Showing papers on "Embedment published in 1983"

Centrifugal Model Tests on Vertical Anchor Plates

Abstract: The stress displacement behavior of vertical anchor plates and continuous anchor walls in dense sand when subjected to horizontal pull‐out forces is presented. Results of a large number of centrifugal tests on 1 in. (25 mm) and 2 in. (50 mm) models subjected to accelerations of up to 40 gravities are presented and the effects of anchor geometry and embedment are examined. Centrifugal test results are compared with those from conventional small model tests thus enabling potential errors in direct extrapolation of the latter to field scale to be evaluated. Considerable overpredictions of pull‐out resistance and under‐estimations of failure displacements are found for 1/20 and 1/40 scale modellings of 19.7 in. (0.5 m) and 39.4 in. (1 m) anchors. The effects of anchor geometry, defined by dimensionless shape factors appear to be sensibly independent of scale. Experimental results are briefly compared with recent theoretical and semiempirical design formulas using shear strengths derived from plane strain comp...

Determination of the integrity of part of structural materials

Abstract: Laminated parts of structural material receive as embedment light transmitting fibers, preferably in addition to reinforcing fibers, and light transmission through the light transmitting fibers is monitored for purposes of determining pattern irregularities and formation of cracks.

Deformation of Cracked Net‐Reinforced Concrete Walls

Abstract: The deformation and crack width in concrete walls of slabs, plates, panels, and shells reinforced by a regular rectangular net of steel bars and subjected to in-plane (membrane) internal forces is analyzed taking into account the frictional-dilatant behavior or rough interlocked cracks, and the dowel action of bars at crack crossings. The tension-stiffening effect, i.e., the restraint of the bars between the cracks due to their embedment in concrete is also taken into account. Numerical computer studies are carried out. Reinforcement designs obtained from equilibrium conditions alone on the basis of either the classical frictionless approach or the recent frictional (slip-free) approach are compared in terms of the resulting crack widths. It is found that the use of frictional equilibrium design based on a low friction coefficient (0.75) leads to a much smaller crack width than the classical frictionless design when the reinforcement is laid in a direction which significantly deviates from the principal internal force direction. The influences of bar diameter and crack spacing on the crack width are also determined. The deformation analysis in which the frictional dilatant behavior of cracks, the dowel action, and tension stiffening are neglected leads to rather different values for the crack width.

On the effect of the rigid sidewall on the dynamic stiffness of embedded circular footings

Abstract: The effect of the rigid sidewall, which is usually combined with embedded footings, on the dynamic stiffness of the footings is considered. An efficient numerical technique is used to calculate the static and dynamic stiffness of circular footings embedded in a stratum. The results show that the increase in static stiffness with increasing height of the sidewall is most significant in the case of rocking. The dynamic stiffness coefficients change considerably, if the sidewall extends higher than about half the depth of embedment. The damping coefficients corresponding to vertical vibrations and rocking are likewise affected by the height of the sidewall. The damping coefficients corresponding to torsional and horizontal vibrations increase considerably with increasing height of the sidewall.

Paintbrush embedment compound and paintbrush construction and method embodying same

Abstract: An embedment compound for a paintbrush or the like, together with a paintbrush construction and method of manufacture embodying the improved embedment compound. The embedment compound is a polyurethane composition having a crosslink density sufficient to render such compound acceptably resistant to all paint solvents. For example, a typical embodiment composition comprises a blend of Mondur MR with a prepolymer prepared from Pluracol TP-440 and Isonate 143L, and the blend cured at 100° C. overnight.

Finite element analysis of the secondary buckling of a flat plate under uniaxial compression

Abstract: Uemura and Byon (Int. J. Non-Linear Mech. 13, 1–14, 1978) presented experimental results and a numerical analysis about the secondary buckling of clamped flal plates under uniaxial compression. However, their numerical analysis is based upon an inconsistent flat plate finite element and it does not take into account the important influence of antisymmetric imperfections. This paper presents and discusses F.E.M. results obtained by two computer codes using very different approaches, and compares these results with the experimental ones.

Experimental studies of dynamic response of foundations

Abstract: An investigation was made into the behavior of rigid foundations and structures resting on the surface or embedded in a cohesionless soil and subjected to transient active or passive excitations and forced vibrations using the centrifuge modeling technique. The investigation was aimed at studying both low and high amplitude vibrations of foundations under machine type loadings, earthquake or wave induced vibrations, and other sources of dynamic loads. Rigid "prototype" foundations of mass and size comparable to foundations of a low rise building were simulated in the centrifuge at a centrifugal acceleration of 50g. Rigid model structures (aluminum towers) attached to foundations of different shapes, sizes, masses, and moments of inertia were tested. The effect of soil depth, boundary conditions, and depth of foundation embedment were investigated. Mainly rocking and horizontal modes of vibration were studied, The impulse rocking-horizontal excitation of the models was provided by actively perturbing the model structures using explosive energy or by passively exciting them by shaking the whole soil bucket using a hydraulic shaking system. The forced vibration was produced by a miniature air-driven counterrotating eccentric mass shaker mounted on the model structures. During the tests detailed measurements of the static and dynamic contact pressure distributions, displacement components of the model, and acceleration amplitudes at different elevations of the model structure were obtained. The acceleration ratios were used to determine the modes of vibration of the foundation systems. Natural frequencies and damping coefficients of the modes were calculated by f1tting the amplitude-frequency response of a single degree of freedom mass-spring dashpot oscillator to the experimental response curves derived from the test data. Experimental results provided information regarding the influence of different geometrical, inertial, and loading conditions on the vibrational characteristics of the soil-structure system. In particular the effect of foundation embedment was to increase the model resonant frequencies and to cause an appreciable change in contact pressure distribution underneath the footing. However, the resonant frequencies predicted by the lumped parameter analysis for a simple two-degree-of-freedom (rocking and translation) model were about 15 to 55 per cent higher than those measured experimentally. These results were approximately consistent with the comparisons made in similar theoretical and experimental studies such as those performed by Morris in the Cambridge centrifuge and those performed on full-scale footings by Stokoe and Richart. Damping ratios of the rocking-sliding vibration did not change considerably when footing size or depth of embedment changed. The existence of rigid boundaries around the soil mass in the bucket, and an inefficient contact between soil and the foundation side walls and lower surface could account for these observations. Uplift and nonlinear large amplitude vibrations were consistently observed during the steady-state vibration tests. Uplift led to a softer vibrating system which behaved non-linearly. As a result the frequency of vibration decreased with the amount of lift-off. In transient vibration uplift reduced the intensity of higher frequency vibration. Soil around the foundation edge yielded and plastic deformations and subsequent softening of the contact soil increased the material damping while it decreased the resonant frequency of the system. It was concluded that elastic half-space theory does not satisfy the needs for analysis of foundation behavior under high amplitude vibrations and more sophisticated methods of analysis are required.

Embedment system for ultrahigh-burning rate propellants of solid propulsion subsystems

Abstract: An improved embedment system is disclosed which is comprised of an embedm granule portion in percent by weight of nitrocellulose of about 23.0, nitroglycerine of about 15.0, resorcinol of about 1.5, 2-nitrodiphenylamine of about 1.0, ammonium perchlorate (10 micrometers) of about 45.5, and aluminum powder (20 micrometers) of about 14.0 and an embedment resin portion in percent by weight of bisphenol A-epichlorohydrin of about 44, epoxidized dimer acid of about 20, and a curative which is the condensation product of 2 moles of 1,2-bis(maleimido)ethane and one mole of triaminotriazine of about 36.0. This embedment system has superior characteristics of a high peel strength and greater resistance to penetration by or absorption of carboranylmethyl propionate or casting solvent absorption.

An embedment anchor

Abstract: A ship 1 carries a high pressure water pump 2 connected by high- pressure hose 3 to a hollow vertical cylindrical member 4 to the lower end of which is detachably engaged the hollow stem of an embedment anchor 5 to which are hinged anchor blades curved in cross-section so as to be foldable upwards against the stem. The blades are equispaced along, and around the circumference of the stem. Attachment eye 5a secures cable 6. When water is pumped down cylindrical member 4 it excavates a pit into which the anchor 5 sinks. The anchor is drawn upwards slightly before the pump is stopped. This opens are hinged blades. Then cylidrical member 4 is disengaged from the anchor 5.

Method for making reinforced concrete products

Abstract: A method for making reinforced concrete including the steps of laying down layers of concrete and contemporaneously automatically cutting, and bodily ejecting into the contemporaneously layed down layers of concrete oriented wire lengths in any desired aligned patterns. In one embodiment the concrete layers are injected into a rotating cylindrical form and the oriented wires are cyclically bodily thrown off at selected angular intervals for embedment in axially aligned annular arrays in the concrete layers.

Pre-embedment localization of antigens by immunofluorescent methods.

Abstract: In recent years semi-thin sections of plastic-embedded tissues have contributed to significant improvements in the quality of histological material.' Details can be better studied because sections of 0.5 to 2.0 hm involve single-cell layers. Furthermore, many of the embedding media are water miscible so that the tissues do not have to be completely dehydrated. Many monomers can be polymerized at low temperature, another factor resulting i n good tissue preservation. klild and incomplete dehydration and embedding at low temperature permit milder non-coagulative fixation, a further factor leading to improved histology. A discrepancy between the observed preservation and identification of antigens in histological material using conventional cryosections or paraffin sections and the potential offered by plastic embedding has stimulated several approaches to improve the quality of immunohistochemical preparations. These can be divided into preand post-embedding staining methods. The obvious advantage of post-embedding staining is that sections from a single tissue block can be stained with a large number of antibodies whereas a separate embedding has to be carried out for each antibody used in pre-embedding staining. Furthermore a more uniform staining can be achieved with post-embedding staining than with pre-embedding staining. Unfortunately, the water-miscible methacrylate monomers used in the low temperature embedding procedures are virtually impossible to dissolve once polymerized. Therefore the possibility of post-embedding staining after embedding in such plastics is limited to the surface and then only if the monomer has not cross-linked to the antigen of interest. A successful example of post-embedding staining using a methyl methacrylate, 2hydroxyethyl methacrylate polymer, for embedding whole joints has been described.' Plastics that can be etched away from the section, such as various epoxy resins?\" require relatively long curing times at relatively high temperatures (45-60OC). In such cases not all antigens are preserved in a sufficiently native form to allow postembedding staining. There may also be chemical binding of the monomer to the antigen of interest but this may be alleviated by reaction of the antigen with ethyl acetimidate prior to embedding.* With the present drawbacks of post-embedding immunohistochemistry in mind, we concentrated our efforts on improvements of pre-embedding immunohistochemistry.s These improvements were concerned with fixation, staining, and Although we employ a standard procedure, applicable for most tissues and most