• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.74-80
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• 2008

This paper evaluates seismic capacities of slab-column joints in flat plate system which has columns with various aspect ratio as experimental parameters. Continuous - bended shear reinforcements were applied for the prevention of punching shear failure in this study. The specimens of FIS1-05, FIS1-10, and FIS1-20 have the aspect ratio of 0.5, 1.0, and 2.0 respectively. Static lateral force was applied to the specimens in a horizontal direction and vertical load was applied by constant gravity load ratio. The test results were evaluated by lateral displacement and strength of slab-column joint. Consequently, the lateral resisting capacity of rectangular type column such as FIS1-05, FIS1-20 is superior to the square type column such as FIS1-10.

• Journal of Korean Society of Steel Construction
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• v.26 no.1
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• pp.43-53
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• 2014

A single plate connection(SPC) consists of a plate welded to the columns and bolts connected to the beam web. The SPC is widely used for a simple shear connection of steel structure because it is easy-to-fabricated, easy-to-installed and economical. The conventional SPC is used for 2 to 12 bolts in a single vertical row. It is designed to limit the plate thickness by bolt diameter to obtain flexible and ductile connections. The design strength for eccentric shear shall be the lesser of the shear strength of bolts or bearing strength of plate and when the design strength is decided by edge distance failure, the results can be very conservative. Although the research on special solution for 'weak-plate/strong-bolt' model with 2 to 4 bolts has been conducted by L. S. Muir, and W. A. Thonton, 2004, study on generalized design procedures did not conduct. This study proposed design procedure for evaluation of the design strength of eccentric shear bolt groups on a single plate connection based on the actual edge distance and the direction of bolt reaction forces by using elastic vector method(EVM) and instantaneous center of rotation method(ICM).

• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.95-98
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• 1992

In large panel structures, the design of joints which interconnect panels, is important deciding the load-bearing capacity of structures. Being various factors in the design of joints, it is difficult to develop a the critical system for the structural analysis of large concrete panel structures. Therefore there is a tendency to depend on the experiment. The purpose of this paper is to investigate the strength and the mechanical behavior of vertical joints in large concrete panel structures.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.185-193
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• 2012

In this study, an estimation equation was proposed to predict the shear strength of RC interior beam-column connections. The proposed equation considered the effect of both truss and arch mechanisms, while the existing equations in the ACI and AIJ design codes consider only arch mechanism. In addition, the proposed equation estimates the shear strength of RC joints by considering the contribution of the vertical and horizontal steel bars on the effective compressive strength of concrete. The shear strength of RC joints calculated by the proposed equation was compared with the test results of 54 RC joints, which failed in shear before plastic hinges developed at the end of the adjacent beams. The comparison study showed that the proposed equation estimated the strength of the 54 specimens with a mean value of 1.14 and the coefficient of variation of 20%. The proposed equation provides improved prediction compared to those obtained from the equations in the ACI and AIJ design codes.

• Computational Structural Engineering
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• v.9 no.2
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• pp.93-101
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• 1996

An artificial neural network is a computational model that mimics the biological system of the brain and it consists of a number of interconnected processing units where it can reasonably infer by them. Because the neural network is particularly useful for evaluating systems with a multitude of nonlinear variables, it can be used in experimental results predictions, in structural planning and in optimum design of structures. This paper describes the basic theory related to the neural networks and discusses the applicability of neural networks to predict the ultimate shear capacity of the precast concrete vertical joints by comparing the neural networks with a conventional method such as regression.

• Journal of Korean Society of Steel Construction
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• v.15 no.5 s.66
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• pp.579-589
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• 2003

Most beam-to-column connections are symmetrically reinforced because of the reverse action caused by earthquakes. However, in weak-earthquake regions like Korea, asymmetrically reinforced connections could be used. In particular, the connections between concrete-filled tube (CFT) column and H-shape beam could be applied using a simplified lower diaphragm. The tensile capacity or Combined Cross Diaphragm for upper reinforcing was tested using a simple tension test. Four types for lower reinforcing combined Cross, none, horizontal T-bar, and vertical plate were tested using the ANSI/AISC SSPEC 2002 loading program. Horizontal T-bar and stud bolts in vertical flat, bar transmit tensile stress from the beam's bottom flange to filled concrete. All test specimens satisfied 0.01 radian inelastic rotational requirement in ordinary moment frame of AISC seismic provision. According to the results of the parametric studies simplified lower diaphragms demonstrated outstanding strength, stiffness, and plastic deformation capacity which could lead to more sufficient seismic performance in the field.

• Korean Journal of Materials Research
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• v.11 no.7
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• pp.556-561
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• 2001

We prepared a new a SOS(silicon-on-silicide) wafer pair which is consisted of Si(100)/1000$\AA$-NiSi Si (100) layers. SOS can be employed in MEMS(micro- electronic-mechanical system) application due to low resistance of the NiSi layer. A thermally evaporated $1000\AA$-thick Ni/Si wafer and a clean Si wafer were pre-mated in the class 100 clean room, then annealed at $300~900^{\circ}C$ for 15hrs to induce silicidation reaction. SOS wafer pairs were investigated by a IR camera to measure bonded area and probed by a SEM(scanning electron microscope) and TEM(transmission electron microscope) to observe cross-sectional view of Si/NiSi. IR camera observation showed that the annealed SOS wafer pairs have over 52% bonded area in all temperature region except silicidation phase transition temperature. By probing cross-sectional view with SEM of magnification of 30,000, we found that $1000\AA$-thick uniform NiSi layer was formed at the center area of bonded wafers without void defects. However we observed debonded area at the edge area of wafers. Through TEM observation, we found that $10-20\AA$ thick amourphous layer formed between Si surface and NiSix near the counter part of SOS. This layer may be an oxide layer and lead to degradation of bonding. At the edge area of wafers, that amorphous layer was formed even to thickness of $1500\AA$ during annealing. Therefore, to increase bonding area of Si NiSi ∥ Si wafer pairs, we may lessen the amorphous layers.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.151-158
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• 2019

A concrete core is used widely as lateral stability systems in high-rise modular buildings. As an alternative to traditional cast in-situ core, the precast concrete(PC) method can accelerate the construction of reinforced concrete cores. A core composed of precast elements differs from a in-situ core in having connections between the precast elements. The typical vertical connection between PC panels is consisted of shear keys, loop bars, lacer bars and grout. In this study, the effect of vertical connection components on shear strength is investigated experimentally. The test results show that the contribution to the shear strength is greater in order of grout strength, shear keys, lacer bars and loop bars. In addition, the numerical models to estimate the shear strength according to two crack patterns in the vertical joint of the PC panels are derived. The feasibility of the numerical models is evaluated by comparing the estimated shear strength and the test results.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.585-593
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• 2010

On the basis of the strain-based shear strength model developed in the previous study, a strength model was developed to predict the direct punching shear capacity and unbalanced moment-carrying capacity of interior and exterior slab-column connections. Since the connections are severely damaged by flexural cracking, punching shear was assumed to be resisted mainly by the compression zone of the slab critical section. Considering the interaction with the compressive normal stress developed by the flexural moment, the shear strength of the compression zone was derived on the basis of the material failure criteria of concrete subjected to multiple stresses. As a result, shear capacity of the critical section was defined according to the degree of flexural damage. Since the exterior slab-column connections have unsymmertical critical sections, the unbalanced moment-carrying capacity was defined according to the direction of unbalanced moment. The proposed strength model was applied to existing test specimens. The results showed that the proposed method predicted the strengths of the test specimens better than current design methods.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.3
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• pp.173-182
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• 2013

The building design projects which are being proceeded nowadays pursue a complex and various shape of structures, escaping from the traditional and regular shape of buildings. In this new trend of the architecture, there rises a demand of the research in the structural engineering for the effective realization of such complex-shaped buildings which disassembles the orthogonality of frames. As a distinguished characteristics of the buildings in a complex-shape, there frequently are inclined columns included in the structural frame. The inclined column causes extra axial force and bending moment at the beam-column connection so it is necessary to assess those effects on the structural behavior of the frame and the connection by experiment or analysis. However, with comparing to the studies on the normal beam-column connections, the inclined column connections have not been studied sufficiently. Therefore, this study evaluated the beam-column connections having an inclined column using nonlinear and finite element analysis method. In this paper, steel moment frames having inclined columns were analyzed by the nonlinear pushover analysis to check the global behavior and beam-column connection models were analyzed by the finite element analysis to check the buckling behavior and the fracture potentials.