• Structural Engineering and Mechanics
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• 제64권5호
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• pp.611-620
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• 2017

A new theory of weightless sagging planer elasto-flexible cables under point loads is developed earlier by the authors and used for predicting the nonlinear dynamic response of cable-suspended linear elastic beams. However, this theory is not valid for nonlinear elastic cracked concrete beams possessing different positive and negative flexural rigidity. In the present paper, the flexural response of simply supported cracked concrete beams suspended from cables by two hangers is presented. Following a procedure established earlier, rate-type constitutive equations and third order nonlinear differential equations of motion for the structures undergoing small elastic displacements are derived. Upon general quasi-static loading, negative nodal forces, moments and support reactions may be introduced in the cable-suspended concrete beams and linear modal frequencies may abruptly change. Subharmonic resonances are predicted under harmonic loading. Uncoupling of the nodal response is proposed as a more general criterion of crossover phenomenon. Significance of the bilinearity ratio of the concrete beam and elasto-configurational displacements of the cable for the structural response is brought out. The relevance of the proposed theory for the analysis and the design of the cable-suspended bridges is critically evaluated.

• Structural Engineering and Mechanics
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• 제90권1호
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• pp.71-81
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• 2024

Fiber Reinforced Polymer (FRP) bars have now been widely adopted as an alternative to traditional steel reinforcements in infrastructure and civil industries worldwide due variety of merits. This paper presents a numerical methodology to investigate FRP bar-reinforced beam-column joint behavior under quasi-static loading. The proposed numerical model is validated with test results considering load-deflection behavior, damage pattern at beam-column joint, and strain variation in reinforcements, wherein the results are in agreement. The numerical model is subsequently employed for parametric investigation to enhance the end-span beam-column joint performance using different joint reinforcement systems. To reduce the manufacturing issue of bend in the FRP bar, the headed FRP bar is employed in a beam-column joint, and performance was investigated at different column axial loads. Headed bar-reinforced beam-column joints show better performance as compared to beam-column joints having an L-bar in terms of concrete damage, load-carrying capacity, and joint shear strength. The applicability and efficiency of FRP bars at different story heights have also been investigated with varying column axial loads.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 가을 학술발표회 논문집
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• pp.176-183
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• 1996

A new iterative scheme is proposed for finite element analysis of wrinkling or tension structures. This enables us to update the stress state and the internal forces correctly taking into account the existence of wrinkling. The finite element implementation of the scheme is straightforward and simple, and only minor modifications of the existing total Lagrangian finite element codes for membranes are needed. The validity of the scheme is demonstrated via numerical examples for the torsion of a membrane and the quasi-static inflation of an automotive airbag, both made of isotropic or anisotropic elastic membranes

• 전산구조공학
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• 제9권1호
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• pp.101-113
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• 1996

준-정적 선형 2차원 열점탄성 문제들의 유한요소해석을 위하여 가상일의 원리를 근거로 하여 새로운 변분공식과 유한요소방정식을 유도한다. 이때 점탄성 재료는 열유동학적으로 단순한 물성을 갖는다. T=T(x)일 경우에 유전적 강성행렬들의 효율적이고 단순화된 계산과정을 소개한다. 몇몇 예제를 해석하고 기존의 발표된 수치결과들과 비교 검토하여 정확성 및 경제성을 입증한다.

• Structural Engineering and Mechanics
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• 제4권6호
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• pp.655-678
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• 1996

The paper reports on alternative hybrid/mixed formulations being developed by the Structural Analysis Research Group of Institute Superior T$\acute{e}$cnico. These formulations open the scope and increase the power of the finite element method by allowing different fields to be independently approximated, within certain consistency criteria, and by enhancing the use of a wide range of approximation functions. They have been applied to the analysis of 2-D problems, laminar structures and solids, using different constitutive relations, both in quasi-static and dynamic regimes. The fundamental properties of the formulations are identified and assessed and their performance is illustrated using simple, linear applications.

• 대한기계학회논문집A
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• 제39권10호
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• pp.1039-1044
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• 2015

차량의 개발단계에서 내구성 평가는 많은 시간과 비용이 소요된다. 최근 완성차 업체들은 자사만의 내구성 평가방법을 개발하고 수정 보완하는데 많은 노력을 기울이고 있다. 본 연구는 토션빔 액슬의 내구성 평가를 위한 통합 CAE 기법을 개발함에 있어 세계적인 자동차 업체의 정형화된 CAE 기법과의 비교를 통해 경제성을 평가하고 실험적 방법을 통해 얻은 데이터와의 비교를 통해 신뢰성을 확보하는 것을 목표로 하였다. 이를 위해 현재까지 널리 사용되어 온 준정적 내구해석의 과정 및 결과에서 보완점과 문제점을 분석하였고, 업계의 요구사항을 면밀히 검토하여 정규모드해석을 통해 다물체 동역학 모델을 구성하고 이를 이용한 동역학 해석을 진행한 후 그 결과를 이용하여 내구해석인 공진 내구해석 기법을 제안하였다.

• Structural Engineering and Mechanics
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• 제61권4호
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• pp.483-496
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• 2017

Earthquake excitations may induce important amount of seismic energy into structures. Current design philosophy mainly deals with the plastic deformations of replaceable energy dissipating devices rather than damages accumulated on structural members. Since earthquake damage is substantially concentrated on these devices they could be replaced after severe earthquakes. In this study, the efficiency of steel cushion (SC) on seismic improvement of a vulnerable reinforced concrete (RC) frame is determined by means of several numerical simulations. The cyclic shear behaviors of SCs were determined by performing quasi-static tests. The test results were the main basis of the theoretical model of SCs which were used in the numerical analysis. These analyses were performed on three types of RC frames namely bare frame (BF), full-braced frame (F-BF) and semi-braced frame (S-BF). According to analysis results; implementation of SCs has considerable effects in reducing the storey shear forces and storey drifts. Moreover plastic energy demands of structural elements were reduced which indicates a significant improvement in seismic behavior of the RC frame preventing damage accumulation on structural elements. Full-braced frame having SCs with the thickness of 25 mm has better performance than semi-braced frame interms of energy dissipation. However, global energy dissipation demand of S-BF and F-BF having SCs with the thickness of 18 mm are almost similar.

• 대한조선학회논문집
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• 제53권2호
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• pp.108-114
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• 2016

Recently, there has been a growing interest in marine leisure sports and high speed power boat for fishing. The prototype of 20 feet class power boat was developed and authors are joined in this government-led project. The research was performed to evaluate the optimal structure and design of the structural strength necessary to ensure the structural safety of the power boat. A new material ROCICORE fiber added to the mat and roving was adopted for high-power tenacity. ANSYS Workbench has been used to make the structural model, evaluate the strength and optimize the structural design. The response of the structure to quasi-static slamming loads according to the rules and regulations of ISO 12215-5, Lloyd’s Register of Shipping and Korean Register has been implemented and studied. An optimization study for the structural response is carried out by changing the plate thickness and section modulus of stiffeners. The power boat structure derived fuel efficiency is optimized by performing the best possible structural design to minimize the hull weight.

• Computers and Concrete
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• 제20권5호
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• pp.539-544
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• 2017

Shear walls have high stiffness and strength; however, they lack energy dissipation and repairability. In this study, an innovative slotted shear wall featuring vertical slots and steel energy dissipation connectors was developed. The ductility and energy dissipation of the shear wall were improved, while sufficient bearing capacity and structural stiffness were retained. Furthermore, the slotted shear wall does not support vertical forces, and thus it does not have to be arranged continuously along the height of the structure, leading to a much free arrangement of the shear wall. A frame-slotted shear wall structure that combines the conventional frame structure and the innovative shear wall was developed. To investigate the ductility and hysteretic behavior of the slotted shear wall, finite element models of two walls with different steel connectors were built, and pushover and quasi-static analyses were conducted. Numerical analysis results indicated that the deformability and energy dissipation were guaranteed only if the steel connectors yielded before plastic hinges in the wall limbs were formed. Finally, a modified D-value method was proposed to estimate the bearing capacity and stiffness of the slotted shear wall. In this method, the wall limbs are analogous to columns and the connectors are analogous to beams. Results obtained from the modified D-value method were compared with those obtained from the finite element analysis. It was found that the internal force and stiffness estimated with the modified D-value method agreed well with those obtained from the finite element analysis.

• 한국안전학회지
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• 제32권3호
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• pp.54-59
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• 2017

This paper presents an efficient finite analysis model and a simulation-based reliability analysis method for stowage device system failure of a container crane with respect to lateral load. A quasi-static analysis model is introduced to simulate the nonlinear resistance characteristics and failure of tie-down and stowage pin, which are the main structural stowage devices of a crane. As a reliability analysis method, a subset simulation method is applied considering the uncertainties of later load and mechanical characteristic parameters of stowage devices. An efficient Markov chain Monte Carlo (MCMC) method is applied to sample random variables. Analysis result shows that the proposed model is able to estimate the probability of failure of crane system effectively which cannot be calculated practically by crude Monte Carlo simulation method.