Browsing by Author "Güneş, Oğuz"

Now showing 1 - 4 of 4

Citation Count: 3
Approximate seismic evaluation methods for large building inventories with high variability in their seismic resistance
(2006) Gunes,B.; Yakut,A.; Gunes,O.; Department of Civil Engineering
Seismic hazard mitigation for urban infrastructures located in seismic regions is a challenge faced by many countries around the world, especially those with infrastructures known for their variability in quality of construction and compliance with the seismic codes. Two recent major earthquakes that hit the densely populated urban areas in Northwest Turkey resulted in a large-scale destruction and loss of life. Scientific studies indicate that the probability of occurrence of another severe earthquake along the North Anatolian Fault near Istanbul is quite high in the next few decades. This situation presents a serious threat to the large building stock and their occupants in Istanbul and adjacent areas. Structures in these areas are known to have high variability in their seismic resistance, which makes it difficult to estimate the potential losses in case of a major earthquake. Thus, there is an urgent need for a systematic strategy that will allow for rapid and reliable assessment of the seismic risk associated with existing buildings through an effective methodology that properly considers the local infrastructure characteristics. In this paper, approximate methods for seismic assessment of buildings are reviewed and are evaluated through their application to a group of 131 reinforced concrete frame buildings located in various seismic regions of Turkey. The results show that the recently developed preliminary methods that are customized for the local building characteristics provide improved prediction of seismic hazard, and may serve as an efficient and reliable risk assessment tool upon further improvement and calibration. The first stage procedures show large variability and result in considerable cases of misclassifications.
Citation Count: 3
Design of FRP retrofitted flexural members against debonding failures
(2006) Gunes,O.; Karaca,E.; Gunes,B.; Department of Civil Engineering
Use of fiber reinforced polymer (FRP) composites in seismic retrofitting of structural members has been steadily increasing in recent years. An important design issue with significant performance and safety implications is the debonding of externally bonded FRP reinforcement in flexural members. This paper provides the highlights of an experimental and analytical research aimed at understanding and modeling of debonding failures in FRP strengthened reinforced concrete beams. An evolutionary experimental program investigated debonding failure mechanisms and modes in beams strengthened in shear and/or flexure in various configurations and tested under monotonic and cyclic loading. A newly developed fracture mechanics based model considers the global energy balance of the system and predicts the debonding failure load by characterizing the dominant mechanisms of energy dissipation during debonding. Validation of the model is performed using experimental data obtained from several independent experimental studies.
Citation Count: 60
A fracture-based model for FRP debonding in strengthened beams
(Pergamon-elsevier Science Ltd, 2009) Gunes, Oguz; Buyukozturk, Oral; Karaca, Erdem; Department of Civil Engineering
This paper presents an experimental and analytical research study aimed at understanding and modeling of debonding failures in fiber reinforced polymer (FRF) strengthened reinforced concrete (RC) beams. The experimental program investigated debonding failure modes and mechanisms in beams strengthened in shear and/or flexure and tested under monotonic loading. A newly developed fracture mechanics based model considers the global energy balance of the system and predicts the FRP debonding failure load by characterizing the dominant mechanisms of energy dissipation during debonding. Validation of the model is performed using experimental data from several independent research studies and a design procedure is outlined. (C) 2009 Elsevier Ltd. All rights reserved.
Citation Count: 11
Use of UHPC in Bridge Structures: Material Modeling and Design
(Hindawi Ltd, 2012) Gunes, Oguz; Yesilmen, Seda; Gunes, Burcu; Ulm, Franz-Joseph; Department of Civil Engineering
Ultra-high-performance concrete (UHPC) is a promising new class of concrete material that is likely to make a significant contribution to addressing the challenges associated with the load capacity, durability, sustainability, economy, and environmental impact of concrete bridge infrastructures. This paper focuses on the material modeling of UHPC and design of bridge girders made of UHPC. A two-phase model used for modeling the behavior of UHPC was briefly discussed, and the model was implemented in a preliminary design case study. Based on the implemented design and the reported use of UHPC in bridge applications, the advantages, limitations, and future prospects of UHPC bridges were discussed, highlighting the need for innovative research and design to make optimum use of the favorable properties of the material in bridge structures.