• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.1-4
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• 2009

Construction automation and robotics are being introduced as an efficient alternative to overcome troubles caused by lack of skilled labors. To accomplish effective automated construction system, design for automation(DFA) should be performed in parallel with the development of core technologies such as control and sensing of robots. In Korea, the development of robotic crane-based construction automation(RCA) system is progressing, and the research group has recently developed newly designed steel joint to improve the efficiency of the system. However, performance of the new system should be examined prior to its application on construction sites. Therefore, This study analyzed performance of the new steel frame focused on its constructibility by carrying out mock-up test. As a result, the steel frame satisfied the standards of allowable stress and deflection. It also enables to reduce the time for installation.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.31-37
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• 2002

Recently a simplified design procedure as well as load transfer model for seismic steel moment connections with welded straight haunch have been proposed by Lee and Uang. Cyclic seismic testing was conducted to verify the proposed design procedure and to develop the details that will prevent the cracking at the haunch tip, where stress concentration was the highest. All the specimens thus designed effectively pushed plastic hinging away from the haunch tip and were able to develop satisfactory plastic rotation capacity of 0.04 radian with no fracture. A sloped edge combined with drilling a hole near the haunch tip or a pair of stiffeners(partially or fully) extended from the beam web successfully prevented the crack initiation at the haunch tip. The strut action of the haunch web, which had been predicted from the previous analytical study, was also experimentally identified through the strain gage readings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.127-135
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• 2019

The seismic performance of non-ductile reinforced concrete (RC) frame retrofitted with H-beam frame and cast expansive mortar into joint between existing RC frame and H-beam frame is investigated experimentally and analytically. RC frames considered in the study contain non-ductile reinforcement details of low-rise school building constructed in Korea before 1988. The tests were conducted on half-scale specimens simulating the lower frame assemblages of a typical school building. Two one-bay, one-story RC frames with and without retrofitting with H-beam frame and expansive joint mortar were tested to failure. Test and analysis results indicated that seismic strengthening using H-beam and expansive joint mortar significantly improved the lateral strength and stiffness of non-ductile RC frame without installing anchor bolts to fit H-beam frame into existing RC frame. The effectiveness of seismic strengthening technology proposed in the study for non-ductile RC frame was verified experimentally and analytically.

• 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.11 no.4 s.41
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• pp.385-395
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• 1999

Square hollow section columns and H-section beams have recently been increasing1y used. Rigid column-beam connections cannot be made for the structural system and thus some measures to improve the rotational stiffness of connections should be developed. For this purpose, several types of connections. such as H-section beams connected to concrete-filled square hollow section columns, have been contrived and put to experiment. Since the experimental works are usually difficult and expensive. Particularly test of all the types of connections with similar behavior may not be feasible. Instead, the numerical analysis will be adopted predict the flexural stiffness of connections. In this work, FEM modeling techniques are examined and parametric analysis study has been carried out. The major parameters considered are concrete strength, thickness of steel column, magnitude and eccentricity of axial forces.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.1-12
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• 2019

The purpose of this study is to enhance the seismic performance of exposed column-base plate weak-axis connections for small-sized steel buildings. According to the site inspection for the small-sized building construction, the arbitrary connection details in steel buildings have been applied at the job site, which is considered to be insufficient to guarantee structural safety and stability considering the increased seismic risk in Korea. Therefore, a series of test programs had been done to develop enhanced connection details in order to ensue the adequate seismic stability and safety of small-sized steel buildings. From the test results, It was found that the exposed column-base plate weak-axis connections commonly used in Korea shows very poor seismic behavior due to the "Rocking" phenomena caused by the residual plastic deformation of anchor bolts between anchor plate and concrete. A series of hysteretic tests for finding that solution were conducted to reduce the "Rocking" phenomena of the column-base plate connections, and local buckling of webs in H-column. Finally the enhanced stable seismic behavior was obtained by reinforcing at least 8 anchor bolts with good bonding strength and stiffeners to the webs in H-column.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.683-691
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• 2003

Recently, the steel has been increaseingly used as an integrated part of high-rise buildings, which often composed of steel structures, steel reinforced concrete structures and composite structures. The steel base is designed to transfer the stresses induced from steel column to the reinforced concrete footing through the base plate. However, in the design of steel structures and steel reinforced concrete structure, it is generally difficult to evaluate the bearing strength of the steel base subjected to large axial force. Furthermore, the material used in steel base is quite different from those used in other connections and a load transferring mechanism of steel base is very complicated in nature. Therefore, a special attention must be placed in design and construction of steel base. In generally, the bearing strength test and research of the steel base subjected to concentrated load are carried out. But, in the design of the structures, uniaxial eccentric load is loaded to the steel base of the steel structures. In this research, the bearing strength and the me of failure considering eccentric loads and eccentric length, were experimented when eccentric load is loaded to the steel base of steel structures. Based on the test results, a basic design reference is suggested for a reasonable design of steel structures, steel reinforced concrete structures and composite structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.67-76
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• 2006

In this paper the moment transfer efficiency of a web and the strain concentration at the RHS (Rectangular Hollow Section) column-to-steel beam connections was evaluated. Initially, non-linear finite element analysis of five bare steel beam models was conducted. The models were designed to have different detail at their beam-to-column connection, so that the flexural moment capacity was different respectively. Analysis results showed that the moment transfer efficiency of the analytical model with RHS-column was poor when comparing to model with WF(Wide Flnage)-column due to out-of-plane deformation of the RHS-column flange. The presence of scallop and thin plate of RHS column was also a reason of the decrease of moment transfer efficiency, which would result in a potential fracture of the steel beam-to-column connections. Analytical results were compared with the previous experimental results. The analytical and the previous experimental results showed that the strain concentration was inversely proportional to the moment transfer efficiency of a beam web and the deformation capacity of connection was poor as their moment transfer efficiency degrades. Further finite element analyses of composite beam with a floor slab revealed that the neutral axis moved toward the top flange and the moment transfer efficiency of a beam web decreased, which led to premature failure of the connection.

• 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.