• Computers and Concrete
• /
• 제31권5호
• /
• pp.419-432
• /
• 2023

Beam-column joints are a critical component of reinforced concrete frame structures. They are responsible for transferring forces between adjoining beams and columns while limiting story drifts and maintaining structural integrity. During severe loading, beam-column joints deform significantly, affecting, and sometimes governing, the overall response of frame structures. While most failure modes for beam and column elements are commonly considered in plastic-hinge-based global frame analyses, the beam-column joint failure modes, such as concrete shear and reinforcement bond slip, are frequently omitted. One reason for this is the dearth of published guidance on what type of hinges to use, how to derive the joint hinge properties, and where to place these hinges. Many beam-column joint models are available in literature but their adoption by practicing structural engineers has been limited due to their complex nature and lack of practical application tools. The objective of this study is to provide a comparative review of the available beam-column joint models and present a practical joint modeling approach for integration into commonly used global frame analysis software. The presented modeling approach uses rotational spring models and is capable of modeling both interior and exterior joints with or without transverse reinforcement. A spreadsheet tool is also developed to execute the mathematical calculations and derive the shear stress-strain and moment-rotation curves ready for inputting into the global frame analysis. The application of the approach is presented by modeling a beam column joint specimen which was tested experimentally. Important modeling considerations are also presented to assist practitioners in properly modeling beam-column joints in frame analyses.

• 한국전자파학회논문지
• /
• 제25권2호
• /
• pp.189-198
• /
• 2014

본 논문에서는 동일 대역에서 동시에 전 이중 통신을 하기 위한 프레임 구조를 사용하는 터보 등화기를 결합한 SSD (Simultaneous Single band Duplex) 시스템을 제안한다. 본 논문에서는 자기 간섭 신호를 보다 효율적으로 제거하기 위하여 프레임 구조를 사용한다. 본 논문에서는 송수신 프레임 구조를 사용할 경우의 시스템의 특성을 분석하기 위하여 프레임 구조를 사용하지 않는 시스템과 성능을 비교하였다. 시뮬레이션 결과로 본 논문에서 제안하는 시스템은 프레임 구조를 사용하였을 경우, 프레임 구조를 사용하지 않았을 경우보다 더 좋은 성능을 내며, 프레임 구조를 사용하는 제안하는 시스템은 더 적은 터보 등화기의 전역 반복으로 프레임 구조를 사용하지 않은 시스템과 유사한 성능을 낼 수 있는 것을 확인하였다.

• Steel and Composite Structures
• /
• 제21권4호
• /
• pp.805-827
• /
• 2016

A new type of precast CFST column to RC beam braced frame is proposed in this paper. A series of shake table tests were conducted to excite a one-third scale six-story model for investigating the global seismic performance of this type of structure against earthquake actions. Particular emphasis was given to its dynamic property, global seismic responses and failure path. Correspondingly, a numerical model built on the basis of fiber-beam-element model, multi-layer shell model and element-deactivation method was developed to simulate the seismic performance of the prototype structure. Numerical results were compared with the measured values from shake table tests to verify the validity and reliability of the numerical model. The results demonstrated that the proposed novel precast CFST column to RC beam braced frame performs excellently under strong earthquake excitations; the "strong CFST column-weak RC beam" and "strong connection-weak member" anti-seismic design principles can be easily achieved; the maximum deflections of precast CFSTC-RCB braced frame satisfied the deflection limitations proposed in national code; the numerical model can properly simulate the dynamic property and responses of the precast CFSTC-RCB braced frame that are highly concerned in engineering practice.

• Advances in concrete construction
• /
• 제9권4호
• /
• pp.423-435
• /
• 2020

Open ground story (OGS) reinforced concrete (RC) buildings are vulnerable to the complete collapse or severe damages under seismic actions. This study investigates the effectiveness of four different strengthening techniques representing the local and global modifications to improve the seismic performance of a non-ductile RC OGS frame. Steel caging and concrete jacketing methods of column strengthening are considered as the local modification techniques, whereas steel bracing and RC shear wall systems are selected as the global strengthening techniques in this study. Performance-based plastic design (PBPD) approach relying on energy-balance concept has been adopted to determine the required design force demand on the strengthening elements. Nonlinear static and dynamic analyses are carried out on the numerical models of study frames to assess the effectiveness of selected strengthening techniques in improving the seismic performance of OGS frame.. Strengthening techniques based on steel braces and RC shear wall significantly reduced the peak interstory drift response of the OGS frame. However, the peak floor acceleration of these strengthened frames is amplified by more than 2.5 times as compared to that of unstrengthened frame. Steel caging technique of column strengthening resulted in a reasonable reduction in the peak interstory drift response without substantial amplification in peak floor acceleration of the OSG frame.

• Structural Engineering and Mechanics
• /
• 제81권2호
• /
• pp.131-146
• /
• 2022

This study highlights the accuracy of several single strut models to predict the global response of infilled reinforced concrete (R/C) frames. To this aim, six experimental tests are selected to calibrate the numerical modeling. The width of the diagonal strut is calculated using several macro models from the literature. The mechanical properties of the diagonal strut are determined by using two methods: (a) by subtracting the bare frame response from that of the infilled frame, and (b) by calculating the axial strength in the diagonal direction. A combination between the different width and the axial force models is carried out to study the effects of each parameter on global response. Non-linear pushover analyses are conducted using SAP2000. The results indicate the accuracy of the macro-modeling approach to predict the behavior of the infilled frames.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
• /
• pp.101-104
• /
• 2001

This paper proposes a unique shot boundary detection algorithm for the video indexing and/or browsing. Conventional methods based on the frame differences and the histogram differences are improved. Instead of using absolute frame differences, block by block based relative frame differences are employed. Frame adaptive thresholding values are also employed for the better detection. for the cases that the frame differences are not enough to detect the shot boundary, histogram differences are selectively applied. Experimental results show that the proposed algorithm reduces both the “false positive” errors and the “false negative” errors especially for the videos of dynamic local and/or global motions

• Computers and Concrete
• /
• 제21권6호
• /
• pp.637-647
• /
• 2018

Numerical approach using finite element method has been used to evaluate the behaviour of reinforced concrete frame structure subjected to fire. The structure is previously designed in accordance with Eurocode standards for the design of structures for earthquake resistance, for the ductility class M. Thermal and structural response are obtained using a commercially available software ANSYS. Temperature-dependent nonlinear thermal and mechanical properties are adopted according to Eurocode standards, with the application of constitutive model for the triaxial behaviour of concrete with a smeared crack approach. Discrete modelling of concrete and reinforcement has enabled monitoring of the behaviour at a global, as well as at a local level, providing information on the level of damage occurring during fire. Critical regions in frame structures are identified and assessed, based on temperatures, displacements, variations of internal forces magnitudes and achieved plastic deformations of main reinforcement bars. Parametric analyses are conducted for different fire scenarios and different types of concrete aggregate to determine their effect on global deformations of frame structures. According to analyses results, the three-dimensional finite element model can be used to evaluate the insulation and mechanical resistance criteria of reinforced concrete frame structures subjected to nominal fire curves.

• 한국언론정보학보
• /
• 제35권
• /
• pp.7-35
• /
• 2006

신자유주의적 세계화가 강화되면서 문화시장 개방을 둘러싼 국제사회의 논쟁 역시 강화되고 있다. 시장개방 촉진자들은 문화영역의 생산물 역시 타 상품과 같은 조건에서 다루어져야 한다고 강변한다. 이의 반대자들은 문화란 개인과 공동체의 의식과 정체성에 영향을 주는 것이기에 상품교역에 있어서도 예외성이 인정되어야 한다고 강조한다. 이 같은 문화시장 개방을 둘러싼 국제 관계의 흐름은 국제사회의 의사결정과 관리에 대한 규범 창출의 이론적 틀을 제시하는 '글로벌 거버넌스(Global Governance)'의 중요성을 부각시킨다. 이에 본 논문은 문화시장 개방을 둘러싸고 서로 다른 입장을 취하고 있는 국제규범과 이의 행위자들에 대한 고찰을 글로벌 거버넌스라는 관점을 통해 살펴보고 있다. 구체적으로 문화시장 개방을 촉진하는 WTO, GATT, GATS와 같은 국제협약 및 행위자들을, 그리고 그 반대편에 위치하면서 '문화적 다양성' 논의를 이끌고 있는 국제협약 및 행위자들을 글로벌 거버넌스라는 틀 속에서 검토하고 있다. 이를 통해 본 논문은 문화시장 개방을 둘러싼 논쟁과 충돌은 패권국가의 힘에 기반한 국제질서가 아니라 다양한 국제사회의 행위자들이 참가하는 글로벌 거버넌스의 구축을 통해 그 해결책이 모색되어야 한다는 것을 강조하고 있다.

• 한국재난관리표준학회지
• /
• 제3권1호
• /
• pp.33-42
• /
• 2010

본 논문에서는 전체해석과 국부해석 조합방법을 이용하여 국부손상 또는 균열의 영향을 반영한 트러스교의 전체지간에서의 응력거동을 예측하였다. 이를 위해서 전체 구조체는 프레임요소에 의한 해석을 수행하고 국부 상세부분은 쉘요소에 의한 해석을 수행하여 두 결과를 조합함으로써 교량의 연결부처럼 응력분포가 복잡한 부분에서 이동하중에 따른 응력이력을 손쉽게 산정하게 된다. 트러스 연결부의 실제 기하학적 형상 및 강성을 전체 프레임해석에 고려하기 위해 국부 쉘모델과 프레임모델의 변위 비교를 통해 프레임 모델의 단면수정계수를 산정하였으며, 실제 공용중인 트러스교의 실험값과 해석값을 비교하여 전체해석-국부해석 조합방법을 검증하였으며, 더 나아가 국부손상의 영향이 반영된 국부 쉘모델 해석결과를 전체해석에 반영시켰다.

• 한국해양공학회지
• /
• 제16권4호
• /
• pp.25-31
• /
• 2002

This paper is to find optimum design of plane framed structures with discrete variables. Global search algorithms for this problem are Genetic Algorithms(GAs), Simulated Annealing(SA) and Shuffled Complex Evolution(SCE), and hybrid methods (GAs-SA, GAs-SCE). GAs and SA are heuristic search algorithms and effective tools which is finding global solution for discrete optimization. In particular, GAs is known as the search method to find global optimum or near global optimum. In this paper, reinforced concrete plane frames with rectangular section and steel plane frames with W-sections are used for the design of discrete optimization. These structures are designed for stress constraints. The robust and effectiveness of Genetic Algorithms are demonstrated through several examples.