• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.473-480
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• 2011

Recently, the resizing algorithms based on the displacement participation factors have been developed for sizing members to satisfy stiffness criteria. It is proved that this resizing algorithms made for utilizing worker's stiffness design are practical and rational due to the simplicity and convenience of the method. The resizing algorithm can be practically and effectively applied to drift design of buildings. However, the researches on the change of inelastic behavior by the resizing algorithm has been insufficient. To identify the effect on the inelastic behavior of buildings by the resizing method, this study used the reinforced concrete shear wall-frame example. Through the application of the resizing method, the weights of shear wall in the lower class and the weights of columns and beams in the upper class increased respectively. And the initial stiffness of the building increased and the ductility of the buildings had similar with that of the initial structure.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.708-713
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• 2001

The paper presented some results of a experimental study of natural convection in partitioned 2D square enclosure. The square enclosure consist of two adiabatic vertical walls and the upper cold and the lower hot walls. A partition is positioned perpendicularly at the center of left vertical insulated wall The PIV mesaurements were performed with the variations of the partition length and inclination of enclosure. The working fluid is water with a Prandtl number of 6.996 at $20^{\circ}C$ temperature. A captured images were calculated by using a Cross-Correlation(Multi-frame/Single-exposure) method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.310-317
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• 2002

In the present study, an experimental study of natural convection in a partitioned 2D square enclosure has been carried out. The square enclosure consist of two adiabatic vertical walls and the upper cold and the lower hot walls. A partition is positioned perpendicularly at the center of the left vortical insulated wall. The PIV measurements were performed with the variations of Rayleigh number, partition length and inclination of the enclosure. The working fluid is water with Prandtl number of 6.996 at 20$\^{C}$. The captured images were analyzed by using a cross-correlation (two-frame/single-exposure) PIV method.

• Structural Engineering and Mechanics
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• v.51 no.3
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• pp.487-502
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• 2014

In buildings structures, the flexural stiffness reduction of beams and columns due to concrete cracking plays an important role in the nonlinear load-deformation response of reinforced concrete structures under service loads. Most Seismic Design Codes do not precise effective stiffness to be used in seismic analysis for structures of reinforced concrete elements, therefore uncracked section properties are usually considered in computing structural stiffness. But, uncracked stiffness will never be fully recovered during or after seismic response. In the present study, the effect of concrete cracking on the lateral response of structure has been taken into account. Totally 120 cases of 3 Dimensional Dynamic Analysis which considers the real and accidental torsional effects are performed using ETABS to determine the effective structural system across the height, which ensures the performance and the economic dimensions that achieve the saving in concrete and steel amounts thus achieve lower cost. The result findings exhibits that the dual system was the most efficient lateral load resisting system based on deflection criterion, as they yielded the least values of lateral displacements and inter-storey drifts. The shear wall system was the most economical lateral load resisting compared to moment resisting frame and dual system but they yielded the large values of lateral displacements in top storeys. Wall systems executes tremendous stiffness at the lower levels of the building, while moment frames typically restrain considerable deformations and provide significant energy dissipation under inelastic deformations at the upper levels. Cracking found to be more impact over moment resisting frames compared to the Shear wall systems. The behavior of various lateral load resisting systems with respect to time period, mode shapes, storey drift etc. are discussed in detail.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.19-32
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• 2003

The structural system of a hybrid building is composed of upper shear wall which resist lateral force by bending deformation and lower frame which resist lateral force by shear deformation. A deep transfer girder is used to transfer gravity load safely from super structures to structural frame beneath. Because of the vertical discontinuity, a building with transfer girder must be analyzed by dynamic analysis. However, this structural system has many problems in performing dynamic analysis that cannot be solved by general analysis procedure. The slabs In transfer floor are considered as either a Plate element or a rigid diaphragm in finite element analysis without appropriate evaluation of their characteristics. Therefore, a reasonable analysis method is proposed in this study by evaluating the diaphragm effect of a hybrid structure system.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.4
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• pp.1-13
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• 2000

상부벽식 하부골조를 가진 복합구조물은 부족한 대지를 효율적으로 활용하기 위하여 건설되고 있다. 이러한 복합건물은 상부벽식-하부골조를 가지는 구조로써 일반적으로 전이보 또는 전이판으로 상하부를 연결하고 있다. 따라서 상하부 구조사이의 강성과 질량에 많은 차이가 발생하게 된다. 구보물의 고유주기는 지진하중과 밑면전단력을 결정하기 위한 중요한 변수이다. 그러나 현재 국내 규준에서 제안하는 고유주기 산정식은 이러한 건물에는 적용할 수 없다. 본 연구에서는 상부벽식-하부골조를 가진 복합구조물의 고유주기의 산정에 영향을 미치는 변수들 중 가장 큰 영향을 미치는 건물의 상하부 층수에 따른 변수만을 고려하여 고유주기산정식을 제안하였다. 하부는 2~5개 층을 가지고, 상부는 10~18개 층을 가지는 15~20층의 건물이면 정형적인 평면을 가지는 복합구조물로 한정하였다. 건물 내부의 채움벽에 대한 효과를 고려한 고유주기 제안식은 다음과 같다. 장변 방향 : $T_{L}$=($0.20H_{h}+0.05H_{i}$)/$sqrt{B}$-0.42 단변 방향 :$T_{S}$=($0.07H_{h}+0.12H_{i}$)/$sqrt{B}$-0.40

• Journal of Korean Society of Steel Construction
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• v.27 no.5
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• pp.471-481
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• 2015

Modular building is a prefabricated construction system for building where factory-produced pre-engineered modular units are delivered to site and assembled as substantial elements of a building. There are two basic kinds of modular structures. One is a load-bearing wall structure designed to transfer the load through longitudinal walls. The other is a frame structure composed of columns and beams. For frame structure, square hollow section is often used as a column member and channel as a beam member in modular unit. Lower and upper modules are fasten with bolts via a pre-installed access hole in the SHS column. However, the access holes can weaken the panel zone that would affect the behavior of beam to column connection. The 5 specimens of beam to column connections with parameters of access hole, column thickness and diaphragm were made and this paper describes the test results.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.1
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• pp.35-43
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• 2009

Two types of piloti-type high-rise RC building structures having irregularity in the lower two stories were selected as prototypes, and nonlinear time history analysis was performed using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. One of the buildings studied had a symmetrical moment-resisting frame (BF), while the other had an infilled shear wall in only one of the exterior frames (ESW). A fiber model, consisting of concrete and reinforcing bar represented from the stress-strain relationship, was adapted and used to simulate the nonlinearity of members, and MVLEM (Multi Vertical Linear Element Model) was used to simulate the behavior of the wall. The analytical results simulate the behavior of piloti-type high-rise RC building structures well, including the stiffness and yield force of piloti stories, the rocking behavior of the upper structure and the variation of the axial stiffness of the column due to variation in loading condition. However, MVLEM has a limitation in simulating the abrupt increasing lateral stiffness of a wall, due to the torsional mode behavior of the building. The design force obtained from a nonlinear time history analysis was shown to be about $20{\sim}30%$ smaller than that obtained in the experiment. For this reason, further research is required to match the analytical results with real structures, in order to use nonlinear time history analysis in designing a piloti-type high-rise RC building.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.55-66
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• 2006

This paper considers the nonlinear direct spectrum method to estimate seismic performance of mixed building structures without iterative computations, given dynamic property $T_1$ from stiffness skeleton curve and nonlinear pseudo acceleration $A_{1y}/g$ and/or ductility ratio p from response spectrum. Nonlinear response history analysis has been performed and analysed with various earthquakes for evaluation of correctness and confidence of nonlinear direct spectrum method. The conclusions of this study are as follows; (1) Nonlinear direct spectrum method is considered as a practical method which is applicable to compute the structural initial elastic period and the yielding strength from stiffness skeleton owe and calculate the nonlinear maximum response of structure directly from nonlinear response spectrum. (2) The comparison of the analysis results from NDSM and NRHA showed that the average errors were less than 20% in about 3/4 of the analysis cases, and that the results obtained from NDSM turned out to be generally larger than those from NRHA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.627-635
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• 2019

A programmable drone is a drone developed not only to experience the basic principles of flight but also to control drones through Arduino-based programming. Due to the nature of the training drones, the main users are students who are inexperienced in controlling the drones, which often cause frequent collisions with external objects, resulting in high damage to the drones' frame. In this study, the structural stability of the drone was evaluated by means of a structural dynamics based collision simulation for educational drone frame. Collision simulations were performed on three cases according to the impact angle of $0^{\circ}$, $+15^{\circ}$ and $-15^{\circ}$, using an analytical model with approximately 240,000 tetrahedron elements. Using ANSYS LS-DYNA, which provides excellent functions for the simulation of the dynamic behavior of three-dimensional structures, the stress distribution and strain generated on the drone upper, the drone lower, and the ring assembly were analyzed when the drones collided against the wall at a rate of 4 m/s. Safety factors resulting from the equivalent stress and the yield strain were calculated in the range of 0.72 to 2.64 and 1.72 to 26.67, respectively. To ensure structural stability for areas where stress exceeds yield strain and ultimate strain according to material properties, the design reinforcement is presented.