• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.351-361
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• 2017

Reinforced concrete(RC) structural walls are major lateral load-resisting structural member in building structures. Generally these RC structural walls are coupled with each other by the coupling beams and slabs, and therefore they behave as RC coupled structural wall system. In the design of these coupled structural wall systems, member forces are calculated using elastic structural analysis. These elastic analysis methodologies for the design of coupled structural wall system was not reasonable because it can not consider their ultimate behavior and assure economic feasibility. Performance based design and moment redistribution method to solve these problems is regarded as a reasonable alternative design method for RC coupled structural wall system. However, it is not verified under various design parameters. In this study, nonlinear analysis of RC coupled structural wall system was performed according to various design parameters such as reinforcement ratio, ultimate concrete strain and wall height. Based on analysis results, design considerations for coupled RC structural wall system was proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.440-447
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• 2020

Masonry structures are used as bearing walls in small buildings, but they are generally considered non-bearing walls. They are used as partition walls that divide the interior spaces of the frame structures of buildings. In addition, wetting techniques that use mortar as an adhesive between blocks or bricks in construction are vulnerable to climatic conditions, especially cracks in mortar, which can cause conduction collapse of the walls in seismic loading. The purpose of this research was to propose a dry concrete block construction method that complements the weak axial shear stiffness and improves the weakness of the wet construction method as well as to investigate its structural behavior. In this study, the material properties of concrete blocks were examined, and the seismic performance of the proposed dry assembly structure was verified by structural behavior tests on horizontal cyclic loads. First, in these study results, concrete blocks can be applied to the dry block construction method instead of wet construction methods because they secure more than C-type blocks in KS regulations. Second, the structural performance of the wall against a horizontal cyclic load indicates that the resisting force of the assembly block wall is increased by increasing the horizontal length of the wall, forming several diagonal cracks. Finally, the proposed dry block wall structure requires a seismic performance assessment considering that the ratio of the shape of the wall by height and length is considered a major influence variable on the structural behavior under a horizontal load.

• Journal of Korean Society of Steel Construction
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• v.27 no.3
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• pp.323-332
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• 2015

Special concentrically braced frames(SCBFs) have distinctive advantages in considerable seismic performance, which make engineers widely use SCBFs as lateral-load resisting systems in buildings and have researchers to develop SCBFs design methods. Compared to the extensive research of SCBF, comparatively little information is currently available on the performance of SCBFs designed and constructed before the early 1990's. Prior to 1988, concentrically braced frames(CBFs) design requirements were substantially less restrictive. As a result, many existing structures designed to these requirements may not ensure ductility and pose a significant concern in current buildings. In this study, these older frames are referred as non-seismic braced frames(NCBFs). In order to investigate the seismic behavior of NCBFs, finite-element(FE) models of SCBF and NCBF were suggested and verified using case investigation of NCBF conducted on the University of Washington. Using these models, the seismic behavior of NCBF with shared welding shear tab, which is the representative of the types of connections, was established and compared with the seismic performance of SCBF.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.59-67
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• 2013

Complex-shaped tall building causes many structural challenges due to its structural characteristics regarding inclined members and complexed shape. This paper is aimed at development of design process using computational-platform which is effective design tool for responding frequent design changes, particularly as to overseas projects. StrAuto, a parametric structural modeling and optimizing system, provides the optimized alternatives according to design intent and realize a swift process converting a series of structural information necessary to nonlinear analytical models. The application of the process was to a 45-story hotel building in Ulanbator, Mongolia adopting shear wall and special moment frame with outrigger systems. To investigate the safety of lateral force resisting system against maximum considered earthquake(MCE), nonlinear response history analysis was conducted using StrAuto.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.265-273
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• 2007

The most common structural system for apartment buildings in Korea is adopted to combine structural systems: for example, a moment-resisting frame will be used for lower stories and bearing wall system for the upper stories. This type of buildings have soft and/or weak stories in lower stories, and it may lead to collapse of those buildings during the large earthquake. Reversed cyclic load tests were conducted to estimate the performance and behavioral characteristics of deep beam and exterior column Joints. Experimental parameter is the amount of transverse reinforcement (designed by ACI code and Sheikh's procedure). The results of this study are as follows: (1) The required transverse reinforcement of column designed by Sheikh's procedure requires 2.9 times larger than that designed by ACI procedure. Large amount of transverse reinforcement increase the ductility of the column. (2) Most of the lateral drift in the column is due to the flexural deformation in the joint and plastic hinge region and up-lift rotation. (3) Transverse reinforcement in the exterior column shall be required not only in the hinge region but also in the joint.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.19-33
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• 2008

Dynamic response measurements from natural excitation were carried out for 25- and 42-story buildings to evaluate their inherent properties, such as natural frequencies, mode shapes and damping ratios. Both are reinforced concrete buildings adopting a core wall, or with shear walls as the major lateral force resisting system, but frames are added in the plan or elevation. In particular, shear walls in a 25-story building are converted to frames from the 4th floor level downwards while maintaining a core wall throughout, resulting in a fairly complex structure. Due to this, along with similar stiffness characteristics in the principal directions, significantly coupled and closely spaced modes of motion are expected in this building, making identification rather difficult. By using various state-of-the-art system identification methods, the modal parameters are extracted, and the results are then compared. Three frequency-domain and four time-domain based operational modal identification methods are considered. Overall, all natural frequencies and damping ratios estimated from the different identification methods showed a greater consistency for both buildings, while mode shapes exhibited some degree of discrepancy, varying from method to method. On the other hand, in comparison with analysis results obtained using the initial finite element(FE) models, test results exhibited a significant difference of about doubled frequencies, at least for the three lower modes in both buildings. To improve the correlation between test and analysis, a few manual schemes of FE model updating based on plausible reasons have been applied, and acceptable results are obtained. The advantages and disadvantages of each identification method used are addressed, and some difficulties that might arise from the updating of FE models, including automatic procedures, for such large structures are carefully discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.84-91
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• 2022

This study investigated the behavior of out-of-plane skewed moment connections that were designed as IMFs, as per the Korean standards. A total of 14 finite element models were constructed with the consideration of two types (single- and double-sided connections) and four levels of skew angle (0°, 10°, 20°, and 30°). The results indicated that the skewed connections considered in this study met the acceptance criteria for IMFs given by the codes. However, the load-carrying capacities of skewed connections were decreased as the skew angle increased. For the connection with a skew angle of 30°, the peak load was noted to be 13% less and the energy dissipation capacity could be 26% less than that of non-skewed connection. In addition, because of the skewed nature, the stress distribution in the skewed beam flange near the connection was asymmetric and the stresses were concentrated on the beam inner flange. Column twisting induced by the skewed configuration was very small and negligible in the beam and column combination considered in this study.