• Steel and Composite Structures
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• 제21권6호
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• pp.1251-1264
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• 2016

After observing relatively poor performance of bolted web-welded flange beam-to-column connections during 1994 Northridge earthquake, various types of connections based on two concepts of: (i) strengthening the connection; and (ii) weakening the beam ends were proposed. Among these modified or newly proposed connections, bolted T-stub connection follows the concept of strengthening. One of the connections with the idea of weakening the beam ends is reduced beam section (RBS). In this paper, finite element simulation is used to study the cyclic behavior of a new proposed connection developed by using a combination of both mentioned concepts. Investigated connections are exterior beam-to-column connections designed to comply with AISC provisions. The results show that moment capacity and dissipated energy of the new proposed connection is almost the same as those computed for a T-stub connection and higher than corresponding values for an RBS connection.

• Steel and Composite Structures
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• 제6권1호
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• pp.33-53
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• 2006

The rotational behaviour of bolted extended end plate beam-to-column connections is evaluated in the context of the component method. The full moment-rotation response is characterized from the force-deformation curve of the individual joint components. The deformability of end plate connections is mostly governed by the bending of the column flange and/or end plate and tension elongation of the bolts. These components form the tension zone of the joint that can be modelled by means of "equivalent T-stubs". A systematic analytical procedure for characterization of the monotonic force-deformation behaviour of individual T-stub connections is proposed. In the framework of the component method, the T-stub is then inserted in the joint spring model to generate the moment-rotation response of the joint. The procedures are validated with the results from an experimental investigation of eight statically loaded extended end plate bolted moment connections carried out at the Delft University of Technology. Because ductility is such an important property in terms of joint performance, particularly in the partial strength joint scenario, special attention is given to this issue.

• 대한토목학회논문집
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• 제33권1호
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• pp.101-113
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• 2013

반복적인 하중을 받는 볼트 연결부의 비선형적인 거동을 예측할 수 있는 역학적 고등해석 모델을 개발하는 데 주된 초점을 두어 본 연구를 수행하였다. 또한 대표적인 접합부 형태인 T-stub 접합부의 연결 컴포넌트에 대한 실제의 하중 재하 실험값을 활용한 해석으로 얻어진 거동에 대한 예측의 정확성 및 모형화의 타당성을 입증하였다. 연결부를 이루고 있는 구성요소들의 거동은 볼트의 인장변형, T-stub 플랜지의 휨변형, T-stub 몸체의 신장, 전단볼트의 지압 및 미끄러짐을 포함하며 접합부내에서 개별적인 힘-변위 메커니즘으로부터 정의된 다중 선형의 강성모델에 의하여 재현된다. 이러한 구성요소들은 그들의 거동특성을 지닌 비선형 스프링으로 모형화되어 역학적 해석 모델에 설치되어 연결부 전체의 거동을 수치해석적인 방법으로 예측하도록 한다. 해석 모델에 의한 예측값은 강성, 강도 및 변형 측면에서 실험값과 비교하여 정확성을 평가하였으며 이를 근거로 본 연구에서 제안된 역학적 해석 모델이 볼트 연결부의 거동과 성능을 만족하며 예측 가능하다는 결론을 내렸다.

• Steel and Composite Structures
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• 제20권2호
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• pp.267-293
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• 2016

It is well known that, in order to accurately predict the behaviour of steel structures a requirement the definition of the mechanical behaviour of beam-to column joints is of primary importance. This goal can be achieved by means of the so-called component method, which, in order to obtain the whole behaviour of connections, provides to break up joints in basic components of deformability and resistance. One of the main joint components used to model bolted connections is the so-called equivalent T-stub in tension, which is normally used to predict the behaviour of bolted plates in bending starting from the behaviour of the single bolt rows. In past decades, significant research efforts have been devoted to the prediction of the behaviour of bolted T-stubs but, to date, no particular attention has been devoted to the characterization of their plastic deformation capacity. To this scope, the work presented in this paper, taking into account the existing technical literature, proposes a new theoretical model for predicting the whole behaviour up to failure of bolted T-stubs under monotonic loading conditions, including some complexities, such as the bolt/plate compatibility requirement and the bolt fracture, which are necessary to accurately evaluate the ultimate displacement. After presenting the advances of the proposed approach, a comparison between theoretical and experimental results is provided in order to verify its accuracy.

• Steel and Composite Structures
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• 제45권4호
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• pp.605-619
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• 2022

The tensile behavior of the Thread-fixed One-side Bolt (TOB) at high temperatures was studied using the Finite Element Modeling (FEM) to explore the structural responses that could not be measured in tests. The accuracy of the FEM was verified using the test results from the failure mode, load-displacement curve as well as yielding load. Three typical failure modes of TOB connected T-stubs were observed, which were the Flange Yielding (FY), the Bolt Failure (BF) and the Coupling Failure mode (CF). The influence of the flange thickness tb and the temperature θ on the tensile behavior of the T-stub were discussed. The initial stiffness and the yielding load decreased with the increase of the temperature. The T-stubs almost lost their resistance when the temperature exceeded 700℃. The failure modes of T-stubs were mainly decided by the flange thickness, which relates to the anchorage of the hole threads and the bending resistance of flange. The failure mode could also be changed by the high temperature. Design equations in EN 1993-1-8 were modified and verified by the FEM results. The results showed that these equations could predict the failure mode and the yielding load at different temperatures with satisfactory accuracy.

• 한국강구조학회 논문집
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• 제28권1호
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• pp.53-64
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• 2016

상 하부 스플릿 티 접합부는 보-기둥 모멘트 접합부의 한 형태로 T-stub 플랜지의 두께, 고장력볼트의 게이지 거리, 고장력볼트의 개수, 고장력볼트의 직경 등의 변화에 따라서 상이한 거동특성을 나타낸다. 상 하부 스플릿 티 접합부는 일반적으로 상 하부에 체결된 T-stub이 휨모멘트를 지지하고 전단탭이 전단력을 지지하는 것으로 이상화하여 설계되고 있다. 그러나 중 저층 강구조물에 상 하부 스플릿 티 접합부가 적용되면 보 부재의 규격이 작아지므로 보 웨브에 전단탭을 설치할 수 없는 경우가 발생할 수 있다. 이 연구는 이와 같이 보 웨브에 전단탭 설치가 어려운 기하학적 형상을 갖는 상 하부 스플릿 티 접합부가 충분한 전단력 지지능력을 발현하도록 하는 접합부상세를 제안하기 위하여 진행하였다. 이를 위하여 상 하부 스플릿 티 접합부에 대한 실험체를 제작하여 실물대 실험을 수행하였다.

• Structural Engineering and Mechanics
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• 제24권4호
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• pp.463-478
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• 2006

The design of structural frameworks for buildings is constantly evolving and is dependent on regional issues such as loading and constructability. One of the most promising recent developments for low to medium rise construction in terms of efficiency of construction, robustness and aesthetic appearance utilises concrete-filled steel tubular sections as the columns in a moment-resisting frame. These are coupled to rigid or semi-rigid connections to composite steel-concrete beams. This paper includes the results of a pilot experimental programme leading towards the development of economical, reliable connections that are easily constructed for this type of frame. The connections must provide the requisite strength, stiffness and ductility to suit gravity loading conditions as well as gravity combined with the governing lateral wind or earthquake loading. The aim is to develop connections that are stiffer, less expensive and easier to construct than those in current use. A proposed fabricated T-stub connection is to be used to connect the beam flanges and the column. These T-stubs are connected to the column using "blind bolts" with extensions, allowing installation from the outside of the tube. In general, the use of the extensions results in a dramatic increase in the strength and stiffness of the T-stub to column connection in tension, since the load is shared between membrane action in the tube wall and the anchorage of the bolts through the extensions into the concrete.

• Steel and Composite Structures
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• 제20권3호
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• pp.501-512
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• 2016

High-strength structural bolts have been utilized for beam-to-column connections in steel-framed structural buildings. Failure of these components may be caused by the bolt shank fracture or threads stripping-off, documented in the literature. Furthermore, these structural bolts are galvanized for corrosion resistance or quenched-and-tempered in the manufacturing process. This paper adopted the finite element simulation to demonstrate discrete mechanical performance for these bolts under tensile loading conditions, the coated and uncoated numerical model has been built up for two numerical integration methods: explicit and implicit. Experimental testing and numerical methods can fully approach the failure mechanism of these bolts and their ultimate load capacities. Comparison has also been conducted for two numerical integration methods, demonstrating that the explicit integration procedure is also suitable for solving quasi-static problems. Furthermore, by using precise bolt models in T-Stub, more accurately simulate the mechanical behavior of T-Stub, which will lay the foundation of the mechanical properties of steel bolted joints.

• Steel and Composite Structures
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• 제23권1호
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• pp.115-130
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• 2017

A new type of moment-resisting bolted connection was developed for use in composite steel- concrete construction to connect composite open section steel beams to concrete filled steel square tubular columns. The connection was made possible using anchored blind bolts along with two through bolts. It was designed to act compositely with the in-situ reinforced concrete slab to achieve an enhanced stiffness and strength. The developed connection was incorporated in the design of a medium rise (five storey) commercial building which was located in low to medium seismicity regions. The lateral load resisting system for the design building consisted of moment resisting frames in two directions. A major full scale test on a sub-assembly of a perimeter moment-resisting frame of the model building was conducted to study the system behaviour incorporating the proposed connection. The behaviour of the proposed connection and its interaction with the floor slab under cyclic loading representing the earthquake events with return periods of 500 years and 2500 years was investigated. The proposed connection was categorized as semi rigid for unbraced frames based on the classification method presented in Eurocode 3. Furthermore, the proposed connection, composite with the floor slab, successfully provided adequate lateral load resistance for the model building.

• Steel and Composite Structures
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• 제38권6호
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• pp.637-656
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• 2021

The component-based method is widely used to analyze the initial stiffness of joint in steel structures. In this study, an analytical component model for determining the column face stiffness of square or rectangular hollow section (SHS/RHS) subjected to tension was established, focusing on endplate connections. Equations for calculating the stiffness of the SHS/RHS column face in bending were derived through regression analysis using numerical results obtained from a finite element model database. Because the presence of bolt holes decreased the bending stiffness of the column face, this effect was calculated using a novel plate-spring-based model through numerical analysis. The developed component model was first applied to predict the bending stiffness of the SHS column face determined through tests. Furthermore, this model was incorporated into the component-based method with other effective components, e.g., bolts under tension, to determine the tensile stiffness of the T-stub connections, which connects the SHS column, and the initial rotational stiffness of the joints. A comparison between the model predictions, test data, and numerical results confirms that the proposed model shows satisfactory accuracy in evaluating the bending stiffness of SHS column faces.