Showing papers on "Embedment published in 1978"

Investigation of the effect of a vertical surcharge on horizontal displacements and resistance of pile columns to horizontal loads

Abstract: 1. The principle of independence of the action of forces in the general case is not applicable to calculation of pile columns with relative embedment < 15. A vertical surcharge can somewhat decrease (in weak saturated soils) or increase (in clays of very stiff consistency) the resistance of pile columns to horizontal loads. In the investigated saturated soils, the bearing capacity decreased by no more than 15%, and in very stiff slump-prone soils it increased by a factor of 1.9.

Dynamics of rectangular footings by finite elements

Abstract: A finite element solution in three dimensions for rectangular footings resting on soil medium has been presented for the vertical mode of vibration. Soil medium has been idealized as an elastic half space. Both linear and nonlinear, as well as depth dependent, soil properties have been considered for analysis. For discretizing into a finite number of elements, the semi-infinite elastic medium is idealized as a bounded region by adopting appropriate boundary conditions. A simple hexadedron isoparametric element with eight nodes (ZIB8) has been taken as basic element. Experimental and analytical studies indicate that the nature of contact pressures at the footing-soil interface changes with the magnitudes of operational frequencies, thus all probable contact pressures have been incorporated in the analysis. Effects of embedment, static surcharge, nonhomogeneity, and nonlinear stress-strain characteristics are shown. Influences of the aforementioned factors on the resonant frequencies have been reported. Results are compared with the existing solutions and presented graphically.

Embedment anchors subjected to repeated loading

Abstract: In order to provide a reliable method of estimating the effects of repeated loading on the holding capacity of an anchorage for the purpose of designing embedment anchor systems for long-term use, tests were performed on circular plate anchors connected to a rigid tie shaft which were placed in a medium, uniform saturated sand. The loading device consisted of a hydraulic loading system capable of applying a variety of static and cyclic load patterns to the anchor. It was found that the deterioration in the cyclic loading-relative movement properties of an embedment anchor appears due to the accumulated amount of cyclic relative movement, whether developed by a few strong or many small stress pulses. However, care must be taken when using simple cyclic loading tests to predict the behavior of anchor systems subjected to long-term sustained-repeated loading conditons. Tests performed at different stress levels for deep anchors suggest that, when the cyclic relative movement of the anchor is kept below about half the relative movmeent to failure in a static pull-out test, there is essentially no reduction in strength due to cyclic loading. If this criteria is adopted, cyclic loading failure could be defined as a cyclic strain of 50 percent of the static strain to failure. Although this investigation is at an early stage, it is clear that cyclic failure of embedment anchors can be better defined in terms of unacceptably high relative movements resulting in significant drops in the anchor static pull-out capacity.

Vertical Line Groups of Horizontal Anchors in Sand

Abstract: It has been established elsewhere that the behavior of a single isolated horizontally loaded vertical plate anchor in sand changes from shallow to deep at a depth of 6.5 times the anchor height. In studies on uplift anchors, Hanna noted that the behavior of anchors and their depth of embedment. Horizontal anchors, such as are used with diaphragm walls, are usually arranged in groups and at varying depths. This note describes an investigation undertaken to study how the pullout capacities of vertical line groups of horizontal anchors are influenced by their center-to-center spacing and their depths of embedment.