• Steel and Composite Structures
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• v.38 no.5
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• pp.547-562
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• 2021

This paper aims to explore the mechanical behavior and moment-rotation model of blind bolted joints between concrete-filled double skin steel tubular columns and steel-concrete composite beams. For this type of joint, the inner tube and sandwiched concrete were additionally identified as basic components compared with CFST blind bolted joint. A modified moment-rotation model for this type of connection was developed, of which the compatibility condition and mechanical equilibrium were employed to determine the internal forces of basic components and neutral axis. Following this, load transfer mechanism among the inner tube, sandwiched concrete and outer tube was discussed to assert the action area of the components. Subsequently, assembly processes of basic coefficients in terms of their stiffness and resistances based on the component method by simplifying them as assemblages of springs in series or in parallel. Finally, an experimental investigation on four substructure joints with CFDST columns for validation purposes was carried out to capture the connection details. The predicted results derived from the mechanical models coincided well with the experimental results. It is demonstrated that the proposed mechanical model is capable of evaluating the complete moment-rotation relationships of blind bolted CFDST column composite connections.

• Steel and Composite Structures
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• v.28 no.6
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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.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.689-697
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• 2005

Recent test results on reduced beam section (RBS) steel moment connections show that specimens with a bolted web connection tend to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. A review of previous test results indicates that the higher incidence of base metal fracture in bolted-web specimens is related, at least in part, to the web bolt slippage and the high stress concentration at the weld access hole with the lowest material toughness. The practice of providing web bolts uniformly along the beam depth based on the classical beam theory is questioned in this paper. A new seismic design procedure, which is more consistent with the actual load path identified from the analytical and experimental studies, is proposed together with improved connection details. A test specimen designed following the proposed procedure exhibited a cyclic connection rotation capacity sufficient for special moment frames without fracture.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.221-230
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• 2003

Employing classical beam theory for the design of RBS seismic steel moment connections was brought into question in this study, Both the experimental strain data and analytical results from the calibrated finite element analysis confirmed that the shear transfer mechanism in the RBS connection is completely different from that as predicted by classical beam theory Plausible explanations of a higher incidence of brittle fractures observed in the specimens with bolted-webs were presented. It was pointed out that the practice of providing web bolts uniformly along the beam depth is not consistent with the load path identified by both experimental and analytical results. More rational bolted-web details were proposed based on the identified principal load path,.

• Structural Engineering and Mechanics
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• v.89 no.2
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• pp.155-170
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• 2024

Several types of column-beam connections are used in the design of steel structures. This situation causes different cross-section effects and, therefore, different displacements and deformations. In other words, connection elements such as welds, bolts, continuity plates, end plates, and stiffness plates used in steel column-beam connections directly affect the section effects. This matter reveals the necessity of knowing the steel column-beam connection behaviours. In this article, behaviours of bolted column-beam connection with end plate widely used in steel structures are investigated comparatively the effects of the stiffness plates added to the beam body, the change in the end plate thickness and bolt diameter. The results obtained reveal that the moment and force carrying capacity of the said connection increases with the increase in the end plate thickness and bolt diameter. In contrast, it causes the other elements to deform and lose their capacity. This matter shows that optimum dimensions are very important in steel column-beam connections. In addition, it has been seen that adding a stiffness plate to the beam body part positively contributes to the connection's moment-carrying capacity.

• Structural Engineering and Mechanics
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• v.68 no.5
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• pp.591-601
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• 2018

Non-moment beam-to-column connections, which are usually referred to as simple or shear connections, are typically designed to carry only gravity loads in the form of vertical shears. Although in the analysis of structures these connections are usually assumed to be pinned, they may provide a small amount of rotational stiffness due to the typical connection details. This paper investigates the effects of this small rotational restraint of simple beam-to-column connections on the behavior and seismic response of steel braced non-moment resisting frames. Two types of commonly used simple connections with bolted angles, i.e., the Double Web angle Connection (DWC) and Unstiffened Seat angle Connection (USC) are considered for this purpose. In addition to the pinned condition - as a simplified representation of these connections - more accurate semi-rigid models are established and then applied to some frame models subjected to nonlinear pushover and nonlinear time history analyses. Although the use of bracing elements generally reduces the sensitivity of the global structural response to the behavior of connections, the obtained results indicate considerable effects on the local responses. Namely, our results show that consideration of the real behavior of connections is essential in designing the column elements where the pin-connection assumption significantly underestimates design of outer columns of upper stories.

• Steel and Composite Structures
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• v.23 no.1
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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.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.789-799
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• 1998

The purpose of this study is to propose the prototypes of bolted end plate moment connection between CFT column and H-beam sections. Nine different types of bolt are designed in this study. The shapes of those bolt are straight. bent, hooked or stud-type. The end plate moment connection between CFT column and H-beam sections which are jointed by those bolts are studied experimentally to compare their performances. The simple beam bending tests are carried out to investigate the structural behavior of beam-to-column connections. The experimental results show that some of the bolted end plate connection types have quite good performance in the structural behavior but still have a lot of week points to be solved for the efficiency of construction.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.87-96
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• 2004

Recent test results on reduced beam section (RBS) steel moment connections showed that specimens with a bolted web tended to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. The measured strain data appeared to imply that a higher incidence of base metal fracture in bolted-web specimens is related to, at least in part, the increased demand on the beam flanges due to the web bolt slippage and the actual load transfer mechanism which is completely different from that usually assumed in connection design. In this paper, the practice of providing web bolts uniformly along the beam depth was brought into question. A new seismic design procedure, which is more consistent with the actual load path identified from the analytical and experimental studies, was proposed together with improved connection details.

• International journal of steel structures
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• v.18 no.5
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• pp.1639-1653
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• 2018

Bolted connections are suitable due to high quality prefabrication in the factory and erection in the workplace. Prefabrication and modularization cause high speed of erection and fabrication, high quality and quick return of investment. Their technical hitches transportation can be removed by prefabrication of joints and small fabrication of components. Box-columns are suitable members for bolted structures such as welded steel structures with moment frames in two directions etc., but their continual fabrication in multi-story buildings and performing the internal continuity plate in them will cause some practical dilemmas. The details of the proposal technique introduced here, is to remove such problems from the box columns. Besides, some other advantages include new prefabricated bolted beam-to-column connections referred to BBCC. This connection is a set of plates joined to columns, beams, support, and bolts. For a better understanding of its fabrication and erection techniques, two connection and one structural maquettes are made. The present work aims to study the cyclic behavior of connection numerically. To verify the accuracy of model, a similar tested connection was modelled. Its verification was then made through comparison with test results. The behavior of connection was evaluated for an exterior connection using three different support shapes. The effects of support shapes on rigidity, ductility, rotation capacity, maximum strength, four rad rotation strength were compared to those of the AISC seismic provision requirements. It was found that single beams support has all the AISC seismic provision requirements for special moment frames with and without a continuity plate, and box with continuity plate is the best support in the BBCC connection.