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CONTENTS
Volume 4, Number 3, September 2012
 

Abstract
The present study is carried out to investigate the strength behaviour of the reference mix containing fly ash + 8% lime + 0.9% gypsum mixed with treated tire chips. The dry tire chip was treated with water, sodium hydroxide and carbon tetrachloride. The tire chip content in the reference mix was varied from 5% to 15% and curing period from 7 days to 180 days. The specimens were cured using three different methods of curing (in a dessicator, burlap and water filled container). The results of this study reveal that the stress − strain relationship, strength characteristics, initial tangent modulus, ultimate strength and secant modulus of the reference mix containing dry tire chips is influenced by the tire chip content, curing period, curing method and the treatment provided on the tire chips. These parameters increased with the treatment provided with water, sodium hydroxide, carbon tetra chloride as well as with the increase in curing period in comparison to dry tire chips in the reference mix. A higher increase in these parameters was observed when specimens were cured in water filled container followed by burlap and dessicator respectively. Study further revealed that these parameters decreased with the increase in tire chip content from 5% to 15% and increased with the increase in the confining pressure. The axial strain at failure increased with the treatment provided with water, sodium hydroxide and carbon tetra chloride in comparison to dry tire chips in the reference mix. The results further revealed that axial strain at failure increased with the increase in curing period, change in curing method and increase in confining pressure. Inclusion of 5% dry/treated tire chips in the reference mix increases the axial strain at failure. Beyond a tire chip content of 5%, the axial strain at failure decreased when the content of tire chip was increased to 10% and 15% respectively.

Key Words
tire chip; strength characteristics; curing period; curing method; treatment.

Address
Department of Civil Engineering, National Institute of Technology, Hamirpur - 177005, Himachal Pradesh, India

Abstract
With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli

Key Words
fiber-section model; shallow foundation element; soil-structure interaction; winkler foundation; soil bearing capacity; rocking foundation; contact-interface element; nonlinear analysis.

Address
Suchart Limkatanyu*,Woraphot Prachasaree and Passagorn Chaiviriyawong : Department of Civil Engineering, Faculty of Engineering, Prince of Songkla University,
Songkhla 90112, Thailand
Minho Kwon : Department of Civil Engineering, ERI, Gyeongsang National University, Jinju, South Korea

Abstract
Due to rapid industrialisation, large scale infrastructure development is taking place worldwide. This includes railways, high speed highways, elevated roads etc. To meet the demands of society and industry, many innovative techniques and materials are being developed. In developed nations like USA, Japan etc. for railways applications, new material like geocells, geogrids are being used successfully to enable fast movement of vehicles. The present research work was aimed to develop design methodologies for improvement of grounds subjected to cyclic loads caused by moving vehicles on roads, rail tracks etc. Deformation behavior of ballast under static and cyclic load tests was studied based on square footing test. The paper presents a study of the effect of geo-synthetic reinforcement on the (cumulative) plastic settlement, of point loaded square footing on a thick layer of granular base overlying different compressible bases. The research findings showed that inclusion of geo-synthetics significantly improves the performance of ballasted tracks and reduces the foundation area. If the area is kept same, higher speed trains can be allowed to pass through the same track with insertion of geosynthetics. Similarly, area of machine foundation may also be reduced where geosynthetics is provided in foundation. The model tests results have been validated by numerical modeling, using FLAC3D.

Key Words
ballast; geosynthetics; coefficient of uniform elastic compression; elastic modulus; ground improvement.

Address
Department of Civil Engineering, IIT Roorkee - 247667, India

Abstract
This paper presents the derivation of an analytical expression for the dynamic active thrust from c-φ (c = cohesion, φ = angle of shearing resistance) soil backfill on rigid retaining walls with wall friction and adhesion. The derivation uses the pseudo-static approach considering tension cracks in the backfill, a uniform surcharge on the backfill, and horizontal and vertical seismic loadings. The development of an explicit analytical expression for the critical inclination of the failure plane within the soil backfill is described. It is shown that the analytical expression gives the same results for simpler special cases previously reported in the literature.

Key Words
c-φ soil backfill; dynamic active thrust; retaining wall; seismic loads; surcharge; tension cracks; wall friction and adhesion

Address
Sanjay K. Shukla : Discipline of Civil Engineering, School of Engineering, Edith Cowan University, 270 Joondalup Drive,
Joondalup, WA 6027, Australia
Department of Civil Engineering, Indian Institute of Technology (BHU), Varanasi - 221 005, India
Richard J. Bathurst : GeoEngineering Centre at Queen

Abstract
Pavement management systems require systematic monitoring of pavement surfaces to determine preventive and corrective maintenance. The process involves the accumulation of large amounts of visual data, typically obtained from site visitation. The pavement surface condition is then correlated to a pavement distress index that is based on a scoring system previously established by state or federal agencies. The scoring system determines if the pavement section requires maintenance, overlay or reconstruction. One of the surface distresses forming part of the overall pavement distress index is the Alligator Crack Index (AC Index). The AC Index involves the visual evaluation of the crack severity of a section of a pavement as being low, medium, or high. This evaluation is then integrated into a formula in order to obtain the AC Index. In this study a quantification of the visual evaluation of the severity of alligator cracking is carried out using photographs and the fractal dimension concept from fractal theory. Pavements with low levels of cracking were found to have a fractal dimension equal to 1.051. Pavements with moderate levels of cracking had a fractal dimension equal to 1.1754. Pavements with high degrees of cracking had a fractal dimension that varied between 1.5037 (high) and 1.7111 (very high). Pavements with a level of cracking equal to 1.8976 represented pavements that disintegrated and developed potholes. Thus, the visual evaluation of the state of cracking of a pavement (the AC Index) could be enhanced with the use of the fractal dimension concept from fractal theory.

Key Words
asphalt pavement, cracking, fractal analysis, fractal dimension.

Address
Department of Civil and Environmental Engineering, 949 Benedum Hall, University of Pittsburgh, Pittsburgh PA 15261 USA


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