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Guliz Bayramoglu,Alpay Ozgen,Enver Altınok 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.4
In this paper, seismic performance of Kozyatagi Bridge is evaluated by employing nonlinear elasto-plastic dynamic analysis and the deformation-based performance. The time-history records of the 1999 Izmit, 1971 San Fernando and 1989 Loma Prieta earthquakes are modified by adopting a probability of exceedance of 2% in 50 years corresponding to the return period of 2475 years. The analysis is carried out for three different bearing cases which are movable bearings, restrained bearings, and movable bearings with viscous fluid dampers in the radial direction. The analysis results show that the bridge can be retrofitted with viscous fluid dampers. In this case the reinforced concrete piers need not be strengthened by any jacketing techniques in order to preserve the original architectural appearance of the bridge. The retrofitting design of the bridge with viscous fluid dampers is also presented in detail.
Bayramoglu, Guliz,Ozgen, Alpay,Altinok, Enver Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.4
In this paper, seismic performance of Kozyatagi Bridge is evaluated by employing nonlinear elasto-plastic dynamic analysis and the deformation-based performance. The time-history records of the 1999 Izmit, 1971 San Fernando and 1989 Loma Prieta earthquakes are modified by adopting a probability of exceedance of 2% in 50 years corresponding to the return period of 2475 years. The analysis is carried out for three different bearing cases which are movable bearings, restrained bearings, and movable bearings with viscous fluid dampers in the radial direction. The analysis results show that the bridge can be retrofitted with viscous fluid dampers. In this case the reinforced concrete piers need not be strengthened by any jacketing techniques in order to preserve the original architectural appearance of the bridge. The retrofitting design of the bridge with viscous fluid dampers is also presented in detail.
Flow characteristics and formability of a bulk metallic glass with a wide undercooled liquid region
Lee, Kwang Seok,Jun, Hyun-Joon,Chang, Young Won Elsevier Sequoia 2007 Materials science & engineering Structural materia Vol.449 No.-
<P><B>Abstract</B></P><P>Deformation behavior of Zr<SUB>44</SUB>Ti<SUB>11</SUB>Cu<SUB>9.8</SUB>Ni<SUB>10.2</SUB>Be<SUB>25</SUB> (number indicate at.%) bulk metallic glass having a wide undercooled liquid temperature interval has been investigated by performing a series of compression tests after rapid heating. The regions of brittle fracture, a non-Newtonian flow, and a Newtonian viscous flow were identified depending on the test conditions in terms of initial strain rate and temperature. A deformation map was constructed by applying both transition state and Newtonian viscous equations to the flow stress data to provide the boundaries between these three different deformation modes. The basic processing map based on a dynamic materials model has also been constructed to obtain an optimal forming condition.</P>
Zr계 벌크 비정질 합금의 균일 변형 영역에서의 변형 모드 및 변형 유기 구조 무질서화에 관한 고찰
이광석,박지언,하태권,장영원 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.4
Deformation behavior of a Zr_(41.2)Ti_(13.8)C_(u12),Ni_(10)Be_(22.5) bulk metallic glass was investigated. Three different types of true stress-strain curves were identified under compressive loading within undercooled liquid region depending on the strain rates and test temperatures. The two theoretical relations, based on a Newtonian viscous flow equation and a transition state theory, have been applied to analyze the transition behavior of deformation modes in homogeneous flow regime in terms of steady-state flow stress. In addition, the change of glass transition peak height by Differential Scanning Calorimetry (DSC) and qualitative RDF by Extended X-ray Absorption Fine Structure (EXAFS) have been used to account for structural states of Zr_(41.2)Ti_(13.8)C_(u12),Ni_(10)Be_(22.5) bulk amorphous alloys after annealing and disrupted compression test at =10^(-3)/s. At 370℃, only a small structural relaxation was observed to proceed in a period of 680 s by annealing. A deformation induced structural disordering (DISD) was, on the other hand, observed at the initial state of a non-Newtonian flow (e=0.03 and 0.076) around the stress overshoot. (Received November 26, 2004)
광폭인장시험을 통한 지오그리드의 시간의존적 변형 거동 고찰
유충식,김선빈,전한용 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.1
This paper presents the reusults of wide width tensile tests under sustained and cyclic loads with vairous loading rate on geogrids. A seires of modified wide width tensile tests were conducted to investigate the effect of tensile strain rate on the deformation behavior of the geogrids. In addition, residual deformation characteristics of a geogrid under sustained or cyclic tests were also investigated. The results indicated that the residual deformation of a geogrid is strongly related to the viscous behavior of the geogrid, and the residual deformation can be well described by a hyperbolic curve. Also revealed was that residual deformation of a geogrid when subject to sustained or cyclic load should be described with the framework of viscous behavior.
Mizuki Shigematsu,Takaaki Udagawa,Satoru Nagase Council on Tall Building and Urban Habitat Korea 2023 International journal of high-rise buildings Vol.12 No.3
This paper presents the structural design and response control system of the JR MEGURO MARC building, a 70 meters high office building with steel structure located in Tokyo (Figure 1). In order to achieve high earthquake resistance and useable office space, this building integrates a centralized response control system with deformation amplification mechanisms and tuned viscous mass dampers on the lower floor. Moreover, buckling-restrained braces (BRB) are installed on the upper floors to increase the effectiveness of centralized response control system and to reduce damage of the main frames in the event of a major earthquake. It features an efficient centralized response control system by amplifying the deformation of the dampers without creating a soft story.
Micro-Forming Characteristics of a Zr-Based Amorphous Alloy with a Gear-Like Mold
( Kyu Yeol Park ),( Young Sang Na ),( Seon Cheon Son ),( Jong Hoon Lee ),( Van Bon Nguyen ) 대한금속재료학회 ( 구 대한금속학회 ) 2007 METALS AND MATERIALS International Vol.13 No.5
The amorphous alloy Zr62Cu17Ni13Al8 exhibits a supercooled liquid state over a wide temperature range under high temperatures. In this present paper, the authors studied the micro-forming ability of the alloy by compressing specimens under a miniature pattern mold with a micro-gear shape. Micro-compressive formation is a formation method in which the surface of specimens of the Zr62Cu17Ni13Al8 amorphous alloy is compressed under conditions of dead loads and high temperatures and maintained for a given period for the fabrication of miniature patterns with a micro-gear shape. All the experiments were carried out under a vacuum environment to prevent the specimens from suffering deleterious effects, such as air traps in the miniature patterns and oxidation at the surface of the Zr62Cu17Ni13Al8 amorphous alloy. The characteristics of micro-compressive formation were investigated at temperatures higher than the glass transition temperature with different experimental parameters of loads and times. In addition, the micro-forming characteristics of the gear-like shape were investigated by means of scanning electron microscopes and a 3-D surface profiler system.
AE-MDB를 이용한 측면충돌안전성 평가시 인체상해 특성에 관한 연구
김도엽(DoYup Kim),장형진(HyungJin Chang),이창석(Changseok Lee),김창현(Changhyun Kim),이재완(JaeWan Lee),김규현(GyunhYun Kim) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
The domestic car to car accident Perpendicular to side car crash in a car accident case, the proportion was the highest. Safety regulations and New Car Assessment Program tests to ensure safety in side impacts tend to strengthen regulatory requirements. Side Pole Impact of the road, trees and utility pole, etc. aspects of vehicle side impact crash tests and more intensive deformation and impact energy after the collision mitigation occurs due to a lack of space and will cause fatal injury to the driver. Being studied in this paper AE-MDB side impact test and Side Pole test change the body injury results data analysis and evaluation methods KNCAP hatch side impact applied to the phase comparison should investigate.
Prediction of the turning and zig-zag maneuvering performance of a surface combatant with URANS
Duman, Suleyman,Bal, Sakir Techno-Press 2017 Ocean systems engineering Vol.7 No.4
The main objective of this study is to investigate the turning and zig-zag maneuvering performance of the well-known naval surface combatant DTMB (David Taylor Model Basin) 5415 hull with URANS (Unsteady Reynolds-averaged Navier-Stokes) method. Numerical simulations of static drift tests have been performed by a commercial RANS solver based on a finite volume method (FVM) in an unsteady manner. The fluid flow is considered as 3-D, incompressible and fully turbulent. Hydrodynamic analyses have been carried out for a fixed Froude number 0.28. During the analyses, the free surface effects have been taken into account using VOF (Volume of Fluid) method and the hull is considered as fixed. First, the code has been validated with the available experimental data in literature. After validation, static drift, static rudder and drift and rudder tests have been simulated. The forces and moments acting on the hull have been computed with URANS approach. Numerical results have been applied to determine the hydrodynamic maneuvering coefficients, such as, velocity terms and rudder terms. The acceleration, angular velocity and cross-coupled terms have been taken from the available experimental data. A computer program has been developed to apply a fast maneuvering simulation technique. Abkowitz's non-linear mathematical model has been used to calculate the forces and moment acting on the hull during the maneuvering motion. Euler method on the other hand has been applied to solve the simultaneous differential equations. Turning and zig-zag maneuvering simulations have been carried out and the maneuvering characteristics have been determined and the numerical simulation results have been compared with the available data in literature. In addition, viscous effects have been investigated using Eulerian approach for several static drift cases.