Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Access Right: Open AccessSubject: search.filters.subject.Earthquake resistant design

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Now showing 1 - 4 of 4
  • Master Thesis
    Performance-Based Seismic Design of Reinforced Concrete Frame Buildings: a Direct Displacement-Based Approach
    (Izmir Institute of Technology, 2015) Karimzada, Nisar Ahmad; Aktaş, Engin; Aktaş, Engin; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Structures are designed using current seismic design codes which are mostly based on Force-Based Design approach. The initial aim of the current codes is the public safety. However, no clear information are provided regarding economic losses and business interruptions or downtime. Some information about damage states of structural components are provided, but very limited information is given for the damage states of non-structural members and content systems. Performance-Based Seismic Design (PBSD), which is a new concept in seismic design of structures, is a reliable approach capable of providing more detailed information on the performance levels of both structural and non-structural elements. Direct Displacement-Based Design (DDBD) approach, which is one of the available PBSD procedures, is implemented in this study. This approach has been utilized on four reinforced concrete irregular frames which are different in terms of number of stories. Story drift ratios were chosen as deformation limits to define the performance levels for specific earthquake hazard levels. DDBD approach in this study has been utilized in compliance with Turkish Seismic Design Code 2007. Furthermore, capacity design principles were adopted to make sure that plastic hinges occur in beams rather than in columns. After obtaining design internal forces (design moments, shear forces and axial forces), TS500 2003, is utilized to design members. Damage states for each member was determined, and non-linear pushover and time history analysis were carried out using SAP2000 v17.10 to check if story drift ratios meet the ones chosen. The base shear forces and the top displacements, in addition, for each frame were also checked with the ones obtained through DDBD approach.
  • Master Thesis
    Seismic Behavior of Steel I-Beams Modified by a Welded Haunch and Reinforced With Glass Fiber Reinforced Polymers
    (Izmir Institute of Technology, 2009) Özdemir, Timur; Eğilmez, Oğuz Özgür; Eğilmez, Oğuz Özgür; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Flange and web local buckling in beam plastic hinge regions of welded steel moment frames (SMF) can prevent beam-column connections to achieve adequate plastic rotations under earthquake-induced forces. As the use of fiber reinforced polymers (FRP) have increased in strengthening and repair of steel members in recent years, using FRPs in stabilizing local instabilities have also attracted attention. Generally, high modulus carbon FRP (CFRP) laminates, with elastic modulus similar to that of steel, are preferred in strengthening applications. On the other hand, glass FRP (GFRP) has a much smaller modulus than that of steel, typically one order of magnitude less, which limits its use in strengthening applications. However, this modulus mismatch is an asset when the primary goal is to stabilize inelastic local buckling with the least possible strength increase in the section. In a steel-GFRP hybrid system, while the low modulus of GFRP will not allow a significant strength increase in the beam, the flexural strength of GFRP can provide bracing to the underlying steel, which is flowing plastically. In this research study, the cyclic behavior of steel beams modified by a triangular haunch welded to the beam bottom flange only and reinforced with GFRP laminates at beam flanges have been investigated by finite element analysis (FEA). Cantilever I-sections with flange-web slenderness ratios higher then those stipulated in current seismic design specifications are analyzed under reversed cyclic loading. Both bare beam sections and sections reinforced with GFRP are investigated. The effects of GFRP thickness, width, and length on stabilizing local buckling are investigated. The flexural resistance of the beams at column face, interlaminar shear stresses in GFRP strips, and shear stresses at beam-GFRP binding surface are examined. The results reveal that the plastic rotation capacity of steel beams can be enhanced by the use of GFRP strips.
  • Master Thesis
    Seismic Behavior of Steel I-Beams Reinfor Ced With Glass Fiber Reinforced Polymer: an Experimental Study
    (Izmir Institute of Technology, 2010) Yormaz, Doruk; Eğilmez, Oğuz Özgür; Eğilmez, Oğuz Özgür; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Design guidelines, which are put into effect in the aftermath of the 1994 Northridge earthquake, require intermediate and special moment frames (IMF and SMF) be capable of maintaining 0.02 and 0.04 radians interstory drift, respectively without significant strength degradation and development of instability. However, local buckles in the plastic hinge region are major hindrances for the ductility capability and stability of the structural system. Thus, the research program aims to mitigate such inelastic instabilities by using glass fiber reinforced polymer (GFRP), which possesses elastic modulus roughly one order of magnitude less than that of steel. On the other hand, this elastic modulus discrepancy between GFRP and steel can be useful for stabilizing local buckles by means of the bracing effect of GFRP during plastic hinge formations. This thesis describes large-scale experimental study of the research program that investigates the seismic behavior of steel I-beams reinforced with GFRP. In this experimental study, four HE400AA beams with welded haunch (WH) modification and three HE500AA beams with no modification were tested under cyclic loading. The results of experimental study indicate that it does not seem possible to rely on GFRP reinforcement to increase the flexural resistance of connections at a rotation of 0.04 radians because the adhesive layer between steel and GFRP fails in rotations much lower than 0.04 radians. However, the seismic performance of the structure can be moderately improved with the bottom flange WH and GFRP reinforcement in order to maintain rotations without local buckles in accordance with the rotation demand of IMFs, which is 0.02 radians.
  • Master Thesis
    Investigation of the Benefits of Variable Orifice Dampers Used in an Earthquake Excited Three Story Structure
    (Izmir Institute of Technology, 2009) Gökdağ, Hakan; Turan, Gürsoy; Turan, Gürsoy; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Research in the field of control of civil engineering structures is a continuing process. The three basic approaches to structural control may be defined as follows passive control systems,active control systems and semi-active control systems. These systems have received much attention recently because they have versatility and adaptability of active control systems. Although there is a wide variety of these energy absorbing devices, but all have one thing in common . they absorb energy from the structure.Semi-active control systems possess the advantages of both active and passive control systems. Variable orifice dampers are semi-active control devices that utilize the hydraulic fluid flow to generate controllable damping forces. Depending on the state of the structure, the energy absorbing property of the variable orifice dampers is changed on the fly. In this study, the proposed semi-active control algorithm and the effect of variable orifice damper for seismic response reduction is examined. To demonstrate the efficiency of the proposed semi-active control algorithm and the usefulness of variable orifice dampers,controlled and uncontrolled behaviour of the three story model structure subjected to earthquake forces are investigated numerically. The three story model structure in Civil Engineering Laboratory in .YTE is utilized for numerical simulations. The results indicate numerically that the proposed semi-active control algorithm with a variable orifice damper can be used effectively to reduce the earthquake induced structural vibrations.