• 한국안전학회지
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• 제16권2호
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• pp.130-135
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• 2001

고속 전철 특징 중의 하나인 장대 레일의 사용으로 인하여 발생하는 추가 응력과 변위에 대하여 대만 고속전철 교량에 대해서 검토한다. 또한 대만 고속 전철 교량 시방 규정의 중요한 특징인 사용지진을 레일-구조물 해석에 고려하도록 하는 규정을 적용 후 단순교의 응력 및 상대변위를 검토한다. 지진 시 지반 운동을 고려하며, 단순교의 지진 응답을 변위로 레일-구조물 상호 작용 해석에 적용시킨다. 지진하중 고려 유무에 따른 단순교의 응력 및 상대 변위를 검토한다.

• Wind and Structures
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• 제38권1호
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• pp.1-13
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• 2024

In order to effectively simulate nonstationary stochastic turbulent wind fields, four separation hybrid (SEP-H) models are proposed in the present study. Based on the assumption that the lateral turbulence component at one single-point is uncorrelated with the longitudinal and vertical turbulence components, the fluctuating wind is separated into 2nV-1D and nV1D nonstationary stochastic vector processes. The first process can be expressed as double proper orthogonal decomposition (DPOD) or proper orthogonal decomposition and spectral representation method (POD-SRM), and the second process can be expressed as POD or SRM. On this basis, four SEP-H models of nonstationary stochastic turbulent wind fields are developed. In addition, the orthogonal random variables in the SEP-H models are presented as random orthogonal functions of elementary random variables. Meanwhile, the number theoretical method (NTM) is conveniently adopted to select representative points set of the elementary random variables. The POD-FFT (Fast Fourier transform) technique is introduced in frequency to give full play to the computational efficiency of the SEP-H models. Finally, taking a long-span bridge as the engineering background, the SEP-H models are compared with the dimension-reduction DPOD (DR-DPOD) model to verify the effectiveness and superiority of the proposed models.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.321-325
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• 2008

공정과 공사비는 건설 프로젝트의 관리에 있어서 매우 중요한 두 가지 요소로써, 그동안 이들을 통합 관리하려는 노력이 많이 이루어져 왔으나 국내의 국가계약법에 따른 내역체계의 한계점과 내역 및 WBS 표준화 작업의 미흡으로 인해 실제 시행에 많은 어려움을 겪고 있다. 본 연구에서는 최신관리기법인 BIM의 객체기반 3D 모델링 정보를 이용하여 비용과 일정정보를 연계하여 관리하는 방안을 제시하였다. 먼저 프로젝트 구성정보를 비용, 일정, 구조물의 부위별 구성요소로 나누고 각 구성정보에 의한 분류체계의 특징을 분석하였고, 국내의 내역중심 관리체계와 전체적인 관리 시스템 상의 한계를 감안하여 제약조건을 절정하고 작업분류체계(WBS)를 통한 일정정보를 중심으로 비용과 3D 모델링의 부위별 객체들을 연계하는 방안을 제시하였다. 제시된 방안의 검증을 위하여 대림산업에서 시공중인 청풍대교 현장에 대하여 사례연구를 실시하였으며, 이를 통하여 일정변화에 따른 시각화 및 비용예측 등의 기대효과를 확인하고 한계점 및 향후 추가 연구사항들을 가늠해볼 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.695-699
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• 2009

공정과 공사비는 건설 프로젝트의 관리에 있어서 매우 중요한 두 가지 요소로써, 그동안 이들을 통합 관리하려는 노력이 많이 이루어져 왔으나 국내의 국가계약법에 따른 내역체계의 한계점과 내역 및 WBS 표준화 작업의 미흡으로 인해 실제 시행에 많은 어려움을 겪고 있다. 본 연구에서는 최신관리기법인 BIM의 객체기반 3D 모델링 정보를 이용하여 비용과 일정정보를 연계하여 관리하는 방안을 제시하였다. 먼저 프로젝트 구성정보를 비용, 일정, 구조물의 부위별 구성요소로 나누고 각 구성정보에 의한 분류체계의 특징을 분석하였고, 국내의 내역중심 관리체계와 전체적인 관리 시스템 상의 한계를 감안하여 제약조건을 설정하고 작업분류체계(WBS)를 통한 일정정보를 중심으로 비용과 3D 모델링의 부위별 객체들을 연계하는 방안을 제시하였다. 제시된 방안의 검증을 위하여 대림산업에서 시공중인 청풍대교 현장에 대하여 사례연구를 실시하였으며, 이를 통하여 일정변화에 따른 시각화 및 비용예측 등의 기대효과를 확인하고 한계점 및 향후 추가 연구사항들을 가늠해볼 수 있었다.

• 대한토목학회논문집
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• 제26권1A호
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• pp.133-142
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• 2006

본 논문은 CHBDC(2000)에서 적용중인 지간 8 m까지 사용 가능한 지중강판 박스구조물의 휨모멘트 설계식을 평가하였다. 3단계의 시공과정(최소 토피고까지의 뒷채움, 토피고까지의 뒷채움, 활하중 재하)을 고려하고 대골형 파형강판을 사용하여 지간 3~12 m에 해당하는 지중강판 박스구조물의 수치해석을 수행하였다. 휨모멘트 계수식은 지간, 토피고, 뒷채움 흙 같은 다양한 설계변수를 고려한 수치해석 결과를 토대로 새롭게 제안되었다. 또한, CHBDC(2000)의 휨모멘트식에서 새롭게 제안된 계수식의 타당성은 기존의 계수식과 수치해석결과와 비교하여 평가되었다. 기존의 CHBDC(2000)의 식으로 구한 모멘트는 지간 8 m이하에서 수치해석 결과와 잘 일치하지만, 지간 8 m이상에서는 과소평가되었다. 반면에, 제안된 식으로 산정한 모멘트는 지간 3~12 m까지 수치해석결과와 잘 일치하였다. 한편, 본 논문은 지간 8 m이상의 장지간 지중강판 박스구조물에 대해 휨강도에 대한 안정성을 확보하기 위해 고강도강의 사용을 제안하였다.

• 대한치과보철학회지
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• 제35권4호
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• pp.793-800
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• 1997

Periotest(Siemens, Germany) has been used to test mobility of the implants clinically, however the effects of target materials and connection methods on the PTVs(Periotest Values) have not been evaluated. Periotest has been regarded as a reliable and objective tool to test implant and natural teeth mobility clinically, however this instrument showed different PTVs under various test conditions. This in vitro study was designed to compare PTVs of different veneering materials and prosthodontic designs (single and bridge restorations). To compare the effects of veneering materials on PTVs, 1 mm thickness of five different testing materials (porcelain, type III gold alloy, pure titanium, composite resin, acrylic resin) were placed on the resin block. Three full length of 13 mm Mark II implant fixtures were embedded into autopolymerizing resin block to fabricate single and bridge restorations. To evaluate effects of the connection method in single restorations, PTVs of screw retained(UCLA type) and cementation type(Cera-One system) were compared. Finally, to test reliability of PTVs of the final restorations, screw retained three unit short span PFM bridges were fabricated on the standard and Estheti-Cone abutments. All testing components were tightened with torque controller and PTVs of all specimens were measured 15 times for statistical analysis with SAS program. Following conclusions were made within the limit of this in vitro study. 1. PTVs of type III gold alloy, grade II titanium, composite resin veneering materials showed no significant differences, however acrylic resin and porcelain showed significant differences (P<0.05). 2. Single tooth restorations showed consistent PTVs as long as proper torque force was applied. 3. PTVs of bridge type prostheses was inconsistent regardless of abutment types. 4. PTVs of the prostheses showed higher scores and standard deviations than those of abutments regardless types of connection (P<0.05).

• Wind and Structures
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• 제20권5호
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• pp.701-718
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• 2015

The joint distribution of wind speed and wind direction at a bridge site is vital to the estimation of the basic wind speed, and hence to the wind-induced vibration analysis of long-span bridges. Instead of the conventional way relying on the weather stations, this study proposed an alternate approach to obtain the original records of wind speed and the corresponding directions based on field measurement supported by the Structural Health Monitoring System (SHMS). Specifically, SHMS of Sutong Cable-stayed Bridge (SCB) is utilized to study the basic wind speed with directional information. Four anemometers are installed in the SHMS of SCB: upstream and downstream of the main deck center, top of the north and south tower respectively. Using the recorded wind data from SHMS, the joint distribution of wind speed and direction is investigated based on statistical methods, and then the basic wind speeds in 10-year and 100-year recurrence intervals at these four key positions are calculated. Analytical results verify the reliability of the recorded wind data from SHMS, and indicate that the joint probability model for the extreme wind speed at SCB site fits well with the Weibull model. It is shown that the calculated basic wind speed is reduced by considering the influence of wind direction. Compared to the design basic wind speed in the Specification of China, basic wind speed considering the influence of direction or not is much smaller, indicating a high safety coefficient in the design of SCB. The results obtained in this study can provide not only references for further wind-resistance research of SCB, but also improve the understanding of the safety coefficient for wind-resistance design of other engineering structures in the similar area.

• 한국구조물진단유지관리공학회 논문집
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• 제17권2호
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• pp.54-61
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• 2013

사장교 케이블은 초기 큰 인장력으로 축강성이 매우 크지만, 횡방향 휨강성은 약하다. 풍하중이나 교통하중은 케이블을 심각하게 진동시켜 사장교의 사용성에 부정적 영향을 끼친다. 그러므로 장대교량에 감쇠장치를 설치하는 진동 저감 계획이 절실히 요구된다. 마찰댐퍼는 교통하중이나 풍하중과 같은 동적하중이 작용하는 케이블 진동에서 진폭과 지속시간을 대폭 감소시킬 수 있는 효과적인 장치임을 알 수 있다. 케이블 진동은 댐퍼제작방법과 설치위치 및 형상에 따라 효율이 달라질 수 있다. 그럼에도 불구하고 본 실험연구의 마찰댐퍼 설치전 후 제진성능효과 분석결과는 향후 사장케이블의 진동을 저감시키는 기본 자료로 활용할 수 있다.

• Earthquakes and Structures
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• 제16권1호
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• pp.11-28
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• 2019

This article investigates the response of Integral Abutment Bridges (IAB) when subjected to a sequence of seasonal thermal loading of the deck followed by ground seismic shaking in the longitudinal direction. Particular emphasis is placed on the effect of pre-seismic thermal Soil-Structure Interaction (SSI) on the seismic performance of the IAB, as well as on the ability of various backfills configurations, to minimize the unfavorable SSI effects. A series of two-dimensional numerical analyses were performed for this purpose, on a complete backfill-integral bridge-foundation soil system, subjected to seasonal cyclic thermal loading of the deck, followed by ground seismic shaking, employing ABAQUS. Various backfill configurations were investigated, including conventional dense cohesionless backfills, mechanically stabilized backfills and backfills isolated by means of compressive inclusions. The responses of the investigated configurations, in terms of backfill deformations and earth pressures, and bridge resultants and displacements, were compared with each other, as well as with relevant predictions from analyses, where the pre-seismic thermal SSI effects were neglected. The effects of pre-seismic thermal SSI on the seismic response of the coupled IAB-soil system were more evident in cases of conventional backfills, while they were almost negligible in case of IAB with mechanically stabilized backfills and isolated abutments. Along these lines, reasonable assumptions should be made in the seismic analysis of IAB with conventional sand backfills, to account for pre-seismic thermal SSI effects. On the contrary, the analysis of the SSI effects, caused by thermal and seismic loading, can be disaggregated in cases of IAB with isolated backfills.

• Wind and Structures
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• 제34권4호
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• pp.355-369
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• 2022

Section model test, as the most commonly used method to evaluate the aerostatic and aeroelastic performances of long-span bridges, may be carried out under different conditions of incoming wind speed, geometric scale and wind tunnel facilities, which may lead to potential Reynolds number (Re) effect, model scaling effect and wind tunnel scale effect, respectively. The Re effect and scale effect on aerostatic force coefficients and aeroelastic characteristics of streamlined bridge decks were investigated via 1:100 and 1:60 scale section model tests. The influence of auxiliary facilities was further investigated by comparative tests between a bare deck section and the deck section with auxiliary facilities. The force measurement results over a Re region from about 1×10⁵ to 4×10⁵ indicate that the drag coefficients of both deck sections show obvious Re effect, while the pitching moment coefficients have weak Re dependence. The lift coefficients of the smaller scale models have more significant Re effect. Comparative tests of different scale models under the same Re number indicate that the static force coefficients have obvious scale effect, which is even more prominent than the Re effect. Additionally, the scale effect induced by lower model length to wind tunnel height ratio may produce static force coefficients with smaller absolute values, which may be less conservative for structural design. The results with respect to flutter stability indicate that the aerodynamic-damping-related flutter derivatives 𝘈^*₂ and 𝐴^*₁𝐻^*₃ have opposite scale effect, which makes the overall scale effect on critical flutter wind speed greatly weakened. The most significant scale effect on critical flutter wind speed occurs at +3° wind angle of attack, which makes the small-scale section models give conservative predictions.