• 한국지진공학회논문집
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• 제5권3호
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• pp.29-36
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• 2001

국내 일반 국도상의 교량을 분석한 결과 형상비가 2.5 내외로서 휨-전단 파괴 거동이 예측되는 교각이 다수 존재하는 것으로 나타났으나 기존의 교각 내진 특성 연구는 주로 휨 파괴 거동을 보이는 교각에 대해 수행되어 왔다. 본 연구에서는 휨-전단 복합모드가 작용하여 파괴에 이를 가능성이 많은 형상비 2.5 내외인 기존 교각을 대상모델로 선정하고 실물크기 모형 및 축소모형 시험체를 제작하여 준정적 실험(quasi static test)을 수행하였다. 실험결과로부터 상사효과(scale effect)가 교각 내진 성능평가에 미치는 영향을 분석하였고, 또한 비내진 상세인 실험대상 교량에 대해 역량스펙트럼법을 이용하여 내진성능을 평가하였다.

• Structural Engineering and Mechanics
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• 제37권5호
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• pp.509-527
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• 2011

The paper investigates the dynamic buckling behaviour of a laminated composite stiffened cylindrical shell using the commercial finite element code ABAQUS. The numerical model of the composite shell is validated by static tests. In particular, the experimental collapse test is numerically simulated by a quasi static analysis carried out by both ABAQUS/Standard and ABAQUS/Explicit. The behaviour in the post-buckling field and the collapse load obtained by the analyses are close to the experimental data. The validated model is then used to study the dynamic buckling behaviour with ABAQUS/Explicit. The effects of the loading magnitude and of the loading duration are investigated, implementing in the analysis also first-ply failure criteria. It is observed that the dynamic buckling load is highly affected by the loading duration.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.209-216
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• 1999

In tunneling and road cuts by blasting, it is of the utmost importance that the remaining rock is of high quality in order to avoid rockfall, rockslides and excessive maintenance work. Therefore, numerous blasting techniques which make use of decoupled charge or shock wave superposition effect have been used to control overbrake. In this paper. some approximate method for the determination of blast load according to the charge condition was introduced at first and, instrumented tests were conducted in small scale transparent material to investigate the shape and amplitude of blast load around the bore hole. Compare to the fully coupled charge, low amplitude of blast load around the bore hole was observed in the decoupled charge and explosion gas pressure was important in the shape of blast load. Therefore, quasi-static behaviour of the crack pattern was shown due to low loading rate.

• Structural Engineering and Mechanics
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• 제37권2호
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• pp.197-213
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• 2011

Concrete is a heterogeneous material exhibiting quasi-brittle behaviour. While homogenization of concrete is commonly accepted in general engineering applications, a detailed description of the material heterogeneity using a mesoscale model becomes desirable and even necessary for problems where drastic spatial and time variation of the stress and strain is involved, for example in the analysis of local damages under impact, shock or blast load. A mesoscale model can also assist in an investigation into the underlying mechanisms affecting the bulk material behaviour under various stress conditions. Extending from existing mesoscale model studies, where use is often made of specialized codes with limited capability in the material description and numerical solutions, this paper presents a mesoscale computational model developed under a general-purpose finite element environment. The aim is to facilitate the utilization of sophisticated material descriptions (e.g., pressure and rate dependency) and advanced numerical solvers to suit a broad range of applications, including high impulsive dynamic analysis. The whole procedure encompasses a module for the generation of concrete mesoscale structure; a process for the generation of the FE mesh, considering two alternative schemes for the interface transition zone (ITZ); and the nonlinear analysis of the mesoscale FE model with an explicit time integration approach. The development of the model and various associated computational considerations are discussed in this paper (Part 1). Further numerical studies using the mesoscale model for both quasi-static and dynamic loadings will be presented in the companion paper (Part 2).

• Steel and Composite Structures
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• 제11권4호
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• pp.291-305
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• 2011

The new structure consisting of continuous compound spiral hoop reinforced concrete (CCSHRC)column and steel concrete composite (SCC) beam has both the advantages of steel structures and concrete structures. Two types of beam-to-column connections applied in this structural system are presented in this paper. The connection details are as follows: the main bars in beam concrete pass through the core zone for both types of connections. For connecting bar connection, the steel I-beam webs are connected by bolts to a steel plate passing through the joint while the top and bottom flanges of the beams are connected by four straight and two X-shaped bars. For bolted end-plate connection, the steel I-beam webs are connected by stiffened extended end-plates and eight long shank bolts passing through the core zone. In order to study the seismic behaviour and failure mechanisms of the connections, quasi-static tests were conducted on both types of full-scale connection subassemblies and core zone specimens. The load-drift hysteresis loops show a plateau for the connecting bar connection while they are excellent plump for bolted end-plate connection. The shear capacity formulas of both types of connections are presented and the values calculated by the formula agree well with the test results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.877-882
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• 2001

Lap splice in plastic hinge region of RC bridge piers is inevitable because of the constructional joint between footing and column. RC circular columns with lap-splice in plastic hinge region are widely used in Korean highway bridges. It is, however, believed that there are not many experimental research works for nonlinear behavior of these columns subjected to earthquake motions. This study has been performed to verify the effect of axial force, lap splice and confinement steel ratio for the seismic behaviour of reinforced concrete bridge piers. Quasi-static test have been done to investigate the physical seismic performance of RC bridge piers, such as displacement ductility and enemy absorption.

• Structural Engineering and Mechanics
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• 제55권5호
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• pp.913-929
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• 2015

The ratcheting and strain cyclic behaviour of joined conical-cylindrical shells under uniaxial strain controlled, uniaxial and multiaxial stress controlled cyclic loading are investigated in the paper. The elasto-plastic deformation of the structure is simulated using Chaboche non-linear kinematic hardening model in finite element package ANSYS 13.0. The stress-strain response near the joint of conical and cylindrical shell portions is discussed in detail. The effects of strain amplitude, mean stress, stress amplitude and temperature on ratcheting are investigated. Under strain symmetric cycling, the stress amplitude increases with the increase in imposed strain amplitude. Under imposed uniaxial/multiaxial stress cycling, ratcheting strain increases with the increasing mean/amplitude values of stress and temperature. The abrupt change in geometry at the joint results in local plastic deformation inducing large strain variations in the vicinity of the joint. The forcing frequency corresponding to peak axial ratcheting strain amplitude is significantly smaller than the frequency of first linear elastic axial vibration mode. The strains predicted from quasi static analysis are significantly smaller as compared to the peak strains from dynamic analysis.

• Steel and Composite Structures
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• 제33권1호
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• pp.19-36
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• 2019

Cyclic behaviour of composite (steel-concrete) plate shear walls (CPSW) with variable column flexural stiffness is experimentally and numerically investigated. The investigation included design, fabrication and testing of three pairs of one-bay one-storey CPSW specimens. The reference specimen pair was designed in way that its column flexural stiffness corresponds to the value required by the design codes, while within the other two specimen pairs column flexural stiffness was reduced by 18% and 36%, respectively. Specimens were subjected to quasi-static cyclic tests. Obtained results indicate that column flexural stiffness reduction in CPSW does not have negative impact on the overall behaviour allowing for satisfactory performance for up to 4% storey drift ratio while also enabling inelastic buckling of the infill steel plate. Additionally, in comparison to similar steel plate shear wall (SPSW) specimens, column "pull-in" deformations are less pronounced within CPSW specimens. Therefore, the results indicate that prescribed minimal column flexural stiffness value used for CPSW might be conservative, and can additionally be reduced when compared to the prescribed value for SPSWs. Furthermore, finite element (FE) pushover simulations were conducted using shell and solid elements. Such FE models can adequately simulate cyclic behaviour of CPSW and as such could be further used for numerical parametric analyses. It is necessary to mention that the implemented pushover FE models were not able to adequately reproduce column "pull-in" deformation and that further development of FE simulations is required where cyclic loading of the shear walls needs to be simulated.

• Composites Research
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• 제16권4호
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• pp.66-73
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• 2003

충격 시나 충격 후 압축 할 때 구조용 복합재의 거동에 대한 중요성은 충격 손상과 충격후압축강도 예측에 대한 해석적 모델을 개발하기 위해 간과될 수 없을 것이다. 본 연구는 3mm두께의 $[45/-45/0/90_{3s}$ - IM7/8552린복합재판들을 이용하여 준정적횡하중시험, 저속충격시험, 충격후압축강도시험 및 구멍이 있는 시편의 압축강도시험 등을 수행한 후 이로 부터 발견된 결과들을 제시하였다 준정적횡하중과 충격하중시험에서 발생한 손상면적들이 서로 유사하며. 또한 5.4 J 부터 18.7 J 까지의 다양한 에너지준위들을 가진 낙하충격 시험 곡선들과 정적시험 곡선들도 서로 유사하다는 결론을 얻었으며. 이때 주어진 에너지 준위에서 정적과 충격시의 최대하중 값들이 잘 일치한다는 사실을 확인 하였다. 충격 후 압축시험에 의한 시편들의 파괴거동이 압축하중하의 구멍이 있는 적층판에서 관찰된 파괴거동과 매우 유사하과는 사실도 확인 되었다. 충격손상 후 잔류강도는 충격손상 등가구멍이 있는 경우의 시편에서 측정된 압축 강도와 잘 일치 하였다. 이와 같은 실험적 연구 결과들은 충격손상면적과 충격후압축강도의 예측에 대한 단순만 해석모델들이 이들 시험결과들로부터 관찰된 파괴기구를 기초로 하여 개발될 수 있음을 제시하고 있다.

• Composites Research
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• 제27권2호
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• pp.42-46
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• 2014

본 연구에서는, 발포 폴리프로필렌의 충격에너지 흡수특성이 충격체 질량과 속도중 어느 변수에 더 많은 영향을 받는 지 고찰해 보기 위하여, 충격체 질량과 속도에 변화를 주어 5개의 조합을 만들고, 이 조합들이 동일한 초기 충격에너지 조건(100 J 및 200 J)이 될 수 있도록, 값을 선정한 뒤, 충격시험을 수행하여, 충격에너지 흡수특성을 실험적으로 규명하였다. 또한 발포 폴리프로필렌의 기본적인 특성을 파악하기 위하여, 준정적 시험(Quasistatic test)도 수행되었다. 준정적 시험은 MTS 858을 이용하였고, 충격시험을 위해, Instron dynatup 9250 HV가 사용되었다. 충격시험결과, 발포 폴리프로필렌은 충격체 속도에 비해 질량에 더 많은 영향을 받는 것으로 나타났다.