• Steel and Composite Structures
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• 제28권6호
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• pp.767-778
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• 2018

The purpose of this study is to investigate how a fully restrained bolted beam splice affects the connection behavior as a column-tree connection in steel special moment frames under cyclic loading when located within the plastic hinge zone. The impacts of this attachment in protected zone are observed by using nonlinear finite element analyses. This type of splice connection is designed as slip-critical connection and thereby, the possible effects of slippage of the bolts due to a possible loss of pretension in the bolts are also investigated. The 3D models with solid elements that have been developed includes three types of connections which are the connection having fully restrained beam splice located in the plastic hinge location, the connection having fully restrained beam splice located out of the plastic hinge and the connection without beam splice. All connection models satisfied the requirement for the special moment frame connections providing sufficient flexural resistance, determined at column face stated in AISC 341-16. In the connection model having fully restrained beam splice located in the plastic hinge, due to the pretension loss in the bolts, the friction force on the contact surfaces is exceeded, resulting in a relative slip. The reduction in the energy dissipation capacity of the connection is observed to be insignificant. The possibility of the crack occurrence around the bolt holes closest to the column face is found to be higher for the splice connection within the protected zone.

• Steel and Composite Structures
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• 제30권5호
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• pp.443-456
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• 2019

Although numerous researchers demonstrated the significant difference in performance between the various beam-to-column connection types, most of the previous studies in the area of infilled steel frames focused on the behaviour of frames with welded connections. Therefore, there is a need for conducting studies on infilled steel frames with other common connection types (extended endplate with and without rib stiffeners, flush endplate and shear connections). In this paper, firstly, a two-dimensional finite-element model simulating the cyclic response of infilled steel frames was presented. The infill-frame interaction, as well as the interactions between connections' components, were properly modelled. Using the previously-validated model, a parametric study on infilled steel frames with five different beam-to-column connection types, under cyclic loading, was carried out. Several parameters, including infill material, fracture energy of masonry and infill thickness, were investigated. The results showed that the infilled frames with welded connections had the highest initial stiffness and load-carrying capacity. However, the infilled frames with extended endplate connections (without rib stiffeners) showed the greatest energy dissipation capacity and about 96% of the load-carrying capacity of frames with welded connections which indicates that this type of connection could have the best performance among the studied connection types. Finally, a simplified analytical model for estimating the stiffness and strength of infilled steel frames (with different beam-to-column connection types) subjected to lateral cyclic loading, was suggested.

• Advances in concrete construction
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• 제15권6호
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• pp.391-404
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• 2023

In this study, the modeling of the transverse connection of fully precast steel-UHPC (Ultra-High-Performance Concrete) lightweight composite bridges were conducted. The transverse connection between precast components plays a critical role in the overall performance and safety of the bridge. To achieve an accurate and reliable simulation of the interface behavior, the cohesive model in ABAQUS was employed, considering both bending-tension and compression-shear behaviors. The parameters of the cohesive model are obtained through interface bending and oblique shear tests on UHPC samples with different surface roughness. By validating the numerical simulation against actual joint tests, the effectiveness and accuracy of the proposed model in capturing the interface behavior of the fully precast steel-UHPC lightweight composite bridge were demonstrated.

• 한국콘텐츠학회논문지
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• 제8권1호
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• pp.169-176
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• 2008

본 논문에서는 접속 (connection)과 패킷의 두 레벨 (level)을 함께 고려하는 IEEE 802.16 망에서의 무선 자원 관리 큐잉 모델을 개발한다. 상위 레벨인 접속 레벨에서는 대역폭 가용여부와 서비스 클래스별 우선순위 큐를 사용하여 접속 수락제어를 모델링하고 하위 레벨인 패킷 전송은 서비스 클래스별 임계치와 현재 가용한 대역폭의 두 항목을 동시에 고려한 동적 대역폭 할당 방법을 모델링 한다. 계층 모델은 페트리 네트의 확장형인 SRN (Stochastic Reward Nets)을 이용하여 개발되며 802.16서비스 클래스별 트래픽에 대한 대역폭 활용률과 처리율을 성능지표로 모델에 대한 수치결과를 구한다.

• 국제강구조저널
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• 제18권4호
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• pp.1464-1469
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• 2018

Steel frames with ductile connections have good seismic performance under strong earthquake, they are now popular for high seismic design. In order to simplify the process of numerical analysis of the steel frames with ductile connections, simplified connection models are introduced, two types of springs are placed in the simplified connection model, which can simulate deformation of the panel zone and members. 6-story-3-bay steel frames with ductile connections are simplified and carried out modal analysis, fundamental periods of the frames predicted by finite-element analysis for simplified steel frame models were compared to the results for actual frame models. 2-story steel frame with reduced beam section connections is simplified and carried out pseudo-static analysis, hysteretic curves and skeleton curves of the frame obtained by finite-element analysis for simplified steel frame model are compared to test results. The comparison show that the difference between them is small, it is reliable and effective to predict mechanical properties of the steel frame with ductile connection by finite-element analysis of simplified steel frame model.

• 대한토목학회논문집
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• 제38권2호
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• pp.349-356
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• 2018

본 논문은 국내에서 연구가 미진한 적재설비의 지진 취약도 평가에 적용할 수 있는 FE 해석 기반의 연결부 모델을 개발하는데 목적이 있다. 이러한 목표를 달성하기 위하여, 적재설비 거동을 파악하기 위한 진동대 실험과 Modal Test, 그리고 구성 부재를 대상으로 한 다양한 부재실험(8가지 Push-over Test)을 진행하였다. 실험결과를 바탕으로 지진취약도 평가에 적용하기 위한 적재설비의 연결부 모델을 개발하기 위하여, NX-Nastran 프로그램을 활용하여 연결부의 상세 모델링을 진행하였다. 특히, 단순 걸쇠 방식으로 연결되는 기둥 부재와 보 부재의 연결을 모사하기 위하여 면대면 표면접촉 요소와 스프링 요소를 적용하였으며, 스프링 요소의 모델은 ARX (Auto Regressive eXogenous) 기반의 수학적 모델을 개발하여 적용하였다. FE 모델 기반의 simulation 결과는 부재 실험 결과와 비교하였을 때, 상호 오차율 8% 미만의 우수한 신뢰도를 보여주었다. 결과적으로 연구에서 개발한 FE해석 기반의 연결부 모델은 적재설비의 지진 취약도 평가를 위한 해석 모델에 활용될 수 있음을 확인하였다.

• Structural Engineering and Mechanics
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• 제12권2호
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• pp.201-214
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• 2001

Four finite element (FE) models are examined to find the one that best estimates moment-rotation characteristics of top- and seat-angle with double web-angle connections. To efficiently simulate the real behavior of connections, finite element analyses are performed with following considerations: 1) all components of connection (beam, column, angles and bolts) are discretized by eight-node solid elements; 2) shapes of bolt shank, head, and nut are precisely taken into account in modeling; and 3) contact surface algorithm is applied as boundary condition. To improve accuracy in predicting moment-rotation behavior of a connection, bolt pretension is introduced before the corresponding connection moment being surcharged. The experimental results are used to investigate the applicability of FE method and to check the performance of three-parameter power model by making comparison among their moment-rotation behaviors and by assessment of deformation and stress distribution patterns at the final stage of loading. This research exposes two important features: (1) the FE method has tremendous potential for connection modeling for both monotonic and cyclic loading; and (2) the power model is able to predict moment-rotation characteristics of semi-rigid connections with acceptable accuracy.

• Computers and Concrete
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• 제21권3호
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• pp.299-310
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• 2018

When reinforced concrete structures are subjected to strong seismic forces, their beam-column connections are very susceptible to be damaged during the earthquake event. Consequently, structural designers try to fit an important quantity of steel reinforcement inside the connection, complicating its construction without a clear justification for this. The aim of this work is to evaluate -and demonstrate- numerically how the quantity and the array of the internal steel reinforcement influences on the nonlinear response of the RC beam-column connection. For this, two specimens (extracted from an experimental test of 12 RC beam-column connections reported in literature) were modeled in the Finite Element code FEAP considering different stirrup's arrays. The nonlinear response of the RC beam-column connection is evaluated taking into account the nonlinear thermodynamic behavior of each component: a damage model is used for concrete; a classical plasticity model is adopted for steel reinforcement; the steel-concrete bonding is considered perfect without degradation. At the end, the experimental responses obtained in the tests are compared to the numerical results, as well as the distribution of shear stresses and damage inside the concrete core of the beam-column connection, which are analyzed for a low and high state of confinement.

• 정보기술과데이타베이스저널
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• 제8권1호
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• pp.105-116
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• 2001

XML is a standard markup language for exchange and storage of formed or well-formed information in World Wide Web. Because the source data of XML message for exchange of information in World Wide Web is stored in legacy database, it is necessary for the easy connection between XML application and database system. In Oracle8i, 9i, Informix and SQL2000, DBMS vendors make upgrade to DBMS for using XML. This method of upgrade between XML application and database system is Platform-dependent and DBMS-dependent. Also It is necessary for the method of the platform- and DBMS-independent connection between XML application and database system. The methods for the connection between XML DTD and RDB schema are studied for the easy connection between XML application and database system. But the study for the easy connection between XML DTD and ORDB schema is a little. For multimedia application, we use the extended DBMS from RDBMS. It is necessary for the study to the transformation from XML DTD to ORDB schema. In this paper, for easier connection between XML application and database system, we propose the method of the transformation from XML DTD to ORDB schema using Object Model.

• Tribology and Lubricants
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• 제37권4호
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• pp.136-143
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• 2021

This paper presents the loosening behavior that occurs after the application of an external load to internal and external connection types of dental implants using the finite element method. We use fastening force between an abutment and a fixture to clamp the dental implant system; however, loosening and breakage may occur owing to cyclic external loads. In this study, we considered the initial fastening condition in the pre-load analysis and then investigated the change in stress and contact surface status when applying external loads. After the application of the initial fastening load, we verified that the internal connection-type model exhibited a relatively lower stress distribution than that of the external connection-type one. Moreover, we found that the former model showed a lower stress concentration after the application of the external load. In addition, after the application of this load, we found that the higher the shear load acting on the implant system, the higher the possibility of loosening. The study results showed the change in stress distribution and contact surface according to the connection type of the dental implants and the phenomenon of loosening by cyclic loads. We expect that the results of this study will be useful for the study of reliability and design of dental implant systems.