Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Finite Elements


Behavior of Plate on Elastic Foundation under Impact Load

Mohammed Y. Fattah; Mohammed J. Hamood; Sura A. Abbas

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 1007-1027

In this study, nonlinear three-dimensional finite element analysis has been used to conduct a numerical investigation of the effect of applied impact load on the foundation based on sandy soil using the finite element method by ANSYS (Version 11) computer program. The 8-node brick elements are used to represent the concrete of foundation and the soil under the foundation which are denoted by Solid 65 for concrete and Solid 45 for the soil and the interface is modeled by using three-dimensional surface-to-surface (Target 170 and Contact 174) contact elements connected with concrete and soil. As a case study, a concrete foundation with dimensions (3×3×0.3) m placed on the soil 15 m deep and 9 m away from the edge of foundation is subjected to impact load. A parametric study is carried out to investigate the effect of several parameters including: foundation dimensions (geometry) and amplitude of impact load.
It was concluded that as the foundation thickness increases, the time for maximum displacement to take place increases due to geometrical damping induced by the foundation. When the length of foundation increases, the oscillation of vertical displacement decreases, which means that the foundation becomes more stable.

Finite Element Analysis of Machine Foundation Resting on End Bearing Piles

Ibtihal A. M. Al-Nakdy; Mohammed Y. Fattah; Mohammed J. Hamood

Engineering and Technology Journal, 2014, Volume 32, Issue 1, Pages 132-153

Dynamic effects of the machines play a major role in sizing of the foundation where conditions, like resonance is avoided by varying the stiffness and the mass of the structure which leads to modifications in foundation sizes. In this paper, a piled machine foundation in sandy soil is analyzed. A detailed 3D finite element analysis approach is considered using finite element software (ANSYS v.11). Machine
foundations resting on end bearing piles are modeled. Harmonic dynamic load is chosen. A parametric study is carried out to investigate the effect of several parameters including: geometry of the piled machine foundation, the amplitude of the dynamic load, and frequency of the dynamic load.
It is concluded that as the pile cap thickness increases, the oscillation of displacement decreases due to geometrical damping of the pile cap. There is a limit of pile cap size at which its stiffness governs its dynamic response, above this size, the weight of the cap overrides its stiffness effect, and the additional weight by cap leads
to increase the foundation displacement. On the other hand, when the pile diameter of the group increases, the frequency, at which the maximum displacement occurs increases hence the system becomes more stable against resonance condition.

Simulation of Behavior of Plate on Elastic Foundation under Impact Load by the Finite Element Method

Mohammed Y. Fattah; Mohammed J. Hamood; Sura Amoori Abbas

Engineering and Technology Journal, 2013, Volume 31, Issue 19, Pages 44-58

Transient response and vibrations of an elastic plate resting on sandy soil are presented. Plates are commonly used structural elements and are subjected to wide variety of static and dynamic loads. Such studies are of particular interest in analytical investigations related to structural foundation on soil media. The influence of impact induced high strain-rates within the structure, which causes property changes in all used materials, has to be regarded according to experimental results.
The main objective of the present paper, using the finite element approach through ANSYS program is the simulation of the dynamic response of the foundation under impact load. As a case study, previous experimental work included application of a dynamic load generated by dropping a steel ball (38.1 mm in diameter, 2.22 N in weight) from a height of 609.6 mm onto an aluminum target plate (203.2 mm in diameter, 12.7 mm thick) placed on top of a sand medium. The impact load is defined as a product of the loading magnitude and a time varying function which is assumed to be a Hanning's function for a monopeak, smooth-shaped curve. The problem is discretised by using four types of elements; Solid 45 to model the soil, Shell 63 to model the aluminum plate and Target 170 and Contact 174 are used to model the contact between the plate and soil. Shell 63 (elastic shell) has both bending and membrane capabilities.
It is noticed that the finite element analysis agrees well with the experimental results throughout the entire range of behavior, and the difference in the ultimate displacement is about 6.2%. It can be concluded that ANSYS program is well suited for impact analyses of soil and structural dynamics problems in the non-linear range.

Experimental Investigation of Composite Steel-Concrete Arches

Husain M. Husain; Hisham M. Al-Hassani; Ahmed Y. A. Zainul-Abideen

Engineering and Technology Journal, 2013, Volume 31, Issue 13, Pages 2393-2414

This research is concerned with behavior of composite steel-concrete arches
under static load. For this purpose, eight models of composite steel-concrete arches
are fabricated as test specimens.According to their supporting systems, the eight
fabricated specimens are equally divided into Hinge-Roller and Hinge-Hinge
supported arches in which varied numbers of shear connectors are used to investigate
the effects of support conditions and degree of shear connection on the behavior of
the composite arches. The specimens are tested under monotonically increasing point
load applied on their crowns (on the top of concrete slabs).
The mechanical properties of the used materials are determined by laboratory
tests. Push-out tests on three specimens, fabricated for this purpose, are also carried
out to determine the properties of the stud shear connectors.
It is concluded that increasing the number of connectors tends to increase the
ultimate load capacity and decrease both displacement and slip in the composite
arches. This trend is considerably satisfied when the horizontal movements of
supports are constrained (Hinge-Hinge supported arches).

Modelling The Behaviour Of Sand Under Strain-Controlled Loading BY The Finite Element Method

Omar al-Farouk S. al-Damluji; Mohammed Yousif Fattah

Engineering and Technology Journal, 2008, Volume 26, Issue 2, Pages 202-227

Strain-controlled tests are conventional in soil mechanics laboratories. It is
intended in this paper to simulate both triaxial and simple shear tests
theoretically by using the finite element method. The solution of the nonlinear
equations is obtained by several iterations. The Newton-Raphson with
tangent stiffness method in which the stiffness matrices are tangents is
adopted. The model used in this paper is the ALTERNAT model which
forms the major component of a double hardening model for the mechanical
behaviour of sand under alternating loading.
The finite element method is used in simulating the behaviour of round
uniform quartz sand under monotonic drained loading with constant mean
stress and cyclic constant volume loading (undrained). The monotonic test
was conducted with constant mean stress, where the specimen was
compressed in one direction and extended in other directions while the mean
stress (the average of the principal stresses) is kept constant and equal to 137
kPa. It is noticed that the peak stress is occurring at very small strain
(0.122). The stress-strain behaviour may be attributed to the particle
roundness and grain size uniformity.
In the cyclic tests, the specimen is sheared by cycling the shear strain while
the volume was kept constant. By doing this, an undrained strain-controlled
cyclic test similar to that typically done in many laboratories is numerically
simulated.
It was found that the mean stress during shearing is higher than the initial
consolidation pressure. This implies that only negative pore pressures occur
in the first two cycles. A careful study shows that there exists an effective
stress ratio line or zero-dilatancy line in both compression and extension
regions, beyond which the specimen dilates.