• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.135-142
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• 2014

In paper after the strong earthquake of recently the Korea neighborhood, the Korean government survey show that the 86% of school buildings in Korea are in potential damage risk and only 14% of them are designed as earthquake-resistance buildings. Earthquake Reinforcing projects of school have been a leading by the ministry of education, however their reinforcing methods done by not proved a engineering by experiment which results in uneconomical and uneffective rehabilitation for the future earthquake. An experimental and analytical study have been conducted for the shear reinforcing method of RC beam by axis and horizontal axis load using attaching composite beam. Based on the previous research, in this study, design examples are given to show the performance evaluation for the column reinforcing of old school buildings using nonlinear analysis is going to be conducted and strengthening method is going to be on the market after their performance is proved by the test.

• Journal of Conservation Science
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• v.20
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• pp.43-54
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• 2007

The Muryangsa temple five-storied stone pagoda (Treasure No. 185) was geographically located in the area of the Baekje Kingdom. The architectural style of the Muryangsa temple five-storied stone pagoda is the pagoda at the early Goryeo Dynasty that was succeeded technique of the Baekje Kingdom and form of the Shilla Kingdom. Because this pagoda is located outside during old time that it received serious petrological and biological weathering in rock blocks and occurred the center subsidence in the upper capstone. This study executed ground stability interpretation in order to know what central subsidence in the upper capstone occurred for soft ground. The ground stability interpretation used seismic survey, electrical resistivity survey and GPR survey by non-destructive method. As the result, the ground appeared in the condition which is good. Specially, high resistance zone appeared from electric resistivity survey which come to seem with ground reinforcement harden. Consequently, central subsidence condition in the upper capstone is not by the instability of ground, and is judged with the thing by the structure instability in rock blocks over the upper capstone. This will be applied basic data with the long-term monitoring or preservation countermeasure of the pagoda.

• Computers and Concrete
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• v.22 no.3
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• pp.279-289
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• 2018

Shear walls are one of the important structural elements for bearing loads imposed on buildings due to winds and earthquakes. Composite shear walls with high lateral resistance, and high energy dissipation capacity are considered as a lateral load system in such buildings. In this paper, a composite shear wall consisting of steel faceplates, infill concrete and tie bars which tied steel faceplates together, and concrete filled steel tubular (CFST) as boundary columns, was modeled numerically. Test results were compared with the existing experimental results in order to validate the proposed numerical model. Then, the effects of some parameters on the behavior of the composite shear wall were studied; so, the diameter and spacing of tie bars, thickness and compressive strength of infill concrete, thickness of steel faceplates, and the effect of strengthening the bottom region of the wall were considered. The seismic behavior of the modeled composite shear wall was evaluated in terms of stiffness, ductility, lateral strength, and energy dissipation capacity. The results of the study showed that the diameter of tie bars had a trivial effect on the performance of the composite shear wall, but increasing the tie bars spacing decreased ductility. Studying the effect of infill concrete thickness, concrete compressive strength, and thickness of steel faceplates also showed that the main role of infill concrete was to prevent buckling of steel faceplates. Also, by strengthening the bottom region of the wall, as long as the strengthened part did not provide a support performance for the upper part, the behavior of the composite shear wall was improved; otherwise, ductility of the wall could be reduced severely.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.375-384
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• 2009

The application of the diagrid structural system has increased of late, but cyclic loadings such as winds and earthquakes cannot be fully understood through only an analytical study due to the difficulty of considering its welding property. In this study, diagrid nodes that had been scaled down to 1/5 of their full sizes were tested to find out their structural behavior under seismic or wind loads. Four specimens were used with five parameters, including the welding method and the design details. Cyclic loading tests were carried out, where a tensile load was applied to one brace member and a compression load to the other. The major failure modes in the tests were only failure of bending with tensile stress and tension failure. The welding method and the design details had no effect on the initial stiffness and yielding stress but play a significant role in the failure mode and energy dissipation, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.113-116
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• 2008

In recent the construction of bridges having hollow sectional piers is gradually increasing since the hollow section is more effective than solid section in resistance against seismic load. It is, therefore, very important to understand the behavior of columns with hollow sections in seismic design. However, many past researches were concentrated only on the flexural deformability of them. In this study the shear characteristics of them have been studied with scale model tests. 7 models having different void and aspect ratios were designed and tested to investigate the effect of them on shear capacities. And then the validity of empirical equations to predict shear capacity was investigated compared with the test results. The test result 80 percent of the valid area of cross section should be adequate. And compared to the proposed four model the experimental shear capacities are in good agreement with the UCB.

• Structural Engineering and Mechanics
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• v.57 no.3
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• pp.507-528
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• 2016

Reduced beam section (RBS) moment resisting connections are among the most economical and practical rigid steel connections developed in the aftermath of the 1994 Northridge and the 1995 Kobe earthquakes. Although the performance of RBS connection has been widely studied, this connection has not been subject to in the skewed conditions. In this study, the seismic performance of dogbone connection was investigated at different angles. The Commercial ABAQUS software was used to simulate the samples. The numerical results are first compared with experimental results to verify the accuracy. Nonlinear static analysis with von Mises yield criterion materials and the finite elements method were used to analyze the behavior of the samples The selected Hardening Strain of materials at cyclic loading and monotonic loading were kinematics and isotropic respectively The results show that in addition to reverse twisting of columns, change in beam angle relative to the central axis of the column has little impact on hysteresis response of samples. Any increase in the angle, leads to increased non-elastic resistance. As for Weak panel zone, with increase of the angle between the beam and the column, the initial submission will take place at a later time and at a larger rotation angle in the panel zone and this represents reduced amount of perpendicular force exerted on the column flange. In balanced and strong panel zones, with increase in the angle between the beam and the central axis of the column, the reduced beam section (RBS), reaches the failure limit faster and at a lower rotation angle. In connection of skewed beam, balanced panel zone, due to its good performance in disposition of plasticity process away from connection points and high energy absorption, is the best choice for panel zone. The ratio of maximum moment developed on the column was found to be within 0.84 to 1 plastic anchor point, which shows prevention of brittle fracture in connections.

• Steel and Composite Structures
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• v.21 no.4
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• pp.687-702
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• 2016

There are many studies in the literature conducted on the subject of ensuring earthquake safety of reinforced concrete and steel structures using steel braced frames, but no detailed study concerning individual behavior of steel braced frames under earthquake loads and strengthening of reinforced concrete structures with out-of-plane steel braced frames has been encountered. In this study, in order to evaluate behaviors of "Concentrically Steel Braced Frames" types defined in TEC-2007 under lateral loads, dimensional analysis of Concentrically Steel Braced Frames designed with different scales and dimensions was conducted, the results were controlled according to TEC-2007, and after conducting static pushover analysis, behavior and load capacity of the Concentrically Steel Braced Frames and hinges sequence of the elements constituting the Concentrically Steel Braced Frames were tested. Concentrically Steel Braced Frames that were tested analytically consist of 2 storey and one bay, and are formed as two groups with the scales 1/2 and 1/3. In the study, Concentrically Steel Braced Frames described in TEC-2007 were designed, which are 7 types in total being non-braced, X-braced, V- braced, $\wedge$- braced, $\backslash$- braced, /- braced and K- braced. Furthermore, in order to verify accuracy of the analytic studies performed, the 1/2 scaled concentrically steel X-braced frame test element made up of box profiles and 1/3 scaled reinforced concrete frame with insufficient earthquake resistance were tested individually under lateral loads, and test results were compared with the results derived from analytic studies and interpreted. Similar results were obtained from both experimental studies and pushover analyses. According to pushover analysis results, load-carrying capacity of 1/3 scaled reinforced concrete frames increased up to 7,01 times as compared to the non-braced specimen upon strengthening. Results acquired from the study revealed that reinforced concrete buildings which have inadequate seismic capacity can be strengthened quickly, easily and economically by this method without evacuating them.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.691-700
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• 2008

Contemporary architectural structures have diverse and complex forms. Such structural variety demands requisite performance from the connections in the steel structure so that the latter could resist a horizontal force, such as an earthquake. The connections are the all-important components that create the discontinuous form and that support stress concentration, determining the stiffness and toughness of the entire steel frame. In this study, a real-scale column-to-beam connection was constructed in the 600MPa-grade high-strength and high-performance steel, to test its behavior. Its material and welding characteristics were examined in this study, and its structural performance was analyzed by conducting seismic-resistance tests on the full-scale, cross-shaped column-to-beam welded connections with non-scallop, ordinary-scallop, and reinforced-scallop details. The weld ability of the high-strength, high-performance steel was also evaluated, and data regarding the seismic design for practical application were provided.

• Steel and Composite Structures
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• v.19 no.5
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• pp.1167-1184
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• 2015

Despite considerable life casualty and financial loss resulting from past earthquakes, many existing steel buildings are still seismically vulnerable as they have no lateral resistance or at least need some sort of retrofitting. Passive control methods with decreasing seismic demand and increasing ductility reduce rate of vulnerability of structures against earthquakes. One of the most effective and practical passive control methods is to use a shear panel system working as a ductile fuse in the structure. The shear Panel System, SPS, is located vertically between apex of two chevron braces and the flange of the floor beam. Seismic energy is highly dissipated through shear yielding of shear panel web while other elements of the structure remain almost elastic. In this paper, lateral behavior and related benefits of this system with narrow-flange link beams is experimentally investigated in chevron braced simple steel frames. For this purpose, five specimens with IPE (narrow-flange I section) shear panels were examined. All of the specimens showed high ductility and dissipated almost all input energy imposed to the structure. For example, maximum SPS shear distortion of 0.128-0.156 rad, overall ductility of 5.3-7.2, response modification factor of 7.1-11.2, and finally maximum equivalent viscous damping ratio of 35.5-40.2% in the last loading cycle corresponding to an average damping ratio of 26.7-30.6% were obtained. It was also shown that the beam, columns and braces remained elastic as expected. Considering this fact, by just changing the probably damaged shear panel pieces after earthquake, the structure can still be continuously used as another benefit of this proposed retrofitting system without the need to change the floor beam.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.4
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• pp.67-75
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• 2008

In construction facilities such as bridges, the fluid boundary layer(or water film) is formed at the structure-soil interface by the inflow into the system due to rainfall or/and rising ground-water. As a result, the structure-soil interaction(SSI) state changes into the structure-fluid-soil interaction(SFSI) state. In general, construction facilities may be endangered by the inflow of water into the soil foundation. Thus, it is important to predict the dynamic SFSI responses accurately so that the facilities may be properly designed against such dangers. It is desired to have the robust tools of attaining such a purpose. However, there has not been any report of a method for the SFSI analyses. The objective of this study is to propose an efficient method of finite element modelling using the new interface element named hybrid interface element capable of giving reasonable predictions of the dynamic SFSI response. This element enables the simulation of the limited normal tensile resistance and the tangential hydro-plane behaviour, which has not been preceded in the previous studies. The hybrid interface element was tested numerically for its validity and employed in the analysis of SFSI responses of the continuous bridge subjected to seismic load under rainfall or/and rising ground-water condition. It showed that dynamic responses of the continuous bridge resting on direct foundation may be amplified under rainfall condition and consequently lead to significant variation of stresses.