Bridges and other coastal structures in Georgia and throughout the Southeast are deteriorating prematurely due to corrosion. Numerous corrosion initiated failures have occurred in precast prestressed concrete (PSC) piles and reinforced concrete (RC) pile caps, leading to the costly repair and replacement of either the entire bridge or the affected members. With the Federal Highway Administration's goal of a 100-year bridge service life and recent legislative action such as the Bridge Life Extension Act, new emphasis has been placed on the development and implementation of new corrosion mitigation techniques. This thesis involves the mechanical testing, and proposed future test program of high-strength stainless steel (HSSS) prestressing strand to be used in prestressed marine bridge piles. The metallurgy for two types of HSSS strand was selected from a previous study of the corrosion resistance, mechanical properties, and feasibility of 6 candidate HSSS drawn wire samples. Duplex stainless steel (DSS) grades 2205 and 2304 were selected for production of 7-wire 1/2" diameter prestressing strand. DSS wire rod was drawn, stranded, and heat-treated using the same production methods and equipment as used for standard of practice, high carbon prestressing strand. The production process was documented to analyze the problems facing this production method and suggest improvement and optimization. After production, the strands were subjected to a series of mechanical tests. Tension testing was performed to provide a stress-strain curve for the strands and related mechanical properties. Wire samples were also taken at varying points in the drawing process to give more information about the work hardening of the stainless steels. Stress relaxation testing was performed on both strand and wire samples to assess the overall losses and to provide comparisons between strand and wire test results as well as drawn wires before and after heat-treatment. An experimental program for future study was designed to assess the HSSS prestressing strand behavior in precast piles. This testing involves assessment of pile driving performance, pile flexural and shear behavior, strand transfer and development length, long-term prestressing force losses, and material durability.

In this study, bending moment distributions developed in laterally loaded passive pile and passive pile groups in cohesionless soil were investigated in laboratory conditions through model pile experiments. Different from the active pile loading, the lateral load was given directly to the piles using a movable large direct shear box. In these experiments strain gauges fastened to the piles and a computer based data reading system were used. The strain values were measured at five levels on the piles. The behavior of a single pile and a pile group having five piles were investigated through strain measurements in order to observe bending moment distribution on the piles. After evaluating the test results, the behavior of passive single pile was found to be similar to the results obtained in early studies. Negative bending moments were observed at the specified depths above the shear plane and positive bending moments were measured at the level of the shear plane and below the shear plane. Maximum bending moments were obtained at 0.7L (L: Length of Pile) for single piles and piles in the group. Above the shear plane, maximum bending moments within the pile group were found to be developed on the piles nearest to the loading. On the shear plane maximum bending moments were developed on the piles farthest from the loading just like active piles. Below the shear plane, maximum bending moments were developed mainly on the piles nearest to the loading.

Two different concepts and design procedures namely settlement reducing piles and piled raft foundations have been studied independently in this thesis. A laboratory study is conducted on model rafts with differing number of model settlement reducing piles. Pile length, pile diameter, type of soil and size of raft are kept constant and settlements are measured under sustained loading. Remolded kaolin is consolidated under controlled stresses before tests are performed in model boxes. The tests are conducted under two sustained loadings of 75 kPa and 40 kPa. 0(raft), 16 and 49 number of piles are used. During the tests, all of the skin friction is mobilized. Several tests are conducted for each combination to see the variability. It is concluded that increasing the pile number beyond an optimum value is inefficient as far as the amount of settlement is considered. Also an analytical procedure has been followed to calculate settlements with increasing number of piles. In the second part of this thesis, finite element analyse have been performed on a piled raft foundation model, using Plaxis 3D Foundation Engineering software. This analyse are supported with analytical methods. The piled raft model is loaded with 450 kPa raft pressure. The studies are conducted in two sets in which different pile lengths are used / 25 m and 30 m respectively. The numbers of piles are increased from 63 to 143. All other parameters are kept constant. The results showed that again an optimum number of piles will be sufficient to reduce the settlement to the acceptable level. The analytical methods indicate a similar behavior. The comparison and results are presented in the study.

To investigate the lateral load distribution of each pile in a pile group, the bending moment distribution along the pile and the lateral group displacements with respect to pile location in the group, pile spacing, pile diameter and soil stiffness three dimensional finite element analysis were performed on 4x4 pile groups in clay. Different Elatic Modulus values, pile spacings, pile diameters and lateral load levels used in this study. In the analysis PLAXIS 3D Foundation geotechnical finite element package was used. It is found that, lateral load distribution among the piles was mainly a function of row location in the group independent from pile spacing. For a given load the leading row piles carried the greatest load. However, the trailing row piles carried almost the same loads. For a given load, bending moment values of the leading row piles were greater than the trailing row piles. On the other hand, as the spacing increased group displacements and individual pile loads decreased under the same applied load. However, this behavior was seen more clearly in the first and the second row piles. For the third and the fourth row piles, pile spacing became a less significant factor affecting the load distribution. It is also found that, pile diameter and soil stiffness are not significant factors on lateral load distribution as row location and pile spacing.

Reproduction de : Thèse de doctorat : Systèmes automatiques : Toulouse, INPT : 2004. / Titre provenant de l'écran-titre. Bibliogr. 45 réf.

Thèse de doctorat : Génie électrique : Vandoeuvre-les-Nancy, INPL : 2005. / Titre provenant de l'écran-titre. Bibliogr.

Thèse de doctorat : Mécanique et Énergétique : Nancy 1 : 2007. / Titre provenant de l'écran-titre. Bibliogr.

Reproduction de : Thèse de doctorat : Science et génie des matériaux : Toulouse 3 : 2008. / Titre provenant de l'écran-titre. Bibliogr. à la fin des chapitres.

Thèse de doctoral : Sciences pour l'ingénieur : Besançon : 2008. Thèse de doctoral : Sciences pour l'ingénieur : Belfort-Montbéliard : 2008. / Réf. bibliogr. à la fin de chaque chapitre.

Reproduction de : Thèse de doctorat : Systèmes automatiques : Toulouse, INPT : 2008. / Titre provenant de l'écran-titre. Bibliogr. 107 réf.