Finite element study on composite slab-beam systems under various fire exposures

Burak K. Cirpici,Suleyman N. Orhan,Turkay Kotan 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.5

This paper presents an investigation of the thermal performance of composite floor slabs with profiled steel decking exposed to fire effects from floor. A detailed finite-element model has been developed by representing the concrete slab with steel decking under of it and steel beam both steel parts protected by intumescent coating. Although this type of floor systems offers a better fire resistance, passive fire protection materials should be applied when a higher fire resistance is desired. Moreover, fire exposed side is so crucial for composite slab systems as the total fire behaviour of the floor system changes dramatically. When the fire attack from steel parts, the temperature rises rapidly resulting in a sudden decrease on the strength of the beam and decking. Herein this paper, the fire attack side is assumed from the face of the concrete floor (top of the concrete assembly). Therefore, the heat is transferred through concrete to the steel decking and reaching finally to the steel beam both protected by intumescent coating. In this work, the numerical model has been established to predict the heat transfer performance including material properties such as thermal conductivity, specific heat and dry film thickness of intumescent coating. The developed numerical model has been divided into different layers to understand the sensitivity of steel temperature to the number of layers of intumescent coating. Results show that the protected composite floors offer a higher fire resistance as the temperature of the steel section remains below 60℃ even after 60-minute Standard (ISO) fire and Fast fire exposure. Obtaining lower temperatures in steel due to the great fire performance of the concrete itself results in lesser reductions of strength and stiffness hence, lesser deflections.

An evaluation of the seismic response of symmetric steel space buildings

Burak Yön 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.2

This paper evaluates the seismic response of three dimensional steel space buildings using the spread plastic hinge approach. A numerical study was carried out in which a sample steel space building was selected for pushover analysis and incremental nonlinear dynamic time history analysis. For the nonlinear analysis, three earthquake acceleration records were selected to ensure compatibility with the design spectrum defined in the Turkish Earthquake Code. The interstorey drift, capacity curve, maximum responses and dynamic pushover curves of the building were obtained. The analysis results were compared and good correlation was obtained between the idealized dynamic analyses envelopes with and static pushover curves for the selected building. As a result to more accurately account response of steel buildings, dynamic pushover envelopes can be obtained and compared with static pushover curve of the building.

Multiple cracking analysis of HTPP-ECC by digital image correlation method

Burak Felekoglu,Muhammer Keskinates 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.6

This study aims to characterize the multiple cracking behavior of HTPP-ECC (High tenacity polypropylene fiber reinforced engineered cementitious composites) by Digital Image Correlation (DIC) Method. Digital images have been captured from a dogbone shaped HTPP-ECC specimen exhibiting 3.1% tensile ductility under loading. Images analyzed by VIC-2D software and εxx strain maps have been obtained. Crack widths were computed from the εxx strain maps and crack width distributions were determined throughout the specimen. The strain values from real LVDTs were also compared with virtual LVDTs digitally attached on digital images. Results confirmed that it is possible to accurately monitor the initiation and propagation of any single crack or multiple cracks by DIC at the whole interval of testing. Although the analysis require some post-processing operations, DIC based crack analysis methodology can be used as a promising and versatile tool for quality control of HTPP-ECC and other strain hardening composites.

The IOC as a transnational organization: Paradigm shift and its rising role in global governance

Burak Herguner 한국외국어대학교 국제지역연구센터 2012 International Area Studies Review Vol.15 No.2

The changes in the aftermath of the Cold War deeply affected the functioning of international organizations, and increased their leverage in international affairs. This article chiefly argues that the paradigm shift in the policies of the International Olympic Committee mitigated the prospect of damage to the Olympic movement and paved the way for the International Olympic Committee to figure in international affairs more effectively. In the article, it is concluded that the Olympic Games have become a significant soft power instrument for states’ foreign policy, rather than being an arena of boycotts or chauvinism, owing to the changing nature of international relations; however, it is more difficult for some states to benefit from this resource of soft power because of domestic issues.

All-arthroscopic, Guideless Single Suture-button Fixation of Acute Acromioclavicular Joint Dislocation

Burak Altintas,Fatih Yildiz,Gokcer Uzer,Mehmet Kapicioglu,Kerem Bilsel 대한견주관절의학회 2017 대한견주관절학회지 Vol.20 No.2

Background: The purpose of this study was to examine the clinical and radiological results of the all-arthroscopic, suture-button fixation technique to treat acute acromioclavicular (AC) joint separations. Methods: All patients with acute AC joint separations received all-arthroscopic, single suture-button (TightRope) procedure without a special guide. Postoperative Constant score (CS), pain level according to visual analogue scale, and range of motion (ROM) were evaluated. For radiological evaluation, coracoclavicular distances were measured bilaterally. Results: Between December 2010 and June 2012, 18 consecutive patients (4 women and 14 men; mean age, 29.3 years) with acute AC joint separations underwent surgical treatment after 6.4 days (range, 2–20 days) following the initial trauma. The average postoperative follow-up was 16.9 months. The mean CS was 92.4 (range, 84–96). The mean external rotation, forward flexion, and abduction were 75.8° (range, 50°–90°), 170° (range, 150°–180°), and 163.8° (range, 140°–180°), respectively. Five patients exhibited coracoclavicular ossifications. In two patients, superficial wound infections were successfully treated with antibiotic therapy. In one patient, a coracoid fracture was observed. No significant differences were found regarding pain, ROM, or strength parameters between both sides. The coracoclavicular distance was discovered to be approximately 2.8 mm greater on the affected side; however, this minimal reduction loss did not affect the functional results. Conclusions: The findings of this study suggests that all-arthroscopic treatment of AC joint separations using the single suture-button technique without a drill guide is safe, yielding good to excellent clinical results.

SOME IDENTITIES ON THE SECOND KIND BERNOULLI POLYNOMIALS OF ORDER AND SECOND KIND EULER POLYNOMIALS OF ORDER WITH THE PARAMETERS a,b,c

BURAK KURT 장전수학회 2013 Proceedings of the Jangjeon mathematical society Vol.16 No.2

In this study, we gave some relations on the second kind Bernoulli polynomials of order and the second kind Euler polynomials of order with the parameters . We proved two theorems on the second kind Bernoulli polynomials. Also, we gave some relations between the second kind Bernoulli polynomials of order with the parameters and the second kind Euler polynomials of order with the parameters a,b,c.

Diastolic Dyssynchrony in Acute ST Segment Elevation Myocardial Infarction and Relationship with Functional Recovery of Left Ventricle

Burak Turan,Tolga Das¸li,Ayhan Erkol,I· smail Erden,Yelda Basaran 한국심초음파학회 2016 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.24 No.3

Background: Incidence of diastolic dyssynchrony (DD) and its impact on functional recovery of left ventricle (LV) after ST segment elevation myocardial infarction (STEMI) is not known. Methods: Consecutive patients with STEMI who underwent successful revascularization were prospectively enrolled. Echocardiography with tissue Doppler imaging was performed within 48 hours of admission and at 6 months. LV end-diastolic volume index (EDVI), end-systolic volume index (ESVI), ejection fraction (EF), and left atrial volume index (LAVI) were calculated. Diastolic delay was calculated from onset of QRS complex to peak of E wave in tissue Doppler image and presented as maximal temporal difference between peak early diastolic velocity of 6 basal segments of LV (TeDiff). Study patients were compared with demographically matched control group. Results: Forty eight consecutive patients (55 ± 10 years, 88% male) and 24 controls (56 ± 6 years, 88% male) were included. TeDiff was higher in STEMI than in controls (35.9 ± 19.9 ms vs. 26.3 ± 6.8 ms, p = 0.025). Presence of DD was higher in STEMI than controls (58% vs. 33%, p = 0.046) according to calculated cut-off value (≥ 29 ms). There was no correlation between TeDiff and change in EDVI, ESVI, and LAVI at 6 months, however TeDiff and change in EF at 6 months was positively correlated (r = 0.328, p = 0.023). Patients with baseline DD experienced remodeling less frequently compared to patients without baseline DD (11% vs. 38%, p = 0.040) during follow-up. Conclusion: STEMI disrupts diastolic synchronicity of LV. However, DD during acute phase of STEMI is associated with better recovery of LV thereafter. This suggests that DD is associated with peri-infarct stunned myocardium that is salvaged with primary intervention as well as infarct size.

Use of Heparin Cream for Venous Congestion in the Extended Reverse Metacarpal Artery Flap: A Case Report

Burak Erguün Tatar,Fahri Sabancıoğullarından,Caner Gelbal,Mehmet Bozkurt 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.5

Finger dorsum defects are a challenging situation. Many reconstruction methods are used in these defects. Extended reverse dorsal metacarpal artery (RDMA) flap is used in dorsal finger reconstruction. Venous congestion in this flap is most important cause of flap failure. In this case, we presented a case in which we used heparin cream due to development of venous congestion in our patient who underwent an extended RDMA flap. A 24-year-old female patient presented to the emergency department with a defect of dorsal of left-hand fourth finger. Defect was covered with an extended RDMA flap. On postoperative first day, venous congestion was observed, and heparin cream was applied three times a day on flap. The signs of venous congestion were regressed. Tissue healed as a result of superficial epidermolysis and skin grafting. No functional limitationwas observed in sixth-month postoperative control. Venous congestion is the most important cause of flap failure of extended RDMA flaps. Generally, subcutaneous heparin administration and leech therapy are used. In our case, heparin was applied as a cream instead of subcutaneously, and flap healing was observed as a result of superficial epidermolysis. Heparin cream application can also be used as a treatment option in flaps with venous congestion.

Ambient vibration testing and seismic performance of precast I beam bridges on a high-speed railway line

Burak Toydemir,Ali Koçak,Barış Sevim,Basak Zengin 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.5

In this study, the seismic performance levels of four bridges are determined using finite element modeling based on ambient vibration testing. The study includes finite element modeling, analytical modal analyses, ambient vibration testing and earthquake analyses of the bridges. For the purpose, four prestressed precast I beam bridges that were constructed for the Ankara-Sivas high speed railway line are selected for analytical and experimental studies. In the study, firstly a literature review related to the dynamic behavior of bridges especially precast beam bridges is given and then the formulation part related to ambient vibration testing and structural performance according to Turkish Seismic Code (2007) is presented. Next, 3D finite element models of the bridge are described and modeled using LARSA 4D software, and analytical dynamic characteristics are obtained. Then ambient vibration testing conducted on the bridges under natural excitations and experimental natural frequencies are estimated. Lastly, time history analyses of the bridges under the 1999 Kocaeli, 1992 Erzincan, and 1999 Düzce Earthquakes are performed and seismic performance levels according to TSC2007 are determined. The results show that the damage on the bridges is all under the minimum damage limit which is in the minimum damage region under all three earthquakes.

Effect of Aggregate Shape on the Surface Properties of Flexible Pavement

Burak Sengoz,Amir Onsori,Ali Topal 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.5

One of the most important properties of flexible pavements in terms of tire-pavement interface is surface texture. The texture of apavement surface and its ability to resist polishing effect of traffic is of prime importance in providing skidding resistance. Pavementsurface texture greatly contributes to tire-pavement skid resistance which has a direct effect on traffic operation and safetyparticularly at high speeds. Doubtless, there exists a close relationship between pavement surface texture and aggregate angularitywithin the wearing course. This paper is aimed to determine the effect of aggregate shape on the surface properties of Hot MixAsphalt (HMA). Two different mineralogical types of aggregate (basalt and limestone) have been crushed with impact, jaw and rolltype of crushers. Various types of aggregate with different shapes have been mixed with 50/70 penetration grade bitumen to formdense graded mixtures. Test methods related with the evaluation of shape and texture characteristics have been utilized tocharacterize the geometrical properties of aggregates. The texture and friction properties of asphalt slabs have been evaluated bymeans of sand patch test, 3D laser scanner and dynamic friction tester respectively. The results indicated that a relationship existsbetween the shape characteristics of aggregate and the surface properties of HMA.