Ferit Cakir

Performance-Based Evaluation of Hydrocarbon Steel Pipes Under Internal Pressure

Hydrocarbon steel pipes have undertaken a very important and fundamental role in the oil and gas industries in the world. Although these pipes are simple structural forms, their structural behaviors are very complex and challenging for the structural engineering community. One of the fundamental problems for pipelines is plastic deformations under internal pressure. This study focuses on to develop a methodology for the performance evaluation of hydrocarbon steel pipes under internal pressure. In this perspective, a hydrocarbon pipe, which is used in natural gas pipelines, is modeled by nonlinear finite element model (FEM) and investigated in terms of structural behavior under different internal pressure conditions; operating pressure (100 bar), design pressure (150 bar) and high pressure (250 bar). In order to obtain an accurate solution, the finite element model is calibrated with a hydrostatic test, which is conducted on a pipe under 133 bar.

Finite element analysis of the impact of screw insertion distal to the trochanter minor on the risk of iatrogenic subtrochanteric fracture

Iatrogenic subtrochanteric fractures are rarely encountered after cannulated screw fixation of femoral neck fractures; however, when they do occur, there can be several complications. Many orthopedic surgeons have concerns about the potential for iatrogenic subtrochanteric fractures after screw fixation distal to the trochanter minor; therefore, some surgeons are typically reluctant to perform this procedure. This study focused on the risk of an iatrogenic subtrochanteric fracture after treating femoral neck fractures with cannulated screws. The main purpose of the study was to understand iatrogenic subtrochanteric fractures and evaluate the effects on these fractures of an inverted triangular–shaped configuration for placement of the cannulated screws. A femur bone with an femoral neck fracture at a 40° incline to the horizontal plane was generated along with a representation of a three-dimensional finite element model, and three inverted triangular–shaped configurations for placement of the cannulated screws were investigated using finite element analyses. Statistical results indicated that the occurrence risk of ISF increases when the screw is located distal to the trochanter minor. Moreover, the risk of occurrence of intertrochanteric fracture increases when the screw is located medial to the trochanter minor because of local concentrated stress on the surface of the screw canals. To avoid the vulnerability of the subtrochanteric region, it was found that proximal placement of the screws using the inverted triangular–shaped configuration could yield better results. In addition, the results of this study provide suggestions on improved screw configurations.

Analiza konstrukcije povijesnih građevina iz arhitektonskog i građevinskog aspekta

Historical structures are integral to the cultural heritage of the world and ought to be safely preserved for posterity. An interdisciplinary approach is critical in the conservation and restoration of masonry structures. Taking this into consideration, this study discusses Gok Madrasah, a 750 year-old structure situated in Amasya, Turkey, in terms of art history and structural engineering. An analysis of decorative elements is made in the paper from an art-history aspect, and a detailed three-dimensional finite element analysis of the structure is conducted.

Architectural and structural analysis of historical structures

Historical structures are integral to the cultural heritage of the world and ought to be safely preserved for posterity. An interdisciplinary approach is critical in the conservation and restoration of masonry structures. Taking this into consideration, this study discusses Gok Madrasah, a 750 year-old structure situated in Amasya, Turkey, in terms of art history and structural engineering. An analysis of decorative elements is made in the paper from an art-history aspect, and a detailed three-dimensional finite element analysis of the structure is conducted.