• 국제강구조저널
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• 제18권5호
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• pp.1607-1616
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• 2018

Quantitatively modeling and propagating all sources of uncertainty stand at the core of seismic fragility assessment of structures. This paper investigates the effects of various sources of uncertainty on seismic responses and seismic fragility estimates of single-layer reticulated domes. Sensitivity analyses are performed to examine the sensitivity of typical seismic responses to uncertainties in structural modeling parameters, and the results suggest that the variability in structural damping, yielding strength, steel ultimate strain, dead load and snow load has significant effects on the seismic responses, and these five parameters should be taken as random variables in the seismic fragility assessment. Based on this, fragility estimates and fragility curves incorporating different levels of uncertainty are obtained on the basis of the results of incremental dynamic analyses on the corresponding set of 40 sample models generated by Latin Hypercube Sampling method. The comparisons of these fragility curves illustrate that, the inclusion of only ground motion uncertainty is inappropriate and inadequate, and the appropriate way is incorporating the variability in the five identified structural modeling parameters as well into the seismic fragility assessment of single-layer reticulated domes.

• Structural Engineering and Mechanics
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• 제28권4호
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• pp.491-494
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• 2008

• 한국방재학회 논문집
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• 제10권1호
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• pp.23-28
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• 2010

구조물의 방재를 위해서 구조물의 효율적인 유지관리는 필수적이며, 여기서 신뢰 있는 구조물의 동적해석은 중요한 역할을 한다. 유한요소법은 구조해석법으로 가장 많이 사용되는 방법으로 자리 잡고 있으며, 요소와 요소망이 제대로 선택되면 신뢰 있는 해석 결과를 출력한다. 시간 영역 동적해석에 유한요소법을 사용하려면 각 시간 단계에서 요소망을 재형성할 필요가 생길 수 있는데, 여기에 연산 시간 측면에서 효율적인 적응적 요소망 전략을 사용하면 편리하다. 본 연구는 시간영역 동적해석에서 전단계 해석 결과를 사용하여 계산된 대표 변형률 값을 오차 평가하는데 사용하고, 요소 세분화는 절점 이동인 r-법과 요소 분할인 h-법의 조합으로 효율적으로 계산하는 적응적 요소망 형성 전략을 제시한다. 적용한 캔틸레버보의 예제를 통하여 정확성과 연산 효율성을 검증하였고 나아가 방법의 간단함이 지진 하중, 풍하중 등에 의한 복잡한 구조 동적 해석에도 효율적으로 사용될 수 있는 것을 보여 준다.

• 한국전산구조공학회논문집
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• 제26권1호
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• pp.89-97
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• 2013

비정형 초고층 건물의 계획 및 시공이 늘어남에 따라 이 연구에서는 프로토타입 모델에 대한 시공단계해석의 적용을 통하여 비정형 초고층 건물의 시공 중 구조적 거동을 분석하고자 하였다. 비틀림 초고층 건물을 대상으로 횡력저항시스템, 비틀림각도, 공법 조건에 따른 총 18개의 모델을 선정하였다. 횡력저항시스템으로는 다이아그리드 시스템과 가새튜브 시스템을 적용하였으며, 각 횡력저항시스템별로 $0^{\circ}$, $1^{\circ}$, $2^{\circ}$ 비틀림각도를 갖는 세 가지 평면 형태와 외곽 튜브와 내부 골조의 시공순서에 따른 세 가지 공법을 가정하였다. 시공 중인 초고층 건물의 구조적 성능은 시공단계해석의 횡변위 결과를 통하여 분석되었으며, 골조 공기와 최대 양중량과 같은 시공성능이 함께 비교되었다.

• Computers and Concrete
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• 제14권5호
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• pp.599-612
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• 2014

This paper presents the effects of the construction stages using time dependent material properties on the structural behaviour of concrete arch dams. For this purpose, a double curvature Type-5 arch dam suggested in "Arch Dams" symposium in England in 1968 is selected as a numerical example. Finite element models of Type-5 arch dam are modelled using SAP2000 program. Geometric nonlinearity is taken into consideration in the construction stage analysis using P-Delta plus large displacement criterion. In addition, the time dependent material strength variations and geometric variations are included in the analysis. Elasticity modulus, creep and shrinkage are computed for different stages of the construction process. In the construction stage analyses, a total of 64 construction stages are included. Each stage has generally $6000m^3$ concrete volume. Total duration is taken into account as 1280 days. Maximum total step and maximum iteration for each step are selected as 200 and 50, respectively. The structural behaviour of the arch dam at different construction stages has been examined. Two different finite element analyses cases are performed. In the first case, construction stages using time dependent material properties are considered. In the second case, only linear static analysis (not considered construction stages) is taken into account. Variation of the displacements and stresses are obtained from the both analyses. It is highlighted that construction stage analysis using time dependent material strength variations and geometric variations has an important effect on the structural behaviour of arch dams. The maximum longitudinal, transverse and vertical displacements obtained from construction stages and static analyses are 1.35 mm and 0 mm; -8.44 and 6.68 mm; -4.00 and -9.90 mm, respectively. In addition, vertical displacements increase from the base to crest of the dam for both analyses. The maximum S11, S22 and S33 stresses are obtained as 1.60MPa and 2.84MPa; 1.39MPa and 2.43MPa; 0.60MPa and 0.50MPa, respectively. The differences between maximum longitudinal, transverse, and vertical stresses obtained from construction stage and static analyses are 78%, 75%, and %17, respectively. On the other hand, there is averagely 12% difference between minimum stresses for all three directions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 가을 학술발표회 논문집
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• pp.201-208
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• 1994

To secure long-term structural safety of underground openings for radioactive waste disposal, the proper structural safety analyses are required. Especially, the structural analysis for underground openings should consider the effects of groundwater pressure. The objective of this study is to develop the structural analysis method for saturated rock masses. In this study, the interaction between groundwater distribution and structural behavior of rock masses are carried out to develop the structural analysis method of saturated rock masses. Then, a 3-Dimensional Multi-Phase Dynamic Analysis Program (MPDAP-3D) has been developed by modifying the existing MPDAP which is based on the concept of 2-dimensional two-phase media.

• Smart Structures and Systems
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• 제15권1호
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• pp.209-225
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• 2015

Compared to ambient vibration testing, impact testing has the merit to extract not only structural modal parameters but also structural flexibility. Therefore, structural deflections under any static load can be predicted from the identified results of the impact test data. In this article, a signal processing procedure for structural flexibility identification is first presented. Especially, practical issues in applying the proposed procedure for structural flexibility identification are investigated, which include sensitivity analyses of three pre-defined parameters required in the data pre-processing stage to investigate how they affect the accuracy of the identified structural flexibility. Finally, multiple-reference impact test data of a three-span reinforced concrete T-beam bridge are simulated by the FE analysis, and they are used as a benchmark structure to investigate the practical issues in the proposed signal processing procedure for structural flexibility identification.

• Structural Engineering and Mechanics
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• 제41권6호
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• pp.735-750
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• 2012

This paper presents a comparison between two different procedures to deal with the geometric nonlinear analysis of space trusses, considering its structural stability aspects. The first nonlinear formulation, called positional, uses nodal positions rather than nodal displacements to describe the finite elements kinematics. The strains are computed directly from the proposed position concept, using a Cartesian coordinate system fixed in space. The second formulation, called corotational, is based on the explicit separation between rigid body motion and deformed motion. The numerical examples demonstrate the performances and the convergence of the responses for both analyzed formulations. Two numerical examples were compared, including a lattice beam with postcritical behavior. Despite the two completely different approaches to deal with the geometrical nonlinear problem, the results present good agreement.

• 한국안전학회지
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• 제8권3호
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• pp.64-72
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• 1993

A large prropotion of structural failures are due to human error at the design stage of a structural engineering project, and many of these failures could have been prevented if there had been proper design checking. Analyses of the data from the 6 engineering firms and 24 professional engineer practitioners are shown on diagrams, also applicated for suggested models; overview checking. And then analyzed results of current work in this area, which examine the effects of error magnitude, are compared to the limit data obtained from the surveys. Overview checking only is analyzed of three typical design checking processes; self checking; Independent detailed checking, and overview checking.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.921-926
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• 2004

In this paper, a nonlinear structural damage identification algorithm is derived by taking into account the non-linearity of damage. The structural damage identification analyses are conducted by using the direct method and the Newton-Raphson method. It is found that, the Newton-Raphson method in general provides the better damage identification results when compared with the results obtained by the direct method.