUTHOR]

This article presents a study of the behavior of hybrid steel beams of I-profile cross section subjected to bending. Numerical models of finite elements were developed and validated in the ABAQUS software. In the models, lateral buckling with torsion was disregarded, since the beam will be laterally restrained, so that only local instabilities are present and thus evaluated. Analyses were divided into two stages: first, the elastic buckling analysis was carried out to obtain the critical buckling loads and the buckling modes of the beams; subsequently, analysis of the ultimate strength capacity of the beams was carried out considering residual stresses and initial imperfections. The numerical model was defined and a sensitivity study of the yield strength of the flange steel was carried out. The obtained results from the developed numerical model were satisfactory and, as expected, showed that the hybrid beams resist a greater bending moment effort when compared to their corresponding homogeneous beams. [ABSTRACT FROM AUTHOR]

Piles in soft soil supporting bridge abutments are often exposed to passive loading induced by adjacent bridge approach embankment. Several methods for analysis of passive piles have been developed, but the international design specifications do not recommend a specific method for the analysis of passive piles. Therefore, the applicability of existing empirical and analytical analysis (conventional) methods is examined by comparing their outputs with those of a validated finite element model (FEM) at various adjacent embankment stress levels, and construction times, soft clay thicknesses, and pile spacing to diameter ratios. Outputs of both conventional methods and FEM show that increasing the embankment stress, thickness of soft clay layer, and pile spacing to diameter ratio results in an increase in the lateral pile displacement, maximum bending moment, and lateral pressure, and vice-versa on increasing embankment construction time. The outputs of the conventional analysis methods are compared to the FEM outputs and are underestimated except for few cases. The conventional analysis methods may yield better predictions at pile diameter-to-spacing ratio equals 3–4 for a soil preloaded prior to pile construction to a degree of consolidation greater than 50%. [ABSTRACT FROM AUTHOR]

When extended distally due to higher loading in the posterior region, implant-supported bar-retained overdentures with cantilever bar extension exhibit greater bending moments on the implants closest to the cantilever bar and increased stresses in the overdenture components. In this study, a new abutment-bar structure connection was introduced to minimize undesired bending moments and reduce the resulting stresses by increasing the rotational mobility of the bar structure on the abutments. Copings of the bar structure were modified to have 2 spherical surfaces, sharing the same center, located at the centroid of the top surface of the coping screw head. The new connection design was applied to a 4 implant-supported mandibular overdenture to create a modified overdenture. Both the classical and modified models had bar structures with cantilever extensions in the first and second molar areas and were analyzed for deformation and stress distribution using finite element analysis, which was also conducted for both the overdenture models without cantilever bar extensions. Real-scale prototypes of both models with cantilever extensions were manufactured, assembled on implants embedded in polyurethane blocks, and subjected to fatigue testing. Both models' implants were subjected to pullout testing. The new connection design increased the rotational mobility of the bar structure, minimized the bending moment effects, and reduced the stress levels in the peri-implant bone and overdenture components, whether cantilevered or not. Our results verify the effects of rotational mobility of the bar structure on the abutments and validate the importance of the abutment-bar connection geometry as a design parameter. [ABSTRACT FROM AUTHOR]

The response characteristics of large-diameter monopiles under lateral loads obviously differ from those of traditional small-diameter piles. To investigate the failure mechanism and soil resistance of laterally-loaded large-diameter monopiles, a series of finite element analyses of monopiles in soft clay were conducted. From the analysis results, an additional rotational soil flow can be observed in the large-diameter soil-monopile system, but there is only a slight difference (approximately 2–6%) in the bearing capacity of monopiles when the p–y method is utilized with and without rotational soil flow. Consequently, the consideration of the wedge-full-flow mechanism is sufficiently accurate for the monopile design of offshore wind turbines. Moreover, the base shear force and bending moment have an important influence on the lateral behaviour of large-diameter monopiles, and ignoring these additional base resistance components can greatly underestimate (even up to − 30%) the lateral bearing capability and lateral stiffness of semi-rigid and rigid large-diameter monopiles. Modal analysis of the 5 MW wind turbine also shows that this ignorance can lead to an underestimation (nearly 13.0%) of the structure's natural frequency. To consider the contributions of the additional base resistances to the lateral stiffness and bearing capacity, we developed two new T–u and M–φ springs to expand the current p–y method. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office 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.)

The work reported in this article numerically investigates the structural forces in a tunnel lining after applying an adjacent loaded pile for varying pile tip positions considering the tunnel and soil stratum. Analysis reveals that the structural responses are strongly associated with the distorted elliptical shape of the deformed tunnel, which depends on the relative position of the pile tip with respect to the tunnel crown. The change in bending moment in the tunnel lining is of greater concern than the change in the axial force of the tunnel lining. Although the maximum change in structural forces can be up to 115% of the initial value, assessment in terms of maximum change in the structural forces is unsuitable. This is because the maximum change does not occur at the location that has large initial forces. The total combined bending moment and axial force in the lining at the tunnel spring line and in the tunnel invert zone are recommended for cases where the pile tip level is at the tunnel spring line and cases with the deepest possible pile tip elevation, respectively, for the assessment. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office 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.)

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum University Editorial Office 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 explored reinforced concrete piles located in a flexible half-space and loaded with external loads, considering various contact elements and the connection between the pile and the ground massif. Piles are mainly solved as axially loaded elements stressed by a vertical force. However, there are also several cases in the construction industry where a pile is stressed by a horizontal force or by a bending moment, producing a bending loaded pile. A static model of a pile and the surrounding subsoil was constructed using software based on FEM. The pile was modelled from 3D finite elements that were rotationally symmetric around the vertical axis of the pile. Additionally, the flexible half-space was modelled from 3D elements that were rotationally symmetrical around the piles. The boundary conditions were applied on the surfaces around the perimeter and at the bottom of the ground massif. The flexible half-space was modelled up to the area where there was zero deformation. The presented analysis focused on the description of different types of contact elements between the surface of the reinforced concrete pile and the surrounding ground mass. This interaction was modelled as a fixed connection or as point-to-point contact, and a contact surface. In the next part, different boundary conditions on the pile bottom were considered. Floating piles, supported by joints or firmly woven into the ground massif, were considered. All these outputs based on FEM were compared with the analytical solution of the bent pile that was published in the 1980s. The deformations and internal forces during different modelling of the contact between the edge of the concrete pile and the surrounding ground mass were compared. The higher values of the studied quantities were for rigid connections, which is logical. For contact elements, the property of the contact was considered. This property introduces less stiffness, and thus, the resulting values were lower compared to those for a fixed connection. The presented analysis of the FEM analytical and numerical solution is also very valuable for engineers working in construction. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. 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.)

The injury conditions of the sitting position occupant inside the military equipment are highly related to the vertical impact environments. In this study, a detailed three-dimensional finite element (FE) model of pelvis-lumbar spine of seated human with nonlinear material property and strain failure criterion was developed and validated. A series of sinusoidal accelerations with a constant peak speed of 8 m/s and frequencies ranging from 10 Hz to 90 Hz were loaded on the FE model to investigate the injury conditions under different high loading rates. The results indicated that the injury patterns mainly include wedge fracture of the junction between lumbar spine and pelvis, and comminuted fracture of ischial tuberosity. The bending moment caused by the large angle deflection of pelvis under 10 Hz case (low rate) and the acting force caused by the excessive curvature of lumbar spine under 30 Hz–70 Hz cases (medium and high rate) cause the junction wedge fractured, while the high impact force under 30 Hz–50 Hz cases (medium rate) leads to comminuted fracture of the ischial tuberosity. The associated mechanism that the shorter the time interval between the peak of seat loading speed and the peak of hip muscle compression, the more serious dynamic responses of pelvis-lumbar spine is revealed for the first time. [ABSTRACT FROM AUTHOR]

In order to investigate the stress characteristics of ballastless track under high latitude, and multi-source and multi-field extreme temperature conditions. Based on the finite element theory and the elastic foundation beam–plate principle, a finite element model of the ballastless track considering the limit convex abutment, gel resin, and interlayer bonding is established. The mechanical characteristics of the ballastless track under the slab–CAM layer bonding state, mortar separation, freeze–thaw degradation and forced deformation of the foundation are studied. Considering the deterioration of materials, the bending moment and reinforcement of track structures in cold regions are checked and calculated. The studies show that under the action of negative temperature gradient load, the edge of the track slab is subjected to tension, and structural separation occurs at the edge of the slab. When the interface between the track slab–CAM layer is poorly bonded, the bearing capacity can be improved, and the amount of separation can be reduced by increasing the structural stiffness of the CAM layer. Under the action of freeze–thaw cycles, the material performance deteriorates seriously, the separation between the track structures intensifies, the baseplate is seriously powdered and cracked, and the maximum tensile stress exceeds 6 MPa. The CAM layer and the baseplate are weak structures, and the foundation frost heave occurs at the expansion joint of the baseplate, which is the frost heave condition. Under freeze–thaw deterioration, the original reinforcement design of the substructure structure does not meet the requirements of structural cracks and reinforcement yield stress. In severely cold areas, the structural reinforcement scheme should be reasonably determined. [ABSTRACT FROM AUTHOR]

This paper analyzes and calculates the mechanical properties of composite tape spring structures during folding and bending and establishes a non-linear control equation for the folding and bending of composite laminate tape spring structures. Accurate expressions for folding and bending displacements are obtained. The influence of the cross-section's central angle and the composite tape spring's ply thickness on their mechanical properties are analyzed. Finite element numerical analysis is performed on [−45 45]s laminated composite tape springs, and the correctness of the theoretical derivation is proved by comparing the curvature radius-bending moment curve. Based on previous research, the mechanical properties of different tape spring materials and structures are compared, further studying the lightweight design of space deployment mechanisms. The results show that the steady-state bending moment performance of composite tape springs is excellent, with a 162.1% improvement in steady-state bending moment performance per unit mass compared to traditional metallic tape springs. Additionally, the critical bending moment performance of negative Poisson ratio honeycomb structure tape springs is also excellent, with a 62.3% improvement in steady-state bending moment performance per unit mass compared to traditional metallic tape springs. [ABSTRACT FROM AUTHOR]

This paper explores a solution to safeguard buried pipes located near constructions in the Al-Bisri region of Assiut Governorate by utilizing the concept of the characteristic damage state. This issue has escalated due to the increasing rate of construction activity near pipelines, resulting in a multitude of legal disputes. This study investigates the behavior of buried pipes when influenced by newly constructed buildings using the finite element method. The paper employs two-dimensional models of a 12-story reinforced concrete building with a raft foundation and a series of piles supporting the buried pipe. In this study, we used the PLAXIS software, a 2D plane strain program, to conduct numerical investigations. The soil was idealized using the Mohr–Coulomb model with a 15-node triangular element, while the piles and structures were idealized with a five-node isoperimetric beam element. The point of contact between the beam and the soil was represented by the interface element. Our research examined the distance between the pipe and the footing edge and the distance between the piles and the footing edge. The finite element model results provided nodal displacements and element straining actions for analysis. The results shed light on the behavior of the sheet pile wall and sewage pipe in various situations. The largest bending moment in the sewage pipe was seen in the absence of piling, in contrast, to pile support at Rx = 0.75. The bending moment in the pipe expanded and always occurred at the same location as Rx rose. The clay layer next to the pipe's lateral deformation was significantly reduced after piling, with the greatest deformation occurring at Rx = 0. [ABSTRACT FROM AUTHOR]

This paper discusses the negative bending behavior of a new type of web-embedded U-shaped steel-concrete composite beams (WUSCBs). Considering the effective width of the concrete slab, a negative bending moment test was performed on eight WUSCB specimens. The web-embedded shear connector in the WUSCB has been shown to have good shear connection performance and maintain the overall function of the WUSCB. The failure process of the specimen was categorized by the cracking, yielding, and buckling loads which correspond to 0.29 P u, 0.79 P u, and 0.90 P u, respectively. Negative bending failure was observed in the WUSCB, evidenced by the steel plate yielding and concrete slab cracking. The WUSCB was found to have good ductility and deformability under negative bending. A finite element model was established to verify with the experimental results. The calculation method for negative bending capacity is proposed; and the calculation results are in good agreement with the test results. [ABSTRACT FROM AUTHOR]

The development of efficient computational models for the accurate prediction of the state variables in general composite laminated shells undergoing uniform edge loadings is a major challenge, especially when stress concentration phenomena such as the free‐edge effect have to be considered. This paper addresses this issue by introducing a higher‐order semi‐analytical approach for the assessment of the three‐dimensional stress field in circular cylindrical composite shells with arbitrary layups subjected to a uniform bending moment. The presented semi‐analytical approach combines a closed‐form analytical plane‐strain solution with a higher‐order layerwise approach, and the governing equations are derived by virtue of the principle of minimum elastic potential. The resulting system of coupled ordinary differential equations is then solved by means of the state‐space approach and the free constants are determined by evaluating the boundary conditions at the traction‐free edges. A comparison of the numerical results of the presented semi‐analytical method with finite element simulations for various composite laminates indicates that the developed method works with high accuracy, although being extremely efficient in terms of computational resources. [ABSTRACT FROM AUTHOR]

In this study, a series of centrifuge tests are performed to investigate the ultimate lateral capacity of a pile group for offshore wind turbines. The validated Finite element models (FEMs) are established. The rotation center and the maximum bending moment occur at 9 D and 3 D of the pile length. A sensitivity study is performed by considering the soil parameters through numerical tests. The internal friction angle is the most influential factor by introducing 32% change in lateral capacity. The key factors of pile number, pile diameter, loading height, and pile spacing are investigated in the following parametric study. Increasing the pile number and the pile diameter is effective for enhancing the lateral capacity. In contrast, a larger eccentricity has a negative effect on the foundation stability. The failure mode of the pile group foundation tends to change from strain softening to strain hardening when the loading height reaches a threshold magnitude. The p-multiplier is calculated to demonstrate the shadowing effect in a pile group foundation. An optimal design method is proposed by integrating the pile number and the pile spacing factors. This study provides some instructions for the application of pile group foundations in the offshore wind industry. [ABSTRACT FROM AUTHOR]

Design methods for corrugated steel culverts in current design standards consider the circumferential force in culvert walls (i.e., hoop thrust) to be the dominant load-carrying mechanism in these structures. However, recent studies have shown that bending moment, rather than thrust, is often the more dominant response for corrugated steel culverts under shallow burial conditions and vehicle loading. In addition, 2D finite element analyses have historically been unable to effectively capture the effects of discrete surface loads, such as wheel loads, on the response of buried metal culverts. To investigate these issues, the bending moment and thrust responses from an experiment involving an elliptical corrugated steel culvert under shallow burial conditions and simulated vehicle loading are compared with the bending moment and thrust estimates from the Canadian bridge design code and CANDE-2019 (a commonly used public domain finite element software package) and the thrust estimates from the American AASHTO LRFD bridge design code (which does not consider moment directly). The comparisons show that the Canadian code and CANDE-2019 models with a fine mesh and the continuous load scaling elasticity-based method appear to be the most effective for the investigated culvert and loading, while there is a need to modify the American AASHTO LRFD code to consider moment more directly. In addition, the results suggest that, under these conditions, the current approaches for estimating the peak bending moment response are more effective compared with the approaches for estimating the peak thrust response. [ABSTRACT FROM AUTHOR]

A two-dimensional plane-strain finite element analysis based study is conducted to investigate the overall response of skirted strip footing resting on layered soil media comprising a loose sand layer overlaying a dense sandy stratum. The influence of different parameters associated with the foundation system, namely the skirt depth, embedment depth of footing, depth of overlying soil layer and its friction angle, are inspected on the load carrying capacity of skirted strip footing. The displacement mechanism beneath the skirted strip footing is also investigated for different depths of overlying soil layer. Finally, the generated axial forces and bending moments in the skirt are analysed for various cases. It is observed that the load carrying capacity, total displacement and shear stress of skirted strip footing are negligibly affected by the underlying dense sandy layer as its depth is superseded by the thickness of the overlying layer. It is also found that the load carrying capacity of skirted strip footing increased by 34% per 5° increase in the friction angle of the overlying layer. Increase in the skirt depth also exhibited reasonable increase in the load bearing capacity by providing additional confinement to the soil beneath the footing. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office 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.)

The tape spring is a crucial component used in the deployment mechanism of spacecraft, and the lightweight design of the deployment mechanism is currently one of the critical issues that need to be addressed. This paper explores the substitution effect of two different negative Poisson's ratio honeycomb-corrugated spring structures for use in space-deployable structures. Theoretical and finite element methods demonstrated that the negative Poisson's ratio honeycomb structure could be equivalent to an orthotropic structure. The cylindrical shell bending theory was adopted, taking into account the nonlinearity of the geometric equation, the influence of cross-sectional deformation and cross-sectional position on the internal force expression, and the influence of the geometric equation to derive expressions for the bending moment and curvature radius during the folding and bending process. Numerical methods were used for comparative analysis. The NSGA-II algorithm optimized the geometric parameters of the negative Poisson's ratio honeycomb, resulting in the optimal solution under given constraints. The results showed that the Auxetic re-entrant honeycomb structure performed better in bending moment capacity than the Star-shaped honeycomb, and the bending moment capacity of the Auxetic re-entrant honeycomb structure per unit mass was superior to that of the traditional tape spring. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office 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.)

A non-destructive diagnostic method based on deflection analysis for monitoring the post-elastic response of beams was developed, and a diagnostic indicator was proposed. The indicator was defined as the second moment of the normalised curvature function about the mid-span, where the curvature was computed from the normalised deflection function. Elastic reference values of the indicator were computed for simply supported beams under uniformly distributed load, three-point, and four-point bending. Development of the indicator under progressive loading was examined with the help of finite element analyses. The indicator value monotonically decreased with increasing deformation provided that maximum bending moment was located between 0.41L and 0.59L, where L is the span of the beam. In this interval, the value of the indicator was unique and enabled the direct monitoring of the post-elastic stress level in the cross-section. The method was validated with the help of available experiments on simply supported beams. For beams working in the elastic range, a mean error of 2.1 % was obtained between the measured and theoretical indicator values. For quasi-brittle material in the post-elastic stage, the decreasing value of the indicator signified the development of damage in accordance with experimental results. [ABSTRACT FROM AUTHOR]

In this paper, a bending test of a precast ultra-high-performance concrete (UHPC) diaphragm slab was carried out. The test revealed that the flexural failure process of specimens under the action of a positive bending moment can be divided into three stages: the elastic, crack-propagation, and yield stages. The first stiffness reduction of the structure was caused by cracks at the bottom of the diaphragm slab, while the second stiffness drop resulted from the yielding of the bottom longitudinal rebars. During the loading process, the ultimate bearing capacity was 3.75 times higher than the design load value (150 kN vs. 40 kN). Additionally, a nonlinear finite element model was established using Abaqus software validated by the test and exploiting parameter analysis. Based on this model, the initial crack stress of the actual slab was determined to be 5.12 MPa. Parameter analysis indicated that the shear strength of the diaphragm slab was stronger than the flexural strength, and the diaphragm slab's bearing capacity could be improved by increasing the ratio of bottom longitudinal reinforcement. This research confirmed that the new UHPC diaphragm slab used in Guangzhou Smart City is safe, and it also helped the design of similar UHPC slabs for utility tunnels. [ABSTRACT FROM AUTHOR]

The pile–beam–arch method (PBA) method is increasingly being used in the construction of metro stations with complex traffic conditions. The rise–span ratio of the arch not only affects the height of the station, but also affects the rationality of the design of subway stations and the safety of construction. The mechanical response of steel pipe piles with different rise–span ratios and the effect of controlled surface settlement have been investigated in the interactions involved in pile–soil system. In this paper, the finite element model of each rise–span ratio was established, and the rationality of the model was demonstrated by comparing the numerical simulation calculation with the field surface settlement monitoring data. The mechanical characteristics and influence analysis of the surface deformation during the excavation of the cave pile method were investigated. The results show that the maximum axial force of the central pile first decreases and then increases with the increase in the rise–span ratio. The maximum bending moment of the arch decreases as the rise–span ratio increases, and the maximum axial force of the arch is negatively correlated with the rise–span ratio. The maximum axial force of the central pile is located at the bottom plate. Due to the symmetry of the structure, the bending moment of the centre pile is small, but the maximum bending moment of the whole station is located at the side wall of the bottom plate. As the rise–span ratio increases, the surface settlement first decreases and then increases. The construction of the pilot tunnel and the upper arch is the most important factor leading to the surface settlement, so it is necessary to strengthen the soil layer. [ABSTRACT FROM AUTHOR]

Summary: A modular prefabricated four‐side connected composite (MPFC) shear wall that consists of a composite shear wall modular (CSWM) and steel frame boundary elements is proposed. First, the finite element model (FEM) of the MPFC shear wall, which considers a plastic‐damage constitutive model of both concrete and steel materials, is established based on the finite‐element software ABAQUS. Second, the FEM accuracy of the MPFC shear wall is verified by the experimental results of a modular prefabricated two‐sided connected buckling‐restrained (MTB) steel plate shear wall. Third, the seismic performance of the MPFC shear wall is investigated based on the verified FEM. The connection between the CSWM and side column is optimized. Finally, the initial stiffness calculation formula of the MPFC shear wall that considers the impact of that the thickness ratio between the connection steel plate (CSP) and inner steel plate (ISP) is deduced. The results show that the peak bearing capacity, initial stiffness, total energy, and total strain energy of the MPFC shear wall increased by 42.47%, 44.81%, 113.24%, and 58.97%, respectively, compared with those of the MTB steel plate shear wall. The compressive corner damage of the reinforcement concrete faceplate (RCF) of the MPFC shear wall with a side column and CSWM is connected by a middle steel plate is effectively improved. Compared with those of the MPFC shear wall in which the side column and CSWM are connected by bolts, the shearing force, axial force, and bending moment of the side column of the MPFC shear wall in which the side column and CSWM are connected by the middle steel plate are notably decreased by 25.32%, 26.08%, and 39.51%, respectively. The FEM results are compared with the formula calculation results to establish its accuracy in calculating the initial stiffness of the MPFC shear wall. [ABSTRACT FROM AUTHOR]

A problem of stability of cylindrical shells made of a composite material is solved, taking into account the momentum and nonlinearity of their subcritical stress–strain state. In geometric terms, the nonlinear stability problem is solved by finite element methods and the Newton–Kantorovich linearization. Critical loads are determined in the process of solving a nonlinear problem using the Sylvester criterion. The study is carried out using the finite elements of composite cylindrical shells of natural curvature developed on the basis of the Timoshenko hypothesis, with rigid displacements being explicitly distinguished within their displacement approximation, which significantly affects the convergence of the solution. The stability of a circular cylindrical shell made of a polymer composite material under combined loading by torque, bending moment, and internal pressure is investigated. This study also touches upon the influence of the stacking method of monolayers, deformation nonlinearity, and internal pressure on critical loads at which shell buckling is observed. [ABSTRACT FROM AUTHOR]

The main aim of the study is an assessment of models suitability for steel beams made of thin-walled cold-formed sigma profiles with respect to different numerical descriptions used in buckling analysis. The analyses are carried out for the sigma profile beam with the height of 140 mm and the span of 2.20 m. The Finite Element (FE) numerical models are developed in the Abaqus program. The boundary conditions are introduced in the formof the so-called fork support with the use of displacement limitations. The beams are discretized using S4R shell finite elements with S4R linear and S8R quadratic shape functions. Local and global instability behaviour is investigated using linear buckling analysis and the models are verified by the comparison with theoretical critical bending moment obtained from the analytical formulae based on the Vlasow beam theory of the thin-walled elements. In addition, the engineering analysis of buckling is carried out for a simple shell (plate) model of the separated cross-section flange wall using the Boundary Element Method (BEM). Special attention was paid to critical bending moment calculated on the basis of the Vlasov beam theory, which does not take into account the loss of local stability or contour deformation. Numerical shell FE models are investigated, which enable a multimodal buckling analysis taking into account interactive buckling. The eigenvalues and shape of first three buckling modes for selected numerical models are calculated but the values of critical bending moments are identified basing on the eigenvalue obtained for the first buckling mode. [ABSTRACT FROM AUTHOR]

The existing anti-cracking measures in the negative bending moment zone of prestressed concrete beam bridges have many disadvantages. The application of Ultra-high-performance concrete (UHPC) provides a new option for the anti-cracking measures in the negative bending moment zone A prefabricated continuous connection structure of UHPC-NC (normal concrete) with a higher reinforcement ratio in the negative bending moment zone was proposed to improve the cracking resistance in the negative bending moment zone. The cracking load calculation method was given based on theoretical analysis under different loading modes of the UHPC-NC structure. The experimental investigations of the scaled models of 1:4 were conducted. The experimental results verified the reliability of the new structures. The thickness of the UHPC layer and the steel reinforcement ratio was considered to calculate the cracking load of the structure by the finite element method. The results show that the relative errors between the proposed method and the FEM are less than 11%. When the bending-shear combination effect is considered, the relative errors between the two methods are less than 10%. The reliability and applicability of the connection structure were verified, which provides a reference for the design and engineering application. [ABSTRACT FROM AUTHOR]

In this paper, a space-time absolute nodal coordinate formulation cable (SAC) element forming technique based on the Lagrange family of shape functions is proposed. Two distinct SAC elements, each with a distinct spatial shape function, have been generated by this method. Moreover, the external forces such as the bending moment and the air resistance formula have been accounted for. The Lagrange multiplier method, along with the concepts of replacement constraint and supplementary constraint, has been employed to provide a solution for the dynamics of constrained mechanical systems. Additionally, a constraint conversion strategy has been suggested. The solver has been constructed through Hamilton's law of varying action. The space-time finite element method is used to solve dynamic problems, employing the Newton algorithm and quasi-Newton algorithm. The accuracy and efficiency of the solution has been verified by three simulations and one experiment. The circle-bending static simulation and the double-ended velocity impact dynamic simulation demonstrate the accuracy of the two elements. The correlation between statics and dynamics has been studied for different discretization methods and different solvers' calculation accuracy and efficiency. Different modeling methods, time steps, order and the application of the quasi-Newton method all have a bearing on the efficiency of the solution. Finally, a comparison with an experiment in the free-pendulum simulation reveals the capability of this model to simulate dynamic problems with air resistance. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office 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.)

The openings at the sidewalls of subway station entrances generally reduce the localized load-bearing capacity of the sidewalls and lead to concentrated stress around the openings. In this study, to strengthen the sidewalls with openings in a newly-developed prefabricated subway station, a prefabricated steel-reinforced concrete (SRC) frame around the entrance was developed. To further investigate the effect of the developed entrance frame on the mechanical behavior of the sidewalls, a monotonic static test and finite element analysis were performed on a 1/2 scale station entrance substructure, including the proposed entrance frame and the adjacent top slab, bottom slab, and sidewalls. It was found that the developed entrance frame could effectively prevent stress concentration in the adjacent sidewall region. The most severe crack development was concentrated at the corner of the opening, which could be attributed to the torsional moment at the SRC beam end. The ratio of the torque shared by the beam to the total bending moment of the slab end varied from 21.2% to 26.8% in the elastic stage of all cases. In addition, both the improvement in the torsional bearing capacity of the SRC beam and the out-of-plane flexural capacity of the SRC column could positively contribute to controlling the crack development around the opening. [ABSTRACT FROM AUTHOR]

T-stubs are important components in the application of the component method; hence it is crucial to clarify the T-stub mechanism for the analysis of the mechanical properties of steel joints. In this study, the mechanical behavior of T-stubs was assessed via 6 static tests and 18 finite element analysis models. The influences of flange thickness, bolt spacing, bolt diameter, and stiffener rib on initial stiffness, ultimate bearing capacity, and bolt force of T-stubs were analyzed. Furthermore, the development process and relations of the T-stub bolt force with and without stiffeners were analyzed. The results show that an effective stiffener arrangement can reduce the bending moment and prying force to a certain degree; however, offsetting the bending moment and prying force entirely is difficult. Furthermore, the influence of bending moment and prying force on the bearing capacity should be considered in the design. [ABSTRACT FROM AUTHOR]

The driving of pile into the ground is one of the important tasks of construction works and especially for new buildings in big city. Difficulties in driving piles for new construction will adversely affect the foundations of neighboring and adjacent building. This research proposes a measure to assess the state of conduct of the pile driving process using a nonlinear Finite Element Method (FEM). Manuscript using Plaxis 3D Foundation analysis software for an existing building with reinforced concrete pile foundation with foundation tower size 2.0 m x 2.0 m on 4 piles with a cross-section of 0.3 m x 0.3 m, length 10.0 m; foundation bearing a load of 1000 kN. Then press the reinforced concrete pile size 0.3 m x 0.3 m, pile length 10.0 m, pressing position 0.5 m from the edge of the existing foundation, pressure 500 kN. The results of the analysis showed the effect of the adjacent pile process to the stress and strain of the neighboring building foundation in cramped land for construction conditions. In order to provide solutions to overcome difficulties for the adjacent building be effective. The effective stress in the existing reinforced concrete pile foundation without adjacent is -273.7 kN/m², but when it is interlocked, it is -3490.0 kN/m². After pressing the piles, the horizontal displacement of the existing piles is 10.2 mm and a bending moment of 48.6 kNm occurs. [ABSTRACT FROM AUTHOR]

Sheet pile wall structures are commonly applied in coastal projects, particularly for the quay wall. This structural type normally is used in places where the ground has a low bearing capacity and is easily penetrable. Many sheet pile quay walls constructed in the past had low front water depth and did not satisfy the requirements of current standards. This issue could be addressed by improving the ground in front of the wall using cement deep mixing (CDM) and then excavating to increase the water depth in front of the wall. This paper numerically evaluated the dynamic behavior of the sheet pile wall after renovation. The numerical model was performed based on the finite element method (FEM) using the PLAXIS 2D program. The study focused on investigating typical parameters of the quay wall improved using the CDM, such as bending moment and displacement of sheet pile and the development of excess pore water pressure (EPWP) in the backfill. These results were compared to those of the quay wall without the CDM to elucidate the advantages of this method. In addition, the influence of some factors on the quay wall behavior, such as earthquake excitation characteristics, CDM area, and CDM strength, was also evaluated. The results demonstrated that the ground improvement using the CDM significantly decreased the bending moment and displacement of the sheet pile wall. The excitation characteristics did not affect the deformed shape of the sheet pile. With the constant CDM depth, the sheet pile displacement decreased with an increase in the improvement width until it reached a limitation. The increasing CDM strength also decreased the displacement of the wall until it raised a certain value. This demonstrated that this method was technically feasible, and it could be considered to study further by experiment before applying in practice. [ABSTRACT FROM AUTHOR]

Frame analysis (FA) is known for its efficiency and low computer resource requirements. However, compared to finite element analysis (FEA), the applicability of FA for the seismic performance assessment of pile-supported wharves (PSWs) is limited, particularly in the ability to account for the kinematic force caused by ground displacement during an earthquake. This study aimed to develop a two-dimensional FA method for PSW seismic response analysis that considers a combination of inertial and kinematic forces. We performed FA and FEA and compared the results. First, we targeted the PSW model without considering the soil slope and discussed the spectral acceleration (SA) evaluation method for calculating inertial force. As a result, an equation for estimating a damping coefficient to evaluate the SA in accordance with the PSW width and natural period was proposed. Next, we targeted the PSW model by considering the soil slope and proposed a method to evaluate the kinematic force based on the amount of ground displacement and the soil spring characteristics. The results revealed that using the proposed method, FA, by considering kinematic and inertial forces, could reproduce the bending moments of the piles comparable to those calculated using FEA. Therefore, solely considering the inertial force for a PSW on a soil slope may cause the bending moment to be underestimated. [ABSTRACT FROM AUTHOR]

Even if precast pre-stressed hollow-core (PPHC) slabs are usually designed as simply supported elements, continuity with the supporting beam may exist when constructed together with a reinforced concrete topping and continuity reinforcing bars. During an earthquake (and possibly other lateral load), this continuity may result in bending moments being induced close to the supports as the buildings sway laterally. The response of precast floors to earthquake-induced demands has been addressed by past research. However, further investigation is required to improve understanding of several aspects of precast floor behaviour either revealed or emphasized by recent earthquakes in New Zealand. This paper proposes a mechanics-based modelling approach for the analysis of PPHC slab-to-beam seating connections. The model has been calibrated against existing test data to predict the failure of a PPHC slab under negative bending moments. The numerical outcomes allow comparison of the moment–drift response, principal tensile stresses, and crack progression during loading. The developed modelling approach will allow future studies to exhaustively investigate all aspects of precast floor behaviour by varying the properties and geometry of the PPHC seating connection. [ABSTRACT FROM AUTHOR]

This paper investigated and compared the dynamic responses of driven and helical piles in cohesive soil using finite element analysis. The finite element models were calibrated based on large-scale field dynamic tests on single steel piles driven into a soft clay layer and embedded in a gravelly sand layer. The soft clay was improved using the cement deep soil mixing technique. The calculated results from the numerical models were in good agreement with the measured response in the field tests. The numerical models were then employed to investigate the dynamic response of helical piles in clay. Driven steel piles and single- and double-helix piles were subjected to lateral dynamic loads, and their responses were compared. The results demonstrated that the helical pile exhibited excellent lateral and axial responses, comparable to that of the driven piles. The lateral displacement of the helical piles was similar to or less than that of longer driven piles depending on the clay strength, number, and spacing of the helices. In addition, the double-helix pile with an inter-helix spacing of 3 times the helix diameter reduced the required width of soil treatment to 7.5 times the pile diameter while achieving the same performance as a driven pile with a treated area 12 times the pile diameter. The kinematic and inertial interaction effects were evaluated for helical piles. It was found that the kinematic interaction forces increased the bending moment at the interface of different layers, while the inertial forces increased the bending moment at the ground level. Finally, the helical pile exhibited lower lateral deformations than the driven pile during the seismic motion, and the maximum bending moment was relatively lower. [ABSTRACT FROM AUTHOR]

Seismic vulnerability of speleothems may serve long-term seismic risk studies. For this reason, the seismic response of stalagmite is computed using a robust FEM model calibrated from free vibration records by Hilbert–Huang modal extraction. It is demonstrated that the stalagmite vibrations consist of pairs of closely coupled flexural natural modes with a negligible role of vertical excitations. The location of the breaking point of the stalagmite is a result of a balance between the overturning bending moment and variations of horizontal cross-sections with height. Safety margins are investigated, and the ultimate peak velocity of excitations equaling 3.4 mm/s is estimated. [ABSTRACT FROM AUTHOR]

Due to rapid urbanization, open excavations are not uncommon these days. However, many issues are arising during the execution of unsupported open excavations when not designed and executed properly. Moreover, in urban areas where new buildings are constructed closer to the existing buildings, these excavations may affect the structural integrity of the adjacent existing buildings. Therefore, there is a need to evaluate the response of multistorey building frame (MBF) subjected to nearby series of unsupported open excavations. In the study, a numerical investigation on response of RCC-MBF structure with raft foundation resting on medium dense sand subjected to adjacent unsupported open excavations is performed using a 3D finite element program PLAXIS-3D. The series of open excavation is simulated considering the different geometrical parameters of excavation, such as varying setback distance, and different excavation volumes. As a response, the four parameters are monitored in the columns of the MBF i.e., displacement of the structure in x- and z-directions (i.e., settlement and tilt), and redistributed bending moments and shear forces in the column of MBF. The linear and non-linear analyses are performed to account the effect of constitutive models on the response of the MBF by assigning the Linear–Elastic and Mohr–Coulomb soil constitutive models to the soil respectively. Further, a sensitivity analysis is performed to evaluate the effect of strength and deformation parameters of the soil, and the geometrical parameters of the excavation on the factor of safety of excavation slope. Based on the results, it is observed that Mohr–Coulomb constitutive model can be used to analyse the response of structure subjected to unsupported open excavations. Finally, the effect of different foundation schemes is also analysed in the study. [ABSTRACT FROM AUTHOR]

Segmental lining is subject to significant upward buoyancy forces when a grouting material (slurry), initially fluid, is adopted to fill the gap between its external profile and the wall of a tunnel excavated with a TBM machine. The analysis of the effects of these forces is important in order to correctly dimension the segmental lining and avoid damage to the lining and subsequent costly maintenance and restoration actions. Given the complexity of the behavior of a segmental lining consisting of segmental rings and circular joints that alternate in the longitudinal direction of the tunnel, a specific numerical model has been implemented, adopting the Finite Element Method (FEM). This model is able to obtain the development of the vertical displacements of the segmental lining starting from the TBM tail, together with the bending moments and the shear forces induced inside it. The developed model is able to assess the risks of breaking and damaging the concrete and steel bolts that are used to connect the segmental rings at the circular joints; therefore, it represents a useful design tool for being able to correctly dimension the segmental lining also in relation to the risks produced by the appearance of considerable buoyancy forces around it, due to the presence of the initially fluid filling material. The proposed numerical model was applied to a real case (Ningbo metro tunnel) and allowed to obtain satisfactory results from the comparison of the calculated displacements with in situ measurements. Some sensitivity analyzes developed on the studied case have made it possible to detect which are the influencing parameters that have the greatest impact on the behavior of segmental lining in the presence of the studied buoyancy forces. [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.)

In all types of new arch bridge structures, the requirements of the foundation are becoming more and more strict. Under the action of horizontal thrust, the distribution of the internal forces of the pile group in which inclined piles participate in an arch foundation is complicated. In this regard, the horizontal forces of each pile in a pile group and the horizontal bearing performance of each pile in a pile group under the action of total thrust are investigated by establishing a pile group foundation model and a p-y curve difference equation. After an in-depth analysis of the simulation results, it is found that the load distribution calculated by the finite element method is very close to that calculated by the p-y curve method, both in terms of curve shape and numerical value, indicating that the pile top load distribution is close to the actual situation. In addition, the maximum shear force of each pile body occurs at the top of the pile, and the maximum bending moment occurs at the point 1/5 away from the top of the pile. Finally, the nonlinear analysis of the p-y curve method can be well applied to the calculation of bridge pile foundations. [ABSTRACT FROM AUTHOR]

Tire-derived aggregate (TDA) has been used successfully as a backfill soil to reduce the applied stresses on buried steel pipes. The preceding study, however, paid no attention to inspecting the TDA efficiency of buried concrete pipes subjected to soil and traffic loads. In addition, it is not clear how the TDA material, traffic loading, burial depth, and road section affect the pipe-bending moment. Therefore, this paper examines the efficiency of TDA in reducing the bending moment of a 0.6 m concrete pipe subjected to combined soil and traffic loads using a validated three-dimensional finite element model. Two trench configurations have been constructed, the first is composed completely of well graded sand, and the second is similar to the first except for the 150 mm layer on the top of the pipe crown, which is replaced with TDA. Furthermore, three road sections (highway, public road, and unpaved road) have been adopted to provide an intensive understanding of the TDA effect for different road conditions. A parametric study is carried out to detect the effect of the burial depth, road section, and traffic load on the efficiency of the TDA of the buried pipe. It is observed that the TDA has no effect on the bending moment distribution around the pipe. Additionally, the TDA reduces the bending moment developed in the pipe wall with a percentage decrease range between 18% and 42% depending on the burial depth and road section. Furthermore, it is also found that the efficiency of the TDA in reducing the maximum bending moment decreases as the burial depth increases. In addition, the best performance for the TDA is found at a burial depth of 1.0 m for all road sections. Importantly, the best performance for the TDA is found for the highway section compared with the other sections, with a maximum percentage decrease of 42% compared to 27% for the public road section and 26% for the unpaved road section. [ABSTRACT FROM AUTHOR]

The interspersed railway track is an enhanced timber railway track, spot-replacing damaged wooden sleepers with new concrete sleepers to improve the bearing capacity of existing railway lines. Although this interspersed solution is characterised by low cost and short maintenance time, the interspersed tracks have worse stability than concrete tracks and can deteriorate quickly when exposed to extreme weather conditions such as heavy rains and floods. In many cases, heavy rains and floods are accompanied by strong winds. Ballast washaway can often be observed under flood conditions while the mass of trains is unevenly distributed on two rails due to the effect of lateral wind load and rail irregularities. The current work is the first in the world to investigate the collective multi-hazard effects of ballast washway and uneven axle loads on the vulnerability of conventional and interspersed railway tracks using nonlinear FEM software, STRAND 7. The train bogie is modelled by two sets of point loads. The maximum displacement, bending moment and twists have been studied to evaluate the worst condition. The novel insights will help the railway industry develop proper operations of interspersed railway tracks against naturally hazardous conditions. [ABSTRACT FROM AUTHOR]

The study presents the design forces of simply supported single-cell reinforced concrete (RC) curved box-girder bridges using a finite element method (FEM) based CSiBridge v.20 software. An existing model has been used to validate the present modelling approach. Models subjected to vertical loading, i.e., dead load (DL) and Indian road congress live load (LL), are considered for investigation. An intensive parametric study examines the maximum values of bending moment (BM), shear force (SF), torsional moment (TM), and vertical deflection (VD) in both girders of bridges. The influences of curve angle and span are considered in the study. The effect of curve angle, up to 12°, is negligible on forces and deflections, and thus such bridges can be analysed as a straight one. Finally, non-dimensional equations are derived for evaluating forces and deflections, so that one may predict these quantities for curved bridges based on straight bridge's results. Engineers and designers may consider present work valuable in analysing, and designing curved box-girder bridges. [ABSTRACT FROM AUTHOR]

This paper focuses on investigating the structural behavior of members and connections that are part of moment frames under the combined effect of bending moment and thermally induced axial force during a compartment-fire event. The finite-element analysis method was employed to conduct this study using models benchmarked against experimental data from several past studies while utilizing temperature-dependent material models. A numerical parametric study on typical floor beams with slender elements for compression were conducted under combined bending and axial loading to develop interaction-capacity curves at temperatures representing fire events. The results were compared against the member-strength equations provided in the AISC Specification. The analysis results demonstrated that the AISC beam-column strength equations including the combined effects of axial-load and bending moment provided reasonable estimates for member-slenderness ratios greater than 60, but overestimated the strength of beams with slender elements for low member-slenderness ratios. Combined-load-strength studies were also conducted on a typical connection used in moment frames. The moment-connection behavior was governed by failure modes exhibited at the ends of floor beams. Therefore, the interaction equations available for beam columns resulted in conservative estimates and are recommended for calculating moment-connection capacity during compartment-fire scenarios. [ABSTRACT FROM AUTHOR]

This paper investigates a novel variable‐grade prefabricated concrete (PC) slab with surrounding composited which has high prefabrication rate, sufficient installation rigidity, high on‐site construction efficiency, and good overall working performance. To improve the crack‐resistance performance of the transverse superposed surface and the overall working performance of the proposed novel PC slab, we optimize the position of variable‐grade and arrange it at the location where the bending moment is close to zero. We perform comparatively bending tests on three two‐span full‐scale slab strips that include boundary and intermediate beam‐slab joints to systematically investigate the flexural behavior of the proposed novel slab. The load versus deflection relationship, failure mode, distribution of cracks, development law of crack width and development of steel strain are comparatively studied. The test results confirm that the flexural behavior of the proposed novel PC slabs are similar and slightly better than that of the cast‐in‐place slab in general. No crack or slippage appears at the interface between the precast panel and the post‐pouring concrete. The connection method of L‐shaped anchorage rebars lap splicing in this study is cost‐effective, efficient, and reliable. Furthermore, we establish a finite element model and perform a parametric investigation on the proposed novel PC slab. Parametric simulations conclude that the increase of the strength of post‐pouring concrete and post‐pouring layer thickness can improve the bearing capacity of the proposed novel PC slabs. [ABSTRACT FROM AUTHOR]