• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.6
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• pp.705-719
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• 2017

Progressive Collapse Method (PCM) has been broadly applied to predict moment-carrying capacity of a hull girder, however accuracy of PCM has not been much studied. Accuracy of PCM is known to be dependent on how Load-Shortening and -Elongation (LSE) curve of a structural units are well predicted. This paper presents a new procedure to determine LSE datum based on box girder Finite Element Analyses (FEAs) instead of using finite element model of stiffened panels. To verify reliability of FEA results, the simple box girder collapse test results are compared with FEA results of same box girders. It reveals one frame-based box girder model is sufficiently accurate in terms of ultimate strengths of the box girders. After extracting LSE data from the box girders, PCM-based moment-carrying capacities are compared with those from FEAs of the box girders. PCM results are found to be equivalent to FEAs in terms of moment-carrying capacity if accurate LSE data are secured. The new procedure is applied to well-known 1/3 scaled frigate full section. Very excellent moment-carrying capacity of frigate hull section is obtained from PCM with LSE data from box girder FEAs.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.74-80
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• 2016

In this paper, structural characteristics for an extradosed prestressed concrete box girder bridge are investigated in terms of selective parameters. These parameters are mainly associated with the structural details of the extradosed bridge and derived from currently available literatures regarding previous design drawings. The analyses have been carried out using general-purpose structural analysis program, RM-Space Frame. The parameters evaluated for the present study represent the most salient features of the extradosed bridge and are as follows; 1) span length ratio(side-span length to center-span length), 2) boundary condition of girder, 3) height of pylon, 4) anchorage location of external cables and 5) girder stiffness. The analytical predictions indicate that span length ratio and pylon height are reasonably adequate in the range of 0.55 to 0.60 and $L_m/8$ to $L_m/12$ respectively for the bridge under consideration. Also, demonstrated is the boundary condition of girder, in which rigid-connection details give more efficiency than the continuous details. In addition, considering structural characteristics of the extradosed bridge, it is desirable that the girder stiffness should be determined by the stress range of external cables rather than bending moment of girder.

• Smart Structures and Systems
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• v.21 no.5
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• pp.549-559
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• 2018

The dynamic behaviors of the bridge structures have great effects on the comfortability and safety of running high-speed trains, which can also reflect the structural degradation. This paper aims to reveal the characteristics of the dynamic behaviors induced by train loadings for a combined highway and railway bridge. Monitoring-based analysis of the acceleration and dynamic displacement of the bridge girder is carried out. The effects of train loadings on the vertical acceleration of the bridge girder are analyzed; the spatial variability of the train-induced lateral girder displacement is studied; and statistical analysis has been performed for the daily extreme values of the train-induced girder deflections. It is revealed that there are great time and spatial variabilities for the acceleration induced by train loadings for the combined highway and railway cable-stayed bridge. The daily extreme values of the train-induced girder deflections can be well fitted by the general extreme value distribution.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.135-143
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• 2004

In this paper, 6 span SCP continuous girder bridge's structural behavior were studied by analytic and experimental method To study structural behavior of SCP girder, we used PSC theory and steel girder theory. To examine slab concrete crack, concrete stress, and fatigue stress of steel, we achieved a static load and fatigue test. In the result, 6 span SCP girder bridge connected at the interior support about actuality bridge have enough structural capacity under service loads.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.407-416
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• 2000

This paper presents the dynamical responses of the plate girder bridge subjected to moving load by experimental method. The upper slab of the plate girder bridges is modelled to the plate element and the girder to the beam element. The small-scaled vehicle model is manufactured as moving load and the acryl-bridge model as the plate-girder bridge. The dynamic responses of the plate-girder bridges under the moving load are obtained by the strain gauges, displacement measurements, accelerometer, and dynamic strain measurement. The maximum dynamic responses from the measured data are compared with those from the finite element method. The experimental model test can be used to obtain to the dynamic responses of the plate-girder bridges.

• Earthquakes and Structures
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• v.8 no.6
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• pp.1481-1497
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• 2015

Vertical earthquake ground motion may magnify vertical dynamic responses of structures, and thus cause serious damage to bridges. As main support structures, piers and bearings play an important role in vertical seismic response analysis of girder bridges. In this study, the pier and bearing are simplified as a vertical series spring system without mass. Then, based on the assumption of small displacement, the equation of motion governing the simply-supported straight girder bridge under vertical ground motion is established including effects of vertical deformation of support structures. Considering boundary conditions, the differential quadrature method (DQM) is applied to discretize the above equation of motion into a MDOF (multi-degree-of-freedom) system. Then seismic responses of this MDOF system are calculated by a step-by-step integration method. Effects of support structures on vertical dynamic responses of girder bridges are studied under different vertical strong earthquake motions. Results indicate that support structures may remarkably increase or decrease vertical seismic responses of girder bridges. So it is of great importance to consider effects of support structures in structural seismic design of girder bridges in near-fault region. Finally, optimization of support structures to resist vertical strong earthquake motions is discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.80-85
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• 2011

For the assessment of statistical characteristics of wave loads in the real sea state, the probability distribution of wave loads are computed based on the sufficient duration of computations in irregular waves. First of all, the estimation of wave impact loads is well modified applying the displacement potential formulation, which was proposed by one of authors, for solving Wagner's flow model. Consequently, the present computation method is also modified. Prior to the computation in irregular waves, preliminary computation to determine the adequate number of realization of irregular waves is examined. The effect of hull girder vibration on the statistical characteristics is examined by means of the computation with/without hull girder vibration. It is found that hull girder vibration has a certain effect on the probability of occurrence of wave loads. Furthermore, computations taking account of the effect of operation, that is the effects of ship speed and course change, is conducted for the rational evaluation of the effects of hull girder vibration. It is clarified that the effect of operation on the statistical characteristics of wave loads is significant. It is verified that the evaluation without the effect of operation may overestimate the effect of hull girder vibration.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.109-116
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• 2012

This paper presents a study on the nonlinear behavior of an innovative bridge girder made from concrete-filled and tied tubular steel arch (CFTA) under static loading. Manufacturing of the CFTA girder may have defects which may highly affect the symmetry and performance of the structure. A simple method is proposed by using stiffness extracted from static test data to detect manufacturing defects of the CFTA girder. A three-dimensional finite element model was used in the numerical analysis in order to verify the method. The proposed method was experimentally validated through static tests of the CFTA girder. The application of the proposed method showed that it is effective in identifying invisible manufacturing defects of the CFTA girder, especially for mass production of a standard type in the factory.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.131-142
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• 1999

The general behavior of the curved girder including the warping effects can be presented as the series of differential equations developed by Vlasov. Generally, bending moment is the most important factor for engineer to decide the section of the girder. In order to accommodate easiness of the structural analysis for the curved girder bridge, this paper suggest the ratios of bending moment of curved gilder to that of straight girder. These ratios are presented by an approximate formula setting central angle ${\theta}(L/R)$ as a variable. The approximate formula of the maximum bending moment ratios and influence lines of all stress resultants can be used to design the three-span curved girder bridges.

• Structural Engineering and Mechanics
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• v.40 no.5
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• pp.719-743
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• 2011

A hybrid damage monitoring scheme using parallel acceleration-impedance approaches is proposed to detect girder damage and support damage in steel plate-girder bridges which are under ambient train-induced excitations. The hybrid scheme consists of three phases: global and local damage monitoring in parallel manner, damage occurrence alarming and local damage identification, and detailed damage estimation. In the first phase, damage occurrence in a structure is globally monitored by changes in vibration features and, at the same moment, damage occurrence in local critical members is monitored by changes in impedance features. In the second phase, the occurrence of damage is alarmed and the type of damage is locally identified by recognizing patterns of vibration and impedance features. In the final phase, the location and severity of the locally identified damage are estimated by using modal strain energy-based damage index methods. The feasibility of the proposed scheme is evaluated on a steel plate-girder bridge model which was experimentally tested under model train-induced excitations. Acceleration responses and electro-mechanical impedance signatures were measured for several damage scenarios of girder damage and support damage.