Effect of connection rotation capacities on seismic performance of IMF systems

Han, Sang Whan,Moon, Ki-Hoon,Ha, Sung Jin Techno-Press 2016 Earthquakes and structures Vol.10 No.1

The seismic performance of moment frames could vary according to the rotation capacity of their connections. The minimum rotation capacity of moment connections for steel intermediate moment frames (IMF) was defined as 0.02 radian in AISC 341-10. This study evaluated the seismic performance of IMF frames with connections having a rotation capacity of 0.02 radian. For this purpose, thirty IMFs were designed according to current seismic design provisions considering different design parameters such as the number of stories, span length, and seismic design categories. The procedure specified in FEMA P695 was used for conducting seismic performance evaluation. It was observed that the rotation capacity of 0.02 radian could not guarantee the satisfactory seismic performance of IMFs. This study also conducted seismic performance evaluation for IMFs with connections having the rotation capacity of 3% and ductile connections for proposing the minimum rotation capacity of IMF connections.

Rotation capacity of composite beam connected to RHS column, experimental test results

Hisashi Namba,Mohammadreza Eslami 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.1

Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (<i>B</i>/<i>t</i>) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.

IMF 시스템에 적용하기 위한 RBS-B 접합부의 설계기준 제안

문기훈(Moon Ki-Hoon),최병길(Choi Byung-Gil),한상환(Han Sang-Whan) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

The purpose of this study is to propose a new design provisions for Reduced Beam Section with bolted web(RBS-B) connections for seismic applications at IMF system. According to the experiment results of RBS connections, the rotation capacity of RBS-B and RBS-W connections which were not occurred fracture at connection had more than 4 % rad. However, the rotation capacity of RBS-B connections which were occurred fracture at connection had less than 4% rad. As a number of parameters which are activated to plastic rotation capacity of RBS-B connections are existed variably, those were analyzed experimental connection data for relations between parameters and rotation capacity at first study. So dominating influence factor for rotation capacity of RBS-B connections were used for new design provision to applicate at IMF system. In this study, the new design provisions of RBS-B connections were proposed for seismic application at IMF system and excess probability of total rotation angle at 0.02 radians respectively 16%, 50%, 84% using dominated parameters, moment strength ratio at plastic capacity of RBS-B connection.

Ultimate behaviour and rotation capacity of stainless steel end-plate connections

Yuchen Song,Brian Uy,Dongxu Li,Jia Wang 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.4

This paper presents a combined experimental and numerical study on stainless steel end-plate connections, with an emphasis placed on their ultimate behaviour and rotation capacity. In the experimental phase, six connection specimens made of austenitic and lean duplex stainless steels are tested under monotonic loads. The tests are specifically designed to examine the close-to-failure behaviour of the connections at large deformations. It is observed that the rotation capacity is closely related to fractures of the stainless steel bolts and end-plates. In the numerical phase, an advanced finite element model suitable for fracture simulation is developed. The incorporated constitutive and fracture models are calibrated based on the material tests of stainless steel bolts and plates. The developed finite element model exhibits a satisfactory accuracy in predicting the close-to-failure behaviour of the tested connections. Finally, the moment resistance and rotation capacity of stainless steel end-plate connections are assessed based on the experimental tests and numerical analyses.

Numerical study on the rotation capacity of CFRP strengthened cold formed steel beams

Mohammed H. Serror,Essam G. Soliman,Ahmed F. Hassan 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.4

Currently, CFRP (Carbon Fiber Reinforced Polymer) plate bonding is used quite extensively as a strengthening method. In this technique, a composite CFRP plate or sheet of relatively small thickness is bonded with an adhesion material to steel or concrete structure in order to improve its structural behavior and strength. The sheets or plates do not require much space and give a composite action between the adherents. In this study, the rotation capacity of CFRP-strengthened cold-formed steel (CFS) beams has been evaluated through numerical investigation. Studies on different structural levels have been performed. At the beam level, C-section has been adopted with different values of profile thickness, web height, and flange width. At the connection level, a web bolted moment resistant type of connection using through plate has been adopted. In web-bolted connections without CFRP strengthening, premature web buckling results in early loss of strength. Hence, CFRP sheets and plates with different mechanical properties and geometric configurations have been examined to delay web and flange buckling and to produce relatively high moment strength and rotation capacity. The numerical results reveal that CFRP strengthening may increase strength, initial stiffness, and rotation capacity when compared with the case without strengthening.

반복하중을 받는 철골보 접합부의 거동

이승준,김상배 한국지진공학회 1999 한국지진공학회논문집 Vol.3 No.4

본 연구에서는 반복하중을 받는 H형강보 접합부의 거동을 실험적인 방법으로 조사하였다. 본 연구의 목적은 H형강보 접합부의 이력거동에 강제의 특성과 스캘럽의 형태가 주는 영향을 조사하는 것이다 5개의 접합부 시험체를 제작하여 반복하중을 재하면서 실험을 수행하였다. 보 접합부에서의 하중-회전변형 곡선을 얻었으며 접합부의 변형능력과 에너지 소산능력을 상호 비교하였다. 강재가 SS400인 시험제는 충분한 변형능력과 에너지소산능력을 보였으나 강재가 SM490인 시험체는 취성적인 파괴를 보였으며 변형능력이 작았다. 접합부 스캘럽의 형태는 접합부의 거동에 영향을 주지않았다. Behavior of H-beam connections under cyclic loadings is investigated experimentally in this study. The purpose of this study is to study the effect of steel properties and coping shape on the hysteretic behavior of H-beam connections. Five beam-to-column connection specimens were fabricated and tested under cyclic loadings. The load-rotation curves of the beam connections were mainly obtained. Deformation capacity and energy dissipation capacity of the connections are compared each other. The connections fabricated from SS400 showed good deformability and energy dissipation capacity, but those from SM490 showed brittle fracture at the connection. The coping shape at the connections showed a little difference in cyclic behavior.

강구조 H형강 기둥-보 접합부의 내진성능에 관한 실험적 연구

서성연(Seo, Seongyeon) 한국방재학회 2020 한국방재학회논문집 Vol.20 No.5

기존 강구조 모멘트골조시스템의 기둥-보 접합부는 노스리지 지진과 고베 지진시 충분한 내진성능을 발휘하지 못하고 접합부에서 조기 취성파괴가 발생하였다. 본 연구는 이러한 문제점을 고려하여 기존 접합부의 형상을 변화하여 H형강 보웨브의 고장력볼트 2면 전단접합과 보플랜지에 리브보강 유무를 변수로 한 실대형 실험을 실시하였다. 실험결과 기존 접합부보다 초기강성, 에너지흡수능력 및 소성회전능력이 각각 높게 나타났으며, 내력상승률 및 변형능력 또한 높게 나타나 비교적 우수한 내진성능을 나타냈다. 그리고 각 시험체가 층간변위비 4.2%, 총 소성회전능력 약 0.027 rad 이상 및 접합부 최대내력이 보의 전소성모멘트의 약 125% 이상을 상회하여 반응수정계수 R값 적용시 중간모멘트골조 이상의 내진설계가 가능하리라 사료된다. In terms of the moment frame system of steel structures, early brittle fractures developed in the H-shaped beam-to-column connection during the Northridge and Kobe earthquakes, thereby indicating insufficient seismic performance of these components. In this study, experiments were conducted on two-side shear connections of web and rib plate reinforcements of the flanges on an H-shaped beam-to-column connection. According to the test results, the H-shaped beam-to-column connections with two-side shear connections of beam web and rib plate reinforcements of the flanges were superior to the existing connections in terms of initial stiffness, energy dissipation capacity, and plastic rotational capacity. The test values exceeded 4.2%, 0.027 rad, and 125% in terms of story drift ratio, total plastic rotation capacity, and full plastic moment of the beam, respectively. Accordingly, the proposed H-shaped beam-to-column connection showed better performance than that of the intermediate moment frame regarding seismic design.

Analytical Models for the Initial Stiffness and Plastic Moment Capacity of an Unstiffened Top and Seat Angle Connection under a Shear Load

양재근,전성삼 한국강구조학회 2009 International Journal of Steel Structures Vol.9 No.3

This study was conducted to propose analytical models that can predict the initial stiffness and plastic moment capacity of an unstiffened top and seat angle connection. These analytical models were developed by considering the moment-rotation curves, plastic hinge lines, and failure modes of an unstiffened top and seat angle connection. In the development of these analytical models, the effects of the prying action and the moment-shear interaction of a top angle were also considered. Application feasibility of these analytical models was verified by comparing these models’ results with those obtained from using the Chen-Kishi and Faella models, as well as the Nethercot experimental test data. Four tests were conducted to obtain the moment-rotation curves and failure modes of an unstiffened top and seat angle connection under shear. This study was conducted to propose analytical models that can predict the initial stiffness and plastic moment capacity of an unstiffened top and seat angle connection. These analytical models were developed by considering the moment-rotation curves, plastic hinge lines, and failure modes of an unstiffened top and seat angle connection. In the development of these analytical models, the effects of the prying action and the moment-shear interaction of a top angle were also considered. Application feasibility of these analytical models was verified by comparing these models’ results with those obtained from using the Chen-Kishi and Faella models, as well as the Nethercot experimental test data. Four tests were conducted to obtain the moment-rotation curves and failure modes of an unstiffened top and seat angle connection under shear.

리브 플레이트 보강 강구조 신형상 기둥-보 접합부의 내진성능에 관한 실험적 연구

서성연 대한건축학회지회연합회 2024 대한건축학회연합논문집 Vol.26 No.3

In terms of the moment frame system of steel structures, early brittle fractures developed in the H-shaped beam-to-column connection during the Northridge and Kobe earthquakes, thereby indicating insufficient seismic performance of these components. In this study, experiments were conducted on one-side shear connections of web and rib plate reinforcements of the flanges on an H-shaped beam-to-column connection. According to the test results, the H-shaped beam-to-column connections with one-side shear connections of beam web and rib plate reinforcements of the flanges were superior to the existing connections in terms of initial stiffness, energy dissipation capacity, and plastic rotational capacity(25%). The test values exceeded 4%, 0.029 rad, and 130% in terms of story drift ratio, total plastic rotation capacity, and full plastic moment of the beam, respectively. Accordingly, the proposed H-shaped beam-to-column connection showed better performance than that of the intermediate moment frame regarding seismic design.

웨브를 볼트 접합한 보 플랜지 절취형 접합부의 회전능력 평가

최병길(Choi Byung-Gil),문기훈(Moon Ki-Hoon),한상환(Han Sang-Whan) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

The purpose of this study is to propose a new design provisions for Reduced Beam Section with bolted web(RBS-B) connections for seismic applications at IMF system. Contents of study are evaluation for rotation capacity of RBS-B connections. RBS connections are newly developed connections for high ductility and energy dissipation capacity. However some experimental specimens have demonstrated that RBS-B connection was abnormally failed at the face of column and did not satisfied enough plastic rotation capacity required for that of region of high seismicity. This experimental results were considered and then RBS-B connection's application range was limited for IMF systems(ANSI/AISC 358-05). In this study, a number of parameters were considered as influences the behavior of RBS-B connection and proposed the new RBS-B design provisions for IMF system's limitation using dominated parameters at plastic capacity of RBS-B connection.