• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.143-157
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• 1992

For the design of structural systems having the prescribed or optimum dynamic characteristics, some design changes of the initially designed system are required. In these cases, if the sensitivity analysis which can predict the changes of dynamic characteristics due to the changes of design variables is applied, the design changes can be carried out rationally and very efficiently. For many structural systems, it is well known that the analysis by the transfer matrix method(TMM) and the combined finite element-transfer matrix method(FETMM) is more efficient than the analysis by the finite element method. However, most known studies on the sensitivity analysis of structural systems premise using the finite element method. In this paper, the sensitivity analysis methods by the TMM and the FETMM are presented and some numerical investigations on the beam-column with elastically restrained ends and intermediate contraints and the stiffened plate having subsystems are carried out. The results of the numerical examples show good accuracy and computational efficiency of the presented methods, and show that the application of sensitivity analysis in the dynamic characteristic reanalysis give good results within the practically changeable range of design variables.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.797-804
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• 2009

The structural designs of RC flat plates that have insufficient flexural stiffness due to lack of support from boundary beams may be governed by serviceability as well as a strength criteira. Specially, since over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction, a construction sequence and its impact on the slab deflections may be decisive factors in designs of flat plate systems. In this study, the procedure of calculating slab deflections considering construction sequences and concrete cracking effects is proposed. The construction steps and the construction loads are defined by the simplified method, and then the slab moments, elastic deflections, and the effective moment of inertia are calculated in each construction step. The elastic deflections in column and middle strips are magnified to inelastic deflections by the effective moment of inertia, and the center deflection of slab are calculated by the crossing beam method. The proposed method is verified by comparisons with the existing test result and the nonlinear analysis result. Also, by applications of the proposed method, the effects of the slab construction cycle and the number of shored floors on the deflections of flat plates under construction are analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.327-336
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• 2012

This study presents the effects of various geometric properties on the ultimate behavior of steel cable-stayed bridges. In general, cable-stayed bridges are well known as a very efficient structural system, because of those geometric characteristics, but at the same time, the structure also shows complex structural behavior including various nonlinearities which significantly affect to the ultimate behavior of the structure. In this study, the effects of various geometric properties of main members on the ultimate behavior under specific live load cases, which had been studied in previous studies, were investigated using a rational analytical method. In this parametric study, sectional dimensions of main members were considered as main geometric parameters. For the rational ultimate analysis under specific live load cases, the 2-step analysis method, which contains initial shape analysis and live load analysis, was used. As the analysis model, 920.0 m long steel cable-stayed bridges were used and two different types of cable arrangement were considered to study the effect of the cable arrangement types. Through this study, the effects of various geometric properties on the characteristics of the ultimate behavior of steel cable-stayed bridges were intensively investigated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.447-454
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• 2016

In the meantime, looking at the present status of how to estimationte the quantity of rebar based on 3D BIM getting the limelight in these days, commercial BIM tools provide rebar modeling functions however it takes a vast amount of modeling time for modeling of rebar in use of that function hence there is no BIM software at present for practical use. Therefore, in this study, we organized and presented a practical rebar quantity estimationtion process in BIM-based design work-site and intended to develop a program named Rebar Automatic Arrangement Program - hereinafter called RAAP - which enables automatic rebar arrangement based on much more precise cross-sectional information of bars in column, beam, slab and wall than the one from existing 2D method under the conditions without any cross-sectional information in the initial design phase. In addition, we intended to establish rebar quantity estimationtion process in the initial design phase through interworking of modeling & quantity estimationtion functions in consideration of joint, anchoring length of BuilderHUB as a BIM software with RAAP. The results from this study are practical in developing a technology that is able to estimationte quantity with more improved reliability than the one from existing 2D-based methods with less effort when the quantity of framework is estimationted in the uncompleted state of cross-sectional design for structural members in the initial design phase of a construction project. And it is expected that it could be utilized as a basic study from which a reasonable quantity estimationtion program can be established in the initial design phase.

• Journal of Korean Society of Steel Construction
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• v.22 no.2
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• pp.151-160
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• 2010

The number of cases of collapsed plastic greenhouses in farmlands has increased due to the heavy local snowfall caused by extraordinary atmospheric phenomena. Consequently, the economic losses of farmers have also increased. However the government policy in relation to damage pretension is insufficient and collapse case is repeated every year. The main reason for frame collapse is that the moment capacity of a steel pipe is not sufficient to resist a heavy snowload. In this study, experiments were conducted on the current frame system of a greenhouse with a tension tie. The frame consisted of two sections(${\phi}25.4{\times}1.5$, ${\phi}31.8{\times}1.5$), and its span length was 6.5 m. A temporary tension tie using a steel wire and a fabric rope was connected to the two joints, to which a curved beam and a straight column were connected. The pretension force was applied at the tension tie, and a vertical force simulating snowfall was applied until failure. The fabric rope frame increased the load-carrying capacity by 10-45% compared to the normal frame without a tension tie, and the steel wire frame increased the load-carrying capacity by 58-73% compared to the normal frame without a tension tie. Steel wire was found to be more effective as far as strength is concerned, but its connection details and pretension application are more difficult and complicated than those of the fabric rope. The test results thus show that the fabric rope is more preferable.

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.418-426
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• 2019

Purpose: After analyzing the seismic capability of low-rise RC grid structures with insufficient seismic performance, the purpose of the project is to install steel slab hysteretic dampers (SSHD) to improve the seismic performance of beams and columns, and to suggest measures to minimize damage to the structure and human damage when an earthquake occurs. Method: The evaluation of the seismic performance of a structure is reviewed based on the assumption that the seismic performance is identified for the grid-type subway systems that are not designed to be seismic resistant and the installation of an SSHD system, a method that minimizes construction period, if insufficient, is required. Result: After the application and reinforce of structure with SSHD, and the results of eigenvalue analysis are as follows. The natural periodicity of longitudinal direction was 0.55s and that of vertical direction was 0.58s. Conclusion: As results of cyclic load test of structure with SSHD, the shear rigidity of damper is 101%, the energy dissipation rate is 108% and, plastic rotation angle of all column and beam is satisfied for $I_o$ level and therefore it is judged that the reinforce effect is sufficient.