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Showing papers on "Embedment published in 1996"


Journal ArticleDOI
TL;DR: In this article, a parametric analysis is made of the interaction effects on the effective period and damping of structures with embedded foundation in a soil layer, where the soil is replaced with impedance functions that are taken from a data base obtained with an appropriate numerical technique, so that suitable springs and -pots dependent on the excitation frequency are used.

70 citations


Dissertation
01 Jan 1996
TL;DR: In this paper, a zero-thickness iso-parametric interface element was formulated for both two and three dimensional analyses to examine the elastic behaviour and stability of circular footings under combined loading.
Abstract: This thesis is concerned with four different types of offshore foundations, namely gravity foundations, jack-up foundations, the mudmats for piled jacket structures and caisson foundations for jacket structures. In most applications, these can be idealised as circular rigid foundations. Unlike onshore foundations, offshore foundations are subjected to large horizontal and moment loads. This research used the finite element method to examine the elastic behaviour and stability of circular footings under combined loading. Due to the circular shape of the footings and the combination of vertical, horizontal and moment loads, three dimensional finite element analysis was used. In-depth analyses of the elastic behaviour of circular footings under combined loading (V,H,M) were performed. The vertical stiffness coefficient was investigated using two dimensional axi-symmetric analyses whereas three dimensional analyses were used to examine the other coefficients. Different features of offshore foundations such as footing embedment and cone angle were taken into consideration. Based on the numerical results, a set of empirical expressions for elastic stiffness coefficient was derived. For footing stability calculations, large horizontal or moment loads can cause the footing to lose contact with the soil, or cause the footing to slide relative to the soil. In finite element analyses, this loss of contact and sliding are modelled by interface elements. A new zero-thickness iso-parametric interface element was formulated for both two and three dimensional analyses. An exact close formed solution for integration of the stress-strain relationship (for the two dimensional interface element) was found. The element is then used to explore footing stability. It was shown that by using a yield criteria which allows the interface to behave as either frictional or cohesive interface, depending upon the normal stress, numerical stability is achieved. The footing stability was examined by establishing the bearing capacity envelope. The envelopes for footings on undrained clays were established for surface flat strip footings and for surface flat circular footings. The effects of soil strength varying with depth, cone angle and embedment on the bearing capacity envelope were also investigated.

46 citations


Journal ArticleDOI
TL;DR: In this article, the load-carrying capacity of a group of anchor plates increases with the spacing between the individual plates up to a limiting critical value, and it is demonstrated how the results of pulling tests with different numbers of plates in a group may be described in a simple unifying manner.
Abstract: Results are presented of model-scale vertical pulling tests carried out on groups of square anchor plates in row and square configurations. The tests were carried out at a single depth of embedment, which ensured shallow anchor behavior in the sand placed at a constant dry density. It is shown that the load-displacement relationships for all groups may be reduced to a common curve. The load-carrying capacity of a group of anchor plates increases with the spacing between the individual plates up to a limiting critical value, and it is demonstrated how the results of pulling tests with different numbers of plates in a group may be described in a simple unifying manner. A possible means of predicting the effect of interaction on the uplift capacity of both modeland full-scale anchors in row configurations is suggested. For laboratory tests on a linear group of five anchors, it is shown that the end anchors attain the highest loads but all loads converge to an equal value as the spacing increases to the criti...

42 citations


Patent
11 Oct 1996
TL;DR: In this article, an improved anchor (A) for embedding in a concrete member (S) to provide a lifting attachement for the member is presented. The anchor is composed of an elongate bar (10) having convergent (16a and 18a) and divergent surfaces (16b and 18b) wherein the convergent surfaces face outwardly to direct axial pull-out forces imparted to the bar divergently and laterally into the member.
Abstract: An improved anchor (A) for embedment in a concrete member (S) to provide a lifting attachement for the member. The anchor (A) comprises an elongate bar (10) having convergent (16a and 18a) and divergent surfaces (16b and 18b) wherein the divergent surfaces (16b and 18b) face outwardly to direct axial pull-out forces imparted to the bar divergently and laterally into a concrete member (S) within which the anchor (A) is embedded. Divergent wings (36) are fixed to and extend laterally from the bar (10) to direct lateral forces imparted to the bar (10) in divergent directions relative to the bar (10).

35 citations


Journal ArticleDOI
TL;DR: In this paper, the static equilibrium of drag anchors during embedding in sand is examined and a limit equilibrium method is developed to allow the anchor holding capacity to be predicted given a specific annealing condition.
Abstract: This paper examines the static equilibrium of drag anchors during embedment in sand. A limit equilibrium method is developed to allow the anchor holding capacity to be predicted given a specific an...

32 citations


Journal ArticleDOI
TL;DR: In this article, the kinematic behavior of a drag anchor during embedding in sand is examined, and the authors provide an essential step towards a theoretical simulation of a complete anchor embedment history and hence a predictive tool for the ultimate holding capacity.
Abstract: The kinematic behaviour of drag achors during embedment in sand is examined in this paper. A series of centrifuge model anchor tests has been performed in silica and calcareous sands in which both force and kinematic data were obtained during the course of anchor embedment. In this paper, the kinematic data have been examined to determine general rules for the kinematic behaviour of a drag anchor during embedment. These rules provide an essential step towards a theoretical simulation of a complete anchor embedment history and hence a predictive tool for the ultimate holding capacity of a drag anchor. Key words: drag anchor, kinematics, sand, limit equilibrium, ultimate holding capacity.

32 citations



Journal ArticleDOI
TL;DR: In this article, free and forced vertical vibration tests were conducted on surface and embedded models for footings on dry and moist poorly graded sand that has the following properties: D10 = 0·21 mm, D30 = 0.305 mm,D60 = 0 ·423 mm, Cu = 2, Cc = 1·05, Gs = 2·66, γmax = 1.74 cm−3 and γmin = 1 ·4 g cm −3.

23 citations


Journal ArticleDOI
TL;DR: In this article, the prediction of tensile capacity as governed by concrete cone failure of single anchors placed in uncracked, unreinforced concrete and located far from a free edge and far from other anchors is discussed.
Abstract: This study concerns the prediction of tensile capacity as governed by concrete cone failure of single anchors placed in uncracked, unreinforced concrete and located far from a free edge and far from other anchors. A total of approximately 801 data points is available from tests on such anchors. A total of 31 data points consisting of data on high-strength anchors previously compiled by Klingner et al., 1 Collins et al., 2 and Cannon is accessible from tests on single anchors failing by fracture of anchor steel. Using common definitions and nomenclature for all variables and material properties, each data set is placed in a database using SI units and concrete cube strengths. The concrete cone failure data are then plotted against capacities predicted by three existing methods: 1) the 45 deg cone method of ACI 349-90, Appendix B; 2) a variable angle cone method (VAC); and 3) the concrete capacity method (CC method). Observed data are compared against these existing methods in terms of average square error and load and resistance factor design (LRFD). Finally, using the principles of load and resistance factor design (LRFD) and following the design procedure of ACI 349-90, Appendix B, the probability of steel or concrete failure under known loads and the probability of concrete failure under unlimited loads are calculated. Based on those comparisons, each approach is evaluated with respect to accuracy and suitability for use in design. For single tension anchors with embedment depths less than 8 in., all three capacity prediction methods fit most of the data relatively well. However, the CC method is more accurate and has a distinctly lower probability offailure when the embedment depth is greater than 8 in.

18 citations


Journal ArticleDOI
TL;DR: In this paper, free vibrations of a fully clamped symmetric laminated skew plate are analyzed by a numerical approach in which the Green function for a static bending problem is used.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of normal pressure on the bond strength of deep beams has been evaluated in the light of current ACI and other design recommendations for deep beams, and the results show that the effect may reduce the required end-anchorage length of the tension reinforcement.
Abstract: Tests were carried out on 24 lightweight concrete deep beams to study how their behavior was affected in the ultimate load range by the embedment lengths for the end-anchorage of the main tension reinforcement. In deep beams, the applied load is transferred to the supports mainly through the compression struts in a truss/arch mechanism. Hence, the main reinforcement has to act as a tension tie, and therefore, requires adequate end-anchorage. Additionally, the compression strut and the support reaction will act together to produce a transverse or normal pressure that may increase the bond strength and thus, the anchorage strength of the main tension reinforcement. This favorable effect, which has been reported by other researchers, may reduce the required embedment length for end-anchorage of the tension reinforcement. In the tests, as the embedment length of the tension reinforcement is reduced, the ultimate behavior of the beams is critically observed in the light of current ACI and other design recommendations for deep beams. To the authors' knowledge, the research described in this paper represents the first direct attempt to validate the favorable effect of normal pressure on bond strength in deep beams.

01 Dec 1996
TL;DR: In this article, the minimum embedment length of resin required for resin-grouted, cable bolt ground support was determined, based on a series of laboratory tests, and the recommended configuration of cables with Garford bulbs and collars.
Abstract: Spokane Research Center personnel are currently conducting research on cable bolts to assess their material and support properties, to provide design criteria for roof control systems under various types of underground mining conditions, and to provide background data for computer models of cable bolt supports. Laboratory studies of cable bolts made of conventional steel cables with Garford bulbs and collars resulted in recommendations on characteristics such as embedment length, hole diameter, cable bolt diameter, and configuration of cables. A completed series of laboratory tests has determined the minimum embedment length of resin required for resin-grouted, cable bolt ground support.

Journal ArticleDOI
TL;DR: In this paper, a simple, albeit approximate, derivation of the pull-out force of axisymmetric headed anchors is given by studying the growth of a penny crack in half space loaded only on its upper face.
Abstract: A simple, albeit approximate, derivation of the pull-out force of axisymmetric headed anchors is given by studying the growth of a penny crack in half space loaded only on its upper face. The initial diameter of the penny crack is equal to the head diameter. The formula so obtained does not contain any unknown constants. It is shown to be particularly accurate at large depths of embedment for which the Code formula overestimates the pull-out force.

Proceedings ArticleDOI
30 May 1996
TL;DR: In this article, a fiber-optic vibration sensor, suitable for embedment or surface mounting has been designed and evaluated. But it was mounted on the surface of specimens of carbon fiber reinforced composite, and proved to be capable of differentiating between the vibrational responses of damaged and undamaged panels.
Abstract: A compact intensity-based fiber-optic vibration sensor, suitable for embedment or surface- mounting has been designed and evaluated. It employs simple and inexpensive instrumentation, and is shown to be responsive to frequencies in the range of 100 - 10,000 Hz. It was mounted onto the surface of specimens of carbon fiber reinforced composite, and proved to be capable of differentiating between the vibrational responses of damaged and undamaged panels. An attempt was made to characterize the sensor's output signal by FFT processing. The sensor also survived embedment in a cementitious composite panel. It is proposed that the device can be used as the sensing element of a real-time mechanical-health- monitoring system.


Journal Article
TL;DR: In this article, a limited equilibrium-type analysis was developed, to as the safety factor (based on soil strength) of a proposed berm-wall geometry, based on the procedures recommended in British Standard BS8002.
Abstract: This technical note outlines a programme of research to investiga the effectiveness of berms of different sizes, and calibrate a li equilibrium calculation for use in designing a retaining wall. E centrifuge model tests were conducted on samples of speswhite kao clay. The tests were supported by a series of plane strain finit element analyses with fully coupled consolidation, using the CRIS program. A limited equilibrium-type analysis was developed, to as the safety factor (based on soil strength) of a proposed berm-wall geometry, based on the procedures recommended in British Standard BS8002. The research provided quantitative evidence of the abili of berms to reduce wall movements. If the wall embedment is sufficient for short-term stability, a larger berm is likely to b more effective than an increased embedment depth in reducing wall movements. Research on the effectiveness of earth berms is continuing in collaboration with the Transport Research Laborator (TRL). If a suitable site can be found, a real construction is t instrumented.

Patent
09 Apr 1996
TL;DR: In this paper, a primary water stop material for a precast concrete case consists of a water stop part 1 which is installed at the coupling end face 7 of PC case 6 for coupling a plurality of PC cases 6 water-tightly.
Abstract: PURPOSE: To make certain stop of water in the coupling part of a precast concrete case (PC case). CONSTITUTION: A primary water stop material for PC case consists of a water stop part 1 which is installed at the coupling end face 7 of PC case 6 for coupling a plurality of PC cases 6 water-tightly, wherein an embedment 4 having a recess 5 for prevention of drawing-out is formed in a single piece with the water stop part 1, and the water stop part 1 is composed of a body part 2 and a seal 3 which encloses the whole periphery of the body 2 and whose end 3a attains the embedment 4. The embedment 4 and the end 3a of the seal 3 are buried under the coupling end 7 of the PC case 6.

Proceedings ArticleDOI
28 Apr 1996
TL;DR: In this article, the authors evaluate the non-destructive use of flexural waves to determine the length of these bridge pile foundations, which is an important problem for federal and state agencies and has been the focus of several studies.
Abstract: For approximately 6000 of Georgia’s 14,500 bridges, pile tip elevations are unknown because design and construction records no longer exist. This lack of information is critical because it is diEcult to determine the capacity of these piles - particuhuly in the presence of scour. The unknown bridge foundation problem is an important problem for federal and state agencies and has been the focus of several studies (Olson et al., 1995; Douglas and Halt, 1993) The unknown bridge foundation problem is one in which either the type and depth of foundation is unknown, or the type of foundation is known but the depth is unknown. Although soil borings and other intrusive tests are capable of determining pile tip elevations, the time and cost of performing these tests on a large number of bridges is prohibitive. Nondestructive tests are an effective alternative for assessing pile tip elevations. This study focuses on bridges which are supported by exposed pile foundations that have unknown lengths. The purpose of this study is to evaluate the nondestructive use of flexural waves to determine the length of these bridge pile foundations. Many nondestructive test methods rely on the use of longitudinal waves excited axially down a pile. This type of testing is not feasible since the bridge superstructure prevents access to the top of a pile. Although the theory behind flexural wave testing is more complicated than that of the traditional longitudinal wave testing, flexural or bending waves can be excited laterally on the side of the pile with no physical interference from the bridge superstructure. The pile in most cases can be modeled as a long slender member since its ratio of length to section depth ratio is large. The propagation of the flexural waves within the beam is a function of its length, mass density, moment of inertia, elastic modulus and end conditions. When dealing with bridge piles, the primary unknown is the embedment length since all of the other variables can be assumed or measured. The nondestructive test method developed in this study uses modal analysis techniques to interpret the pile length. A three-step approach is used. First, the response model of the pile is determined by measuring a set of frequency response functions for the pile. Second, the modal model consisting of the natural frequencies, modal damping parameters, and mode shapes is calculated from the response model. Finally, the spatial model is determined from which the embedded length of the pile can be obtained.

Journal ArticleDOI
01 Mar 1996-Wear
TL;DR: In this paper, the authors extended the upper bound method developed by the authors earlier to find the configuration of a stress-free surface for a more complicated kinematic field and geometry of indenter, and used it to model the indentation of a rigid wheel pressed into rigid-perfectly plastic material, and then dragged through it, leaving a groove behind.

Patent
12 Jan 1996
TL;DR: In this article, an earthing pole is fixed on the outer surface of an insulator, where the inner surface is composed of bytyl rubber and its outer surface is polyethylene resin, and the insulator is heated and contracted so as to be integrally installed.
Abstract: PURPOSE:To simplify ground, and make low earthing resistance excellent by installing an insulator around the circumference and bottom surface of the embedment section of a concrete column, and concurrently fixing an earthing pole firmly on the outer circumferential surface of the column. CONSTITUTION:The outer surface of the definite height of an embedment section 2 and its bottom surface are shielded with an insulator 3 where its inner surface is composed of bytyl rubber, and its outer surface is composed of polyethylene resin, and the insulator is heated and contracted so as to be integrally installed. An earthing pole 4 firmly fixed on the outer surface of the insulator 3 is mated along the circumferential surface of a concrete column 1, and the upper and lower sections of the pole are firmly fastened by bands 5. An insulating wire is wired down to the earth hole of the concrete column 1 within a column body, and the wire is connected to the earthing pole 4. When the embedment section 2 is put into a hole so as to be erected, the hole is backfilled with conductive concrete 13 up to the upper end of the earthing pole 4, and the rest of the hole is backfilled with common earth 14 up to the ground surface. By this constitution, excellent low earthing resistance can thereby be obtained without driving an earthing bar therein.


Journal ArticleDOI
TL;DR: In this article, a plane truss model for the design of reinforcing bars in negative moment regions is presented to clarify the effects of diagonal cracking, stirrup strength, bar embedment length, and beam depth on bond failure load.
Abstract: A plane truss model for the design of reinforcing bars in negative moment regions is presented herein to clarify the effects of diagonal cracking, stirrup strength, bar embedment length, and beam depth on bond failure load. Understanding these aspects of bond in load transfer help to overcome the current empiricism in this area. The truss model is developed for the limit analysis capable of explaining failure modes involving bond strength that cannot be explained by current truss models. This study finds that the pull-out length over which bond strength fully develops is lower than the whole embedment length in the negative moment region of RC beams, and bond failure is combined with diagonal tension failure at support. The model provides a rational design methodology and a basis for the revision of current design provisions regarding bar cutoff.

Patent
24 Dec 1996
TL;DR: In this article, an embedment type frame for concrete placement having high bending strength, low shrinkage on drying and excellent durability by using a specific cement compsn. is presented.
Abstract: PURPOSE: To obtain an embedment type frame for concrete placement having high bending strength, low shrinkage on drying and excellent durability by using a specific cement compsn. CONSTITUTION: This cement compsn. contains (A) b) 3 to 30 pts.wt. gypsum, c) 0.5 to 5 pts.wt. shrinkage decreasing agent and d) <=5 pts.wt. high-performance water-reducing agent consisting essentially of any of a polyalkyl allyl sulfonate system, melamine formalin resin sulfonate system, arom. amino sulfonate system and polycarboxylate system in a) 100 pts.wt. cement and (B) contg. broad end metallic fibers having the fiber length of 1 to 60mm, a fiber width of 0.1 to 5mm and the broad parts at both ends of the fiber width of 1.5 to 10 times the fiber width at 0.5 to 5 pts.vol. in total 100 pts.vol. of the cement compsn. and aggregate. (C) The embedment type frame is produced by kneading the cement compsn. and <=40 pts.wt. water and 100 to 500 pts.wt. aggregate for general concrete per 100 pts.wt. cement.

Patent
17 Jan 1996
TL;DR: In this paper, a wall-tie is constructed with a turned-up portion with an aperture at its base through which the other member can pass before it is fixed to the first member.
Abstract: To provide a stronger e.g. welded, joint, one member, e.g. (7a) has a turned-up portion (7c) with an aperture (9) at its base through which the other member can pass before it is fixed to the first member. In a wall-tie the first member may be a plate (20) intended for embedment in one wall skin, and the second member a wire component (16).

Proceedings ArticleDOI
26 Apr 1996
TL;DR: In this paper, the development of a thin transducer using a comb-like array of piezoelectric elements has been investigated and a prototype designed to work on surface is presented and Lamb waves generation is compared with classical oblic incidence sensors.
Abstract: Lamb waves are used in the non destructive evaluation of composite materials as they can propagate over long distances. The usual method of generation relying on a transducer that can not be reduced to a low thickness (oblic incidence transducer), the development of a thin transducer using a comb-like array of piezoelectric elements has been investigated. It requires a deep understanding of the dispersion relations in the material, in order to determine its geometrical parameters for a set of frequencies. Then, a prototype designed to work on surface is presented and Lamb waves generation is compared with classical oblic incidence sensors.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.


31 Dec 1996
TL;DR: In this article, a new computer-controlled laboratory technique has been developed to measure propped fracture width and embedment in weakly consolidated cores or unconsolidated sands under simulated downhole conditions.
Abstract: A new computer-controlled laboratory technique has been developed to measure propped fracture width and embedment in weakly consolidated cores or unconsolidated sands under simulated down-hole conditions. Previously laboratory studies on cores have determined embedment in hard rocks where embedment is normally limited to 50% of the proppant grain diameter. Several studies also indicated the importance of embedment with one monolayer or less of proppant coverage. The effects of water saturation and fracture fluid filtrate on formation softness and embedment have not been previously published. Consequently, the objectives of the current paper are to extend previous research results to include soft weakly-consolidated cores and unconsolidated sands with multiple proppant layers. The influence of water saturation and dynamic fluid leakoff on embedment are also investigated. The current investigations indicate that embedment becomes a problem when the Brinell hardness of the formation is less than about 20 kg/mm{sup 2} or when the static Young`s modulus of formations cores is less than about 2 million psi (13 GPa). Embedment has been determined for cores with static Young`s moduli between 0.1 and 1.4 million psi (0.7 to 9.6 GPa). In soft and wet sandstone, embedment can reduce fracture width up to 60% or more formore » proppant concentrations of 2 lb/ft{sup 2}. For unconsolidated sands, embedment is influenced by fracturing fluid type, water saturation and down-hole conditions. Cyclic loading conditions associated with well shut-ins also increase embedment in unconsolidated sands. Test data on formation cores from South Texas, New Mexico, the North Sea and the Gulf of Mexico arc reviewed and discussed. Current fracture design programs often neglect embedment problems in calculating fracture width and assume that most formations are hard as steel.« less