Effect Of Bending Moment Research Articles

Study on plastic yield surfaces of pyramidal lattice materials with circular and rectangular cross-sections

The yield surfaces and the evolution of yield surfaces of a bending-dominated pyramidal lattice material under complex stress states considering the coupling effect of axial force and bending moment of a strut are studied theoretically. The two-dimensional primary yield surfaces, secondary yield surfaces, and complete yield surfaces of pyramidal lattice materials of two kinds of cross-section struts are obtained, and the analytical expressions of yield surfaces are established. The effects of the inclination angle and diameter-to-length ratio of the struts on the yield surfaces of pyramidal lattice materials with circular cross-sections are discussed. The results provide a basis for analyzing homogenized plastic properties of complex lattice material structures.

Development of a new analytical model for circular concrete ring segments with dry joints under combined effects

AbstractPrevious models of circular ring segment joints have been inadequate in describing their loading capacity due to the lack of consideration for the interaction between shear force and bending moment. Consequently, these models have led to over‐ or underestimation of the joints' capacity. The increasing use of dry joint connection technology in wind turbine towers and prefabricated segmental bridge constructions necessitates the development of advanced computational models for these connections. This study presents a new model that considers the effects of bending moment, shear force, and torsion on the loading capacity of circular ring segment joints. Numerical simulations were conducted to validate the developed model under different load combinations, and the results demonstrate excellent agreement between the model predictions and numerical simulations.

Comparison Between the Behavior of Reinforced Concrete Beams and RPC Beams Under Bending and Torsion Moments

Abstract Typically, the beams were subjected to bending and torsion moments especially at building edge. However, most of the studies focus on the flexural or torsional behavior of the beams independently, and few studies investigated these two combined effects. The research intends to explore the structural behavior of eight 1500mm x 200 mm x 150 mm rectangular beams that were tested under the combined effects of bending and torsional moments, with four main values of (T/M) ratio: pure bending, pure torsion, and two combined cases. The research investigates the effect of using reactive powder concrete (RPC) on beam behavior compared to normal concrete (NC). The outcome demonstrates that using RPC in beams instead of NC beams will significantly increases the cracking capacity by 136.4% in the case of pure bending and significantly increases the ultimate capacity by 118% in the case of combined moments with (T/M = 1). Also, using RPC leads to significant reduction in deflection and rotation values especially after beam cracking. RPC reduces compressive concrete strain and values of strains in longitudinal and transverse reinforcement especially in advanced loading stages.

Effect of steel fibers and the fiber-concrete adhesion stress on the nonlinear shear behavior of beams

In this article, a theoretical model in nonlinear elasticity is presented to analyze the influence of the percentage of steel fibers and the effect of the fiber-concrete bond stress on the shear force at the rupture of beams subjected to the combined effect of bending moment, normal force, and shear force. For a given beam section, it is defined by a succession of layers of concrete and longitudinal steel elements. Each layer is defined by its height hi, width bi, and position relative to one end of the section YGi. Each longitudinal steel element is also defined by its cross-sectional area and position relative to one end of the section. The steel fibers are defined by volume percentages of 0.5%, 1%, 1.5%, and 2%, taking into account the mechanical nonlinearity of the materials. This model is based on the multilayer analysis of sections and an iterative solution procedure for each layer and each section, considering a given longitudinal deformation state and shear stress. The global equilibrium of the sections is analyzed under the assumption of flat longitudinal deformations but with, in principle, an interdependence of longitudinal normal stresses and shear stresses. In this study, using the principle of virtual work, equilibrium equations for deformations and stresses, as well as partial compatibility equations between concrete deformations and mean deformations, are derived. Comparative examples between ordinary reinforced concrete beams with variable shapes and reinforcement details, and those reinforced with steel fibers, are presented to demonstrate the accuracy of the proposed model for simulating the nonlinear shear response of beams.

Numerical Simulation Study on the Spacing of Landslide Anti-slip Piles Based on Strength Reduction Method

In landslide control engineering, anti-slip piles are the most commonly used means. This article established a numerical model of the interaction between fully weathered granite landslides and anti-slip piles based on the strength reduction method. Firstly, five pile-soil interaction models with different pile spacing were established using Abaqus software, and individual components were generated and assembled using the stretching function. The friction surface is used between the pile and soil, and the normal and tangential contact characteristics are both Penalties. Secondly, the strength reduction method based on displacement criteria is used to reduce the rock and soil parameters to the unstable stage before failure, while calculating the slope safety factor. Then, the influence of anti-slip pile spacing on slope stability, pile shear force, bending moment, and soil arch effect are studied. The strength reduction method and pile-soil interaction model used in this article can effectively avoid single pile effects and have high accuracy in characterizing soil arching effects. The results afford certain application and promotion values by providing theoretical references and technical guidance for similar anti-slide pile reinforced slope projects.

Stress and Deformation Analysis of Prestressed Wound Composite Components with an Arch-Shaped Metal Liner.

The stress distribution in prestressed filament wound components plays a crucial role in determining the quality of these components during their operational lifespan. This article proposes a physical model to analyze the stress and deformation of prestressed wound composite components with arch-shaped sections. Drawing upon the principles of beam theory, we delve into the analysis of prestressed wound components with metal liners featuring arch-shaped sections. Our investigation revealed a noteworthy phenomenon termed the "additional bending moment effect" within prestressed wound components with arch-shaped sections. Furthermore, this study establishes a relationship between this additional bending moment and the external pressure. In addition, a 3D finite element (FE) model for prestressed wound components with arch-shaped sections incorporating metal liners was developed. The model's accuracy was validated through a comparison with prestressed wound experiments, showcasing an error margin of less than 2%. In comparison with prestressed wound components with circular cross-sections under identical load and dimensional parameters, it was observed that prestressed wound components with arch-shaped sections exhibit stress distributions in the arc segments akin to their circular counterparts, with differences not exceeding 5%. Notably, when the ratio of the straight segment length to the inner diameter of the arc segment inner is less than 4, the deformation on the symmetric plane of the arc segment in an arch-shaped component can be effectively considered as the summation of deformations in equivalent-sized arc and straight segments under identical loading conditions. This yields an equivalent physical model and a streamlined analysis and design methodology for describing the deformation characteristics of prestressed wound components with arch-shaped sections.

Structural behavior of RPC beams subjected to flexural and torsional effects

This research is concerned with the behavior of reactive powder concrete beams (RPC) under the combined effects of bending and torsion moments, with three main parameters: torsional to bending moments ratio (T/M), longitudinal reinforcement ratio ( ), and transverse reinforcement ratio ( ). 12 rectangular reinforced RPC beams with dimensions of (1500 200 150) mm were tested. The outcome demonstrated that increasing the longitudinal reinforcement ratio from =0.009 to =0.016 improved the ultimate capacity significantly by 34.16%, and 35.54% in cases of (T/M) =0, and 0.5 respectively, also it significantly improved moment-deflection response in the case of (T/M) = 1, and well improved torque-rotation response in cases of (T/M)=0.5, and 1. Increasing the transverse reinforcement ratio from = 0.0042 to =0.0075 improved the ultimate capacity significantly by 49.22% in case of pure torsion and slightly improved it in other cases. Also it significantly improved moment- deflection response in case of (T/M) = 1 and improved torque -rotation response in cases of (T/M)=1and ꝏ.

Structural behavior of RPC beams subjected to flexural and torsional effects

This research is concerned with the behavior of reactive powder concrete beams (RPC) under the combined effects of bending and torsion moments, with three main parameters: torsional to bending moments ratio (T/M), longitudinal reinforcement ratio ( ), and transverse reinforcement ratio ( ). 12 rectangular reinforced RPC beams with dimensions of (1500 200 150) mm were tested. The outcome demonstrated that increasing the longitudinal reinforcement ratio from =0.009 to =0.016 improved the ultimate capacity significantly by 34.16%, and 35.54% in cases of (T/M) =0, and 0.5 respectively, also it significantly improved moment-deflection response in the case of (T/M) = 1, and well improved torque-rotation response in cases of (T/M)=0.5, and 1. Increasing the transverse reinforcement ratio from = 0.0042 to =0.0075 improved the ultimate capacity significantly by 49.22% in case of pure torsion and slightly improved it in other cases. Also it significantly improved moment- deflection response in case of (T/M) = 1 and improved torque -rotation response in cases of (T/M)=1and ꝏ.

Buckling behavior of cold-formed steel sigma and lipped channel section beam-columns: Experimental and numerical investigation

In this study, the buckling behavior of cold-formed beam-column members with sigma and lipped channel sections under the combined effect of axial load and biaxial bending moment (P-Mx-My) was compared. A total of 30 specimens (15 with sigma sections and 15 with lipped channel sections), each measuring 1500 mm in length, were tested under monotonic loading. The performances of the specimens under eccentric loading such as strength and energy absorption capacity were investigated experimentally and numerically. The local, distortional and global buckling modes that determine the bearing capacity of the section and the length of the sigma and lipped channel member where all these buckling modes can be seen were determined. Finite element analysis (FEA) was performed with Abaqus software, and the numerical results were verified against experimental results. Using the validated finite element model, a comprehensive parametric study was carried out by performing 2894 FEA on sigma and lipped channel section members with various cross-sectional dimensions and lengths. Experimental results show that there are significant differences in load bearing capacity, energy absorption capacity and buckling modes of sigma and lipped channel section members. In the FEA/ AISI-S100 code comparison made at the end of the parametric study, it was determined that differences occurred according to the lengths, cross-sectional properties and loading points of the members. It was determined that the error rate was safer when the lips were subjected to tensile stresses than when they were subjected to compressive stresses. Finally, it was determined that the FEA/AISI-S100 error rate decreased as the length of the sigma-section members increased.

Influence of the ground motion directionality on the global ductility of 3D RC structures

This study examines the influence of ground motion directionality on global ductility μ_s of framed reinforced concrete structures. Suitable values of angle of attack θ, longitudinal reinforcement ratio ρ_l, dimensionless axial stress υ and mechanical ratio of transverse reinforcement ω_wd were assumed. Detailed nonlinear modeling was adopted to reproduce the behavior of reinforced concrete elements in the plastic field considering, also, the confinement effect on concrete mechanical properties. Nonlinear static simulations were carried out with the capabilities of the OpenSees code to evaluate the capacity curves and the corresponding global ductility. The results show that plastic hinges develop on the columns for the combined effect of bending moments transmitted by the beams framing into the same joint for values of the angle θ equal to 30° and 45°. Consequently, the formation of soft-storey mechanisms significantly reduces the global ductility μ_s. A design formula is proposed to avoid such collapse mechanism for framed reinforced concrete structures in ductility class high

Investigation of the Cross Section of the Pile Foundation on the Combined Effect of Calculated Stresses on the Resistance of Materials.

This study investigates the cross-sectional behavior of pile foundations under the simultaneous influence of bending moments, transverse and longitudinal forces, assessing calculated stresses in accordance with material resistance. The goals involve determining non-central compression or elongation in pile foundations due to the combined effects to evaluate cross-sectional resistance. Employing analytical methods, the study presents results revealing the intricate interplay of these forces on the foundation's behavior. The implication of this research lies in enhancing the understanding of pile foundation response to complex loading conditions, providing valuable insights for optimizing foundation design in diverse geotechnical contexts. Highlights: Integrated Analysis: Comprehensive investigation of pile foundations, considering the combined effects of bending moments, transverse and longitudinal forces, offering insights into their holistic behavior. Material Resistance Assessment: Evaluation of calculated stresses in pile foundations, determining non-central compression or elongation, contributing to a refined understanding of cross-sectional resistance. Optimization Implications: Implications for geotechnical engineering, providing valuable insights for optimizing pile foundation design under diverse loading conditions, with potential applications in real-world structural projects. Keywords: Pile foundations, Combined loading, Cross-sectional behavior, Material resistance, Geotechnical engineering.

Nonlinear mechanical behavior and stress amplification effect correction of thin plate welded structure considering initial deformation

With the continuous development of light weight of ships, thin plate welded structures are widely used in superstructure of large hull structures and high-speed boats. However, the thin-plate welded structure has a special nonlinear mechanical behavior because of its small stiffness, more complicated welding deformation. The nonlinear mechanical behavior of thin plate welded structure is mainly caused by large slenderness ratio and complex initial buckling deformation, which can be characterized and quantified by defining global deformation angle αG and local deformation angle αL. Because of the welding angle deformation and welding dislocation, there is obvious stress amplification effect at the welding corner, but the traditional stress amplification correction formula is only suitable for thick plate welding structure. Aiming at the nonlinear mechanical behavior and secondary bending moment effect of thin plate welded structure, an analytical model of thin plate welded structure with initial deformation is established by combining theoretical derivation and numerical method. The results show that the additional bending moment effect caused by local welding deformation angle cannot be ignored. Finally, combined with a series of fatigue tests, the additional bending moment caused by bending deformation and angular deformation of typical welded joints is analyzed, and the notch stress field and fatigue strength correction of thin plate welded structures with initial defects are realized.

Elastic effect on the final deflection of rigid-plastic square plates under pulse loading

Rigid-perfectly plastic (R-PP) models are widely employed in the study of structural impact dynamics. However, due to the complexity of dynamic elastic-plastic behavior and the limitations of numerical simulation, it is of great significance to evaluate the elastic effect on the structural response to pulse loading. This paper examines the validity of the R-PP theoretical solutions on large deflection of pulse-loaded square plates. First, by exploring the characteristic of “plastic membrane” and considering the effect of membrane forces and bending moments on energy dissipation, an energy ratio R and a characteristic time ratio are precisely defined. Then based on the R-PP complete solutions recently developed for square plates under rectangular pressure pulse, the discrepancies in final deflection and in saturated impulse between the R-PP theoretical predictions and the elastic-perfectly plastic (E-PP) simulation results are evaluated and elaborated. It is revealed that the discrepancy in final deflection is dependent on the dimensionless stiffness ζplate and the dimensionless pulse magnitude λ. Moreover, the discrepancies in final deflection are compared between square plates and beams via a thorough analysis of key parameters, indicating that most characteristics of the elastic effect are similar for both cases, i.e., the R-PP solutions for both square plates and beams can reliably provide theoretical predictions for engineering applications if energy ratios R>5, with no limitation on the pulse duration. With the same geometric and material parameters, however, the energy ratio R of square plates is about twice that of beams, the discrepancy in final deflection of plates is larger than that of beams, but the absolute value of the discrepancy in final deflection for the clamped square plates remains in the order of 1/(1.5R) and can be bounded by 1/[4λ(λ-1)].

Experimental and numerical study on a precast partially connected buckling-restrained arc-opening steel plate shear wall

With the goal to decrease the detrimental bending moment effect of the steel plate shear wall (SPSW) on the frame, the frame's material waste and section requirements, and facilitate the arrangement of building equipment and pipelines, three one-third scale novel SPSW were designed and tested, including two four-sided partially connected buckling-restrained SPSW (PPBSW, PPBASW), and one non-buckling-restrained SPSW (PPASW). The damage pattern, hysteresis curve, stiffness degradation, energy dissipation capacity, and ductility were explored under consideration of arc openings and equipped with buckling-restrained concrete slabs. The outcomes shown that: The buckling-restrained concrete slab efficiently inhibited the low-order buckling of SPSW and enhanced the seismic performance of the steel shear wall. Compared to specimen PPASW, an increment in the bearing capacity for specimens PPBASW and PPBSW, was 55.4% and 61.3%, respectively. The corresponding initial stiffness increased by 41% and 43% due to the existence of the covered concrete slabs. There was a harmless difference in energy dissipation, secant stiffness, and bearing capacity for specimens PPBSW and PPBASW, indicating that the material's utilization and contribution had been improved. Moreover, finite element models (FEM) were established based on ABAQUS, showing a good fit between the test curves and simulation results, an error within 6.5%. Furthermore, a series of design parameters analysis for specimen PPBASW were carried out based on the established FEM. Following that, based on the test and simulation results, theoretical models for calculating the shear-bearing capacities of specimens PPASW, PPBAW, and PPBASW were developed, with the yield-bearing capacity and ultimate bearing capacities of PPBASW having maximum calculation errors of no more than 7.5% and 3.6%, respectively.

Flexural behavior of circular concrete filled steel tubular members strengthened by CFRP sheets

The flexural behavior of CFRP-strengthened circular concrete filled steel tubular (CFRP-C-CFST) members was investigated experimentally and theoretically. A total of nine specimens were tested through four-point bending method, including a comparative CFST specimen without CFRP strengthening (C-CFST), and eight CFRP-C-CFST specimens. Based on experimental results, the effects of different CFRP wrapping length, number of CFRP layers and wrapping schemes on the flexural behavior of the CFRP-C-CFST specimens are analyzed. Two failure modes, including CFRP debonding and CFRP fracture, are observed from the tested CFRP-C-CFST specimens. Increasing the length of CFRP delays debonding, while increasing the number of CFRP layers causes debonding to occur earlier. The flexural capacity of CFRP-C-CFST specimens with two-four CFRP layers is increased by about 20%-70% compared to the C-CFST specimens. A theoretical model based on fiber element method is proposed. This model considers the bi-directional stress state of the steel tube and the effect of bending moment on the confinement factor. A representative test result is selected to calibrate the distribution law of the confinement factor, and all the test results are predicted based on the calibrated parameters. The comparison between the predicted and the test results shows that the fiber element model can simulate the bending moment-deflection curves of C-CFST and CFRP-C-CFST members, and hence it can predict the flexural capacity, stiffness and ductility accurately.

A numerical and experimental analysis of noncircular blank spinning

The process of conventional spinning has been widely used in the production of sheet metal parts, but nearly in all cases, the initial blank of the process has a circular shape. In this article, the novel idea of spinning non-circular blanks is studied. To do so, an octagonal blank made of AL-1050 was chosen and the experimental works as well as numerical simulations, taking the effects of anisotropy into account, were performed. Shape deviation from the ideal form in terms of springback and strain distribution was studied for the deformed component. The numerical simulations revealed that uneven compressive strains at the edges as well as bending moment effects at the edges are responsible for the specific shape deviation in the final geometry. The comparison between the anisotropic and isotropic behavior of shell and solid elements with experimental results in three different thicknesses showed the shell element predicts the springback phenomena better than the solid element. On the other hand, solid element gives better results in the prediction of major and minor strains. The results of the numerical simulations and the experimental works show that more variety of geometries that would otherwise need an extra cutting process can be produced by deviating the initial blank geometry from circular form.

Behavior and Capacity of Moment-Frame Members and Connections during Fire

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.

Abutment-Bar Structure Connection Geometry: An Important Design Parameter for Implant-Supported Bar-Retained Overdentures With Cantilever Extension.

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.

Mechanical analysis of finned special-shaped tubes in bending-torsional coupling deformation

Because of the excellent thermal conductivity and increased strength, finned special-shaped tube (FSST) is frequently utilized in a variety of industrial applications. However, duo to the complex section structure of FSST, the elastic–plastic evolution of the FSST section is more complex than that of circular and rectangular tubes, when FSST is subjected to various coupling effects of bending moment and torque. Moreover, until now, no literature has studied the bending-torsional-coupled deformation of FSST. In this study, based on the power-law stress–strain curve model and the Henky-Ilyushin equations, an analytical model that can precisely characterize the bending-torsional-coupled deformation of the FSST section is established by using the stress method. According to the boundary conditions divided by the geometric characteristics of FSST, the stress and strain distribution, elastic–plastic evolution, and the coupling relationship between the base circle and fins under different bending radii and unit torsion angles are discussed in detail. Besides, the relationship between bending radius and unit torsion angle and bending moment and torque on the section is presented based on the concept of section moment superposition. Finally, the rationality and accuracy of the proposed analytical model are verified by simplified finite element model (FEM), FEM, and practical tests.

Mechanical properties of corrugated steel lap joint under combined compression and bending

The lap joint of a prefabricated corrugated steel structure is one of the most critical components to be considered during design. Full-scale mechanical tests under combined compression and bending (N–M) were conducted to investigate the effect of axial forces and bending moments on the mechanical behavior of lap joints. Numerical methods were used to examine the effects of different axial forces on the bending behavior of the joint. Analysis revealed that buckling of the corrugated steel plate lapped on the upper layer, located near the innermost row of bolt holes, was the failure mode of the lap joint. The yield of the bolt holes on the compression (crest) and tension (valley) sides was accelerated and postponed by the axial force, respectively. Additionally, three phases with linear, nonlinear, and linear characteristics were identified from the bending moment-rotational angle (M–θ) curves. The initial rotational stiffness of the joint was the highest and decreased gradually with increasing axial force. The residual rotational stiffness of the joint was minimal and was only minimally affected by the axial force. A greater axial force on the joint lowered the bending capacity. Compared with N = 0, when N = 1200 kN, the corresponding bending moment decreased by approximately 17.1% and 9.6% for θ = 0.02 and 0.1, respectively. An empirical formula for calculating the joint rotational stiffness (Kθ) was proposed based on the N–M–Kθ relationship. These findings provide a reference for the joint design of prefabricated corrugated steel structures.