Torsional Moment Research Articles

Ultimate load-bearing capacity of reinforced concrete pylon under dynamic loading with bending and torsional moments

Ultimate load-bearing capacity of reinforced concrete pylon under dynamic loading with bending and torsional moments

Real-time prediction of wave-induced hull girder loads for a large container ship based on the recurrent neural network model and error correction strategy

Real-time acquisition of wave-induced hull girder loads of a sailing ship will help the captain make reasonable decisions, which is of great significance for improving the safety of the ship's navigation. This paper investigates the real-time prediction method of hull girder loads based on the Recurrent Neural Network (RNN) model and error correction strategy. Firstly, taking the vertical bending moment, horizontal bending moment, and torsional moment at the mid-ship position of a large container ship as examples, corresponding neural network prediction models are established through parameter influence analysis. Secondly, various sea state conditions are used to verify the feasibility of established network prediction models to predict the hull girder loads in real-time. The VBM prediction model performs better than the TM prediction model and HBM prediction model, and the errors of the TM prediction model and HBM prediction model are slightly larger in some cases. Lastly, an improved prediction model based on an error correction strategy is proposed to improve the prediction accuracy of the neural network prediction model, and the adequate performance of the error correction strategy is discussed.

Marked differences between continuous long-term and clinical snapshot examinations: is the current standard of back pain diagnostics outdated?

Current clinical examination of low back pain (LBP) patients primarily relies on static clinical examinations, which rarely represent the dynamic postures patients adopt during daily activities. To gain an overview on the dynamic kinematics-kinetics changes over a day, the lumbar back kinematics of asymptomatic individuals and LBP patients were measured over 24h, and the passively resisted bending and torsional moments were estimated. 208 asymptomatic subjects (115 females) and 116 LBP patients (71 females) were analysed. Compared to static upright standing, the mean lumbar lordosis of asymptomatic subjects drops significantly by 21° during everyday life (p < 0.01). Maximum bending moments of 44.0-50.6Nm were estimated at the L2-L3. LBP patients showed significantly lower (p < 0.01) lumbar flattening during daily life of about 16°. Maximum bending moments of 27-52Nm were found at the L3-L4. The initial static upright lumbar lordosis was significantly lower in LBP population (by 6°) resulting in almost similar average lumbar shapes during daily activities in both groups. The torsional movements were with 2.2° greatest in L1-L2 independent of sex (p = 0.19) and LBP (p = 0.54) with moments of 6-16Nm. The lumbar profile and associated internal moments during daily life differ substantially from those recorded during clinical examinations. LBP patients demonstrates significantly lower lordosis at the snapshot assessment and significantly lower movement variations and internal moments during daily life. Only the dynamic long-term assessments unravelled a less flexed posture in LBP population. Apparently, such a reduced dynamic flexed posture indicates a compensatory habit for pain relief.

Creep–fatigue damage assessment in high-temperature piping system under bending and torsional moments using wireless MEMS-type gyro sensor

Creep–fatigue damage assessment in high-temperature piping system under bending and torsional moments using wireless MEMS-type gyro sensor

Comparative analysis of seismic performance enhancement in irregular RC buildings using friction and viscous dampers

The purpose of this study is to demonstrate the impacts of friction dampers (FD) or fluid viscous dampers (FVD) in irregular (in plan and elevation) reinforced concrete (RC) buildings. The buildings (a four-story, a nine-story, and a twenty-story skyscraper) were analyzed using nonlinear dynamic time-history analysis on earthquake-recorded accelerograms, three of which were real while the other four were artificial. For this purpose, 70 nonlinear dynamic analyses were carried out. This paper describes the optimal design of FDs and FVDs, with a focus on minimizing the following parameters: (i) maximum displacement (top of the structures), (ii) building torsion, and (iii) maximum horizontal inter-story drift. Two different placements of the dampers have been studied in each building. The consequences of each strengthening method are shown, and other relevant results were obtained from this creative comparison (optimal design, two passive energy systems, and three different story numbers). The comparable results show that in low-rise structures, FD was more successful than FVD in reducing torsional moment; however, in medium and high-rise buildings, VDF was more effective at improving the seismic performance of the structures.

Efeitos de interferência nas cargas do vento prescritos por códigos e normas: eles podem ser generalizados?

Abstract Understanding and quantifying the effects of aerodynamic interference is fundamental to designing safe and efficient buildings; however, there is a complexity in this phenomenon that characterizes it as the greatest challenge of wind engineering and thus limits improving design guidelines in a normative way. Therefore, this study investigated the impacts of building interference on wind-induced loads on a tall building through wind tunnel tests conducted using the synchronous pressure measurement technique. This impact was quantified using the interference factors (IFs) on the along-wind, across-wind and torsional force coefficients, which were mapped considering different wind angles, relative positions and number of buildings, in addition to the terrain roughness. It was observed that the protection effect in a static analysis is a dominant phenomenon in most studied scenarios when there is wind interference. The largest extension of the amplification zones occurred in scenarios in which the wind blew against the smallest facade of the analyzed building and the largest facade of the interfering building, where the coefficient of torsional moment was more sensitive to changes in wind turbulence.

Multilayered Inhomogeneous Beams under Torsion and Bending: An Analytical Study of Energy Dissipation

The present theoretical paper is devoted to the problem of energy dissipation in multilayered inhomogeneous beam structures of visoelastic behaviour. In particular, our attention is concentrated on studying the energy dissipation for the case of a beam that is loaded simultaneously in torsion and bending. Both torsion and bending moments which are applied on the beam change with time so that the angles of twist and rotation of the beam end vary continuously with time. The viscoelastic mechanical behaviour of the beam under torsion is treated by a viscoelastic model that has two linear springs and a linear dashpot. The model is under time-dependent shear stress. The viscoelastic behaviour of the beam under bending is modelled in a similar way. An analytical approach of deriving the energy dissipation is applied. The approach treats a multilayered beam that has an arbitrary number of layers of different thicknesses and material properties. The layers are longitudinally inhomogeneous. An investigation of the energy dissipation is carried-out to clarify the effect of the parameters of the time-dependent bending and torsion moments, the material inhomogeneity and the beam size on the energy dissipation.

Linear Longitudinal Strength Analysis of a Multipurpose Cargo Ship under Combined Bending and Torsional Load

Cargo ships with wide hatches usually have thin walls and limited torsional rigidity. Consequently, conducting a comprehensive torsional analysis is important because these loads can exert a significant impact. In this paper, the structural response of a multipurpose cargo ship to combined bending and torsional loads is studied using finite element analysis. The bending and torsional moments are calculated following the rules and standard regulations followed by the classification society. The ship’s 3D finite element model was verified using beam theory and direct calculations. In contrast, the accuracy of torsional stress was confirmed by comparing thin wall girder theory with direct calculation results. This study thoroughly examined the impacts of the still water bending moment, the vertical wave bending moment, and the wave-induced torsional moment on the structural response of ships. Furthermore, it scrutinised the impact of torsion on both open-deck and closed-deck ships. Hull girder normal stresses at midship due to still water and the vertical wave bending moment are shown to contribute to almost 70% of total stress in an inclined condition; stresses resulting from the horizontal wave bending moment contribute nearly 10%, while warping stresses contribute approximately 20% in open-deck ships. It is also shown that torsion has little impact on closed-deck ships. Finally, a buckling analysis was conducted to assess the ship’s buckling criteria, confirming that the linear buckling criteria were satisfied.

Seismic behaviour of the curved bridge with friction pendulum system

ABSTRACT The friction pendulum system (FPS) is a crucial tool for seismic protection. However, effectiveness in curved bridges, especially controlling torsional moments (TMs), has not been thoroughly assessed. This study evaluates how well a continuously curved bridge equipped with FPS performs under various earthquake loadings. The study assesses FPS efficiency, considering factors like multidirectional impacts, seismic motion strength, incidence angle variations, and ground motion characteristics. Finite element modeling of the bridge structure was conducted using SAP2000v20 Finite Element Analysis software. Three earthquake scenarios (near fault, far fault and forward directivity) were considered. The study also examines the bidirectional behavior’s impact on the bearing and pier interaction. A sensitivity analysis was performed for the bridge response concerning bearing design parameters for each earthquake scenario. The results show that FPS bearings significantly reduce the bridge’s seismic response. Bidirectional excitation was found to be critical for curved bridges, increasing displacement compared to unidirectional motion. Under unidirectional excitation, the isolated bridge with FPS reduces TMs by approximately 26–54%. In bidirectional excitation, FPS remains effective, reducing TMs by about 14–43%. This study underscores the importance of FPS in enhancing seismic resilience, particularly in controlling torsional responses in complex, curved bridges in varying seismic conditions.

Behaviour of circular concrete bridge columns internally reinforced with GFRP under reversed-cyclic loading including torsion

This study investigates experimentally the behaviour of circular reinforced concrete (RC) bridge columns internally reinforced with glass-fiber-reinforced polymer (GFRP) bars and spirals under cyclic combined loading conditions of bending, shear, and torsion. The study involved testing four large-scale column-footing connections, including one steel and three GFRP-RC columns. The effects of the reinforcement type (GFRP and steel) and torsion-to-bending ratios (tm) (0, 0.2 and 0.4) on seismic indexes, such as mode of failure, deformation and twist capacity, hysteretic responses, energy dissipation, ultimate strength and stiffness were evaluated. The results showed that the mode of failure varied according to the tm. Under combined loading with a tm of 0.2, both GFRP-RC and its steel-RC counterpart specimen were able to sustain similar lateral load and torsional moment capacities. Moreover, under the effect of combined loadings, the GFRP-RC columns showed a stable seismic response with adequate deformability. The GFRP-RC columns exhibited a decrease in ultimate lateral load and displacement capacity with increasing tm, however, their torsional moment carrying capacity increased. All GFRP-RC columns met the ductility requirements of North American codes, while their torsional stiffness degraded faster than their bending stiffness under combined torsion and bending loadings.

Application and Experimental Validation of Seven-Degree-of-Freedom Beam Element for Girder Bridges during Deck Construction

During bridge deck construction, the deck finishing machine and the fresh concrete often produce large vertical loads and torsional moments acting on the bridge girder system. In some cases, these loads can cause excessive vertical deflection and transverse rotation in the bridge girders, leading to many maintenance and safety problems, such as changes in deck thickness and local and global instabilities during construction. To minimize the potential problems caused by deck construction, the AASHOTO LRFD Bridge Design Specification requires consideration of these torsional moments during the design procedure, and a detailed three-dimensional finite element analysis may be conducted. However, for bridge girders with open-section thin-walled sections, only the solid or shell element can be used to recognize the warping of the girder since the torsional warping effect is not included in the classical beam element. In this research, a warping degree of freedom was added to a beam element, and a three-dimensional beam element with seven degrees of freedom (7-DOF) at each node was derived as an alternative method for analyzing girder bridges during deck construction. A computer program based on the 7-DOF beam element was also developed in MATLAB. To assess the 7-DOF beam element, one bridge was selected to measure the transverse rotation, vertical deflection, and stress of the exterior girder and the first interior girder during deck construction. Also, three full-scale numerical models using solid elements, classical three-dimensional beam elements, and 7-DOF beam elements were created based on the geometries and loads of the experimental bridge. A comparative study was conducted by comparing the results from the numerical models and experimental monitoring data to evaluate the 7-DOF beam element. The results showed that the 7-DOF beam element had excellent behavior in analyzing the girder bridges under construction load, especially in the torsional analysis of bridge girders. Also, unlike the solid element model, which also provided reasonable results, the 7-DOF beam element model can compute the internal forces of the cross-sections along the bridge, which allows the 7-DOF beam element to be an alternative approach for design and research requiring less modeling effort and computational complexity.

Research on cord-laying angle and mechanical balance of rolling lobe air springs

The inflation of the rubber bellow leads to flexion and deformation during the operational process. The cord, serving as the primary load-bearing element of the rubber bellow in air springs, undergoes continuous changes in angle due to bending, torsion, and internal stress and moment within the bellow. This alteration causes the resultant force on the cord to deviate from its original direction, disrupting the force balance of the bellow and subsequently diminishing its fatigue life. To identify an optimal cord-laying angle that minimizes deviation from the cord's direction under the resulting force during operation, a theoretical model is established for the rubber bellow in rolling lobe air springs. This model is based on thin shell momentless theory and a force analysis of bellow micro-elements. The mapping relationship between the inflated cord angle and the uninflated cord-laying angle is examined. Furthermore, the dynamic variation of the cord angle along the longitudinal direction after the inflation of the rubber bellow is explored in this article. Additionally, a novel indirect measurement method for determining the outer diameter of the bellow is proposed to acquire the cord angle. This method is employed to verify the validity of the optimal cord-laying angle and the finite element model. The results indicate that the optimal setting interval Y for the cord-laying angle of sample A is [45°, 47°]. This finding not only offers theoretical support for the forming process of rubber bellows in rolling lobe air springs and the optimization of bellow characteristics but also introduces a new approach for measuring cord angle variations.

Study of Zero Gravity Unloading Effect of Mechanical Steerable Satellite Antenna

Due to the limitations of self-structure and test conditions, the actual unloading point is difficult to coincide with the theoretical centroids in a mechanically steerable satellite antenna’s ground zero gravity simulation test. There is a residual moment of unloading. Three-axis mechanical steerable antenna was taken as the research object. Based on a suspension system, the static models of antenna unloading under vertical and horizontal deployment modes were established. The general formula of the joint residual moment was derived. The influence of deployment mode on the joint torsional moment under different working stages was studied. The result shows that the joint torque in the horizontal deployment test is much better than that in the vertical deployment test, with low data peaks and good stability. The horizontal deployment test is preferred for the ground test. The method has been successfully applied to the antenna development of multiple satellites. It has practical guidance and application value for subsequent similar antenna unloading scheme designs.

Numerical study on the torsional behavior of CFRP-strengthened RC beams

The present paper offers a numerical study on the behavior of reinforced concrete (RC) beams strengthened with carbon fiber reinforced polymer (CFRP) under pure torsional loading. The failure mode of RC beams significantly changed in accordance with torsional loading. Therefore, the effect of strengthening RC beams by CFRP under torsion is a vital area of study. This paper attempted to fill the gap by conducting a numerical (Abaqus) study, whereby the numerical investigation was in line with the parametric for a previous study of an experimental program. The numerical model achieved agreement with the results of the experimental program, then, this model was used by applying CFRP, instead of GFRP. Additionally, the numerical study was completely in line with the parametric study in terms of sample dimensions, steel reinforcement, number of FRP layers, and width of FRP strips, for the aim of comparing results. The comparative evaluation in this study aims to contrast the behavior of RC beams strengthened by CFRP with the behavior of those strengthened by GFRP under pure torsion. Parameters such as ultimate torsional moment, and the maximum angle of twist were studied. The study revealed that strengthening with CFRP improved the ultimate strength and post-cracking stiffness, in addition to localizing the damage.

A monitoring method of hull structural bending and torsional moment

The online identification of wave bending and torsional moment can be used for hull structural safety monitoring, that is, identifying the wave bending and torsional moment of the key cross section of the hull structure, comparing it to the threshold of the bending and torsional moment of the cross section, and finally evaluating the safety of the hull structure online. Therefore, the premise of the aforementioned structural safety monitoring is to accurately identify wave bending and torsional moments. For hull structures without large openings, a stable and high-precision method for identifying the wave bending moment is proposed, in which the position where the long baseline strain gauge (LBSG) installed is optimised using C-optimal and D-optimal design methods, and the mathematical model of the proposed method is established using a full-ship finite element simulation. The accuracy of the method for identifying the wave bending moment was verified using several numerical examples and the on-site monitoring of a large semi-submersible vessel. The results of the numerical simulations and onsite monitoring showed that the method for identifying the bending moment has high accuracy. For hull structures with large openings, a joint dual-section monitoring method (JDSMM) is proposed, in which two adjacent cross sections of the hull structure are monitored simultaneously; the vertical and horizontal bending moments, free torsional moment, and bimoment of the two cross sections being monitored are first identified, and then the bending and torsional moments of the middle section are obtained. The accuracy of the JDSMM was verified using several time-domain numerical examples. The results of the numerical simulations indicated that the JDSMM can accurately identify wave bending and torsional moment.

Stability of cylindrical anisotropic composite shells under torsion in a three-dimensional formulation

The article presents a calculation of the stability of non-thin cylindrical anisotropic layered shells under the action of end torsional moments in a spatial formulation. The anisotropy of the used material is characterized by one plane of elastic symmetry of characteristics. This is caused by the mismatch between the main elastic directions of the composite fibrous orthotropic material and the axes of the curvilinear cylindrical coordinate system.&#x0D; A three-dimensional inhomogeneous system of partial differential equations describing the subcritical stress-strain state within the linear theory of elasticity is derived using the Hu-Washizu variational principle. Reducing the dimension of the problem under consideration from three-dimensional to one-dimensional is carried out by taking into account the axial symmetry of the deformation of the cylindrical shell and using the method of straight lines along the generatrix.&#x0D; Based on the modified Hu-Washizu variational principle, a three-dimensional system of homogeneous partial differential stability equations is derived within the framework of the spatial theory of elasticity. The reduction of a three-dimensional system to a one-dimensional one is carried out along the generatrix and in the circular direction - by expanding the components of stresses and displacements into double trigonometric series when applying the procedure of the Bubnov-Galorkin method, as well as taking into account the periodicity of the resolving functions.&#x0D; An algorithm has been developed, implemented in the form of application software packages for PCs. In it, in a single computational process using the numerical method of discrete orthogonalization in the direction normal to the middle surface of the shell, the establishment of the parameters of the subcritical stress-strain state and the solution on this basis of stability problems for non-thin anisotropic cylindrical shells under the influence of torsion are combined.&#x0D; The problem of the influence on the stability of an anisotropic cylindrical non-thin shell of an increase in the number of cross-reinforced layers depending on the angle of rotation of the main directions of elasticity of the material and the direction of application of torque is considered. The obtained results of stability calculations according to the proposed approach were compared with critical torsion loads calculated using an orthotropic model for calculating anisotropic shells. It is shown that for single-layer cylindrical shells the difference between the compared results reaches 69%. An increase in the number of cross-reinforced layers leads to a decrease in this discrepancy, and with seven to eight layers, the difference between the critical loads obtained using the described approach and the orthotropic model is within 5%. This result is consistent with those obtained using classical or refined theories of calculations of both thin and non-thin anisotropic cylindrical shells.

Long-term extreme responses of torsional moments at two-directional hinges for moored very large floating structures

This paper presents an analysis procedure for estimating long-term extreme torsional moments at connections of very large floating structures (VLFS) with two-directional hinges and mooring lines under random waves. This procedure, compared to the common short-term estimation method, can accurately and quickly calculate the extreme response at a certain return period. Applying a coupled frequency-time domain approach, we simulate the hydroelastic response of VLFS with two-directional hinges and vertical mooring lines. In order to validate the proposed approach, numerical simulations are firstly carried out under the action of regular waves. The present approach demonstrates a high level of consistency with experimental data and numerical results from existing studies in terms of vertical displacement, bending moment and shear force. Then, on the basis of the short-term extreme response distribution and environmental model, a procedure for solving long-term extreme responses of the structure is introduced. The long-term extreme response characteristics of the torsional moment at hinges are evaluated and studied in depth using the procedure, providing a reference for the structural design of moored VLFS with two-directional hinges.

Experimental Investigations of the Detachment of Different Particle Structures from a Magnetizable Fiber in the Gas Phase

A current subject of research is the application of magnetic effects for the detachment of accumulated particles of fibrous collectors in gas particle separation. Initial studies have already shown the magnetically induced detachment behavior of a compact particle structure after a single deflection from a single fiber. In this study, the detachment behavior of particle structures with different morphologies from a single fiber is investigated as a function of the particle loading stage on the fiber, the external magnetic flux density, the inflow velocity and the number of regenerations of the fiber for a certain parameter range. Diffusive and more compact particle structures with non-magnetic properties are deposited on the magnetizable single fiber. By applying an external magnetic field, the fiber is magnetized and experiences a torsional moment. The deposited particle structures on the fiber are detached by the acceleration forces. The detachment of the particle structures is observed using a high-speed camera and the image sequences are analyzed. By determining the projection area before and after the fiber deflection, a degree of regeneration is calculated. With magnetic-induced regeneration, high degrees of regeneration close to 100% can be achieved. Repetitive fiber deflections improve the detachment of the particle structures. The magnetic-induced regeneration is suitable for applications where flow reversal is not possible and can be performed either online or offline. Due to the gentle regeneration, fewer emissions are produced on the clean gas side than, for example, with jet pulse cleaning. It makes it easier to achieve emission limits and simplifies product recovery.

Determination of the actual deflection of the cutting tool ın turning by the Castigliano theorem

The turning method is a widely utilized technique in machining. The effect of machining parameters on the machining quality in turning is quite high. A longer tool overhang reduces tool rigidity, leading to increased tool deflection and subsequently, a decrease in machining quality. The tool overhang should be as short as possible in order to reduce tool deflection and eliminate the negative effects of vibration. Another critical factor affecting machining quality, as much as the tool overhang length is the distance between the main cutting edge and the tool holder axis. In the turning process, the alteration of the main cutting-edge position significantly influences the amount of tool deflection. When the main cutting edge is positioned farther from the tool holder axis, it generates a greater torsional moment effect, which negatively impacts machining quality. However, although the main cutting edge position of the turning tool has a great effect on the machining quality, it has not been adequately explored in the existing literature.This study examines how deflection values vary concerning the deviation of the main cutting edge from the tool holder axis using various methods and compares the results. In contrast to the commonly used deviation equation, this research applies the Castigliano theorem, which provides results much closer to actual tool deflection values. The outcomes derived from the Castigliano theorem are then compared with finite element analysis (FEM) and experimental studies. The proposed theoretical approach aligns well with the experimental results, highlighting the significance of considering torsional moments alongside bending moments as they both play a substantial role in tool deflection.

The elasto-plastic numerical study of crack initiation in notched PMMA specimens under uniaxial loading conditions – Tension and torsion

This paper presents the results of FEM numerical calculations aimed at describing the plastic strain and stress fields under critical loading conditions: tensile force or torsional moment. The calculations were carried out with reference to the results of experimental tensile and torsional tests of flat PMMA specimens weakened with V-notches of different root radii: 0.5, 2 and 10 mm. The procedure for conducting nonlinear numerical analyses is described, including the determination of the actual hardening curve by the hybrid method. A high level of consistency between the results of the experimental and numerical calculations was obtained through description of PMMA with the elastic–plastic material model. The points of occurrence of stress maxima and plastic strain were indicated, which were taken as potential crack initiation sites. On the basis of the stress and plastic strain values measured at the critical points, a stress–strain fracture criterion was formulated, which was then positively verified.