Journal articles on the topic 'Limiting bending moment'
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1
Fang, Shu Tian, Ying Zhang, and Wen Zhao Zhong. "Nonlinear Finite Element Analysis on Statically Indeterminate Prestressed Concrete Beam." Advanced Materials Research 482-484 (February 2012): 647–50. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.647.
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Embarked from the ductility theory, the bending moment amplitude modulation limiting value ductility expression which satisfies the bearing capacity requirements have been deduced，on the value of the bending moment amplitude modulation coefficient, the influence of the using stage crack width limiting value has been considered, and the suggesting formula of the bending moment amplitude modulation coefficient has been proposed. With the aid of APDL language in the ANSYS, the entire process force analysis to statically indeterminate prestressed concrete beam has been carried on, the finite element computed result and the experiment result has been confirmed, through the example drew correlation curve, confirmed with the experiment, the beam's ultimate bearing capacity has been discussed, and the plastic hinge's formation and the influence of moment redistribution to the ultimate bearing capacity has been analyzed.
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GUPTA, RAJ K., SHAM S. MALIK, J. S. BATRA, PETER O. HESS, and WERNER SCHEID. "PHENOMENOLOGY OF NUCLEI AT VERY HIGH ANGULAR MOMENTA USING PARAMETRIZED TWO-CENTER NUCLEAR SHAPES." International Journal of Modern Physics E 04, no. 04 (December 1995): 789–800. http://dx.doi.org/10.1142/s0218301395000262.
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The nuclear shapes and variation of moment of inertia with angular momentum, as well as the limiting angular momentum carried by a nucleus at its fissioning stage, are derived from the observed data of the ground-state yrast band and quadrupole deformations of these states. The necking-in of the nuclear shapes are shown to start already at J*~14+−18+. The empirical variation of moment of inertia with angular momentum is found to include the back-bending and forward-bending effects and supports the nuclear softness model of the nucleus. The fission of nuclei is shown to occur at very high angular momenta, which is different for different nuclei. The role of deformation energy is analyzed and the possibility of predicting the quadrupole deformations, or B(E2) transitions, for very high spin states is discussed. The calculations are presented for 156Dy, 158Er, and 164Hf.
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Yee, Albert G., and C. Daniel Mote. "Forces and Moments at the Knee and Boot Top: Models for an Alpine Skiing Population." Journal of Applied Biomechanics 13, no. 3 (August 1997): 373–84. http://dx.doi.org/10.1123/jab.13.3.373.
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The purpose of this study was to identify regression models to predict moments at the boot top and knee from the force components at the bindings for a sample of skiers. Six subjects skied a slalom course, first with their boots set to the least stiff setting and then with their boots set to the most stiff setting. Six load component dynamometers measured force and moment components at the toe and heel bindings. An electrogoniometer measured ankle flexion. Regression models were developed for the subject sample that predicted quasi-static moment components at the boot top and knee from measurements of ankle flexion and the quasi-static force components at the bindings. Large anterior bending moment was not necessarily accompanied by large ankle flexion, which emphasized that binding designs and standards for injury prevention must account for forces and moments at the sites of potential injury, rather than limiting consideration to boot stiffness or forces at the bindings.
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Petranović, Tamara, Antonio Mikulić, Marko Katalinić, Maro Ćorak, and Joško Parunov. "Method for Prediction of Extreme Wave Loads Based on Ship Operability Analysis Using Hindcast Wave Database." Journal of Marine Science and Engineering 9, no. 9 (September 14, 2021): 1002. http://dx.doi.org/10.3390/jmse9091002.
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The method for the prediction of extreme vertical wave bending moments on a passenger ship based on the hindcast database along the shipping route is presented. Operability analysis is performed to identify sea states when the ship is not able to normally operate and which are likely to be avoided. Closed-form expressions are used for the calculation of transfer functions of ship motions and loads. Multiple operability criteria are used and compared to the corresponding limiting values. The most probable extreme wave bending moments for the short-term sea states at discrete locations along the shipping route are calculated, and annual maximum extreme values are determined. Gumbel probability distribution is then fitted to the annual extreme values, and wave bending moments corresponding to a return period of 20 years are determined for discrete locations. The system reliability approach is used to calculate combined extreme vertical wave bending moment along the shipping route. The method is employed on the example of a passenger ship sailing across the Adriatic Sea (Split, Croatia, to Ancona, Italy). The contribution of the study is the method for the extreme values of wave loads using the hindcast wave database and accounting for ship operational restrictions.
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Becht, C. "Behavior of Pressure-Induced Discontinuity Stresses at Elevated Temperature." Journal of Pressure Vessel Technology 111, no. 3 (August 1, 1989): 322–25. http://dx.doi.org/10.1115/1.3265682.
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Conventional wisdom has been that discontinuity bending stresses at temperatures within the creep regime are self-limiting, and therefore secondary. A series of creep relaxation analyses were performed on typical discontinuities (junctions). The analyses show that, in general, discontinuity bending moment and stress due to pressure do not relax, but remain more or less constant with time. These stresses should therefore be evaluated as primary. A creep follow-up mechanism was identified that sustains the discontinuity stresses. The implications for design are discussed.
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Wiśniewski, Jan, Krzysztof Rogowski, Konrad Gumowski, and Jacek Szumbarski. "Wind tunnel comparison of four VAWT configurations to test load-limiting concept and CFD validation." Wind Energy Science 6, no. 1 (February 24, 2021): 287–94. http://dx.doi.org/10.5194/wes-6-287-2021.
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Abstract. The article describes results of experimental wind tunnel testing of four different straight-bladed vertical axis wind turbine model configurations. The experiment tested a novel concept of vertically dividing and azimuthally shifting a turbine rotor into two parts with a specific uneven height division in order to limit cycle amplitudes and average cycle values of bending moments at the bottom of the turbine shaft to increase product lifetime, especially for industrial-scale turbines. Testing reduction effects of simultaneously including a vertical gap between turbine rotor levels, increasing shaft length but also reducing aerodynamic interaction between rotor levels, has also been performed. Experiment results have shown very significant decreases of bending moment cycle amplitudes and average cycle values, for a wide range of measured wind speeds, for dual-level turbine configurations as compared to a single-level turbine configuration. The vertical spacing between levels equal to a blade's single chord length has proven to be sufficient, on laboratory scale, to limit interaction between turbine levels in order to achieve optimal reductions of tested parameters through an operating cycle shift between two position-locked rotor levels during a turbine's expected lifetime. CFD validation of maintaining the effect on industrial scale has been conducted, confirming the initial conclusions.
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Vales, Jan, Zdenek Kala, and Jindrich Melcher. "Application of Fuzzy Set Theory to the Serviceability Limit State of a Steel Beam under Bending." Applied Mechanics and Materials 769 (June 2015): 91–96. http://dx.doi.org/10.4028/www.scientific.net/amm.769.91.
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Deformations of an I-section steel beam under equal end moments are studied in this article. Initial geometric imperfection of the beam axis was introduced according to the Eurocode standard. Numerical studies have shown that the lateral deflection of slender beams under major axis bending can be relatively high. The acceptability of high values of lateral deflections within the framework of the serviceability limit state is discussed. In the next part of the paper, the limit value of maximum deflection was introduced as a fuzzy number. Fuzzy analysis of the maximum moment, which causes maximum deflection, was performed. The slenderness values of beams for which the serviceability limit state is the limiting condition for design were identified.
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REN, Zhigui, Junli WANG, Zhihong ZOU, Yanyan WANG, and Haojie ZHU. "Modeling of the limiting digging force of hydraulic excavator based on resistance characteristics." Mechanics 25, no. 5 (October 22, 2019): 357–62. http://dx.doi.org/10.5755/j01.mech.25.5.22805.
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Based on the resistance characteristics, a model of theoretical digging force was proposed in this paper, taking the tangential force, the normal force, and the bending moment into account simultaneously. Utilizing the relation among the normal resistance, the resistance moment, and the tangential resistance in practical digging process, three independent unknown quantities are transformed into only one variable. Afterwards, according to different digging patterns and complete machine limiting conditions, this research derived the constraint inequalities of the limiting digging force (LDF) and established the calculation models for LDF. Then, based on the value distribution laws of the digging resistance coefficient and the resistance moment coefficient, the calculation process and corresponding method of LDF under a given digging posture were obtained. Taking the digging resistance obtained by testing for 35 t hydraulic excavator with backhoe attachment as the reference, this paper compared the calculation results of the theoretical digging force for complete machine with those of the LDF model proposed in this research. The comparative results indicate that the LDF is consistent with the fact that the theoretical digging force is larger than or at least equal to the actual digging resistance. So, the LDF can exactly show the real limiting digging ability of the excavator more accurately. In this way, it can provide basis for mechanism optimization, structural strength design, trajectory planning, and control automation of the excavator.
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Pasini, D., D. J. Smith, and S. C. Burgess. "Structural efficiency maps for beams subjected to bending." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 217, no. 3 (July 1, 2003): 207–20. http://dx.doi.org/10.1177/146442070321700303.
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The structural efficiency of different cross-sections subjected to bending is considered in this paper. An envelope efficiency parameter, λ, is defined in terms of two shape transformers, A and 1. These transformers describe the relative ratio of the area and the second moment of area of the cross-sectional shape with respect to a rectangular envelope surrounding the shape. It is shown in a structural efficiency map that the mass efficiency of all cross-sectional shapes subjected to bending is bounded by two limiting curves. One limit curve represents cross-sections with material as far as possible from the neutral axis, the other limit curve is for cross-sections with material close to the neutral axis. The application of the map to two practical cases is also considered, together with scaling of the rectangular envelope.
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Elliott, Kim S. "Comparison of the design of prestressed concrete hollow-core floor units with Eurocode 2 and ACI 318." PCI Journal 66, no. 2 (2021): 21–57. http://dx.doi.org/10.15554/pcij66.2-01.
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A typical 1200 mm (48 in.) wide × 200 mm (8 in.) deep prestressed concrete hollow-core unit is analyzed and designed in order to make a comparison between Eurocode 2 and ACI 318-08. This includes calculations for serviceability limit state of stress and moment of resistance, ultimate moment of resistance, ultimate shear capacities, flexural stiffness (that is, for deflection), and cover to pretensioning tendons for conditions of environmental exposure and fire resistance. Concrete cylinder strength is 40 MPa (5.8 ksi), and concrete cube strength is 50 MPa (7.3 ksi). The hollow-core unit is pretensioned using seven-wire helical strands. Worked examples are presented in parallel formation according to Eurocode 2 and ACI 318. For uniformly distributed loads, the design criterion between the service moment to service moment of resistance (Ms/Msr for EC2 and Ms/Msn for ACI 318) and the ultimate design bending moment to ultimate moment of resistance (MEd/MRd for EC2 and Mu/φMn for ACI 318) is well balanced for this example. Usually the service moment is critical unless the amount of prestress is small. For EC2-1-1, flexurally uncracked shear capacity VRd,c is only limiting when the span-to-depth ratio in this example is less than about 35. For ACI 318, flexurally cracked shear capacity φVci is limiting when span-to-depth ratio is 42, showing that shear cracked in flexure will often be the governing criterion.
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Talman, Richard. "Prospects for Electric Dipole Moment Measurement Using Electrostatic Accelerators." Reviews of Accelerator Science and Technology 10, no. 01 (August 2019): 267–301. http://dx.doi.org/10.1142/s1793626819300147.
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Electrostatic accelerators have played a glorious role in physics, especially for low energy atomic and nuclear physics and electron microscopy. But circular accelerators have depended almost exclusively on the far greater bending force possible with static magnetic, rather than electric, fields. There is a potential exception to this magnetic bending monopoly for experimental high energy elementary particle physics — it is the possibility of measuring the electric dipole moments (EDMs) of charged elementary particles, such as proton, deuteron, or electron, using an electrostatic storage ring. Any such non-zero EDM would demonstrate violation of both parity (P) and time-reversal (T) invariance. One way of understanding the preponderance of matter over anti-matter in the present-day universe pre-supposes the existence of violations of P and T substantially greater than are allowed by the “standard model” of elementary particle physics. This provides the leading motivation for measuring EDMs. Currently, only upper limits are known for these EDMs. The very same smallness that makes it important to determine them makes their measurement difficult. Accepting as obvious the particle physics motivation, this paper concentrates on the accelerator physics of the (not very) high energy electrostatic accelerators needed for EDM measurements. Developments already completed are emphasized. Impressive advances have been made in the diagnostic tools, spin control and polarimetry that will make EDM measurement possible. Ring design for minimizing spin decoherence and limiting systematic EDM errors is presented. There have, however, been worrisome indications from low energy rings, concerning beam current limitations. A prototype ring design is proposed for investigating and addressing this concern.
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Ghomi, Shervin K., and Ehab El-Salakawy. "Seismic performance improvement of GFRP-RC moment frames." Canadian Journal of Civil Engineering 47, no. 6 (June 2020): 704–17. http://dx.doi.org/10.1139/cjce-2019-0274.
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Although structures made of concrete reinforced with fiber-reinforced polymers (FRP) have shown promising performance under gravity loads, their performance under cyclic loading is still one of the main concerns. Although the linear nature of FRP reinforcement could be advantageous in terms of limiting the residual damage after an earthquake event, it lowers the energy dissipation of the structure, which can compromise its seismic performance. In this research, adding steel plates at selected locations in moment-resisting frames is proposed as a solution to improve seismic performance of FRP-reinforced concrete (FRP-RC) structures. Three full-scale cantilever beams, one steel-RC, one FRP-RC, and one FRP-RC with proposed steel plates, were constructed and tested under reversed cyclic loading. The results indicated that the proposed mechanism effectively improves the seismic performance of FRP-RC beams by increasing their initial stiffness and energy dissipation. Moreover, a computer simulation, using the moment–curvature determination process, was conducted to calculate bending moment capacity of FRP-RC beams with steel plates.
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Shen, Hui-Shen. "Non-linear bending of shear deformable laminated plates under lateral pressure and thermal loading and resting on elastic foundations." Journal of Strain Analysis for Engineering Design 35, no. 2 (February 1, 2000): 93–103. http://dx.doi.org/10.1243/0309324001514053.
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A non-linear bending analysis is presented for a simply supported shear deformable composite laminated plate subjected to a combined uniform lateral pressure and thermal loading and resting on a two-parameter (Pasternak-type) elastic foundation. The formulations are based on Reddy's higher-order shear deformation plate theory, including the plate-foundation interaction and thermal effects. The analysis uses a mixed Galerkin-perturbation technique to determine the load-deflection curves and load-bending moment curves. Numerical examples are presented that relate to the performances of antisymmetric angleply and symmetric cross-ply laminated plates subjected to thermomechanical loading and resting on two-parameter elastic foundations from which results for Winkler elastic foundations are obtained as a limiting case. The influences due to a number of effects e.g. foundation stiffness, plate aspect ratio, total number of plies, fibre orientation and initial thermal bending stress, are studied. Typical results are presented in a dimensionless graphical form.
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Шишов, Ivan Shishov, Рязанов, Maksim Ryazanov, Рощина, Svetlana Roshchina, Лукин, and Mikhail Lukin. "CALCULATION OF THE BENDING ELEMENTS WITH ALLOWANCE FOR THE PHYSICAL NONLINEARITY OF THE STRAIN." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 1, no. 12 (November 11, 2016): 58–64. http://dx.doi.org/10.12737/22764.
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An algorithm of the reinforced binding elements calculation with allowance for the physical strain of concrete and reinforcement has been suggested. The three linear diagram of the concrete condition and the two linear of the tensile reinforcement that correspond to the recommended norms in Russia have been used. The task has been solved by the method of linear approximation. The finite difference method has been used at each approximation that allows to define the beam rigidity individually for each dot j =1,2 , dotted on the beam with some small spacing. A method of determining the deflection curve bending, the bending moment, the rigidity as well as the compression areas of the reinforcement suitable for any deformation of the concrete most tensile fabric from 0 to limiting value ε_b2 has been suggested. A solution for the continuous three-span beam has also been introduced.
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Lee, Sen Yung, and Shueei Muh Lin. "Bending Vibrations of Rotating Nonuniform Timoshenko Beams With an Elastically Restrained Root." Journal of Applied Mechanics 61, no. 4 (December 1, 1994): 949–55. http://dx.doi.org/10.1115/1.2901584.
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Without considering the Coriolis force, the governing differential equations for the pure bending vibrations of a rotating nonuniform Timoshenko beam are derived. The two coupled differential equations are reduced into two complete fourth-order differential equations with variable coefficients in the flexural displacement and in the angle of rotation due to bending, respectively. The explicit relation between the flexural displacement and the angle of rotation due to bending is established. The frequency equations of the beam with a general elastically restrained root are derived and expressed in terms of the four normalized fundamental solutions of the associated governing differential equations. Consequently, if the geometric and material properties of the beam are in polynomial forms, then the exact solution for the problem can be obtained. Finally, the limiting cases are examined. The influence of the coupling effect of the rotating speed and the mass moment of inertia, the setting angle, the rotating speed and taper ratio on the natural frequencies, and the phenomenon of divergence instability (tension buckling) are investigated.
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Nicholson, D. W. "Large Deformation Analysis of an Elastic-Plastic Cantilevered Beam." Journal of Pressure Vessel Technology 111, no. 3 (August 1, 1989): 312–15. http://dx.doi.org/10.1115/1.3265680.
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This study concerns the analysis of the deflection of an elastic-plastic cantilevered beam. Three regions of solution are treated: (i) purely elastic response at low loads; (ii) elastic-plastic response without a hinge, for intermediate loads; and (iii) elastic-plastic response with a hinge for loads corresponding to the fully plastic bending moment at the built-in end. Most existing solutions for this type of problem involve various approximations avoided here, for example, ignoring the elastic part of the strain or using upper bounds based on limit analysis. By avoiding such approximations, the solution given here may be useful as a benchmark for validating finite element codes in the large deformation elastic-plastic regime. Several aspects of the solution are analyzed: (i) the load-deflection relation; (ii) the growth of the elastic-plastic zone; (iii) limiting cases; (iv) the residual configuration; (v) the small bending configuration. A numerical procedure based on Runge-Kutta methods is used, leading to the load-deflection relation in graphical form.
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Trahair, N. S., Y.-L. Pi, M. J. Clarke, and J. P. Papangelis. "Plastic Design of Steel Arches." Advances in Structural Engineering 1, no. 1 (January 1997): 1–9. http://dx.doi.org/10.1177/136943329700100102.
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The in-plane failure modes of steel arches range from the extremes of plastic collapse for stocky arches with significant bending actions to elastic buckling for slender arches in uniform compression. Between these extremes, failure involves an interaction between plastic collapse and elastic buckling which depends on the arch profile, support conditions, loading, and slenderness, and is influenced by geometrical imperfections and residual stresses. Few design codes give methods for designing steel arches against in-plane failure. The methods that are used are essentially based either on the buckling strengths of equivalent columns, or on the use of moment amplification or second-order elastic analysis and the attainment of a limiting stress. Any method based solely on elastic analysis and a limiting stress is necessarily conservative for stocky arches with negligible stability effects, since it ignores the often substantial redistributions that take place after first yield. This paper discusses the use of the method of plastic collapse analysis for the in-plane design of steel arches.
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Leen, S. B., T. H. Hyde, C. H. H. Ratsimba, E. J. Williams, and I. R. McColl. "An investigation of the fatigue and fretting performance of a representative aero-engine spline coupling." Journal of Strain Analysis for Engineering Design 37, no. 6 (August 1, 2002): 565–83. http://dx.doi.org/10.1243/030932402320950161.
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The fatigue behaviour of a representative high-performance aero-engine spline coupling is investigated under test conditions designed to simulate in-service conditions. The test load cycles consist of major cycle torque and axial load, simulating maximum thrust, combined with minor cycle rotating bending moment and fluctuating torque, simulating life-limiting conditions at take-off. The objective of the study is to develop understanding of the fatigue behaviour of the coupling over a range of loading conditions, including interaction between low-cycle fatigue, fretting fatigue and fretting wear. This information is necessary for the development of fatigue and fretting-fatigue life prediction techniques. The test results are interpreted with the help of three-dimensional finite element models, which include the frictional contact between the spline teeth.
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Berezhna, Katerina, and Sergey Krasnov. "Analysis of the effect of reinforcement of diaphragm spans on their spatial work." Bulletin of Kharkov National Automobile and Highway University, no. 93 (May 27, 2021): 93–97. http://dx.doi.org/10.30977/bul.2219-5548.2021.93.0.93.
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A large number of bridges in Ukraine have been built in the 60–70 s (about 54 % of the total number). In that regard, the number of cases of detecting various types of damage on the elements of bridge structures is increasing, which can cause emergencies in the future. It also suggests that most of the bridges and overpasses were built according to the old technical standards and now do not meet the modern standards of DBN V.2.3-14: 2006 and DBN V.2.3-22: 2009, both in terms of carrying capacity and dimensions of the roadway. Therefore, the issues of strengthening the existing spans are relevant. Goal. The work analyzes the effect of reinforcement of diaphragm spans on their spatial work in order to determine the effectiveness of reinforcement by gluing additional rigid reinforcement and installing transverse metal beams. The tasks that have been solved in the work are as follows: creating an adequate finite element model of the diaphragm span; limiting the number of options for design schemes to the optimal number; construction and analysis of the graphs of bending moments and deflections in the cross-section in the middle of the span of beams. Results. The graphs of the distribution of bending moments in the beams of the superstructure for different dimensions show that the presence of reinforcement does not affect the value of the bending moment, and the distribution of forces between the beams of the superstructure becomes less uniform with an increase in their number. The deflections for all load cases and dimensions are greater than the deflections of beams with reinforcement; however, the installation of an additional transverse metal beam does not affect the values and distribution of deflections. Beam deflection graphs become less uniform with an increase in their number. Practical value. Analysis of the effect of reinforcement on the spatial work of span structures has shown that only reinforcement of beams with longitudinal rigid reinforcement without installing transverse beams is expedient in practice.
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Mufti, A. A., and J. P. Newhook. "On the use of steel-free concrete bridge decks in continuous span bridges." Canadian Journal of Civil Engineering 26, no. 5 (October 1, 1999): 667–72. http://dx.doi.org/10.1139/l99-023.
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This note discusses the use of the steel-free concrete bridge deck technology in continuous span bridge structures. Conventional slab-on-girder design often utilizes the longitudinal steel reinforcement in the deck to resist the negative bending moments created at the internal piers of continuous bridges. The steel-free bridge deck is devoid of all internal steel reinforcement and hence requires an alternate design approach which is presented in this note. A key aspect of this approach is the recommended use of fibre-reinforced polymer reinforcement to control cracking of the deck over the intermediate supports. Limiting these crack widths is essential to the durability performance of the concrete, particularly in freeze-thaw environments. The results of an experimental program are also reviewed. The tensile stresses from the global longitudinal negative moment are shown to have little effect on the punching behaviour of the slab. It is noted that the concepts presented in this note were utilized in the construction of a three-span highway bridge which incorporated the steel-free bridge deck technology.Key words: bridges, design, continuous span, concrete decks, punching-shear, fibre-reinforced polymers.
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Bai, Liang, Tian Hua Zhou, and Xing Wen Liang. "Research on Deformation Capacity Design Method of Steel High Performance Concrete Structural Walls." Advanced Materials Research 163-167 (December 2010): 1540–46. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1540.
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The cyclic loading test of three steel high performance concrete(SHPC) structural walls was conducted and the failure pattern of the structural walls under the combined effect of axial force, bending moment, and shear force was researched. Based on the experimental results, the displacement-based deformation capacity design method was proposed for SHPC structural walls. It is obtained for the interrelated relationships among the ultimate drift ratio, the axial load ratio, the characteristic value of stirrup content and the aspect ratio. It is concluded that the increasing the characteristic value of stirrup content and limiting the axial load ratio were effective means to improve ductility. The characteristic value of stirrup content of SHPC structural walls with different ultimate drift ratio and axial load ratio were proposed and the conclusion can be referred by the design of SHPC structural walls.
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Singh, Priyanka, Mirza Jahangir Baig, Bhumika Pandey, and Kartik Papreja. "Analysis of the behaviour of Cable stayed bridge with different types of Pylon." E3S Web of Conferences 304 (2021): 02006. http://dx.doi.org/10.1051/e3sconf/202130402006.
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Cable stayed bridges are known for their good stability, It has been the most favorable use of structural design, for comparatively low designing and maintenance costs, and for effective structural characteristics. Therefore, this type of bridges are gaining popularity and are generally selected for long spans when compared to suspension bridges. A cable stayed bridge comprises of pylons with cables withstanding the weight of deck. There are different types of pylons i.e. ; H-type pylon, A-type pylon, inverted Y-type pylon, and diamond shaped pylon. In this paper the bridge design, model, and analyses for these different types of pylons is done using STAAD Pro. The comparison for three cases are done on the basis of shear force and bending moment in terms of self weight to obtain the most efficient type of pylon design. The results thus obtained are useful in limiting the drawbacks of other types of pylon.
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Adebar, Perry, and Michael P. Collins. "Shear strength of members without transverse reinforcement." Canadian Journal of Civil Engineering 23, no. 1 (February 1, 1996): 30–41. http://dx.doi.org/10.1139/l96-004.
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The variable angle truss model is extended to members without transverse reinforcement by introducing concrete tension ties perpendicular to concrete compression struts. The modified compression field theory approach of limiting the shear transfer across diagonal cracks is combined with the variable angle truss model to develop equations for the shear capacity of members without transverse reinforcement. These equations are the theoretical basis of tabulated values for members without stirrups in the general shear design method of the 1994 Canadian concrete code. This paper also presents the results from an experimental study in which 27 narrow (beam-like) wall elements, with significant longitudinal reinforcement and little or no transverse reinforcement, were subjected to combined axial tension, bending moment, and shear. The experimental results are compared with predictions from the 1994 Canadian concrete code, as well as the American Concrete Institute building code. Key words: building codes, reinforced concrete, shear strength, structural design, tension, tests, truss model.
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ANDROSOVA, N. B., and V. I. KOLCHUNOV. "SURVIVABILITY OF THE FRAME-ROD REINFORCED CONCRETE BUILDING FRAMEWORK IN ACCIDENTAL ACTION." Building and reconstruction 97, no. 5 (2021): 40–50. http://dx.doi.org/10.33979/2073-7416-2021-97-5-40-50.
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A methodology and an algorithm for calculating the survivability parameters of a long-term deformable reinforced concrete building frame in extreme states are presented. Analytical dependencies for determining the value of the creep measure are taken in accordance with the use of approximate dependencies from the recommendations of the NIIZHB. On this basis, a method is proposed for determining the cross-section bending stiffness of the frame elements. The deformation criterion of a special limiting state is formulated taking into account the nonequilibrium processes of prolonged deformation of the structural system elements. The numerical analysis results of the long-term deformable reinforced concrete frame survivability potential with a sudden removal of the one structural element, taking into account the long-term deformation prehistory of the considered building frame under an operating load, are presented. The exposure of the structural system survivability from the its loading moment to its transformation into a kinematically variable system has been determined.
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Gao, Hao, Yanchen Song, Junjie Wang, and Huijie Liu. "Design Criterion and a Technical Approach for the Controlled Seismic Behavior of Continuous Girder Bridges." Shock and Vibration 2019 (October 30, 2019): 1–17. http://dx.doi.org/10.1155/2019/4568732.
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Seismic design involving “fuse components” between the superstructure and substructure can improve the seismic performance of continuous girder bridges during strong earthquakes by ensuring an elastic working state. The mechanical properties of the “fuse components” directly affect the seismic behavior of continuous girder bridges, and many theoretical and experimental studies of isolation devices to achieve the controlled seismic behavior of continuous girder bridges have been carried out, and some devices are in use in large-scale construction projects. However, there is a lack of evidence from structures that have been subject to earthquakes. Test results show that the shear behavior of isolation bearings is unpredictable and the friction behavior is uncontrollable. Further, limiting devices often suffer from an insufficient deformation capacity and have large space requirements. Therefore, we propose a new type of spherical steel bearing and two kinds of large-stroke steel damping devices with different space requirements. The full-scale test results reveal that the bearing has strong controllability with respect to shearing, stable friction behavior after fracture, and little unpredictability in the friction-based processes. Furthermore, the large-stroke steel damping device shows a full hysteresis curve and excellent energy dissipation characteristics. Finally, using a continuous girder bridge as an example and combined with the results of mechanical tests, the effectiveness of the controlled design criterion was verified using numerical simulations. The calculated results show that, compared with conventional fixed bearings, the shear and bending moments are decreased by 60% and 53%, respectively, and the ratio of both the shear and bending moment response of the pier bottom to its capacity is less than 0.5. However, the ratio of the maximum deformation of the damper to its capacity is only 0.28, and the residual displacement is 0.01 m. Therefore, an alternative scheme is provided for postearthquake maintenance and replacement.
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Zhang, Yumin, Yun Shi, and Dengke Liu. "Seismic Effectiveness of Multiple Seismic Measures on a Continuous Girder Bridge." Applied Sciences 10, no. 2 (January 15, 2020): 624. http://dx.doi.org/10.3390/app10020624.
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Seismic hazards, such as bridge pounding, unseating, collapse, etc., cause significant economic losses and affect traffic and safety. Research on seismic measures, such as limiting and unseating prevention devices for the bridge, can effectively prevent damage to the bearings, such as excessive displacement, the pounding of the beam end, etc., in an earthquake. In this paper, the dynamic time-history analysis method was used to study the mechanical behaviors of the bridge structure, such as its seismic performance, structural displacement, pier bending moment, etc. We found that different combinations of seismic measures can effectively reduce the displacement at the bridge expansion joint and bearings. The joint application of an expansion device, restrainer, and unseating prevention devices shows the best limiting effect on bridge displacement and expansion joint displacement. The maximum reduction of bridge expansion joint displacement reaches 48% and is within the allowable deformation range of an expansion device in a large earthquake, and the maximum reduction of bearing displacement reaches 34%, which only slightly exceeds the shear deformation of the bearing. The expansion device, restrainer, and unseating prevention devices have smaller internal forces in this case than other cases, without damage. In contrast to the previous studies on single seismic measures of unseating restrainers, this study investigates the combination of multiple seismic measures and earthquakes of various magnitude. It reveals the catastrophe process of the bridge structure and the cooperation law of seismic measures in an earthquake.
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Soroka, Mykola. "Bearing Capacity of Structures Made of Materials with Different Tensile and Compression Strengths." Materials Science Forum 968 (August 2019): 200–208. http://dx.doi.org/10.4028/www.scientific.net/msf.968.200.
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The paper considers the problem of the ultimate load finding for structures made of a material with different limits of tensile strength and compression. The modulus of elasticity under tension and compression is the same. It is assumed that upon reaching the ultimate strength, the material is deformed indefinitely. The calculations use a simplified material deformation diagram — Prandtl diagrams. The limiting state of a solid rectangular section under the action of a longitudinal force and a bending moment is considered. The dependences describing the boundary of the strength of a rectangular cross section are obtained. Formulas allowing the calculation of the values of the limit forces and under the action of which the cross section passes into the plastic state are derived. Examples of the analytical calculation of the maximum load for the frame and two-hinged arch are given. An algorithm is proposed and a program for calculating arbitrary flat rod systems according to the limit state using the finite element method is compiled. The proposed algorithm does not involve the use of iterative processes, which leads to an exact calculation of the maximum load within the accepted assumptions.
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Zhu, Q. A., Y. B. Park, S. G. Sjovold, C. A. Niosi, D. C. Wilson, P. A. Cripton, and T. R. Oxland. "Can extra-articular strains be used to measure facet contact forces in the lumbar spine? An in-vitro biomechanical study." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 222, no. 2 (February 1, 2008): 171–84. http://dx.doi.org/10.1243/09544119jeim290.
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Experimental measurement of the load-bearing patterns of the facet joints in the lumbar spine remains a challenge, thereby limiting the assessment of facet joint function under various surgical conditions and the validation of computational models. The extra-articular strain (EAS) technique, a non-invasive measurement of the contact load, has been used for unilateral facet joints but does not incorporate strain coupling, i.e. ipsilateral EASs due to forces on the contralateral facet joint. The objectives of the present study were to establish a bilateral model for facet contact force measurement using the EAS technique and to determine its effectiveness in measuring these facet joint contact forces during three-dimensional flexibility tests in the lumbar spine. Specific goals were to assess the accuracy and repeatability of the technique and to assess the effect of soft-tissue artefacts. In the accuracy and repeatability tests, ten uniaxial strain gauges were bonded to the external surface of the inferior facets of L3 of ten fresh lumbar spine specimens. Two pressure-sensitive sensors (Tekscan) were inserted into the joints after the capsules were cut. Facet contact forces were measured with the EAS and Tekscan techniques for each specimen in flexion, extension, axial rotation, and lateral bending under a ±7.5 N m pure moment. Four of the ten specimens were tested five times in axial rotation and extension for repeatability. These same specimens were disarticulated and known forces were applied across the facet joint using a manual probe (direct accuracy) and a materials-testing system (disarticulated accuracy). In soft-tissue artefact tests, a separate set of six lumbar spine specimens was used to document the virtual facet joint contact forces during a flexibility test following removal of the superior facet processes. Linear strain coupling was observed in all specimens. The average peak facet joint contact forces during flexibility testing was greatest in axial rotation (71±25 N), followed by extension (27±35 N) and lateral bending (25±28 N), and they were most repeatable in axial rotation (coefficient of variation, 5 per cent). The EAS accuracy was about 20 per cent in the direct accuracy assessment and about 30 per cent in the disarticulated accuracy test. The latter was very similar to the Tekscan accuracy in the same test. Virtual facet loads (r.m.s.) were small in axial rotation (12 N) and lateral bending (20 N), but relatively large in flexion (34 N) and extension (35 N). The results suggested that the bilateral EAS model could be used to determine the facet joint contact forces in axial rotation but may result in considerable error in flexion, extension, and lateral bending.
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Merkulov, S., S. Esipov, and D. Esipova. "COMPOSITE SYSTEMS OF EXTERNAL REINFORCEMENT OF REINFORCED CONCRETE STRUCTURES." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 7, no. 4 (April 11, 2022): 39–48. http://dx.doi.org/10.34031/2071-7318-2021-7-4-39-48.
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The article discusses the design solutions of systems of external reinforcement of reinforced concrete structures with composite materials. Schemes of deformation and collapse of structures under static bending are studied. The obtained dependences and laws of joint work of concrete and non-metallic reinforcement are generalized. The results of experimental studies of reinforced concrete structures by several authors are presented, a comparison is made that shows the similarity of the results of empirical methods in the approaches of various scientists. It is shown that the operation of a composite structure with external reinforcement is significantly influenced by the presence of a stress-strain state and force damage at the moment of amplification, as well as their level relative to critical values. The hypothesis of a change in the typical nature of the destruction of structures, namely, due to the loss of strength for the perception of tangential stresses of the contact zones of concrete and external reinforcement, is confirmed. It is shown that the work of concrete in the compressed zone determines the load-bearing capacity to a lesser extent in reinforced structures than in non-reinforced ones. A new method of assessing the load-bearing capacity is proposed by introducing the concept of limiting relative deformations of the adhesive seam in the contact zone. The dependence between the strength of the contact zone and the strength of the reinforced concrete structure is obtained.
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Soroka, М. М. "LIMIT STATE OF ARCHES OF VARIABLE STIFFNESS." Bulletin of Odessa State Academy of Civil Engineering and Architecture, no. 81 (December 7, 2020): 97–104. http://dx.doi.org/10.31650/2415-377x-2020-81-97-104.
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Abstract. An algorithm is proposed for numerically solving the problem of finding the maximum load for flat bar systems having a rectangular section of variable height. The material is elastoplastic; its physical properties are described by the Prandtl diagram. It is assumed that the compressive and tensile strength of the material are different. The modulus of elasticity in tension and compression is the same. The limiting state of a rectangular cross section under the simultaneous action of a longitudinal force and a bending moment is described. Using the proposed algorithm, a program was developed for calculating rod systems by the limit equilibrium. The C++ programming language was used to create a program for the numerical determination of the ultimate load for rod systems. The finite element method was used as the most universal to write a module that performs static analysis of the bar system. Its use makes it easy to design rod systems of arbitrary configuration with arbitrary boundary conditions. As a test example, a hinged circular arch loaded with a uniformly distributed vertical load is considered. Analytical dependences are written, which allow to obtain the ultimate load for an arch of variable section. Examples of calculating the limiting state of the arch and comparing the ultimate loads with and without longitudinal force are considered. The analytical solution is compared with the numerical solution found by the author's program. Good convergence of analytical and numerical solutions is shown. The proposed algorithm for the numerical calculation of the limit states uses the so-called direct method for finding the ultimate load. This allows not only to obtain the value of the ultimate load, but also to establish the order of formation of plastic regions in the sections of the rod system. The calculation algorithm does not imply the use of iterative processes, which has a positive effect on the speed of calculations. Within the accepted assumptions, the calculation methodology is accurate.
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Olagunju, Solomon O., Muftau O. Atayese, Olalekan S. Sakariyawo, and Enoch O. Dare. "Effects of multi-growth stage water deficit and orthosilicic acid fertiliser on lodging resistance of rice cultivars." Crop & Pasture Science 73, no. 4 (February 28, 2022): 370–89. http://dx.doi.org/10.1071/cp21563.
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Lodging and water deficit (WD) are both yield limiting factors for rice production in Africa. A number of New Rice for Africa (NERICA) cultivars with drought adaptive and high yielding ability have been released but the extent of their lodging susceptibility due to water deficit is unclear. Application of orthosilicic acid (OSA) fertiliser can reduce lodging due to water deficit. An experiment was therefore conducted involving six cultivars (NERICAs 1, 4, 6, 7, 8 and Moroberekan), subjected to five multi-growth stage WD treatments: non-stressed (Nst), 10-day stress at each of any two stages of vegetative (Veg), reproductive (Rep) and grain filling (Grain) stages viz (Veg10 + Rep10), (Veg10 + Grain10), (Rep10 + Grain10), and 7-day stress at each stage (Veg7 + Rep7 + Grain7) and with/without 500 mL ha−1 of OSA fertiliser. Lodging traits (LTs) such as lumen diameter, bending moment, panicle weight (PW) and grain yield (GY) were increased by OSA fertiliser. Under Veg7 + Rep7 + Grain7 stress, OSA fertiliser increased rice vigour through increases in internode length, lumen diameters and cross-section modulus by 7%, 18% and 18%, respectively, while under Veg10 + Rep10 stress, culm wall thickness was increased by 20%. Veg10 + Rep10 stress caused the most significant reduction in all LTs but with lowest lodging index (LI, 0.32) attributed to reduced PW and GY. Among the cultivars, Moroberekan combined higher GY with average LI (0.40) across the stress conditions while NERICA 1 had the lowest LI (0.34) attributed mainly to its short height. Although water deficit caused a reduction in lodging resistant traits, resistance to lodging under Veg10 + Rep10 and Veg7 + Rep7 + Grain7 stresses can be enhanced with OSA fertiliser.
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Skopinskii, V. N., N. A. Berkov, N. V. Vozhova, and A. B. Smetankin. "Limiting Plastic Load in a Pressure Vessel with a Branch Pipe under Combined Internal Pressure and Bending Moments." Chemical and Petroleum Engineering 49, no. 7-8 (November 2013): 549–54. http://dx.doi.org/10.1007/s10556-013-9791-8.
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Shiah, Y. C., Jiunn Fang, Chin-Yi Wei, and Y. C. Liang. "In-Plane Bending Fracture of a Large Beam Containing a Circular-Arc Crack." Journal of Mechanics 18, no. 3 (September 2002): 145–51. http://dx.doi.org/10.1017/s1727719100002112.
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AbstractIn this paper, the crack problem of a large beam-like strip weakened by a circular arc crack with in-plane bending moments applied at both ends is approximately solved using the complex variable technique. Complex stress functions corresponding to the applied bending moments are superposed with those due to the disturbance of the crack to satisfy the governing boundary equation. The conformal mapping function devised to transform the contour surface of a circular arc crack to a unit circle is then substituted in the boundary equation to facilitate the evaluation of Cauchy integrals. In this way, the complex stress functions due to the crack disturbance are determined and the stress intensity factors are calculated through a limiting process to give their explicit forms. Eventually, the geometric functions for the variation of the stress intensity factors on account of the crack shape are plotted as a function of the curvature of a circular-arc crack.
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Brüchert, Franka, Olga Speck, and Hanns–Christof Spatz. "Oscillations of plants' stems and their damping: theory and experimentation." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 358, no. 1437 (August 13, 2003): 1487–92. http://dx.doi.org/10.1098/rstb.2003.1348.
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Free oscillations of upright plants' stems, or in technical terms slender tapered rods with one end free, can be modelled by considering the equilibrium between bending moments and moments resulting from inertia. For stems with apical loads and negligible mass of the stem and for stems with finite mass but without top loading, analytical solutions of the differential equations with appropriate boundary conditions are available for a finite number of cases. For other cases approximations leading to an upper and a lower estimate of the frequency of oscillation ω can be derived. For the limiting case of ω = 0, the differential equations are identical with Greenhill's equations for the stability against Euler buckling of slender poles. To illustrate, the oscillation frequencies of 25 spruce trees ( Picea sitchensis (Bong.) Carr.) were compared with those calculated on the basis of their morphology, their density and their static elasticity modulus. For Arundo donax L. and Cyperus alternifolius L. the observed oscillation frequency was used in turn to calculate the dynamic elasticity modulus, which was compared with that determined in three–point bending. Oscillation damping was observed for A. donax and C. alternifolius for plants' stems with and without leaves or inflorescence. In C. alternifolius the difference can be attributed to the aerodynamic resistance of the leaves, whereas in A. donax structural damping in addition plays a major role.
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Karahalios, Dean G., Taro Kaibara, Randall W. Porter, Udaya K. Kakarla, Phillip M. Reyes, Ali A. Baaj, Ali S. Yaqoobi, and Neil R. Crawford. "Biomechanics of a lumbar interspinous anchor with anterior lumbar interbody fusion." Journal of Neurosurgery: Spine 12, no. 4 (April 2010): 372–80. http://dx.doi.org/10.3171/2009.10.spine09305.
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Object An interspinous anchor (ISA) provides fixation to the lumbar spine to facilitate fusion. The biomechanical stability provided by the Aspen ISA was studied in applications utilizing an anterior lumbar interbody fusion (ALIF) construct. Methods Seven human cadaveric L3–S1 specimens were tested in the following states: 1) intact; 2) after placing an ISA at L4–5; 3) after ALIF with an ISA; 4) after ALIF with an ISA and anterior screw/plate fixation system; 5) after removing the ISA (ALIF with plate only); 6) after removing the plate (ALIF only); and 7) after applying bilateral pedicle screws and rods. Pure moments (7.5 Nm maximum) were applied in flexion and extension, lateral bending, and axial rotation while recording angular motion optoelectronically. Changes in angulation as well as foraminal height were also measured. Results All instrumentation variances except ALIF alone reduced angular range of motion (ROM) significantly from normal in all directions of loading. The ISA was most effective in limiting flexion and extension (25% of normal) and less effective in reducing lateral bending (71% of normal) and axial rotation (71% of normal). Overall, ALIF with an ISA provided stability that was statistically equivalent to ALIF with bilateral pedicle screws and rods. An ISA-augmented ALIF allowed less ROM than plate-augmented ALIF during flexion, extension, and lateral bending. Use of the ISA resulted in flexion at the index level, with a resultant increase in foraminal height. Compensatory extension at the adjacent levels prevented any significant change in overall sagittal balance. Conclusions When used with ALIF at L4–5, the ISA provides immediate rigid immobilization of the lumbar spine, allowing equivalent ROM to that of a pedicle screw/rod system, and smaller ROM than an anterior plate. When used with ALIF, the ISA may offer an alternative to anterior plate fixation or bilateral pedicle screw/rod constructs.
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Lalin, Vladimir V., Olga N. Pertseva, Vladimir R. Kamaltdinov, Gleb V. Martynov, Daria E. Monastyreva, and Roman S. Tikhonov. "Calculation of prestressed structures for shock loading." Vestnik MGSU, no. 4 (April 2020): 482–95. http://dx.doi.org/10.22227/1997-0935.2020.4.482-495.
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Introduction. With the use of prestressing, coatings are made for special-purpose buildings, requiring calculations for extreme impacts. Such impacts include an airplane strike. Modeling of prestressed structures and calculation of shock loads is difficult to implement in classical calculation programs. A universal tool for solving such problems is the PC SOFiSTIK. This software complex allows you to interact with the most modern software solutions.
Materials and methods. For the description of the method, special-purpose coating was selected and the strike calculation of the Learjet 23 aircraft was performed. For modeling prestressing, the SOFIPLUS interface is used. To describe the impact, the internal programming language CADINP is used.
Results. The nature of the change in the coating deformations in the first seconds of the aircraft crash is presented graphically. Also, iso-ares of internal bending moments of the coating were derived for the selection of reinforcement and the diagram of the moments of the beams from the action of prestressing, taking into account tension losses.
Conclusions. SOFiSTIK PC allows you to solve complex engineering problems with a high degree of automation. Thanks to the open source code, it becomes possible to calculate atypical extreme effects. The obtained graphs and diagrams confirm the passage of checks on the limiting states of the coating, and can also be used to design and calculate similar special-purpose structures.
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Jacobs, David K. "Sutural pattern and shell stress in Baculites with implications for other cephalopod shell morphologies." Paleobiology 16, no. 3 (1990): 336–48. http://dx.doi.org/10.1017/s0094837300010034.
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In Baculites, a straight shelled ammonite, the constructional limits on shell shape resulting from the limited strength of nacre in tension are circumvented by a system of vaults in the phragmocone. Vaults bridge between regions of the phragmocone supported by the complex ammonite septal suture, and maintain the shell wall in compression when hydrostatic load induces bending moments. To determine how these vaults interact in the phragmocone to resist hydrostatic loading, measurements were made on a suite of Baculites specimens. In Baculites there is a statistically significant inverse relationship between circumferential curvature (radius of curvature) of the vaulted shell surface and the size of vaults spanning between sutural elements supporting the phragmocone. The inverse relationship between radius of curvature and the sizes of spans in this system of vaults results in the generation of comparable reactive forces at the ends of the vault spans where adjacent vaults interact. The equivalence of these reactive forces prevents the lateral displacement of the vault ends. Consequently, compressive stresses from adjacent vaults are superimposed on, and reduce, the tensional stress component of bending. Limiting tensile stress is of utmost importance in a lightweight shell composed of a brittle material such as nacre, which is strong in compression but weak in tension.Baculites is particularly appropriate for this study because its straight shell is curved only in the circumferential direction, thus simplifying the problem. However, sutural patterns in coiled ammonites appear to be similarly constrained to produce vaults in the phragmocone which vary inversely in curvature and span size.
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Orobey, V., O. Lymarenko, A. Bazhanova, V. Khamray, and A. Ponomarenko. "CALCULATION OF THE STABILITY FLAT SHAPE BENDING OF THE RACING CAR FRAME STRUCTURAL ELEMENTS IN THE CIRCULAR ARCHES FORM." Odes’kyi Politechnichnyi Universytet Pratsi 2, no. 64 (2021): 5–12. http://dx.doi.org/10.15276/opu.2.64.2021.01.
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To increase the strength and rigidity of the characteristics, the articulated elements of structural racing cars have a large ratio of axial moments of inertia of the cross sections. The method of solving boundary value problems of stability of the flat form of bending of racing car structural elements in the form of circular arches with sections having several axes of symmetry is obtained. In Formula Class cars, these elements are most responsible for the safety of the pilot. The system of integration of two differential equations of stability of the specified constructive elements of a car racing frame in the form of circular arches or curvilinear cores is executed in work. The numerical-analytical method of limiting elements developed by Professor V.F. Orobey was used for the research. The article presents two variants of systems of fundamental orthonormal functions for differential equations of stability of circular arches with constant coefficients obtained during research. The problem of stability of structural elements of racing cars on the geometry corresponding to circular arches is solved by a numerical method acquiring rapid development; the method has theoretically proved exact decisions. The equation obtained in the course of research is applicable to the solution of very complex problems of stability of various structures containing rods delineated along the arc of a circle. The equations can be used to solve very complex problems of stability of various structures containing rods drawn along the arc of a circle. Such structural elements are used in many designs of industrial engineering.
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Diachenko, Leonid, Andrey Benin, Vladimir Smirnov, and Anastasia Diachenko. "Rating of Dynamic Coefficient for Simple Beam Bridge Design on High-Speed Railways." Civil and Environmental Engineering 14, no. 1 (June 1, 2018): 37–43. http://dx.doi.org/10.2478/cee-2018-0005.
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AbstractThe aim of the work is to improve the methodology for the dynamic computation of simple beam spans during the impact of high-speed trains.Mathematical simulation utilizing numerical and analytical methods of structural mechanics is used in the research.The article analyses parameters of the effect of high-speed trains on simple beam spanning bridge structures and suggests a technique of determining of the dynamic index to the live load. Reliability of the proposed methodology is confirmed by results of numerical simulation of high-speed train passage over spans with different speeds. The proposed algorithm of dynamic computation is based on a connection between maximum acceleration of the span in the resonance mode of vibrations and the main factors of stress-strain state. The methodology allows determining maximum and also minimum values of the main efforts in the construction that makes possible to perform endurance tests. It is noted that dynamic additions for the components of the stress-strain state (bending moments, transverse force and vertical deflections) are different. This condition determines the necessity for differentiated approach to evaluation of dynamic coefficients performing design verification of I and II groups of limiting state. The practical importance: the methodology of determining the dynamic coefficients allows making dynamic calculation and determining the main efforts in split beam spans without numerical simulation and direct dynamic analysis that significantly reduces the labour costs for design.
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Chou, Dean, Adolfo Espinoza Larios, Robert H. Chamberlain, Mary S. Fifield, Roger Hartl, Curtis A. Dickman, Volker K. H. Sonntag, and Neil R. Crawford. "A biomechanical comparison of three anterior thoracolumbar implants after corpectomy: are two screws better than one?" Journal of Neurosurgery: Spine 4, no. 3 (March 2006): 213–18. http://dx.doi.org/10.3171/spi.2006.4.3.213.
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Object A flexibility experiment using human cadaveric thoracic spine specimens was performed to determine biomechanical differences among thoracolumbar two-screw plate, single-screw plate, and dual-rod systems. A secondary goal was to investigate differences in the ability of the systems to stabilize the spine after a one- or two-level corpectomy. Methods The authors evaluated 21 cadaveric spines implanted with a titanium mesh cage and three types of anterior thoracolumbar supplementary instrumentation after one-level thoracic corpectomies. Pure moments were applied quasistatically while three-dimensional motion was measured optoelectronically. The lax zone, stiff zone, and range of motion (ROM) were measured during flexion, extension, left and right lateral bending, and left and right axial rotation. Corpectomies were expanded to two levels, and testing was repeated with longer hardware. Biomechanical testing showed that the single-bolt plate system was no different from the dual-rod system with two screws in limiting ROM. The single-bolt plate system performed slightly better than the two-screw plate system. Across the same two levels, there was an average of 19% more motion after a two-level corpectomy than after a one-level corpectomy. In general, however, the difference across the different loading modes was insignificant. Conclusions Biomechanically, the single-screw plate system is equivalent to a two-screw dual-rod and a two-screw plate system. All three systems performed similarly in stabilizing the spine after one- or two-level corpectomies.
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Anssari-Benam, Afshin, and Cornelius O. Horgan. "New results in the theory of plane strain flexure of incompressible isotropic hyperelastic materials." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 478, no. 2258 (February 2022). http://dx.doi.org/10.1098/rspa.2021.0773.
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New results on the classical problem of bending by end moments for incompressible isotropic hyperelastic materials within the framework of nonlinear elasticity are investigated and presented in this paper. The particular results of concern here include (i) the adaptation of Rivlin's standard analysis to the case where one end of the beam is fixed and the other end is subjected to a bending moment; and (ii) results on the finite bending of (infinitesimally) thin isotropic hyperelastic plates which are valid for large deformations , extending the classical results from the linear elasticity theory which are restricted to small deformations. An interesting feature observed in this context is that a flexed thin plate develops an oscillatory surface along the circular arc near the free end, due to local (small) deviations of the radius of curvature. A potential application to the bending of a biological soft tissue, namely the aortic valve leaflet, is briefly described by way of an example. Finally, some new results are obtained for finite bending of hyperelastic materials that exhibit limiting chain extensibility at the molecular level and involve constraints on the deformation. The amount of bending that such materials can sustain is limited by the constraint. On using a limiting chain extensibility model, closed-form solutions for the Cauchy stress components, the bending moment and the normal out-of-plane force required to sustain the bending deformation are derived.
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Jaumard, Nicolas V., Joel A. Bauman, Christine L. Weisshaar, Benjamin B. Guarino, William C. Welch, and Beth A. Winkelstein. "Contact Pressure in the Facet Joint During Sagittal Bending of the Cadaveric Cervical Spine." Journal of Biomechanical Engineering 133, no. 7 (July 1, 2011). http://dx.doi.org/10.1115/1.4004409.
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The facet joint contributes to the normal biomechanical function of the spine by transmitting loads and limiting motions via articular contact. However, little is known about the contact pressure response for this joint. Such information can provide a quantitative measure of the facet joint’s local environment. The objective of this study was to measure facet pressure during physiologic bending in the cervical spine, using a joint capsule-sparing technique. Flexion and extension bending moments were applied to six human cadaveric cervical spines. Global motions (C2-T1) were defined using infra-red cameras to track markers on each vertebra. Contact pressure in the C5-C6 facet was also measured using a tip-mounted pressure transducer inserted into the joint space through a hole in the postero-inferior region of the C5 lateral mass. Facet contact pressure increased by 67.6 ± 26.9 kPa under a 2.4 Nm extension moment and decreased by 10.3 ± 9.7 kPa under a 2.7 Nm flexion moment. The mean rotation of the overall cervical specimen motion segments was 9.6 ± 0.8° and was 1.6 ± 0.7° for the C5-C6 joint, respectively, for extension. The change in pressure during extension was linearly related to both the change in moment (51.4 ± 42.6 kPa/Nm) and the change in C5-C6 angle (18.0 ± 108.9 kPa/deg). Contact pressure in the inferior region of the cervical facet joint increases during extension as the articular surfaces come in contact, and decreases in flexion as the joint opens, similar to reports in the lumbar spine despite the difference in facet orientation in those spinal regions. Joint contact pressure is linearly related to both sagittal moment and spinal rotation. Cartilage degeneration and the presence of meniscoids may account for the variation in the pressure profiles measured during physiologic sagittal bending. This study shows that cervical facet contact pressure can be directly measured with minimal disruption to the joint and is the first to provide local pressure values for the cervical joint in a cadaveric model.
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Clauss, Günther F., Marco Klein, Carlos Guedes Soares, and Nuno Fonseca. "Response Based Identification of Critical Wave Scenarios." Journal of Offshore Mechanics and Arctic Engineering 135, no. 3 (June 6, 2013). http://dx.doi.org/10.1115/1.4024269.
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In the past few years the identification and investigation of critical wave sequences in terms of offshore structure responses became one of the main topics in the ocean engineering community. Thereby the area of interest covers the entire field of application spectra at sea—from efficient and economic offshore operations in moderate sea states to reliability as well as survival in extreme wave conditions. For most cases, the focus lies on limiting criteria for the design, such as maximum global loads, maximum relative motions between two or more vessels, or maximum accelerations, at which the floating structure has to operate or to survive. These criteria are typically combined with a limiting characteristic sea state (Hs, Tp) or a rogue wave. For the investigation of offshore structures as well as the identification of critical wave sequences, different approaches are available—most of them are based on linear transfer functions as it is an efficient procedure for the fast holistic evaluation. But, for some cases the linear method approach implies uncertainties due to nonlinear response behavior, in particular in extreme wave conditions. This paper presents an approach to these challenges, a response based optimization tool for critical wave sequence detection. This tool, which has been successfully introduced for the evaluation of the applicability of a multibody system based on the linear method approach, is adjusted to a nonlinear task—the vertical bending moment of a chemical tanker in extreme wave conditions. Therefore a nonlinear strip theory solver is introduced into the optimization routine to capture the nonlinear effects on the vertical bending moment due to steep waves. The goal of the procedure is to find a worst case wave sequence for a certain critical sea state. This includes intensive numerical investigation as well as model test validation.
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Oukaili, Nazar. "ON THE REDUCTION OF PRESTRESSING FORCE NEAR SUPPORTS IN PARTIALLY PRESTRESSED CONCRETE FLEXURAL MEMBERS." Proceedings of International Structural Engineering and Construction 5, no. 2 (December 2018). http://dx.doi.org/10.14455/isec.res.2018.114.
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Straight tendons in pretensioned members can cause high-tensile stresses in the concrete extreme fibers at end sections because of the absence of the bending stresses due to self-weight and superimposed loads and the dominance of the moment due to prestressing force alone. Accordingly, the concrete tensile stresses at the ends of a member prestressed with straight tendons may limit the service load capacity of the member. It is therefore important to establish limiting zone in the concrete section within which the prestressing force can be applied without causing tension in the extreme concrete fibers. Two practical methods are available to reduce the stresses at the end sections due to the prestressing force. The first method based on changing the eccentricity of some tendons by raising them towards the end zone. The second method is based on bond prevention by encasing some of the tendons in plastic sheathing, effectively moving the point of application of prestressing force inward toward midspan for part of tendons. The present study focuses on a proposed third method to reduce the effect of the prestressing force near end supports by using straight strands with limited initial prestressing value in compression zone. New equations were suggested for the cracking moment and the prestressing force which consider the prestressed tendons in compression zone.
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Teo, Fwu Chyi, Leong Hien Poh, and Sze Dai Pang. "On the Flexural Failure of Thick Ice Against Sloping Structures." Journal of Offshore Mechanics and Arctic Engineering 139, no. 4 (May 5, 2017). http://dx.doi.org/10.1115/1.4035771.
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This paper investigates the breaking load of ice sheets up to 6 m thick, against a sloping structure. The reference model by Croasdale, which the design code is based on, neglects the edge moment arising from the loading eccentricity, as well as a second-order bending effect induced by the axial loading in its formulation. In this paper, the model is reformulated to incorporate these effects into the governing equation, as well as to account for the occurrence of local crushing at the point of contact between the ice sheet and sloping structure. For thin ice, predictions from the modified model resemble closely those by Croasdale's model. As the ice thickness increases, however, significant deviations from the reference model can be observed. For thick ice, the terms omitted for brevity in the reference model have a significant influence, without which the breaking load is under-estimated. It is furthermore demonstrated that against sloping structures, the dominant failure mode is that of flexural, except in very limiting cases where it switches to crushing.
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Radhakrishna Deulgaonkar, Vikas, Varun A. Shitole, and Rohan M. Panage. "Design and Analysis of State Transport Utility Vehicle-Bus." International Journal of Vehicle Structures and Systems 11, no. 2 (August 12, 2019). http://dx.doi.org/10.4273/ijvss.11.2.02.
Full textAbstract:
Passenger transport is an inseparable ingredient of public transport system for developing and developed nations. In present work design and analysis of state transport utility vehicle ~ bus is carried out. Present paper focuses on the design enhancements in structural features of sub and superstructure without any alterations on the chassis provided by OEMs. Limiting dimensions of bus as prescribed by automotive industry standard and central motor vehicle rules are the design constraints accounted in the present work. This work was commenced with the thorough study of sub and superstructure configurations, seat locations, passenger load patterns, locations of doors, windows and emergency exits and other relevant bus attributes. Hand calculations for evaluation gross section modulus of chassis and cross member combination are presented. Usage of shear force and bending moment diagrams to evaluate the stress and deflection for the proposed load patterns is made before proceeding for finite element analysis. Finite element modelling and analysis of the sub and super structure combination is carried using shell elements with the presumption that chassis of the bus is rigid. Roll-over analysis of bus for the present configuration is presented.
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Nourpanah, Nikzad, and Farid Taheri. "Effect of Lüders Plateau on Fracture Response and Toughness of Pipelines Subject to Extreme Plastic Bending." Journal of Pressure Vessel Technology 133, no. 5 (July 11, 2011). http://dx.doi.org/10.1115/1.4002930.
Full textAbstract:
The reeling technique presents an economical pipeline installation method for offshore oil and gas applications, especially for thick-wall (low D/t) pipelines. During reeling, the pipe is subjected to large plastic bending strains up to 3%. In thick-wall pipes, the tensile fracture response of the pipeline/girth weld would normally be the governing limit state. Seamless line pipes are preferred for the reeling applications in which the Lüders plateau is often exhibited in materials stress-strain response. In this paper, the fracture response of such pipelines is investigated from a continuum perspective using a nonlinear 3D finite element analysis. A typical pipeline with a hypothetical defect is considered, with the material having a range of Lüders strains and strain hardening indices. Results show that the Lüders plateau modifies the shape of the moment-strain response curves of the pipe, as well as the J-integral fracture response. It is observed that the response is always bounded between two limiting material models, which are (i) the elastic-perfectly plastic stress-strain response and (ii) the conventional elastic-strain hardening plasticity response, without a Lüders plateau. Also, the Lüders plateau was observed to decrease the crack opening stress ahead of the crack tip and thus the crack tip constraint. On the other hand, the presence of a Lüders plateau elevates the near tip plastic strain and stress triaxiality fields, thus promoting ductile fracture. A micromechanical damage integral model coupled with a modified boundary layer analysis was incorporated to study this aspect. Based on the findings of this study, it is believed that the presence of Lüders plateau could significantly alter the fracture response and toughness of pipes subject to relatively high strains.
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Plott, Jeffrey, Xiaoqing Tian, and Albert Shih. "Measurement and Modeling of Forces in Extrusion-Based Additive Manufacturing of Flexible Silicone Elastomer With Thin Wall Structures." Journal of Manufacturing Science and Engineering 140, no. 9 (June 28, 2018). http://dx.doi.org/10.1115/1.4040350.
Full textAbstract:
Flexible thin wall silicone parts fabricated via extrusion-based additive manufacturing (AM) tend to deform due to the AM forces, limiting the maximum build height. The tangential and normal forces in AM were measured to investigate effects of three key process parameters (volumetric flow rate Q, nozzle tip inner diameter di, and layer height t) on the build height. The interaction between the nozzle tip and the extruded silicone bead is controlled to prevent interaction, flatten the top surface of the extruded silicone, or immerse the nozzle in the extruded silicone. Results show that tangential and normal forces in AM strongly depend on this interaction. Specifically, the AM forces remained low (less than 0.2 mN) if the nozzle tip did not contact the extruded silicone bead. Once the nozzle interaction with extruded silicone came into effect, the AM forces quickly grew to over 1 mN. The single wall tower configuration was developed to determine a predictive deflection resistance approach based on the measured AM forces and the resultant bending moment of inertia. This approach shows that a smaller di can produce taller towers, while a larger di is better at bridging and overhangs. These results are applied to the AM of a hollow thin wall silicone prosthetic hand.
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Ayturk, Ugur M., Jose J. Garcia, and Christian M. Puttlitz. "The Micromechanical Role of the Annulus Fibrosus Components Under Physiological Loading of the Lumbar Spine." Journal of Biomechanical Engineering 132, no. 6 (April 22, 2010). http://dx.doi.org/10.1115/1.4001032.
Full textAbstract:
To date, studies that have investigated the kinematics of spinal motion segments have largely focused on the contributions that the spinal ligaments play in the resultant motion patterns. However, the specific roles played by intervertebral disk components, in particular the annulus fibrosus, with respect to global motion is not well understood in spite of the relatively large literature base with respect to the local ex vivo mechanical properties of the tissue. The primary objective of this study was to implement the nonlinear and orthotropic mechanical behavior of the annulus fibrosus in a finite element model of an L4/L5 functional spinal unit in the form of a strain energy potential where the individual mechanical contributions of the ground substance and fibers were explicitly defined. The model was validated biomechanically under pure moment loading to ensure that the individual role of each soft tissue structure during load bearing was consistent throughout the physiologically relevant loading range. The fibrous network of the annulus was found to play critical roles in limiting the magnitude of the neutral zone and determining the stiffness of the elastic zone. Under flexion, lateral bending, and axial rotation, the collagen fibers were observed to bear the majority of the load applied to the annulus fibrosus, especially in radially peripheral regions where disk bulging occurred. For the first time, our data explicitly demonstrate that the exact fiber recruitment sequence is critically important for establishing the range of motion and neutral zone magnitudes of lumbar spinal motion segments.
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Liu, M., and C. Cross. "Subsea Pipeline Lateral Buckling Design—Strain Concentration or Strain Capacity Reduction Factors." Journal of Offshore Mechanics and Arctic Engineering 140, no. 3 (January 2, 2018). http://dx.doi.org/10.1115/1.4038502.
Full textAbstract:
A strain concentration factor is typically incorporated in the higher-pressure and high-temperature (HPHT) pipeline lateral buckling assessment to account for nonuniform stiffness or plastic bending moment. Increased strain concentration can compromise pipeline low cycle fatigue and lateral buckling capacity, leading to an early onset of local buckling failure. In this paper, the philosophy of local buckling mitigation using the strain concentration factor is examined. The local buckling behavior is evaluated. Global strain reduction and evolution against buckling are analyzed with respect to varying joint mismatch level. The concept of a strain reduction factor (SNRF) due to joint mismatch is developed based on the global strain capacity reduction with reference to the uniform configuration. It is demonstrated that the SNRF in terms of strain capacity reduction is a unique characteristic parameter. As opposed to strain concentration, it is an invariant insensitive to evaluation methods and design strain demand level, hence more representative as a limiting design metric to maintain the safety margin. The rationale for its introduction as an alternative to the strain concentration factor is outlined and its benefits are established. The method for obtaining the SNRF and its application is developed. The discernible difference and scenarios for application of either factor are discussed, including low and high cycle fatigue, linearity and stress concentration, engineering criticality assessment (ECA), and lateral buckling. Additional causal factors giving rise to mismatch such as pipe schedule transition and buckler arrestor are also discussed. Iterations of finite element (FE) analyses are performed for a pipe-in-pipe (PIP) configuration in a case study.