• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.71-77
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• 2016

In this study, the seismic performance of connections between filled composite beam (CG beams) and forming angle composite (FAC) column was experimentally evaluated. First, the bending tests were conducted on two CG beams and the axial tests were conducted on two FAC columns. Then, based on these preliminary test results, the cyclic loading test were performed on two interior connections between CG beam and FAC column. The main difference of two specimens is the plate shape of the CG beam. The test results showed that both specimens achieved the maximum story drift capacity over 0.04 radian which is required for special moment frame.

• Steel and Composite Structures
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• v.23 no.4
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• pp.453-464
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• 2017

The square tubed-reinforced concrete (TRC) column is a kind of special concrete-filled steel tube (CFST) columns, in which the outer thin-walled steel tube does not pass through the beam-column joint, so that the longitudinal steel reinforcing bars in the RC beam are continuous through the connection zone. However, there is a possible decrease of the axial bearing capacity at the TRC column to RC beam connection due to the discontinuity of the column tube, which is a concern to engineers. 24 connections and 7 square TRC columns were tested under axial compression. The primary parameters considered in the tests are: (1) connection location (corner, exterior and interior); (2) dimensions of RC beam cross section; (3) RC beam type (with or without horizontal haunches); (4) tube type (with or without stiffening ribs). The test results show that all specimens have relatively high load-carrying capacity and satisfactory ductility. With a proper design, the connections exhibit higher axial resistance and better ductility performance than the TRC column. The feasibility of this type of connections is verified.

• Steel and Composite Structures
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• v.26 no.3
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• pp.315-328
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• 2018

Built-up Double-I (BD-I) columns consist of two hot rolled IPE sections and two cover plates which are welded by fillet welds. In Iran, this type of column is commonly used in braced frames with simple connections and sometimes in low-rise Moment Resisting Frames (MRF) with Welded Flange Plate (WFP) beam-column detailing. To evaluate the seismic performance of WFP connection of I-beam to BD-I column, traditional and modified exterior MRF connections were tested subjected to cyclic prescribed loading of AISC. Test results indicate that the traditional connection does not achieve the intended behavior while the modified connection can moderately meet the requirements of MRF connection. The numerical models of the connections were developed in ABAQUS finite element software and validated with the test results. For this purpose, moment-rotation curves and failure modes of the tested connections were compared with the simulation results. Moreover to avoid improper failure modes, some improvements of the connections were evaluated through a numerical study.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.163-171
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• 2003

Most of existing beam-to-column connections are reinforced symmetrically because of reverse action cause by earthquake but in the weak-earthquake region like Korea connections reinforced asymmetrically can be used. Specially, the connections between CFT(Concrete Filled Tube) column and H-shape beam can be applied by simplified lower diaphragm. The tensile capacity of Combined Cross Diaphragm for upper reinforcing was tested by simple tension test and four types for lower reinforcing; Combined Cross, None, Horizontal T-bar and Vertical Plate were tested by ANSI/AISC SSPEC 2002 loading program. Horizontal T-bar and stud bolts in vertical flat bar transmit tensile stress from bottom flange of beam to filled concrete. All test specimens were satisfied 0.01 radian of inelastic rotational requirement in ordinary moment frame of AISC seismic provision. As the results of parametric studies, simplified lower diaphragms demonstrated an outstanding strength, stiffness and plastic deformation capacity to use sufficient seismic performance in the field.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.639-647
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• 2019

The performance of precast concrete structures is greatly influenced by the behaviour of beam-to-column connections. A single connection may be required to transfer several loads simultaneously so each one of those loads must be considered in the design. A good connection combines practicality and economy, which requires an understanding of several factors; including strength, serviceability, erection and economics. This research work focuses on the performance aspect of a specific type of beam-to-column connection using partly hidden corbel in precast concrete structures. In this study, the results of experimental assessment of the proposed beam-to-column connection in precast concrete frames was used. The purpose of this research is to develop and apply the Extreme Learning Machine (ELM) for moment-rotation prediction of precast beam-to-column connections. The ELM results are compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models was accessed based on simulation results and using several statistical indicators.

• Steel and Composite Structures
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• v.29 no.1
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• pp.1-22
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• 2018

Multi-storey precast concrete skeletal structures are assembled from individual prefabricated components which are erected on-site using various types of connections. In the current design of these structures, beam-to-column connections are assumed to be pin jointed. Welded plate beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is at present limited information concerning their detailed structural behaviour under bending and shear loadings. The experimental work has involved the determination of moment-rotation relationships for semi-rigid precast concrete connections in full scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and weld arrangements conformed with successful commercial practice. Proprietary hollow core slabs were tied to the beams by tensile reinforcing bars, which also provide the in-plane continuity across the connections. The strength of the connections in the double sided tests was at least 0.84 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.7 to 3.9 times the flexural stiffness of the attached beam. When the connections were tested without the floor slabs and tie steel, the reduced strength and stiffness were approximately a third and half respectively. This remarkable contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. In general, the double sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided welded plate connection test results are presented in this paper. The behaviour of single sided welded plate connection test results is the subject of another paper.

• Steel and Composite Structures
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• v.34 no.6
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• pp.803-818
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• 2020

Semi-rigid connections with blind bolts could solve the difficulty that traditional high strength bolts were unavailable to splice a steel/composite beam to a closed section column. However, insufficient investigations have focused on the performance of semi-rigid connection to square concrete filled double-skin steel tubular (CFDST) columns. In this paper, a component model was developed to evaluate the mechanical behavior of semi-rigid composite connections to CFDST columns considering the stiffness and strength of column face in compression and column web in shear which were determined by the load transfer mechanism and superstition method. Then, experimental investigations on blind bolted composite joints to square CFDST columns were conducted to validate the accuracy of the component model. Dominant failure modes of the connections were analyzed and this type of joint behaved semi-rigid manner. More importantly, strain responses of CFDST column web and tubes verified that stiffness and strength of column face in compression and column web in shear significantly affected the connection mechanical behavior owing to the hollow part of the cross-section for CFDST column. The experimental and analytical results showed that the CFDST column to steel-concrete composite beam semi-rigid joints could be employed for the assembled structures in high intensity seismic regions.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.263-266
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• 2005

Many RC structures built without seismic provisions have exhibited brittle shear failures in the beam-column joint area, and resulted in large permanent deformations and structural collapse. This paper presents the results of an experimental investigation pertaining to the use of carbon fiber-reinforced polymer(FRP) for strengthening of RC beam-column connections. The selective upgrade is obtained by choosing different combinations and locations of carbon FRP sheets to determine the effective way to improve the structural performance of joints. Experimental results demonstrate significant improvement of flexural capacity and ductility of beam-column connections originally built without seismic details.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.663-670
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• 2007

Column-tree beam-to-column joints are widely used in moment-resisting frames in Korea. In this study, we proposed four different arrangements for weak-axis moment-resisting beam-to-column connections, which are more economical than the conventional connection, while developing similar structural performance. We investigated the proposed connections whose connection details were different from the conventional one. The experiment was also conducted on a total of five beam-to-column joint specimensto verify the structural performance of the proposed connections. All four connections proposed in this study were found to be more economical that the conventional connection. Three out of four specimens with proposed details were able to developa structural performance similar to that of the specimen with the conventional detail.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.45-52
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• 2017

The precast concrete (PC) method has many advantages in fast construction, quality control, etc. In domestic construction market, however, its application has been quite limited because of the concerns about structural integrity and seismic performances due to the discrete connections between precast concrete members. By applying the post-tensioning method, the precast beam-column connection can be well tightened, allowing improved structural integrity, and proper seismic performances can be also achieved. In this study, reversed cyclic tests have been conducted on the beam-column connection specimens, where the test variables included the compressive strength of grouting mortar and the tensile strengths of prestressing strands, based on which their seismic performances have been examined in detail. The post-tensioned PC beam-column connections showed good seismic performances comparable to that of the monolithic reinforced concrete connection specimen. When 2400 MPa prestressing strands are applied to the beam-column connection, it is preferable to adjust the prestress level similar to that applied for the 1860 MPa prestressing strands to avoid premature local crushing failures at the beam-column connections.