• 한국강구조학회 논문집
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• 제16권3호통권70호
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• pp.325-332
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• 2004

강합성거더 교량의 단면은 강거더와 콘크리트 슬래브의 합성정도에 따라 각각 비합성, 부분합성 그리고 완전합성 단면들로 구분 할 수 있다. 국내의 경우 강합성거더 교량의 단면을 합성시키기 위하여 일반적으로 전단 연결재 중 스터드를 사용하도록 규정하고 있고, 진단 연결재가 없는 경우 즉 비합성 단면의 경우에는 바닥판 앵커를 설치하도록 경험적으로 규정하고 있다. 그러나 바닥판 앵커를 사용한 단면의 실제 거동은 비합성 거동이 아닌 부분합성의 거동을 나타낸다. 그러한 이유로 본 연구에서는 바닥판 앵커를 사용한 플레이트거더교의 부분합성에 관한 해석 및 실험연구를 수행하였다. 실험연구를 통해서 바닥판 앵커의 초기강성을 산정하였고, 해석연구를 통해서 바닥판 앵커를 사용한 단순 및 2경간 연속 플레이트거더교의 합성정도를 비교$\cdot$분석하였다. 또한, 실험에 의해 산정된 강성 값에 근거하여, 2경간 연속 플레이트거더교에 바닥판 앵커를 적용하였을 때 발생할 수 있는 내부지점부 콘크리트의 인장응력 저감 효과를 검토하였다.

• Smart Structures and Systems
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• 제4권5호
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• pp.605-628
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• 2008

In bridge structures, damage may induce an additional deflection which may naturally contain essential information about the damage. However, inverse mapping from the damage-induced deflection to the actual damage location and severity is generally complex, particularly for statically indeterminate systems. In this paper, a new load concept, called the positive-bending-inspection-load (PBIL) is proposed to construct a simple inverse mapping from the damage-induced deflection to the actual damage location. A PBIL for an inspection region is defined as a load or a system of loads which guarantees the bending moment to be positive in the inspection region. From the theoretical investigations, it was proven that the damage-induced chord-wise deflection (DI-CD) has the maximum value with the abrupt change in its slope at the damage location under a PBIL. Hence, a novel damage localization method is proposed based on the DI-CD under a PBIL. The procedure may be summarized as: (1) identification of the modal flexibility matrices from acceleration measurements, (2) design for a PBIL for an inspection region of interest in a structure, (3) calculation of the chord-wise deflections for the PBIL using the modal flexibility matrices, and (4) damage localization by finding the location with the maximum DI-CD with the abrupt change in its slope within the inspection region. Procedures from (2)-(4) can be repeated for several inspection regions to cover the whole structure complementarily. Numerical verification studies were carried out on a simply supported beam and a three-span continuous beam model. Experimental verification study was also carried out on a two-span continuous beam structure with a steel box-girder. It was found that the proposed method can identify the damage existence and damage location for small damage cases with narrow cuts at the bottom flange.

• 한국강구조학회 논문집
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• 제14권6호
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• pp.691-699
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• 2002

본 논문에서는 수직 및 수평 브레이싱을 생략하고 I-형 거더를 가로보만으로 연결한 다주형 강합성 플레이트거더교 형식에서 가로보의 적정 배치 간격 및 소요 휨강성의 산정을 위한 연구를 수행하였다. 이를 위해 지간 40m의 단순교와 40+50+40m의 2차로 4주형 연속교를 예제교량으로 시산 설계하였다. 본 교량에 대해 중간가로보의 배치 간격과 휨강성를 매개변수로 하여 합성전 후 고정하중, 활하중 및 지진하중을 포함하는 설계하중에 대한 응력 해석을 수행한 후 강재 주형 및 라로보의 격자구조에 대해 합성전 고정하중을 고려한 재료-기하비선형해석으로부터 횡비틀림 좌굴강도를 평가하였다. 이상의 두 가지 국면 해석 결과를 토대로 단부 및 중간가로보의 적정 배치 간격과 소요 휨강성을 제안하였다.

• Smart Structures and Systems
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• 제24권1호
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• pp.127-139
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• 2019

Residual drifts after an earthquake can incur huge repair costs and might need to replace the infrastructure because of its non-reparability. Proper functioning of bridges is also essential in the aftermath of an earthquake. In order to mitigate pounding and unseating damage of bridges subjected to earthquakes, a self-adaptive Ni-Ti shape memory alloy (SMA)-cable-based frictional sliding bearing (SMAFSB) is proposed considering self-adaptive centering, high energy dissipation, better fatigue, and corrosion resistance from SMA-cable component. The developed novel bearing is associated with the properties of modularity, replaceability, and earthquake isolation capacity, which could reduce the repair time and increase the resilience of highway bridges. To evaluate the super-elasticity of the SMA-cable, pseudo-static tests and numerical simulation on the SMA-cable specimens with a diameter of 7 mm are conducted and one dimensional (1D) constitutive hysteretic model of the SMAFSB is developed considering the effects of gap, self-centering, and high energy dissipation. Two types of the SMAFSB (i.e., movable and fixed SMAFSBs) are applied to a two-span continuous reinforced concrete (RC) bridge. The seismic vulnerabilities of the RC bridge, utilizing movable SMAFSB with the constant gap size of 60 mm and the fixed SMAFSBs with different gap sizes (e.g., 0, 30, and 60 mm), are assessed at component and system levels, respectively. It can be observed that the fixed SMAFSB with a gap of 30 mm gained the most retrofitting effect among the three cases.

• Smart Structures and Systems
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• 제11권1호
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• pp.123-134
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• 2013

Identifying structural modal parameters, especially those modes within high frequency range, from ambient data is still a challenging problem due to various kinds of uncertainty involved in vibration measurements. A procedure applying an ensemble empirical mode decomposition (EEMD) method is proposed for accurate and robust structural modal identification. In the proposed method, the EEMD process is first implemented to decompose the original ambient data to a set of intrinsic mode functions (IMFs), which are zero-mean time series with energy in narrow frequency bands. Subsequently, a Sub-PolyMAX method is performed in narrow frequency bands by using IMFs as primary data for structural modal identification. The merit of the proposed method is that it performs structural identification in narrow frequency bands (take IMFs as primary data), unlike the traditional method in the whole frequency space (take original measurements as primary data), thus it produces more accurate identification results. A numerical example and a multiple-span continuous steel bridge have been investigated to verify the effectiveness of the proposed method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.477-482
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• 2003

The railway bridges on the new high-speed line are the first structures designed and constructed by our local engineers for high-speed running. In securing running stability and riding comfort in high-speed running, it is very important to verify the performance of structures and local specifications and design criteria by measuring and analyzing the dynamic behavior of main structural members. In this study, 4 different types(simple-span, 2, 3, 4-continuous spans) of PCS Box bridges on the test line(Yongwa$\~$Simok section) were selected, each representing a different type of superstructures, in order to verify the performance of the bridges by measuring dynamic responses during the test-run of KTX. Reviews of the running stability and the riding comfort were carried out with the results of the measurement and the analyses of vibration acceleration, endrotation, distortion and deflection at midspan.

• Structural Engineering and Mechanics
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• 제48권2호
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• pp.275-289
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• 2013

The cross sections of multi-span beams are sometimes suddenly increased at the interior support of continuous beams to resist high negative moment. An earlier study on elastic lateral torsional buckling of stepped beams was conducted to propose new design equations. This research aims to continue the earlier study by considering the effect of inelastic buckling of stepped beams subjected to pure bending and general loading condition. A three-dimensional finite element-program ABAQUS and a statistical program MINITAB were used in the development of new design equations. The inelastic lateral torsional buckling strengths of 36 and 27 models for singly and doubly stepped beams, respectively, were investigated. The general loading condition consists of 15 loading cases based on the number of inflection point within the unbraced length of the stepped beams. The combined effects of residual stresses and geometrical imperfection were also considered to evaluate the inelastic buckling strengths. The proposed equations in this study will definitely improve current design methods for the inelastic lateral-torsional buckling of stepped beams and will increase efficiency in building and bridge design.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.382-387
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• 2003

This research has investigated structural characteristics of curved two girder bridges proposed for AGT system and analyzed the results of the structural analysis of three different modelings for 3 span continuous bridge, each modeled in grillage modeling, simplified 3D modeling, and detailed 3D modeling respectively. The grillage modeling appeared to be somewhat underestimated in deflection and overestimated in rotation with respect to 3D modelings. Also, it is impossible to make a detailed examination of local buckling and details of cross beams, etc. The point that warping effect cannot be considered may cause the structural analysis unsafe, accordingly the structural analysis of curved two girder bridges should be done with 3D modelings.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.236-243
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• 1999

A comparative study on aseismatic performances of various base isolation systems for the multi-span continuous bridge is carried out. Several leading base isolation systems the LRB system the RF system the R-FBI system and the EDF system are considered, The displacement of the deck the deformation of the upper ends of the piers the shear force and the bending moment of the lower ends of the piers are obtained by using the accelerograms of the N00W component of El Centro earthquake(1940) and the N90W component of Mexico City earthquake(1985) Nonlinear time-history analysis is carried out. comparisons of the results with the conventional bearing show that the base isolation systems are very effective in reducing the forces transmitted to the superstructures. Furthermore the results also show that the friction-type base isolation systems are less sensitive to unexpected variations in frequency content of the ground acceleration. The R-FBI system shows a good aseismatic performance comparing with other base isolation systems.

• Earthquakes and Structures
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• 제1권1호
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• pp.21-41
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• 2010

Multi-span steel-concrete composite (SCC) bridges are very sensitive to earthquake loading. Extensive damage may occur not only in the substructures (piers), which are expected to yield, but also in the other components (e.g., deck, abutments) involved in carrying the seismic loads. Current seismic codes allow the design of regular bridges by means of linear elastic analysis based on inelastic design spectra. In bridges with superstructure transverse motion restrained at the abutments, a dual load path behavior is observed. The sequential yielding of the piers can lead to a substantial change in the stiffness distribution. Thus, force distributions and displacement demand can significantly differ from linear elastic analysis predictions. The objectives of this study are assessing the influence of piers-deck stiffness ratio and of soil-structure interaction effects on the seismic behavior of continuous SCC bridges with dual load path, and evaluating the suitability of linear elastic analysis in predicting the actual seismic behavior of these bridges. Parametric analysis results are presented and discussed for a common bridge typology. The response dependence on the parameters is studied by nonlinear multi-record incremental dynamic analysis (IDA). Comparisons are made with linear time history analysis results. The results presented suggest that simplified linear elastic analysis based on inelastic design spectra could produce very inaccurate estimates of the structural behavior of SCC bridges with dual load path.