Browsing by Author "Bilen, Mahmut Bugra"

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Buckling Response of Externally Pressurised Sealed and Retrofitted Steel Cylindrical Shells
(Elsevier Sci Ltd, 2023) Maali, Mahyar; Bilen, Mahmut Bugra; Simsek, Murat; Firouzsalari, Saeed Eyvazinejad
Buckling response of steel cylindrical shells with no reinforcement or seal, cylindrical shells reinforced with CFRP, and cylindrical shells sealed against leakage was experimentally compared. Twelve cylindrical shells were tested; four had no reinforcement/seal, four were reinforced with CFRP, and four were sealed. The cylindrical shells had the same radius-to-thickness ratio of 445 but had various height-to-radius ratios of 2, 4, and 6. Results indicated that the buckling capacity of the shells decreased with increasing the shell height. Whilst a postbuckling response was established for the sealed shells, CFRP-reinforced shells had no post-buckling response. CFRP reinforcement significantly increased the shells' initial and overall buckling load, but the sealing was only effective in the initial buckling load.
Cold-Formed Steel Beam-to Screw Connections Exposed to High Temperatures Reinforced with CFRP
(Springer Int Publ Ag, 2023) Sagiroglu, Merve; Maali, Mahyar; Kar, Mert; Bilen, Mahmut Bugra
This study uses eight tests to show the experimental behavior of cold-formed steel beam-to-column screw connections exposed to high temperatures reinforced with CFRP. The structural beam members were heated from room temperature to 600 degrees C, held at that temperature for 5 h, and then cooled to room temperature before being reinforced with CFRP (carbon fiber-reinforced polymer). The joint's energy dissipation capacity, moment-rotation behavior, and ductility under high-temperature conditions were investigated using different beam thicknesses, gusset thicknesses, and stiffeners. The results demonstrate that increasing the gusset thickness reduced the moment, stiffness, and rotational values of the connection for beams without stiffeners but increased the beam's ductility. Using stiffeners reduced the beam's ductility but increased its energy dissipation capacity. In addition, increasing the profile thickness decreased the energy dissipation capacity. The collapse modes under high-temperature reinforced with CFRP conditions were compared to ambient temperature and post-fire conditions. The findings show that the buckling of models is affected by the thickness of the beam's wall. When the thickness of the beam wall exceeds the thickness of the gusset plate, collapse mode occurs, resulting in screw breakage. Beam buckling does not appear in beams that have stiffeners at the connection. This means that the beam will not buckle no matter how many stiffeners are employed in the connection. In addition, beam buckling was too common in beams exposed to high temperatures. Furthermore, the use of CFRP in the beam reduced buckling. All connection collapses are induced by the screw when the beam thickness divided by the gusset thickness is less than one; otherwise, they are caused by the gusset yield with screw rupture.
Investigation of Buckling Capacity Behaviours of Corroded Tanks
(Elsevier Science Ltd, 2024) Maali, Mahyar; Tizi, Harun; Tizi, Yasin; Bilen, Mahmut Bugra
The use of thin-walled steel shells is rapidly becoming widespread. Depending on their purpose, they can be susceptible to corrosion in the environments they are used in. This leads to metal loss and consequently a decrease in buckling strength. In this study, the effect of corrosion and CFRP reinforcement on thin-walled cylindrical steel tanks was experimentally investigated. Six samples with a length and diameter of 400 mm were tested; two samples were not subjected to corrosion, two samples were subjected to 2.5% HCl corrosion, and two samples were subjected to 5% HCl corrosion. The effect of CFRP usage was examined in both corroded and noncorroded samples. The results show that as the corrosion rate increases, the buckling strength decreases, and CFRP reinforcement recruitments the loss in buckling strength.