• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.1-11
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• 1993

Precast/Prestressed concrete segmental bridges with moderate range of span length normally have a constant section height for economic segment manufacturing. Inside sectional dimension is often controlled for design of non-prismatic section between supports when variable stiffness is required. It is usual, in the preliminary design stage, to adopt trial bridge sections by past experience or by approximately estimated member forces. Three bridge models of different member stiffness have been selected to investigate flexural stiffness effects on member forces for preliminary design stage. The selected bridge stiffness has been determined by the flexibility index from review of the practically usable sections.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.37-44
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• 2020

This research aimed to propose the more proper equation than the leading and existing equations to predict the optimum location of offset outrigger. In this study, a 79 existing models of offset outrigger system were examined. And the key factors in the existing offset outrigger models were the stiffness of shear wall and offset outrigger system, the stiffness of exterior column connected in offset outrigger, the frame stiffness, the ratios of lateral stiffness of frame in shear wall-frame structures, and all that. This paper proposed the modified equation of predicting the optimal location of offset outrigger system. Additionally, the findings of this study provided the important structure engineering materials of the optimal offset outrigger position in tall building.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.43-52
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• 2015

In this study, to minimize both the costs associated with track maintenance and the energy consumption for train operation, a numerical method that evaluates the optimal vertical stiffness of a fastener for concrete track is presented. A progress model of the track damage is established in order to calculate the concrete track maintenance cost according to the fastener stiffness. Also, the quantitative relationship between the progress of the track damage and the maintenance of the concrete track is derived. The wheel load is more exactly evaluated by using the advanced vehicle-track interaction model, which can precisely consider the behaviors of the track components. An optimal range for the stiffness of the fastener, a range that is applicable to the design of concrete track for domestic high speed lines, is proposed.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.72-79
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• 2021

In this study, as part of the development of an autonomous flying personal aircraft, an equivalent model of the main wing assembly of an Optionally Piloted Personal Air Vehicle (OPPAV) was developed. Reliability of the developed equivalent model was verified by eigenvalue analysis. The main wing assembly consisted of a main wing, an inboard pod, and an outboard pod. First, for developing an equivalent model of each component, components to produce the equivalent model were divided into several sections. Nodes were then created on the axis of the equivalent model at both ends of each section. In addition, static analysis with unit force and unit moment was performed to calculate the deformation or the amount of rotation at the node to be used in the equivalent model. Equivalent axial, bending, and torsional stiffness of each section were calculated by applying the beam theory. Once the equivalent stiffness of each section was calculated, information of a mass and moment of inertia for each section was entered by creating a lumped mass in the center of each section. An equivalent model was developed using beam element. Finally, the reliability of the developed equivalent model was verified by comparison with results of mode analysis of the fine model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.377-386
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• 2003

The proposed simplified MDOF model is applied to a half-scale single-story reinforced masonry test building with a single diagonally-sheathed diaphragm. Comparisons of analytical studies to experimental tests can be valuable for understanding the seismic response of these types of buildings and for determining the qualities and limitations of the simplified models. A model calibration process is performed in this paper to determine the required structural properties based on the elastic and inelastic test responses for test building. This approach is necessary since established methods to determine the in-plane and out-of-plane stiffness, strength, and hysteresis do not exist.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.459-467
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• 2004

This paper presents an efficient reanalysis algorithm, named PRAS (Partial Reanalysis algorithm using Adaptable Substructuring), for the partially changed structures. The algorithm recalculates directly any displacement or member force under consideration in real time without a full reanalysis in spite of local changes in member stiffness or connectivity_ The key procedures consists of 1) partitioning the whole structure into the changed part and the unchanged part, 2) condensing the internal degrees of freedom and forming the unchanged part substructure, 3) assembling and solving the new stiffness matrix from the unchanged part substructure and the changed members.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.45-54
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• 2004

Since existing hysteretic models for R/C members focused on presenting the degrading stiffness using empirical equations based on experiments, they cannot accurately predict the energy dissipation capacity during cyclic loading. Recently, design equations which can evaluate the energy dissipation capacity of R/C members were developed. Based on those equations, in the present study, an energy-based hysteretic model for flexure-dominated R/C members was developed. The proposed model was devised to dissipate the same energy as the actual one dissipated during a complete load cycle. The proposed model represents the hysteretic behaviors of R/C members accompanied by stiffness degradation and pinching using primary and cyclic curves and six unloading/reloading rules. The proposed model was verified by comparisons with various experimental results. The energy-based hysteretic model can be used to develop computer programs for static and dynamic analysis/design because it is simple and easily applicable to numerical analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.25-30
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• 1992

최근 전자계산기를 이용한 진동해석 방법이 눈부시게 발달하여, 일반 구조물 이나 기계 구조물 등의 동특성을 설계 단계에서 정도 높게 예측하는 것이 가능하게 되었다. 그러나 종래의 구조해석은 주어진 시스템의 동특성을 위한 것으로 얻어진 동특성으로부터 질량, 관성제원 및 스프링상수값 등의 설계상 수값을 규명하는 연구는 미미한 실정이다. 이것에 대한 해결방법으로 크게 해석적인 방법과 실험적인 방법으로의 접근이 있어 왔다. 해석적인 방법으로 유한요소해석에서 얻은 모드좌표를 물리좌표로 변환하는 방법으로 Guyan의 정축소와 같은 절점축소를 행하는 방법이 고찰되었다. 실험적인 방법으로 가 진실험에서 얻은 전달함수나 모드파라미터로부터 [M], [K] 행렬을 결정하는 연구가 있었지만 어떤것도 질량, 스프링상수 등의 설계상수를 완전히 규명하 지는 못하였다. 또한, 설계 단계에서 필요한 질량, 관성제원 또는 스프링상수 등의 최적한 값이나, 원하는 시스템특성을 얻을 수 있는 설계상수의 적정한 폭을 구하는 연구는 설계자의 경험과 반복된 시행착오에 의존하는 실정이다. 감도해석은 이러한 문제점을 개선하는 수단으로 설계변수에 대한 동특성의 변화율을 구하는 것이다. 감도해석을 수행하는 것은 어느 설계변수를 수정하 는 것이 주어진 동특성에 부합되는 지를 알려주고, 어느 것을 수정하는 것이 원하는 방향의 동특성변화에 가장 효과적인지를 알려주는 것이다. 따라서 감 도해석을 이용하여 설계의 최적화 프로그램을 만들수 있고, 이것은 설계자가 요구하는 동특성을 목적함수로 하여 주어진 구조물을 최적화하는 설계상수 값을 얻을 수 있게 한다. 본 논문에서는 강체모델의 동특성으로부터 모델의 설계 상수를 규명하고, 동특성의 개선을 위하여 설계변수의 변경량을 물리좌 표계에서 얻는것을 목적으로 한다. 강체 마운트계의 관성제원 및 마운트강성 의 규명을 위하여 임으로 주어진 설계상수를 모델데이타로 하여 관성제원과 스프링 강성을 구하였다. 관성제원의 규명은 주어진 모델의 관성값을 모르는 것으로 하여 임의의 초기 관성값으로 감도해석에 의해 주어진 계의 관성값 을 물리 좌표계에서 규명하였다. 마운트 강성의 규명도 관성제원의 규명과 같은 방법으로 임의의 강성값으로 감도해석을 하여 강성값을 규명하였다. 또 한 감도해석에 의한 동특성 변경은 특정한 고유진동 수의 변경이 필요할 때, 고유진동수의 이동을 위한 관성제원의 변경 및 마운트 강성변경값을 예측할 수 있다. 본 연구수행의 기본적인 흐름도는 Fig.1.1과 같다. 위와 같은 작업 으로 엔진 마운트와 같은 강체 모델의 시스템 규명을 행하는 경우에 유한요 소해석 및 가진 실험으로 얻은 고유진동수의 정보 또는 원하는 고유진동수 의 특성을 기본으로 실제 설계에서 사용이 가능하도록 물리 좌표계에서 관 성 제원 및 스프링상수를 구할 수 있을 것이다.

• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.279-287
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• 2012

A double split tee connection is used as a connection that is suitable for ordinary moment frames or special moment frames according to the combination of variables of the thickness of the T-stub flange and the gauge distance of the high-strength bolts. In order to demonstrate safe structural behavior, a double split tee connection must meet the requirements for inter-story drift angles and the moment of connection, as defined in the Korea Building Code-Structural. In order to determine whether the these requirements are met, it is necessary to predict rotational stiffness and the ultimate plastic moment of the connection. Therefore, this study primarily aimed to propose an analytical model for predicting the rotational stiffness of a double split tee connection under a static load. Toward this end, a three-dimensional, non-linear finite element analysis was carried out. Then, the applicability of the proposed model was verified after comparing the test results of this study with other studies.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.303-312
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• 2008

In this paper, the seismic behavior of shear wal-frame systems is analyzed. The governing equations of the wall-frame systems with outrigger truss are formulated through the continuum approach and the whole structure is idealized as a shear-flexural cantileverwith rotational spring. The effect of shear deformation and flexural deformation of the wall-frame and outrigger trusses are considered and incorporated in the formulation of the wall-frame structures with and without outriggers are compared by using finite element analysis incorporated with the Newmark-${\beta}$ method. Numerical results are obtained and compared with the finite element package MIDAS. The proposed method is found to be simple and efficient, and provides reason ably accurate results in the early design stage of tall building structures.