İnşaat Mühendisliği

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Browsing İnşaat Mühendisliği by Subject "Anchorage (Structural engineering)"

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    Corner effects in deep excavations
    (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2019., 2019.) Güner, Mert.; Çinicioğlu, Özer.
    The precise calculation of the anchorage free length used in retaining structures plays a crucial role in the design of such structures. The most important factors to be considered while determining the free length of the anchorages are the slip surfaces and their respective outer boundaries. The reason for that is to reach the calculated anchorage capacities, the roots of the anchorages must be installed in inert soil. There are a lot of factors which influence the outer boundaries of the slip surfaces. The corners in retaining structures are one of the most important of these factors. Models based on plain-strain are not adequate to determine possible active slip surfaces at the corners or at locations close to the corner. Taking this inadequacy into consideration, the effects of corners in retaining structures on active slip surfaces are researched. In this context, how corners between two adjacent retaining walls, the distance from the said corner and the variation of internal friction angle and dilatation angle depending on the relative density affect the outer boundary of the slip surface is researched. For this research, numerical models are created by using a finite element modelling program called Plaxis 3D. But before that, to determine the parameters of the models and verify the accuracy of the models, small-scale retaining wall models carried out within the scope of TUBITAK Project No:114M329 are modelled using Plaxis 3D. The results from the small-scale retaining wall models and the results of their respective numerical models are compared and it is seen that the predetermined parameters match with the results obtained from the numerical model test. Lastly, verified model specifications are used in creating the necessary models and the effects of the variables influencing the outer boundary of the slip surface are shown.
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    The effects of tendon bond lenght of prestressed ground anchors to the stability of anchored retaining systems
    (Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2004., 2004.) Özhan, Hakkı Oral.; Güler, Erol.
    Prestressed ground anchors are mainly used for reinforcing lateral earth support systems. Prestressed ground anchorage technology has become popular just after they were first used in 1930s and today anchored systems are designed offering economical solutions to both temporary and permanent stability problems.Tendon steel of a prestressed anchor is the prestressing element and it consists of grouted and ungrouted parts. Grouted part is the tendon bond length that transmits the applied tensile load to the ground and ungrouted part is the free tendon length that transfers the resisting force from the bond length to the facing. In this thesis, pull-out tests and an analysis of field tests using slope stability technique were performed. The effect of tendon bond length to the factor of safeties of anchored retaining systems was analyzed in both field tests and stability analysis. According to the pull-out tests, anchors that did not satisfy the acceptance criteria had much longer or shorter tendon bond length values than the design bond length. In the literature research, a designed tendon bond length value was obtained for prestressed ground anchors. Even though tendon bond lengths shorter than the design value reduce the factor of safety, the result of the conducted analysis and software computations indicate that also an increase in bonded length causes a reduction in the factor of safety.
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    Use of glass fiber reinforced polymer (GFRP) for reinforcing in-situ soils
    (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2017., 2017.) Aydın, Hasan Can.; Güler, Erol.
    Ground anchoring is a technique in which slender pre-stressed components are embedded into the in-situ soil or rock to counterbalance the uplift or tensile forces. It is a practical technique which have been used widely since the end of 18th century. However, corrosion issue is a great restriction for the use of ground anchors in corrosive environments for long term conditions. Nowadays, a newly emerged material called Glass fiber reinforced polymer is a promising alternative for this problem due to its high corrosion resistance, high specific strength and light weight. This present master’s thesis aim is to compare the behaviour of GFRP materials over Steel ones in grouted ground anchors in several variable conditions to understand the feasibility of the use of Glass fiber reinforced polymer for reinforcing in-situ soils. In total of 18 pull-out numerical simulations are conducted by using Plaxis 2D v.2016.01. Pull out of a ground anchor with three distinctive fixed lengths (6m, 8m and 12m) are analyzed. In the FE models, ground anchors are embedded in three different geo-materials (over consolidates clay, dense sand and rock). As tendon material GFRP and Steel was used separately. All combinations of soil, tendon type and length have been analyzed and results are obtained for both traditional steel and GFRP tendon. Under high loads, Ground anchors with GFRP tendons embedded in highly stiff rock, presented increased deflections comparing with the steel. However, this situation becomes insignificant while using allowable load capacities (displacement control) with universally accepted factor of safety values.