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CONTENTS
Volume 5, Number 4, August 2013
 

Abstract
The aim of this paper is to investigate how the soil-structure interaction affects sloshing response of the elevated tanks. For this purpose, the elevated tanks with two different types of supporting systems which are built on six different soil profiles are analyzed for both embedded and surface foundation cases. Thus, considering these six different profiles described in well-known earthquake codes as supporting medium, a series of transient analysis have been performed to assess the effect of both fluid sloshing and soil-structure interaction (SSI). Fluid-Elevated Tank-Soil/Foundation systems are modeled with the finite element (FE) technique. In these models fluid-structure interaction is taken into account by implementing Lagrangian fluid FE approximation into the general purpose structural analysis computer code ANSYS. A 3-D FE model with viscous boundary is used in the analyses of elevated tanks-soil/foundation interaction. Formed models are analyzed for embedment and no embedment cases. Finally results from analyses showed that the soil-structure interaction and the structural properties of supporting system for the elevated tanks affected the sloshing response of the fluid inside the vessel.

Key Words
elevated tank; sloshing; fluid-structure interaction; soil-structure interaction: supporting system

Address
Ramazan Livaoglu: Department of Civil Engineering, Uludağ University, 16059 Bursa, Turkey

Abstract
The horizontal pullout capacity of a group of two vertical strip plate anchors, placed along the same vertical plane, in a fully cohesive soil has been computed by using the lower bound finite element limit analysis. The effect of spacing between the plate anchors on the magnitude of total group failure load (PuT) has been evaluated. An increase of soil cohesion with depth has also been incorporated in the analysis. For a weightless medium, the total pullout resistance of the group becomes maximum corresponding to a certain optimum spacing between the anchor plates which has been found to vary generally between 0.5B and B; where B is the width of the anchor plate. As compared to a single plate anchor, the increase in the pullout resistance for a group of two anchors becomes greater at a higher embedment ratio. The effect of soil unit weight has also been analyzed. It is noted that the interference effect on the pullout resistance increases further with an increase in the unit weight of soil mass.

Key Words
anchors; clays; failure; finite elements; limit analysis; pullout load

Address
1 Paramita Bhattacharya: Civil Engineering Dept., Indian Institute of Technology Kharagpur, INDIA 721302;
2 Jyant Kumar: Civil Engineering Dept., Indian Institute of Science Bangalore, INDIA - 560012

Abstract
Vetiver grass (Vetiveria zizanioides) is being effectively used in many countries to protect embankment and slopes for their characteristics of having long and strong roots. In this paper, in-situ shear tests of the ground with the vetiver roots have been conducted to investigate the stabilization properties corresponding to the embankment slopes. Numerical analyses have also been performed with the finite element method using elastoplastic subloading tij model, which can simulate typical soil behavior. It is revealed from field tests that the shear strength of vetiver rooted soil matrix is higher than that of the unreinforced soil. The reinforced soil with vetiver root also shows ductile behavior. The numerical analyses capture well the results of the in-situ shear tests. Effectiveness of vetiver root in geotechnical structures.strip foundation and embankment slope has been evaluated by finite element analyses. It is found that the reinforcement with vetiver root enhances the bearing capacities of the grounds and stabilizes the embankment slopes.

Key Words
eco-engineering; FE analysis; slope stabilization; vegetation; vetiver root

Address
1 Mohammad S. Islam: Dept. of Civil Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh;
2 Hossain M. Shahin: Dept. of Civil Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan

Abstract
The major factors that control the performance of reinforced soil structures is the interaction between the soil and the reinforcement. Thus it is necessary to obtain the accurate bond parameters to be used in the design of these structures. To evaluate the behavior of flyash + clay soil reinforced with a woven geotextile, 36 Unconsolidated-Undrained (UU) and 12 reinforced Consolidated.Undrainrained (CU) triaxial compression tests were conducted. The moisture content of soil during remolding, confining pressures and arrangement of geotextile layers were all varied so that the behavior of the sample could be examined. The stress strain patterns, drainage, modulus of deformation, effect of confinement pressures, effects of moisture content have been evaluated. The impact of moisture content in flyash + clay backfills on critical shear parameters was also studied to recommend placement moisture for compaction to MDDM. The results indicate that geotextile reinforced flyash + clay backfill might be a viable alternative in reinforced soil structures if good-quality granular backfill material is not readily available.

Key Words
geotextiles; flyash; clay; shear parameters; triaxial tests

Address
Jigisha M. Vashi, Atul K. Desai and Chandresh H. Solanki: Applied Mechanics Department, S V National Institute of Technology, Surat - 395007, Gujarat, India

Abstract
Simple relationships are proposed in this paper by modifying the Schmertmann\'s equation for settlement estimations of footings (i.e., B/L ≈ 1) carrying vertical loads in saturated and unsaturated sandy soils. The modified method is developed using model plate load tests (PLTs) and cone penetration tests (CPTs) results conducted in saturated and unsaturated sand in a controlled laboratory environment. Seven in-situ large-scale footings tested under both saturated and unsaturated conditions in sands were used to validate the proposed technique. The results of the study are encouraging as they provide reliable estimates of the settlement of shallow footings in both saturated and unsaturated sands using the conventional CPT results.

Key Words
shallow footings; unsaturated sand; matric suction; settlement; PLT; CPT

Address
Fathi M.O. Mohamed, Sai K. Vanapalli and Murat Saatcioglu: Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5, CANADA

Abstract
Any structure constructed on the earth is supported by the underlying soil. Foundation is an interfacing element between superstructure and the underlying soil that transmits the loads supported by the foundation including its self weight. Foundation design requires evaluation of safe bearing capacity along with both immediate and long term settlements. Weak and compressible soils are subjected to problems related to bearing capacity and settlement. The conventional method of design of footing requires sufficient safety against failure and the settlement must be kept within the allowable limit. These requirements are dependent on the bearing capacity of soil. Thus, the estimation of load carrying capacity of footing is the most important step in the design of foundation. A number of theoretical approaches, in-situ tests and laboratory model tests are available to find out the bearing capacity of footings. The reliability of any theory can be demonstrated by comparing it with the experimental results. Results from laboratory model tests on square footings resting on sand are presented in this paper. The variation of bearing capacity of sand below a model plate footing of square shape with variation in size, depth and the effect of permissible settlement are evaluated. A steel tank of size 900 mm

Key Words
square footing; model test; sand; depth; ultimate bearing capacity; settlement

Address
Manish S. Dixit and Kailas A. Patil: Department of Civil Engineering, Government College of Engineering, Aurangabad (Maharashtra State), India, 431 005


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