• Steel and Composite Structures
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• v.36 no.2
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• pp.213-228
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• 2020

Shape Memory Alloys (SMAs) are new materials used in various fields of science and engineering, one of which is civil engineering. Owing to their distinguished capabilities such as super elasticity, energy dissipation, and tolerating cyclic deformations, these materials have been of interest to engineers. On the other hand, the connections of a steel structure are of paramount importance because of their vulnerabilities during an earthquake. Therefore, it is indispensable to find approaches to augment the efficiency and safety of the connection. This research investigates the behavior of steel connections with extended end plates equipped hybridly with 8 rows of high strength bolts as well as Nitinol superelastic SMA bolts. The connections are studied using component method in dual form. In this method, the components affecting the connections behavior, such as beam flange, beam web, column web, extended end plate, and bolts are considered as parallel and series springs according to the Euro-Code3. Then, the nonlinear force- displacement response of the connection is presented in the form of moment-rotation curve. The results obtained from this survey demonstrate that the connection has ductility, in addition to its high strength, due to high ductility of SMA bolts.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.453-461
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• 2014

In this study, the stub columns of built-up H-section and square hollow section subjected to eccentrical loads are tested to evaluate the applicability of the structural members with 800MPa high-strength steel (HSA800) on current design specification. Analytical studies of FE model are conducted to validate the test results and then the verified FE models are used for extensive parametric studies for checking up the applicability of current design code. The parameters are width-to-thickness ratios and axial load ratios. From P-M correlations on parameter models, all stub columns with non-compact sections exceed the current design requirements about axial force and flexural strength ratios are sufficiently secured as the axial load ratios are decreased. The built-up hollow sections with slender section model do not satisfy the current design specification about axial force.

• Fire Science and Engineering
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• v.25 no.5
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• pp.85-92
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• 2011

Along the fire resisting capacity of high strength concrete has been brought up as a social issue, and the Ministry of Land also had notified the control standard about it, the researches for improving the fire resisting capacity have been considerably activated these days. In this study, we performed a research for developing a high strength concrete, contains the fiber cocktail, which is a hybrid of polypropylene fiber as organic matter, and steel fiber. As we analyzed the temperature of the steel part during the fire test with 100 MPa high strength concrete, there was a tendency that the lower temperature comes out with the larger cross section, and the $600{\times}600mm$, $800{\times}800mm$ cross sectioned can secure the fire resistance capability, so the $600{\times}600mm$ is deducted as the optimal size if we consider the double economic feasibility. As well, among them the best qualified $600{\times}600mm$ shapes, the fiber cocktail hybrid of $1.5kg/m^3$ PP fiber and $40kg/m^3$ of steel, comes out the best ratio.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.447-453
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• 2004

Various structural materials have been used in construction projects using stones, connotes, and steels materials. Among of these projects, concretes may use widely because concretes have high compressive strength, and comparatively easy maintenance and management. Reinforced concrete Buildings will be deteriorated as time passed. These problems will be accelerated by propagation of cracks. In order to manage such cracks, time, efforts and expense are required. In this study, leakages of fluorescence and adhesive material were investigated using glass sensors that were embedded in a model beam and column. In addition, currents in glass pipe sensor were observed to find leakage of liquid in glass pipes. Progressive cracks were generated by fracture of glass me sensor. In this investigation, a reinforcement clothing system was wrapped for a glass pipe sensor, The glass pipe sensor that can make control and reinforce cracks simultaneously.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.799-804
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• 2002

The compatibility of concrete repairs is proposed by D. Cusson et al. and N. K. Emberson et al. But this is the general compatibility of concrete repairs. This study is actualized the general compatibility of concrete repairs on the flexural specimen under bending load. This study is obtained following results. 1) As a results of analysis for repair effects on failure shape, debonding between concrete and repairs, yielding load and ultimate/yielding ratio, the repair effects is ascertained that the repair R3 is much excellent than the repair R7, but on the other hand R7 is very high than R3 on the viewpoint of compressive strength, where repair R7, R3 is a product. 2) Therefore the compatibility of concrete repair proposed by D. Cusson et al. and N. K. Emberson et al. must be reanalyzed for structures types of column, beam, wall, slab et al.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.494-497
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• 2006

The objectives of this study are to develop and evaluate the Neural Network algorithm which can predict the inelastic shortening such as the creep strain and the drying shrinkage strain of reinforced concrete members using the previous test data. New learning algorithms for the prediction of creep strain and the drying shrinkage strain are proposed focusing on input layer components and a normalization method for input data and their validity is examined through several test data. In Neural Network algorithm, the main input data to be trained are the compressive strength of the concrete, volume to surface ratio, curing condition, relative humidity, and the applied load. The results show that the new algorithms proposed herein successfully predict creep strain and the drying shrinkage strain.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.73-82
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• 2017

Vertical shortening in tall buildings would be of little concern if all vertical elements shortened evenly. However, vertical elements such as walls and columns may shorten different amounts due to different service axial stress levels. With height, the differential shortening may become significant and impact the strength design and serviceability of the building. Sometimes column transfers or other vertical structural irregularities may cause differential shortening. If differential shortening is not addressed properly, it can impact the serviceability of the building. This paper takes the perspective of a structural engineer in planning the design, predicting the shortening and its effects, and communicating the information to the contractor.

• Corrosion Science and Technology
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• v.4 no.1
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• pp.29-32
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• 2005

A various structural materials are used in construction projects such as a stone, concrete, steel materials. Between of them, concrete are used widely. The compressive strength of concrete is high, and its maintenance and management is comparatively easy. The R.C Building will be superannuated as time passes. This program is generated by propagation of cracks. In order to manage such cracks, time and efforts, expense, etc. are required. In this study, glass sensors were embedding in a model beam and column and leakage of fluorescence and adhesive material was investigated. Further, currents in glass pipe were observed to find the leakage of liquid in glass pipes. Progressive cracks generated by cause the fracture of glass pipes. Therefore, the liquid become to flow and electric current stops, and the cracked part of the member can be found easily. Moreover, the adhesive delays progressive cracking system that responds in air, and the life of a structure can be made to extend. The purpose of this research is to develop of low price sensors that can perform of self-diagnosis in addition to ability of concrete repair concrete to damage.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.389-392
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• 2005

In this study, the effect of thickness of sprayed fireproofing on temperature of main bars under fire test was investigated for high strength concrete member(column) prevented the spalling. The thicknesses of sprayed fireproofing were 0, 10, 20 and 30mm. Test was carried out according to ISO-KS standard temperature-time curve during 3hrs. Based on temperature results of main bars after 3hrs, it appears that the temperatures of the main coner bar are about 400$^{circ}C$ and 500$^{circ}C$, when the thicknesses of sprayed fireproofing are 5mm and 2mm, respectively.

• International Journal of High-Rise Buildings
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• v.4 no.3
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• pp.209-217
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• 2015

Outrigger systems are highly efficient since they utilize the perimeter zone to resist lateral forces, similar to tubular systems. The entire structural weight can be reduced due to the system's significant lateral strength. Therefore, it is the most commonly selected structural system for tall and supertall buildings built in recent years. In this paper, issues regarding the differential shortening effect during construction of the outrigger system and the special joints used to solve these issues will be addressed. Additionally, the characteristics of wind and seismic loads in Korea will be briefly discussed. Lastly, buildings in Korea using an outrigger as their major structural system will be introduced and the structural role of the system will be analyzed.