Showing papers on "Bending moment published in 1980"

Dynamic Plastic Response of Circular Plates With Transverse Shear and Rotatory Inertia

Abstract: : The response of a simply supported circular plate made from a rigid perfectly plastic material and subjected to a uniformly distributed impulsive velocity is developed herein. Plastic yielding of the material is controlled by a yield criterion which retains the transverse shear force as well as bending moments and the influence of rotatory inertia is included in the governing equations. Various equations and numerical results are presented which may be used to assess the importance of transverse shear effects and rotatory inertia for this particular problem. (Author)

Bridge dynamic loading due to road surface irregularities and braking of vehicle

Abstract: Single span highway bridges of composite construction are idealized as beams as well as orthotropic plates. A standard HS–20–44 highway vehicle is represented by a planar, two-axle, sprung mass system with frictional device. The response equations are derived in terms of the natural modal co-ordinates of the bridge and of displacement co-ordinates of the vehicle. The road surface irregularities, generally found at the junctions of the approach road and bridge ends, are idealized as a 45° ramp. The maximum impact factors for bending moment and deflection are obtained due to the ramp and in combination with the braking of vehicle for symmetric as well as essentric loading of the vehicle.

Intermediate weight drill string member

Abstract: An improved intermediate weight member to be put in a drill string between the collars and the drill pipe which has a spiraled outer surface, and which is so configured as to provide a uniform bending moment of inertia over its length including the slip area.

Analysis of Centrifuge Pile Tests; Simulation of Pile-Driving

Abstract: Previous studies on the centrifuge have been directed towards simulating the behavior of a laterally-loaded pile in fine, dry and saturated sand. After data had been obtained on the model pile, attention was turned to modelling the soil-pile interaction behavior. Since the Winkler [continuous reaction elements (springs) distributed along the pile length] foundation representation is the simplest that can be adduced, and, moreover, has been found to give adequate results for design in a variety of foundation problems, attempts were made to extract a Winkler type of function from the model pile test results. The pile response is obtained from the output of a series of strain gauges attached to the pile. In effect these indicate the bending moment in the pile as a function of length along it. As a consequence, to obtain the pile-soil interaction behavior at various locations along the pile, it is necessary to integrate the bending moment function twice for each level of applied load to obtain pile displacements (the top displacement is measured and known), and to differentiate it twice, to get the soil interaction pressure. Then, at a given point on the pile, the pile-soil interaction behavior is given by plotting the pressure versus the displacement at various load levels. A series of such functions at different depths gives the information required for subsequent analyses. The troubles with this procedure are well-known. Double integration is satisfactory and gives a good indication of pile deflections, since the smoothing process eliminates the effect of random errors in the measurement of pile strains. However, double differentiation exaggerates the same errors, and the resulting pressure function can be quite erratic. It is necessary to smooth the strain gauge data first before processing it; various smoothing techniques are available and have been tried. The results of preliminary attempts at obtaining a smoothing function are described in a previous report (3). In the stage of the work reported here, a revised method of analysis was developed, and applied both to calibration tests of the pile, and to the tests carried out in dry and saturated sand. The results of these applications are described below.

Apparatus for bending a pressure roll of a rotary printing press

Abstract: A lever at each end of a pressure roll has one arm connecting with means for applying a force thereto and another arm applying a bending moment through rotary bearings to the shell of a pressure roll. In one embodiment, the axle is non-rotating and is forked at the ends and mounted in a sliding carriage on stationary supports there, on which carriage a pressure and cylinder and piston are provided for carrying a force to a lever pivoted on a pin bridging the fork of the axle end to apply the bending moment to the roll shell through a rotary bearing. In another embodiment, the axle is rotary and connected at various places intermediate the roll ends by connection pieces past which bending moments may be transmitted and the lever is tubular and mounted on a stub of the axle by a swing bearing, and the bending moment is transferred to the shell by another swing bearing. Application of force to the lever for bending the roll shell in this case can be done manually with a set screw.

The mechanism of failure in bending of paperboard

Abstract: The behaviour of paperboard beams subjected to pure bending is analysed and related to tensile and compression stress-strain behaviour. Since the compression strength is lower than the tensile strength, beam failure occurs in compression. However, beam failure does not occur when the ultimate strain in pure compression is reached in the surface fibres. A plastic yielding in compression, which gives good agreement between experimentally-determined and theoretically-calculated bending moments up to failure is therefore suggested. At failure, the elastic energy stored in the sample causes propagation of an interlaminar crack at the compression side, which is observed in scanning electron micrographs.

Ultimate strength of a ship's hull girder in plastic and buckling modes

Abstract: Knowledge of the limiting conditions beyond which a ship's hull girder will fail to perform its function is important in assessing accurately the true margin of safety in the design of ships. Such information is essential also for developing design procedures, requirements, and rules which achieve uniform standards among vessels of different sizes and types. In this report, these limiting conditions were analyzed with the objective of determining the ultimate strength of a hull girder. The ship was considered to be subjected to a realistic loading consisting of vertical and lateral bending moments and torsional moment. Buckling and instability of the hull stiffened plates, the fully plastic yield moments, and the shakedown moments were further developed in a procedure for estimating the ultimate capacity of the hull. New interaction relations for the ultimate strength of ships subjected to combined moments were developed in this study. The fracture (fatigue and brittle) modes of failure were not included. An application to a 200,000 ton displacement tanker was carried out to show the details of the procedure and to examine the effects of various factors on the ultimate capacity of the hull. Lack of adequate formulations in certain areas were pointed out particularly when the collapse mode involved coupling between several mechanisms of failure. Analytical studies as well as a two-part test program were recommended with their objectives outlined.

Ultimate strength of ship hull girders under moment, shear and torque

Abstract: A method is described for the determination of the behavior and ultimate strength of longitudinally stiffened ship hull girder segments of rectangular single-cell cross section, subjected to bending, shear and torque. The basic requirement of the method is to maintain the compatibility of deformations between the individual nonlinear components of the cross section. The compression flange is assumed to be formed from identical beam-columns each consisting of a plate-stiffener combination; residual stresses and pre- and post-buckling behavior of the plate, as well as, large deformations and plastification of the stiffener, are all taken into account. The tension flange is assumed to be elastic-plastic. The webs (sides) are analyzed by a multiple tension-field approach which considers redistribution of normal and shearing stresses between the plate subpanels. It is assumed in the method that a section plane before deformations remains plane after deformations (Navier-Bernoulli) and that shearing stresses in flanges have no effect on deformations or conditions of buckling or yielding. A comparison of the method with the results of two tests on a small hull girder specimen showed that the method is acceptably accurate for the loading case of moment and shear (symmetrical loads) but should be modified for the general loading case of moment, shear and torque (unsymmetrical loads) to include the effect of warping deformations (deplanation) of the cross section.

Optimal design of beam-columns subjected to concentrated moments

Abstract: The paper is concerned with the problem of minimizing the transverse deflection at the free end of a cantilevered, elastic beam-column of given mass. The beam-column is acted upon simultaneously by an axial compression, a transverse concentrated load and a concentrated bending moment at the free end. The concentrated bending moment may be regarded as the reaction on the beam-column from the rest of the rigid frame of which it is an integral part. Solutions are presented for beam-columns of sandwich and solid cross-section. It is shown that optimization leads to a substantial decrease in the free end deflection compared to that of a prismatic member.

Limit Analysis for Plastic Plates

Abstract: The collapse problem for plate bending is considered as an infinite dimensional mathematical programming problem. The duality between the static and kinematic formulations of limit analysis is proved, and it is shown that limit fields for bending moments and displacement rates exist. Finally we analyze the approximation of the continuous problem by finite-dimensional convex programming problems using the finite element method.

Moment resisting connections for mixed construction

Abstract: These 22 test indicate that headed metal studs can be used to connect steel beams to concrete columns and shear walls. Such connections can transfer both shear force and moment, but their ability to resist moment is severely limited by the tensile capacity of the studs and their vertical spacing. Such connections are ductile when the shear force is high and the moment is low. High moments produce high tensile forces in some of the studs, and a relatively brittle failure may occur if the tension studs are not deeply embedded. The plastic distribution method described in this paper provides the best method for predicting the ultimate design capacity of such connections. However, if the ratio of the design moment to shear on the connection exceeds half the vertical spacing of the studs, it is recommended that the strength reduction factor for concrete be taken as 0.6 or less in pedicting the fully embedded condition. The likelihood of brittle failure is then reduced without making the design overly conservative. Severe cyclic loading reduces the ultimate strength of such connections and produces a deteriorating stiffness. It is recommended that when such connections are subjected to severe cyclic loads, they be designed conservatively until studied further. These tests also indicate that the best method for increasing connection bending moments and shear forces, is to add tensile studs. (Author)

Interaction of flexure and torsion in steel-concrete composite beams

Abstract: The results of tests on five composite beams, tested to destruction under combined flexure and torsion, are discussed with reference to earlier published data. In the tests, the ratios between the bending and torsional moments were maintained constant. The ultimate strengths of the reinforced concrete slab and composite beam are assessed from tests carried out in simple torsion. (Author/TRRL)

Improved Figure Control With Edge Application Of Forces And Moments

Abstract: A new actuation scheme for mirror figure control, introducing a complete set of membrane shear and bending stresses onto the edges of the mirror, is presented. Thermoelastic response of both segmented and continuous mirrors is analyzed from a closed form solution of the "exact" Love theory of thin spherical shells. There are significant departures from Reissner's theory of shallow shells. Very low residual figure error is possible by edge control alone, lower than with interior point loads. Minimum rms residual error stress profiles are computed. Engineering applications are discussed.

Strength increasing process for gear-teeth - uses roller to provide plastic deformation of metal at tooth root

Abstract: The strength of gear teeth can be increased by plastic deformation of the regions which are critical from consideration of the bending moment. A roller (20) with a rim of wedge-shaped cross-section is pressed into the space between two adjacent teeth (5, 6). The metal at the root of the tooth is subjected to a high compressive stress which causes plastic deformation so that there is a residual compressive stress after the roller is removed. This residual stress reduces the maximum tensile stress at the roots when the teeth are subjected to a bending moment.

Moving load on a two-layered plate with imperfect bonding, resting on a fluid half-space

Abstract: An analysis is made of the problem of vibrations of a two-layered plate resting on a compressible fluid half-space. The infinitely long layers are joined together by an elastic bonding agent and one of the layers is subjected to a step load which moves with a constant speed along the layer. The solution is presented within the framework of a plate theory which includes the effects of shear deformation and rotary inertia. An example is provided where the bending moments of the layers and the fluid pressure are calculated. From the results of theoretical analysis, it becomes evident that the stiffness of the bonding agent has considerable effect upon the dynamic behaviour of the system.

Composite bridge with precompression system

Abstract: A composite bridge structure having a precompressed beam for supporting loads thereon is described. A plurality of spaced apart consoles are secured to the beam, the consoles being urged apart to create a bending moment in the beam having a substantially parabolic distribution between the ends of the beam. The bending moment is in a direction opposite to the direction of the moment created by the loads supported by the beam. As a consequence of the precompression, a longitudinal force and bending moment working on the composite bridge structure improves the load carrying capacity of the structure.

On the possibility of decrease of bending moments in circular coils of toroidal magnets

Abstract: It is shown that (1) if an angular dimension of the supporting structure is large enough, the so‐called modified D‐shaped coil of toroidal magnet differs slightly from the circular one, (2) with the increase of support angle maximum bending moment in a circular toroidal field coil diminishes rapidly. Thus the realistic choice of support angle can guarantee practically pure tension in circular toroidal field coils.

Earthquake load analysis of tunnels and shafts

Abstract: This paper presents a closed-form solution for determining bending moments and axial loads for tunnels and shafts under earthquake load, while considering soil-structure interaction as a pseudostatic problem. The results are presented graphically in terms of nondimensional parameters, such that these curves can be used directly to aid in design-load calculations. The solutions are particularly useful for relatively rigid structures embedded in soft soils, or for tunnels/shafts with small segment lengths.

Resonance type fatigue test device

Abstract: PURPOSE:To obtain a resonance type fatigue test device with a stable operation performance by making a test piece produce an iterative bending moment in its central part on applying alternate force to the lower end of one of the vibrating plates which are symmetric with respect to the upper-lower sides and right-left sides. CONSTITUTION:The vibrating plates 5, 5' are rectangular plates which are symmetric with respect to the upper-lower sides and right-left sides, the journals of crankshaft as a test piece are shrunk in the center of both plates. A vibrator 6 is mounted on the lower end of one of the plates, a face vibration is produced in the crankshaft by alternate force, a resonance takes place and a large iterative moment is applied to the center of pin of the crankshaft when the number of vibration is agreed with the number of natural vibration of the vibration system. Since the vibration system is made up so that its form and load distribution are symmetic and stable, only a face vibration can be produced without a torsion and a rolling, a resonance type fatigue test device with a stable operation performance can be obtained.

Bending method for austenitic stainless cast steel pipe by high frequency induction heating

Abstract: PURPOSE:To continuously plastically deform the austenitic stainless cast steel pipe in order to make it bendable without causing cracks, by limiting the working condition. CONSTITUTION:The austenitic stainless cast steel pipe P is passed through the guide rolls 1, 2, and the heater 3, and is clamped by the clamp 6 of the arm 5 at the suitable position. Next, the pipe P is continuously sent forward at a speed 0.2- 1.0mm/sec and is heated to 1,060-1,300 deg.C by the heater 3; immediately after that, the pipe P is water cooled by the cooler 4. Hereupon, a bending moment is continuously given to the pipe P in the heating zone, in order to cause the continuous plastic deformation by the bending radius R, 1.5-3 times of the length of the pipe P; hereby, the bending work is applied to the pipe P. Besides, the reason of limiting the working condition is because that the slower the sending speed for the pipe P is, the less is the generation of cracks, however, if the speed exceeds the limited range, the productivity is lowered. And the smaller the bending radius is, the higher the heating temperature is required to be, however, if the temperature exceeds the limited range, the postwork material quality is deteriorated.

An investigation of first- and second-order mixed plate-bending elements

Abstract: Numerical convergence of first- and second-order plate-bending elements is investigated. Using iso-parametric formulation, general bilinear and biquadratic quadrilaterals, with the three moment components and the transverse deflection as dependent variables, are obtained. The same elements are also used as degenerate triangles by collapsing one side. A constant bending moment patch test, applied numerically to the elements, indicated poor performance for linear triangles, while the bilinear, quadratic and biquadratic elements behaved well, with exact results in uniform meshes. Further numerical examples showed the same general trend as the patch test. Although bilinear, quadratic and biquadratic elements were always able to yield the correct solutions with mesh refinements, the linear triangles were in general unable to do so.