• Journal of Korean Society of Steel Construction
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• v.15 no.5 s.66
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• pp.551-559
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• 2003

In steel frames, the analysis and design techniques are based on either idealized fixed or pinned connections. In this case, it has the advantage that the structural analysis and the design procedure were simplified, but there could be given different results of analysis between the real steel frame connections and the idealized fixed and pinned connection. This is because the real connections would be analyzed by semi-rigid, and have some transfer of moment and rotational constraint about the loads. In this study, structural analysis program with considered connections that have joint rigidity of fixed, pinned and semi-rigid, was developed. Then, the effects of joint rigidity on strength and displacement. in steel frames subjected to lateral forces and axial forces, were investigate, and the results were compared with those of the Midas Gen. w program.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.291-301
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• 1998

This paper is a study on the structural behavior of CFCT(Concrete-Filled Circular Tubular) column to H-beam connections with longitudinal rib. The important parameters are being longitudinal rib or not. variable column thickness(5.8mm. 9.2mm. 12.0mm. 15.0mm) around the joint between CFCT and H-beam and the width of flange to diameter. Test results are summarized for the strength, initial stiffness, failure mode and energy absorption capacities of each specimen. These are compared with the theoretical results(Yield line theory, numerical analysis). Therefore, the purpose of this paper is to investigate the stiffness and the strength of connections to evaluate the structural behavior of the CFCT column to H-beam connections with longitudinal rib.

• Earthquakes and Structures
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• v.10 no.6
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• pp.1467-1486
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• 2016

This research focuses on seismic performance of a class of single pier skewed bridges with three different pier-deck connections; skew angles vary from $0^{\circ}$ to $60^{\circ}$. A well-documented four span continuous deck bridge has been modeled and verified. Seat-type connections with fixed and sliding bearings plus monolithic pier-deck connections are studied. Shear keys are considered either fully operational or ineffective. Seismic performances of the bridges and the structural components are investigated conducting bidirectional nonlinear time history analysis in OpenSees. Several global and intermediate engineering demand parameters (EDP) have been studied. On the basis of results, the values of demand parameters of skewed bridges, such as displacement and rotation of the deck plus plastic deformation and torsional demand of the piers, increase as the skew angle increases. In order to eliminate the deck collapse probability, the threshold skew angle is considered as $30^{\circ}$ in seat-type bridges. For bridges with skew angles greater than $30^{\circ}$, monolithic pier-deck connections should be applied. The functionality of shear keys is critical in preventing large displacements in the bearings. Pinned piers experience considerable ductility demand at the bottom.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.435-438
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• 2005

The use of new hybrid systems that combine the advantages of steel and reinforced concrete structures has gained popularity. One of these new mixed systems consists of steel beams and reinforced concrete shear wall, which represents a cost- and time-effective type of construction. A number of previous studies have focused on examining the seismic response of steel coupling beams in a hybrid wall system. However, the shear transfer of steel coupling beam-wall connections with panel shear failure has not been thoroughly investigated. The objective of this research was to investigate the seismic performance of steel coupling beamwall connections governed by panel shear failure. To evaluate the contribution of each mechanism, depending upon connection details, an experimental study was carried out The test variables included the reinforcement details that confer a ductile behaviour on the steel coupling beam-wall connection, i.e., the face bearing plates and the horizontal ties in the panel region of steel coupling beam-wall connections. It investigates the seismic behaviour of the steel coupling beams-wall connections in terms of the deformation characteristics. The results and discussion presented in this paper provide background for a companion paper that includes a design model for calculating panel shear strength of the steel coupling beam-wall connections.

• Structural Engineering and Mechanics
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• v.59 no.2
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• pp.209-226
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• 2016

Integral bridges are typically designed with flexible foundations that include one row of piles. The construction of integral bridges solves difficulties due to the maintenance of expansion joints and bearings during serviceability. It causes integral bridges to become more economic comparing with conventional bridges. Research has been focused not only to enhance the seismic performance of newly designed bridges, but also to develop retrofit strategies for existing ones. The local performance of the pile to abutment connection will have a major effect on the performance of the structure and the embedment length of pile inside the abutment has a key role to provide shear and flexural resistance of pile-abutment connections. In this paper, a simple method was developed to estimate the initial value of embedment length of the pile for retrofitting of specimens. Four specimens of pile-abutment connections were constructed with different embedment lengths of pile inside the abutment to evaluate their performances. The results of the experimentation in conjunction with numerical and analytical studies showed that retrofitting pile-abutment connections with CFRP wraps increased the strength of the connection up to 86%. Also, designed connections with the proposed method had sufficient resistance against lateral load.

• Steel and Composite Structures
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• v.11 no.4
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• pp.291-305
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• 2011

The new structure consisting of continuous compound spiral hoop reinforced concrete (CCSHRC)column and steel concrete composite (SCC) beam has both the advantages of steel structures and concrete structures. Two types of beam-to-column connections applied in this structural system are presented in this paper. The connection details are as follows: the main bars in beam concrete pass through the core zone for both types of connections. For connecting bar connection, the steel I-beam webs are connected by bolts to a steel plate passing through the joint while the top and bottom flanges of the beams are connected by four straight and two X-shaped bars. For bolted end-plate connection, the steel I-beam webs are connected by stiffened extended end-plates and eight long shank bolts passing through the core zone. In order to study the seismic behaviour and failure mechanisms of the connections, quasi-static tests were conducted on both types of full-scale connection subassemblies and core zone specimens. The load-drift hysteresis loops show a plateau for the connecting bar connection while they are excellent plump for bolted end-plate connection. The shear capacity formulas of both types of connections are presented and the values calculated by the formula agree well with the test results.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.3
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• pp.249-255
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• 2017

This paper presents air-gap control according to Y and Delta connections of a double-sided air-gap permanent magnet synchronous motor (DA-PMSM) with independent three-phase structure. In particular, the DA-PMSM used in this study can be applied to low-speed and high-torque applications, such as wind turbines, tidal power generations, and electric propulsion ships, because of its modular stators and a rotor with numerous permanent magnets. Unlike conventional three-phase machines, the DA-PMSM has a symmetrical configuration with double-sided air-gap. Therefore, Y/Delta winding connections and serial/parallel configurations between stator modules are possible. To identify the DA-PMSM operating characteristics, mathematical modeling is analyzed according to the Y/Delta connections. Moreover, air-gap control performances by applying the winding connection methods are verified through experimental results.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.529-537
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• 2008

The objective of this paper is to propose retrofit design methods of theRHS column-to-H beam connections with floor slabs. Referring to previous studies on the retrofitting of moment connections, it is clear that connections retrofitted with a stiffened RBS (SR) or a lengthened horizontal stiffener (LH) has an effect on decreasing the stress/strain concentration. A new design procedure using these two retrofitting methods was thus presented. In addition, this paper addressed various design or detailing options and recommended a procedure for designing the improved retrofitting method of steel moment connections. Finally, a pilot test was conducted to verify the design procedure.

• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.343-362
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• 2018

A simplified spring connection modelling approach for steel flush endplate beam-to-column connections in fire has been developed to enable realistic behaviour of connections to be incorporated into full-scale frame analyses at elevated temperature. Due to its simplicity and reliability, the proposed approach permits full-scale high-temperature frame analysis to be conducted without high computational cost. The proposed simplified spring connection modelling approach has been used to investigate the influence of connection ductility (both axial and rotational) on frame behaviour in fire. 2D steel and 3D composite frames with a range of beam spans were modelled to aid the understanding of the differences in frame response in fire where the beam-to-column connections have different axial and rotational ductility assumptions. The modelling results highlight that adopting the conventional rigid or pinned connection assumptions does not permit the axial forces acting on the connections to be accurately predicted, since the axial ductility of the connection is completely neglected when the rotational ductility is either fully restrained or free. By accounting for realistic axial and rotational ductilities of beam-to-column connections, the frame response in fire can be predicted more accurately, which is advantageous in performance-based structural fire engineering design.

• Structural Engineering and Mechanics
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• v.72 no.3
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• pp.367-382
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• 2019

This paper presents experimental and analytical investigations on additional fixed-end rotations resulting from the strain penetration of high-strength reinforcement in reinforced concrete (RC) beam-column connections under monotonic loading. The experimental part included the test of 18 interior beam-column connections with straight long steel bars and 24 exterior beam-column connections with hooked and headed steel bars. Rebar strains along the anchorage length were recorded at the yielding and ultimate states. Furthermore, a numerical program was developed to study the effect of strain penetration in beam-column connections. The numerical results showed good agreement with the test results. Finally, 87 simulated specimens were designed with various parameters based on the test specimens. The effect of concrete compressive strength ($f_c$), yield strength ($f_y$), diameter ($d_b$), and anchorage length ($l_{ah}$) of the reinforcement in the beam-column connection was examined through a parametric study. The results indicated that additional fixed-end rotations increased with a decrease in $f_c$ and an increase in $f_y$, $d_b$ and $l_{ah}$. Moreover, the growth rate of additional fixed-end rotations at the yielding state was faster than that at the ultimate state when high-strength steel bars were used.