• 한국지진공학회논문집
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• 제14권5호
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• pp.13-22
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• 2010

철근콘크리트 건축물에서 비내력벽(Masonry Infill Walls)은 내부 칸막이벽이나 중저층 규모의 건물 외벽에 흔히 사용된다. 그렇지만 대부분의 경우에 비내력벽은 비구조체이므로 구조설계시 건물의 모형화에서 무시된다. 따라서 본 연구에서는 비내력벽을 보편화된 모형화 방법인 등가의 대각 압축 스트럿(Equivalent Diagonal Strut)으로 고려하여 비내력벽의 유무에 따른 저층 철근콘크리트 건축물의 전체적인 지진거동의 양상을 평가하고자 하였다. 해석결과로 비내력벽을 고려하면 시스템의 추가적인 강도 및 강성을 확보하여 층간변위비를 줄일 수 있으나 진동주기가 짧아져서 설계단계에서 고려한 지진하중보다 큰 하중을 받게 된다. 연약층이 있는 모델의 경우에는 기둥에 소성거동이 집중됨을 알 수 있으며 부분적인 붕괴가 전체 시스템의 붕괴 원인의 가능성을 가진다.

• Structural Engineering and Mechanics
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• 제32권5호
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• pp.667-683
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• 2009

FE model-based dynamic analysis has been widely used to predict the dynamic characteristics of civil structures. In a physical point of view, an FE model is unavoidably different from the actual structure as being formulated based on extremely idealized engineering drawings and design data. The conventional model updating methods such as direct method and sensitivity-based parameter estimation are not flexible for model updating of complex and large structures. Thus, it is needed to develop a model updating method applicable to complex structures without restriction. The main objective of this paper is to present the model updating method based on the hybrid genetic algorithm (HGA) by combining the genetic algorithm as global optimization method and modified Nelder-Mead's Simplex method as local optimization method. This FE model updating method using HGA does not need the derivation of derivative function related to parameters and without application of complicated inverse analysis methods. In order to allow its application on diversified and complex structures, a commercial FEA tool is adopted to exploit previously developed element library and analysis algorithms. Moreover, an output-level objective function making use of measurement and analytical results is also presented to update simultaneously the stiffness and mass of the analysis model. The numerical examples demonstrated that the proposed method based on HGA is effective for the updating of the FE model of bridge structures.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.483-489
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• 2008

Masonry infill walls are frequently used as interior partitions and exterior walls in low- or middlerise RC buildings In the structural design and assessment of structural behaviors of buildings, the infill walls are usually treated as non-structural elements and they are ignored in analytical models. In this study, seismic behaviors of RC frame with/without masonry infill walls were investigated. To this end, the infill walls were modeled as equivalent diagonal struts. Based on analytical results, it has been shown that masonry infill walls can increase the global strength and stiffness of a structure. Accordingly, inter-story drift ratio will be decreased but seismic forces applied to the structure were increased than design seismic load because natural period of the structure was decreased. It is also seen from the analytical results that the inelastic deformation of RC frame with soft story is concentrated on the first story columns and thus, partial damage may have possibility of collapse of system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.590-595
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• 2008

In the present paper, the impact damage behavior of steel plate reinforced concrete panels exposed to shock impulsive loading and fragment impact loading is investigated. To evaluate the retrofit performance of a steel-strengthened concrete panels, a numerical experiment using a numerical simulation with AUTODYN, an explicit analysis program is introduced because a real explosion experiment requires the vast investment and expense for facilities as well as the deformation mechanisms are too complicated to be reproduced with a conventional closed-form analyses. The model for the analysis is simplified and idealized as a two-dimensional and axisymmetric case controled with geometry, boundary condition and material properties in order to obtain a resonable computation time. As a result of the analysis, panels subject to either shock loading or fragment loading without the steel plate reinforcement experience the perforation with spalled fragments. In addition, the panels reinforced with steel plate can prevent the perforation and provide the good mechanical effect such as the increase of global stiffness and strength through the composite action between the concrete slab and the steel plate.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.197-202
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• 2008

In this paper, a hybrid vibration-impedance approaches is newly proposed to detect the occurrence of damage, the location of damage, and extent of damage in steel plate-girder bridges. The hybrid scheme mainly consists of three sequential phases: 1) to alarm the occurrence of damage, 2) to classify the alarmed damage, and 3) to estimate the classified damage in detail. Damage types of interest include flexural stiffness-loss in girder and bolts-loose in supports. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the alarmed damage is classified into subsystems by recognizing patterns of impedance features. In the final phase, the location and the extent of damage are estimated by using modal strain energy-based damage index method and root mean square deviation method. The feasibility of the proposed system is evaluated on a laboratory-scaled steel plate-girder bridge model for which hybrid vibration-impedance signatures were measured for several damage scenarios.

• 한국지진공학회논문집
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• 제11권4호
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• pp.13-23
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• 2007

This paper focuses on providing a practical approach for decision making in Performance-Based Design (PBD). Satisfactory performance is defined by several performance objectives that place limits on direct (monetary) loss and on a tolerable probability of collapse. No specific limits are placed on conventional engineering parameters such as forces or deformations, although it is assumed that sound capacity design principles are followed in the design process. The proposed design procedure incorporates different performance objectives up front, before the structural system is created, and assists engineers in making informed decisions on the choice of an effective structural system and its stiffness (period), base shear strength, and other important global structural parameters. The tools needed to implement this design process are (1) hazard curves for a specific ground motion intensity measure, (2) mean loss curves for structural and nonstructural subsystems, (3) structural response curves that relate, for different structural systems, a ground motion intensity measure to the engineering demand parameter (e.g., interstory drift or floor acceleration) on which the subsystem loss depends, and (4) collapse fragility curves. Since the proposed procedure facilitates decision making in the conceptual design process, it is referred to as a Design Decision Support System, DDSS. Implementation of the DDSS is illustrated in an example to demonstrate its practicality.

• Smart Structures and Systems
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• 제25권2호
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• pp.169-181
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• 2020

Sensor placement is a crucial aspect of bridge health monitoring (BHM) dedicated to accurately estimate and locate structural damages. In addressing this goal, a sensor placement framework based on the deflection influence line (DIL) analysis is here proposed, for the optimal design of damage detection-oriented BHM system. In order to improve damage detection accuracy, we explore the change of global stiffness matrix, damage coefficient matrix and DIL vector caused by structural damage, and thus develop a novel sensor placement framework based on the Fisher information matrix. Our approach seeks to determine the contribution of each sensing node to damage detection, and adopts a distance correction coefficient to eliminate the information redundancy among sensors. The proposed damage detection-oriented optimal sensor placement (OSP) method is verified by two examples: (1) a numerically simulated three-span continuous beam, and (2) the Pinghu bridge which has existing real damage conditions. These two examples verify the performance of the distance corrected damage sensitivity of influence line (DSIL) method in significantly higher contribution to damage detection and lower information redundancy, and demonstrate the proposed OSP framework can be potentially employed in BHM practices.

• 대한기계학회논문집A
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• 제22권1호
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• pp.23-32
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• 1998

A shape estimation is needed to control actively a smart structure. A method is, hence, proposed to predict the deformed shape of the structure subjected to unknown external load using the signal from sensors attached to the structure. The shape estimation is based on the relationship between the deformation of the structure and the signal from the sensors. The matrix containing the relationship between the deformation and signal is obtained using fictitious force or eigenvector of global stiffness matrix. Then the deformed shape can be predicted using the linear matrix and signal from sensors attached to the structure. To verify this method, experiment and FEM were performed and it was shown that the shape estimation method based on the fictitious force predicts deflections well and more accurately than that based on eigenvector.

• 대한기계학회논문집A
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• 제29권12권
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• pp.1586-1596
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• 2005

In this paper, a structural damage identification method (SDIM) is developed to identify the line crack-like directional damages generated within a cylindrical shell. First, the equations of motion for a damaged cylindrical shell are derived. Based on a theory of continuum damage mechanics, a small material volume containing a directional damage is represented by the effective orthotropic elastic stiffness, which is dependent of the size and the orientation of the damage with respect to the global coordinates. The present SDIM is then derived from the frequency response function (FRF) directly solved from the equations of motion of a damaged shell. In contrast with most existing SDIMs which require the modal parameters measured in both intact and damaged states, the present SDIM may require only the FRF-data measured at damaged state. By virtue of utilizing FRF-data, one may choose as many sets of excitation frequency and FRF measurement point as needed to acquire a sufficient number of equations for damage identification analysis. The numerically simulated damage identification tests are conducted to study the feasibility of the present SDIM.

• 한국도로학회논문집
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• 제13권2호
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• pp.21-29
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• 2011

최근 들어 온난화 등의 영향으로 태풍이나 집중호우가 빈번히 발생하고 있으며 이로 인한 산지 도로의 산사태, 토석류, 상향침투수압 등에 의한 인명, 시설물 피해도 극심하게 나타나고 있다. 산지 도로의 상향침투수압은 심각한 포장 파손을 발생시키기도 한다. 산지 측의 높은 지하수위로 인한 상향침투수압을 감소시키기 위해서는 지하배수공법이 매우 효과적 이라고 판단된다. 지하배수 공법을 원활하게 작동하기 위해서는 배수기층이 적합한 투수계수와 지지력을 갖추어야 한다. 따라서 본 연구에서는 적절한 투수성과 지반 지지력을 확보할 수 있는 최적의 배수기층 입도에 대한 연구를 수행하였다.