Fragility analysis of R/C frame buildings based on different types of hysteretic model

Muzaffer Borekci,Murat S. Kirçil 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.6

Estimation of damage probability of buildings under a future earthquake is an essential issue to ensure the seismic reliability. Fragility curves are useful tools for showing the probability of structural damage due to earthquakes as a function of ground motion indices. The purpose of this study is to compare the damage probability of R/C buildings with low and high level of strength and ductility through fragility analysis. Two different types of sample buildings have been considered which represent the building types mentioned above. The first one was designed according to TEC-2007 and the latter was designed according to TEC-1975. The pushover curves of sample buildings were obtained via pushover analyses. Using 60 ground motion records, nonlinear time-history analyses of equivalent single degree of freedom systems were performed using bilinear hysteretic model and peak-oriented hysteretic model with stiffness – strength deterioration for each scaled elastic spectral displacement. The damage measure is maximum inter-story drift ratio and each performance level considered in this study has an assumed limit value of damage measure. Discrete damage probabilities were calculated using statistical methods for each considered performance level and elastic spectral displacement. Consequently, continuous fragility curves have been constructed based on the lognormal distribution assumption. Furthermore, the effect of hysteresis model parameters on the damage probability is investigated.

Seasonal Variation in Propensity to Travel in the U . S .

( Muzaffer Uysal ),( Heung Chul Oh ),( Joseph T . O'Leary ) 관광품질시스템학회 1995 관광품질시스템연구 Vol.1 No.1

Noncompaction of Ventricular Myocardium Involving the Right Ventricle

Muzaffer Saglam,Hasan Saygin,Huseyin Kozan,Ersin Ozturk,Hakan Mutlu 대한심장학회 2015 Korean Circulation Journal Vol.45 No.5

Noncompaction ventricular myocardium is an unusual cause of cardiomyopathy. It is association with congenital heart defects, most often with outflow obstructive lesions or coronary anomalies. However, no factor could explain the arrest of development of myocardial structure (isolated form). The pathogenesis of isolated noncompaction is thought to be an arrest in endomyocardial morphogenesis. It has been reported that myocardial noncompaction could present as acquired disease. The most common site of involvement is the left ventricle, with right ventricular involvement being reported in a few cases. In this report, we present a case with noncompaction of the right ventricle (RV). Cardiac computed tomography angiography and magnetic resonance imaging demonstrated morphological abnormalities of the RV

Does the Time From Biopsy to Radical Prostatectomy Affect Gleason Score Upgrading in Patients With Clinical T1c Prostate Cancer?

Muzaffer Eroglu,Omer Gokhan Doluoglu,Hasmet Sarici,Onur Telli,Berat Cem Ozgur,Selen Bozkurt 대한비뇨의학회 2014 Investigative and Clinical Urology Vol.55 No.6

Purpose: It is debated whether treatment delay worsens oncologic results in localizedprostate cancer (PCa). Few studies have focused on the role of a delay between the timeof biopsy and the time of surgery. Thus, we aimed to investigate the effect of the timeperiod between biopsy and surgery on Gleason score upgrading (GSU). Materials and Methods: A total of 290 patients who underwent radical retropubic prostatectomyin Ankara Training and Research Hospital were included in the study. Thebiopsy Gleason score, age, total prostate-specific antigen (PSA) value, prostate volumes,and PSA density (PSAD) were analyzed in all patients. The patients were dividedinto two groups: patients with GSU (group 1) and patients without GSU (group 2). Variables having a p-value of ≤0.05 in the univariate analysis were selected and thenevaluated by use of multivariate logistic regression models. Results were consideredsignificant at p<0.05. Results: GSU occurred in 121 of 290 patients (41.7%). The mean age of the patientswas 66.0±7.2 years in group 1 and 65.05±5.60 years in group 2 (p=0.18). The mean PSAvalues of groups 1 and 2 were 8.6±4.1 and 8.8±4.3 ng/dL, respectively. The mean prostatevolumes of groups 1 and 2 were 43.8±14.1 and 59.5±29.8 mL, respectively. ThePSAD of group 1 was significantly higher than that of group 2 (0.20 vs. 0.17, p=0.003). The mean time to surgery was shorter in group 2 (group 1, 52.2±22.6 days; group 2,45.3±15.5 days; p=0.004). According to the logistic regression, time from biopsy to surgeryis important in the prediction of GSU. Conclusions: We suggest that the time period between biopsy and surgery is a significantfactor that affects GSU in patients with clinically localized PCa.

SEASONAL VARIATION IN PROPENSITY TO TRAVEL IN THE U.S.

Muzaffer Uyasl,Oh, Heung Chul,O'Leary, Joseph T. 관광품질시스템학회 1995 관광품질시스템연구 Vol.1 No.1

This study provides information on the nature of travel flows as indicated by the number of estimated trips between nine travel regions in the United States. The study examined seasonal variation in propensity to travel by pur pose of trip and explored the relative travel generation power of the nine travel regions by comparing and contrasting the concepts of Region Potential Generation Index(RPGI) and Gross Travel Propensity(GTP). The study demonstrated that these indices may provide a useful complement to the traditional absolute travel net flow figures in spatial analysis of leisure behavior.

Fatigue Life Evaluation of Tripod Offshore Structure Using 3D Fatigue FE Analysis

Muzaffer Shazia,장경호,신왕섭 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.6

Off shore wind power became an important source of renewable energy that is rapidly growing over the past several years. Large off shore wind turbines require strong and large support structures. The support substructures are exposed to diverse dynamic and static loads such as waves, snow, wind ice, earthquakes, and tides. These unstable, destructive repeated loads lead to material degradation or damage accumulation which in turn leads to the failure of off shore structures. Fatigue is considered one of the signifi cant modes of failure in off shore structures. The constant exposure of welded multiplanar tubular joints of tripod structure under cyclic loading or the presence of fl aws due to fabrication and construction induces high-stress concentration at these joints. The material degradation or damage accumulation at welded joints gives rise to the formation or propagation of cracks, and ultimately leads to a collapse of giant steel structures. This research aimed at investigating the origin of crack positions and fatigue life in tripod off shore structures. The 3-D fatigue FE analysis was carried out in two steps, Firstly, the welding deformation and welding residual stress were calculated in thermal and mechanical analysis. Secondly, 3D fatigue crack analysis based on cyclic hysteresis constitutive equation and fatigue damage theory was used to calculate the fatigue life and crack initiation in tripod off shores structure. Results obtained from the analysis were compared with the results from hot-spot stress method and Eurocode 3. From the results, it was considered that 3D-fatigue FEM is a useful method to estimate fatigue life and crack initiation.

Fatigue analysis of overlapped tubular joints

Shazia Muzaffer,Kyong-Ho Chang,ZhenMing Wang,Wang-Sub Shin 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

The increasing demand of on the use of wind energy during recent years, have led to installation of more durable, safe and stable offshore structures in deep waters. The circular hollow section tubular joints are generally preferred in offshore structures. The overlapped joints are considered better than simple gap K-joints because of their higher axial strength, high stiffness and high durability. These tubular joints being subjected to combination of wind and waves load during their design period, the constantly acting loads deteriorates the structure, which often results in total collapse of offshore structures. In order to allow for cost effective and reliable design, the substantial requirement is to do accurate and reliable simulation. In this study in order to understand the behavior of crack initiation and the fatigue life of overlapped joints, the 3D fatigue FEM analysis of overlapped joint was carried out. The 3D fatigue FEM study based on continuum damage mechanics and constitutive model, was carried out in two steps namely 3D thermo elastic-plastic analysis and 3D non-steady heat conduction analysis. The fatigue life and crack initiation positions were determined. Finally, S-N curves were plotted and the results from FEM analysis were compared with Hot Spot Stress and with S-N curves recommended by Eurocode 3.

Fragility analysis of R/C frame buildings based on different types of hysteretic model

Borekci, Muzaffer,Kircil, Murat S. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.6

Estimation of damage probability of buildings under a future earthquake is an essential issue to ensure the seismic reliability. Fragility curves are useful tools for showing the probability of structural damage due to earthquakes as a function of ground motion indices. The purpose of this study is to compare the damage probability of R/C buildings with low and high level of strength and ductility through fragility analysis. Two different types of sample buildings have been considered which represent the building types mentioned above. The first one was designed according to TEC-2007 and the latter was designed according to TEC-1975. The pushover curves of sample buildings were obtained via pushover analyses. Using 60 ground motion records, nonlinear time-history analyses of equivalent single degree of freedom systems were performed using bilinear hysteretic model and peak-oriented hysteretic model with stiffness - strength deterioration for each scaled elastic spectral displacement. The damage measure is maximum inter-story drift ratio and each performance level considered in this study has an assumed limit value of damage measure. Discrete damage probabilities were calculated using statistical methods for each considered performance level and elastic spectral displacement. Consequently, continuous fragility curves have been constructed based on the lognormal distribution assumption. Furthermore, the effect of hysteresis model parameters on the damage probability is investigated.

Crack initiation and fatigue life of overlapped tubular K- joints

Shazia, Muzaffer(사지아),Chang, Kyong Ho(장경호),Shin, Wang Sub(신왕섭),Sazid, Nizam Khan(니잠) 한국강구조학회 2022 한국강구조학회 학술대회 발표집 Vol.33 No.1

Crack initiation and fatigue life of completely overlapped tubular N- joints

Shazia, Muzaffer(사지아),Chang, Kyong-Ho(장경호),Wang, Zhen Ming(왕진명),Lee, Yong-Su(이용수),Roque Eguillos 한국강구조학회 2023 한국강구조학회 학술대회 발표집 Vol.34 No.6