Effect of parapets to pressure distribution on flat top of a finite cylinder

Ozmen, Y. Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.5

In this paper, the effects of parapets on the mean and fluctuating wind pressures which are acting on a flat top of a finite cylinder vertically placed on a flat plate have experimentally been investigated. The aspect ratio (AR) of cylinder is 1 and the Reynolds number (Re) based on cylinder diameter and free stream velocity is 150000. The pressure distributions on the flat top and the side wall of the finite cylinder immersed in a simulated atmospheric boundary layer have been obtained for different parapet heights. The large magnitudes of mean and minimum suction pressures occurring near the leading edge were measured for the cases with and without parapet. They shift to the further downstream on the circular top with increasing parapet height. It is seen that the parapets reduce the local high suction on the top up to 24%.

An investigation of torsionally irregular multi-story buildings under earthquake loading

Ozmen, G.,Gulay, F.G. Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.2

It is well known that torsionally unbalanced buildings are more vulnerable to earthquake hazards than are the regular structural systems. In this paper, a parametric investigation is presented, in order to observe the amplification in the internal forces, when increased eccentricities are used instead of the ones corresponding to the 5% accidental eccentricity. A series of five, ten-story framed and walled structures, with rather high torsional irregularity coefficients, are selected and a numerical test procedure is applied. Numerical results show that the maximum amplification in the internal forces at the most critical beams and columns at the flexible sides of the structures is about 10%. It is concluded that, more serious measures in the codes are needed in the case of this rather dangerous type of irregularity.

Wind pressures on different roof shapes of a finite height circular cylinder

Ozmen, Y.,Aksu, E. Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.24 No.1

The effects of finite cylinder free end shape on the mean and fluctuating wind pressures were investigated experimentally and numerically by using three different roof shapes: flat, conical and hemispherical. The pressure distributions on the roofs and the side walls of the finite cylinders partially immersed in a simulated atmospheric boundary layer have been obtained for three different roof shapes. Realizable $k-{\varepsilon}$ turbulence model was used for numerical simulations. Change in roof shapes has caused significant differences on the pressure distributions. When compared the pressure distributions on the different roofs, it is seen from the results that hemispherical roof has the most critical pressure field among the others. It is found a good agreement between numerical and experimental results.

Buckling lengths of unbraced multi-storey frame columns

Ozmen, Gunay,Girgin, Konuralp Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.1

In several design codes and specifications, simplified formulae and diagrams are given for determining the buckling lengths of frame columns. It is shown that these formulae may yield rather erroneous results in certain cases. This is due to the fact that, the code formulae utilise only local stiffness distributions. In this paper, a simplified procedure for determining approximate values for the buckling loads of multi-storey frames is developed. The procedure utilises lateral load analysis of frames and yields errors in the order of 10%, which may be considered suitable for design purposes. The proposed procedure is applied to several numerical examples and it is shown that all the errors are in the acceptable range and on the safe side.

Leadership styles embedded in the Turkish National Police

Aziz Ozmen,Hasan Arslan 아시아경찰학회 2006 아시아경찰학회 국제학술회의 Vol.2006 No.-

In recent years, organizations have gone through dramatic changes, including flatter and looser structures, downsizing, and horizontal approaches to information flow. On the one hand, these changes are due to rapid technological developments, global competition, and the changing nature of the workforce. On the other hand, these organizational transformations and innovations are triggered by interventions, such as total quality management and principle-based management. This new leadership formation has taken many forms in non-profit organizations, particularly in law enforcement agencies. Leadership is regarded as a critical factor in the initiation and implementation of the transformation in organizations. If leadership is to succeed in engendering a positive impact on individuals, teams, and organizations, traditional leadership paradigms, such as directive versus participative leadership, consideration versus initiating structure, autocratic versus democratic leadership, and task versus relations-oriented leadership, should be broadened (see for example, Avolio & Bass, 1998; Bass & Avolio, 1990; Conger, 1993; Ekvall & Arvonen, 1991, 1994; Puffer & McCarthy, 1996). With respect to the management of transformation processes in organizations, there is a strong need for leaders who are more change-centered. These leaders place value on the development of a clear vision and inspire followers to pursue the vision. In this way, they provide a strong motivational force for change in followers. These authors suggest that besides a participative leadership style, having a clear vision of the mission is most likely to foster innovation. Leaders who enhance followers’ confidence and skills to devise innovative responses, by being creative and taking risks can facilitate the changeover processes in organizations (Howell & Avolio, 1989). As a result of such processes, a new paradigm applied in the last two decade advocating “new leadership” theories, such as transformational and transactional leadership. As promoters of change, transformational leaders elicit performance beyond expectations by instilling pride, communicating personal respect, facilitating creative thinking, and providing inspiration (Bass, 1985; Bass & Avolio, 1993). The goal of this paper is to determine the underlying leadership structures in the Turkish National Police and, if so, by introducing transformational leadership and sticking to its foundation and tenets, to name these structures consistent with the changing roles of police managers and leaders. In this perspective, the paper argues what underlying structure exists among the thirty one variables by applying the Multifactor Leadership Questionnaire formed by Bass (Bass, 1985). A variety of research studies in the transformational literature review demonstrate that findings based on this questionnaire can identify the potential of leadership style in the Turkish National Police. Moreover, this study can be evaluated as a replication of another study, “Policing in Time of Transformation: An Examination of the Future of the Turkish Police,” conducted by this researcher in Spring and Summer, 2005. Almost the same results as those obtained in the former study demonstrate consistency and prove the reliability of data.

Wind pressures on different roof shapes of a finite height circular cylinder

Y. Ozmen,E. Aksu 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.24 No.1

The effects of finite cylinder free end shape on the mean and fluctuating wind pressures were investigated experimentally and numerically by using three different roof shapes: flat, conical and hemispherical. The pressure distributions on the roofs and the side walls of the finite cylinders partially immersed in a simulated atmospheric boundary layer have been obtained for three different roof shapes. Realizable k-e turbulence model was used for numerical simulations. Change in roof shapes has caused significant differences on the pressure distributions. When compared the pressure distributions on the different roofs, it is seen from the results that hemispherical roof has the most critical pressure field among the others. It is found a good agreement between numerical and experimental results.

An investigation of torsionally irregular multi-storybuildings under earthquake loading

G.Ozmen,F.G.G?lay 국제구조공학회 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.6

Effect of parapets to pressure distribution on flat top of a finite cylinder

Y. Ozmen 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.17 No.5

In this paper, the effects of parapets on the mean and fluctuating wind pressures which are acting on a flat top of a finite cylinder vertically placed on a flat plate have experimentally been investigated. The aspect ratio (AR) of cylinder is 1 and the Reynolds number (Re) based on cylinder diameter and free stream velocity is 150000. The pressure distributions on the flat top and the side wall of the finite cylinder immersed in a simulated atmospheric boundary layer have been obtained for different parapet heights. The large magnitudes of mean and minimum suction pressures occurring near the leading edge were measured for the cases with and without parapet. They shift to the further downstream on the circular top with increasing parapet height. It is seen that the parapets reduce the local high suction on the top up to 24%.

Effect of rapid screening parameters on seismic performance of RC buildings

Hayri B. Ozmen,Mehmet Inel 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.4

This study investigates the effects of soft story, short columns, heavy overhangs, pounding, and construction and workmanship quality parameters on seismic response of reinforced concrete buildings through nonlinear static and dynamic procedures. The accounted parameters are selected for their common use in rapid screening of RC buildings. The 4- and 7-story buildings designed according to pre-modern codes are used to reflect majority of the existing building stock. The relative penalty scores are employed in this study to evaluate relative importance of certain irregularities in the existing rapid seismic assessment procedures. Comparison of relative scores for the irregularities considered in this study show that the overall trend is similar. The relatively small differences may be accounted for regional construction practices. It is concluded that initial-phase seismic assessment procedures based on architectural features yield in somewhat similar results independent of their bases. However, the differences in the scores emphasize the proper selection of the method based on the regional structure characteristics.

Investigation of antimicrobial activity and entA and entB genes in Enterococcus faecium and Enterococcus faecalis strains isolated from naturally fermented Turkish white cheeses

Togay, Sine Ozmen,Ay, Mustafa,Guneser, Onur,Yuceer, Yonca Karagul 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.6

In this research, the antagonistic effects of Enterococcus faecalis and E. faecium bacteria isolated from naturally fermented Turkish white cheeses, produced without starter culture, against Listeria monocytogenes, L. innocua, L. ivanovii, Staphylococcus aureus, and E. faecalis were evaluated. The presence of entA and entB genes was also detected in the isolates, which had antimicrobial activity. Total 71 strains of E. faecalis and 7 strains of E. faecium were tested; 20 of E. faecalis and none of E. faecium strains showed antimicrobial activity against the tested bacteria using agar spot method. Among E. faecalis strains, which had antimicrobial activity, three strains contained both entA and entB genes, two strains carried only entA gene, and five strains had only entB gene. These cheese-sourced enterococcal strains or their enterocins should be considered to be used for food preservation especially in the dairy industry.