Showing papers on "Embedment published in 1987"

Uplift of Anchor Plates in Sand

Abstract: An investigation into the vertical uplift of anchor plates in a cohesionless medium is described. Factors investigated in relation to the loaddisplacement response were the size and shape of plate,...

Impedance functions for foundations embedded in a layered medium: An integral equation approach

Abstract: An integral equation technique to calculate the dynamic response of foundations embedded in a layered viscoelastic half-space when subjected to external forces and moments is presented. The technique is based on representing the radiated field as resulting from a set of sources distributed over a surface internal to the actual boundary of the foundation and by imposing the boundary conditions in an integral sense. The resulting non-singular integral equation with symmetric kernel is solved by discretization and reduction to a system of linear algebraic equations. The technique is validated by comparison with previous results for cylindrical foundations with different embedment ratios.

Horizontal Stiffness of Arbitrarily Shaped Embedded Foundations

Abstract: Using a boundary element formulation, a systematic parametric study is performed on the static and dynamic horizontal stiffness of arbitrarily shaped rigid foundations embedded in a reasonably deep and homogeneous soil deposit. Results are presented for rectangular base shapes of aspect ratios up to 10, a wide range of embedment depths, three values of the Poisson ratio, and an ample range of frequencies. The height of the foundation sidewalls is varied parametrically between the two extremes of no sidewall and complete sidewall with height equal to embedment depth and in perfect contact with the surrounding soil. Results have been obtained for circular and triangular plan shapes as well, including cases of non‐uniform contact along the foundation perimeter. The results are presented in the form of simple and versatile analytical expressions and dimensionless graphs. Two examples illustrate their direct practical applicability.

Bond-slip-strain relationship of deformed bars embedded in massive concrete

Abstract: Bond tests of deformed bar embedded in massive concrete which have no effect of splitting crack were carried out. Bond-slip relationships obtained from extremely short embedment test are different from those obtained from long embedment test. Relationships between bond stress and slip depend on the location along a bar in short embedded pull-out test and in short embedded axial tension test. Bond-slip relationship of aluminium bar is different from that of steel bar. These results can be obtained by the analysis of using an unique bond-slip-strain relationship. The bond-slip-strain relationship model is formulated. This model includes the effect of bar diameter and concrete strength. In the case of condition that the strain is zero where slip is zero, the bond stress can be expressed only by the slip. The bond-slip relationship is formulated in simple form.

E' and Its Variation With Depth

Abstract: The modulus of soil reaction, E’, characterizes the stiffness of soil backfill placed at the sides of buried flexible pipelines for the purpose of evaluation deflection caused by the weight of backfill above the pipe. In this study, the nature of E’ is investigated in detail to determine whether its magnitude increases with increasing depth of embedment. The development of E’ in the literature is reviewed, and data from field installations are presented to establish that E’ can be shown to increase with depth on the basis of previous research. Analytical methods, based on elastic theory and finite element techniques, are also used to demonstrate the dependence of E’ on depth. Design values of E’, which vary with depth, are presented, together with recommendations regarding the use of E’ in the Iowa formula.

An analytical model for the pull-out of rigid anchors

Abstract: A linear elastic fracture mechanics model is presented for the pull-out failure caused by a rigid anchor embedded in a brittle material. The anchor is modeled as a vertically loaded, partly bonded rigid plate in an elastic half-space, and failure is assumed to arise from cracking which emanates from the edges of the plate. The two-dimensional elasticity problem is reduced to solving numerically a system of coupled singular integral equations. Stress intensity factors are presented for several combinations of load geometry, crack length, crack extension angle, and embedment depth. The stress intensity factors are used to construct crack paths and to determine the stability of crack propagation.

Use of guardrails on low fill bridge length culverts. final report

Abstract: When multiple box culverts span over 20 ft, they are defined by AASHTO as bridge length and thus normally require the use of a full strength rigid bridge rail. The use of a rigid bridge rail creates a transition problem between the flexible metal beam guard fence which is commonly used upstream of the bridge rail. It would be safer and more economical to continue the flexible metal beam guard fence across the culvert even when the culvert length is over 20 ft and even when the soil fill depth over the culvert is less than the standard guardrail post embedment depth of 38 in. in Texas. It was believed that more post could be used with a shallow embedment to achieve the desired guardrail strength. A metal beam guard fence design of this type was crash tested in this study and proved to be unsatisfactory. Another concept investigated was to rigidly mount steel guard fence post (with blockout) to the top of the culvert deck when full soil embedment could not be achieved. A design of this type was also crash tested in this study and proved to be satisfactory.

Uplift Capacity of Model Group Anchors in Sand

Abstract: Small-scale laboratory experimental results for the ultimate uplift capacity of shallow horizontal circular single and group anchors embedded in sand have been presented. The experimental ultimate uplift capacity of single anchors has been compared with theories provided by Meyerhof and Adams, Vesic, and Clemence and Veesaert. For anchor groups, the uplift efficiency varies with the number of anchors, center-to-center anchor spacing, embedment ratio, and soil friction angle. The experimental uplift efficiency of group anchors has been compared with the theory of Meyerhof and Adams.

Standard Fatigue Test Specimens for Fastener Evaluation

Abstract: : An AGARD coordinated programme which examines the fatigue performance and joint characteristics of a number of mechanically fastened joints has been completed. This report describes the programme which examines mechanically fastened joints with 1) no or low secondary bending and 2) with high secondary bending. In part 1, three types of joint are assessed which exhibit no, low and high amounts of load transfer by the fastener. The no load transfer joint was rejected and the low and high load transfer joints were considered to be equivalent in rating fastener systems. In part 2, three types of single shear joint are considered. They are compared on basis of load transfer and secondary bending characteristic and also on the fatigue endurance with a range of fastener systems installed. Only one joint, the UK designed Q-joint, adequately fulfilled the requirement of a standard joint for fastener evaluation purposes.

On The Modelling of Inelastic Interfaces in Fibrous Composites

Abstract: The classical fiber pull-out problem has been formulated in one-dimension with a view to focus on the nonlinear interfacial response. The fiber and the cocentric matrix are assumed to behave elastically. The local interfacial bond-slip characteristic has been idealized to be elastic-linear softening. This greatly simplifies the otherwise implicit governing differential equation of the debonding process. Solutions to the fiber axial force and interfacial shear stress along the embedded length of the fiber have been obtained by applying appropriate boundary and continuity conditions. The stability of the debonding process has been investigated by varying the fundamental characteristics of the fiber-matrix interface, the fiber embedment length and the fiber diameter. The analytical model has been successfully used to predict many of the characteristics experimentally observed in fibrous composites that fail by fiber pull-out.

Measurement of internal concrete strains using embedment strain gauges

Abstract: Synopsis The use of embedment strain gauges—electric resistance strain gauges encapsulated in acrylic resin—for the measurement of internal concrete strain distributions infive tension specimens is described. Results are presented to illustrate the performance of the technique.

Embedment of piping and cable

Abstract: PURPOSE:To execute the piping embedment work in which piping and a cable along the piping are embedded, at low cost by embedding the piping and the cable with a resin foamed block allocated around the piping and the cable. CONSTITUTION:In the embedment work of a piping 2 and a communication cable, a resin foamed block 4a is inserted into an embedment groove 40, a piping 2 is installed inside the groove 40, and a resin foamed block 4b is piled on the groove 40. Next, resin foamed blocks 4c and 4e are piled on the resin foamed block 4b, a communication cable 3 is installed in the groove 40 and resin formed blocks 4d and 4f are put on the blocks 4c and 4e. Earth and sand 5 are thrown back on the blocks 4d and 4f and the pavement work 6 is done. As a result, the amount of the thrown back earth and sand may be little and the coating of the piping is not damaged. There is little possibility of generating a load stress on the piping or the like due to sinking of the ground.

Lapped joints in reinforced concrete

Abstract: This thesis is concerned with an experimental investigation of the behaviour of lapped joints in reinforced concrete. A review of existing literature highlights the need to establish the longitudinal strain distribution along lap joints. This has been achieved experimentally, with detailed strain measurements being taken using a technique of internally gauging the reinforcing rods. In some specimens, strain concentration gauges were installed at the tip of the lap to permit the acquisition of particularly localised information. Computer programs were developed to process the substantial amounts of data generated during the course of each test. Two series of tests were undertaken, both using axially loaded specimens, and dealing with tension and compression lap joints respectively. The laps ranged in length from 125 to 750 mm, and comprised bars of either 12 or 20 mm diameter. Transverse reinforcement was provided in two of the tension specimens. Greater emphasis was placed on the first series, with fifteen tension specimens being tested. Thirteen of these tests were each completed within a single day but, additionally, two long-term tests were undertaken. In the latter, a constant load was sustained for up to 81 days. The measurements clearly showed the changing behaviour of the specimens, first as transverse cracks developed and subsequently as failure of the lap joint was approached. The comprehensive analysis of the test results includes a comparison of the ultimate behaviour of these joints with existing design proposals and regulations. The detailed information provided by the strain measurements enables the justification of design assumptions regarding lap joint behaviour, and thus lends greater confidence to existing design regulations. The results from five compression specimens were analysed and compared with the tension tests. The significant contribution to force transfer made by the bearing of the free end of the steel against the concrete was evident. The specimens were loaded to the rig capacity without failing. Additional strain measurements were taken in one tension and one compression specimen by casting embedment gauges within the concrete. These gauges were arranged to measure the circumferential strains in the specimen, and were complemented by strain gauges mounted on the surface of the concrete. The data thus obtained permitted a comparison of the bursting forces set up inside and outside the lap joints. The work showed that some aspects of lap joint behaviour require clarification. Suggestions for further work are included.

The design of independent anchor blocks for vehicular-impact loadings

Abstract: A simplified method for the analysis and design of independent anchor blocks is presented. Independent anchor blocks are structures designed to provide adequate guardrail-system anchorage and still remain independent of the bridge rail structure in guardrail-bridge rail transitions. Critical loadings for independent anchor blocks are discussed as well as the dynamic ultimate strength of soils. Equations of motion are developed from dynamic equilibrium considerations, and design curves are developed that can assist the designer in selecting the most appropriate geometry. Given the length and width of a particular independent anchor block, the design curves indicate what minimum embedment depth is required to minimize deflections in the critical-loading cases. Finally, the results of two full-scale crash tests are presented that verify the design curves.

Structural body for cleaning up waste water

Abstract: PURPOSE:To extend the sevice life of a titled body and to permit the easy embedment thereof in a horizontal state by mounting a water impermeable rigid body to the outside peripheral surface in the lower part of a water permeable tubular body so that the clogging by sludge-like scum and anaerobic microorganisms hardly arises. CONSTITUTION:The water impermeable rigid body 3 is mounted to the outside peripheral surface in the lower part of the water permeable tubular body 2 having through-holes 1. As a result, the clogging by the sludge-like scum and anaerobic microorganisms hardly arises and the service life is longer. The embedment and installation of the structural body in the horizontal state are easy; in addition, the structural body is hardly deformable by land subsidence and load bearing after the embedment.