• Structural Monitoring and Maintenance
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• v.1 no.3
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• pp.249-271
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• 2014

This paper presents a unique study of Structural Health Monitoring (SHM) for the maintenance decision making about a real life movable bridge. The mechanical components of movable bridges are maintained on a scheduled basis. However, it is desired to have a condition-based maintenance by taking advantage of SHM. The main objective is to track the operation of a gearbox and a rack-pinion/open gear assembly, which are critical parts of bascule type movable bridges. Maintenance needs that may lead to major damage to these components needs to be identified and diagnosed timely since an early detection of faults may help avoid unexpected bridge closures or costly repairs. The fault prediction of the gearbox and rack-pinion/open gear is carried out using two types of Artificial Neural Networks (ANNs): 1) Multi-Layer Perceptron Neural Networks (MLP-NNs) and 2) Fuzzy Neural Networks (FNNs). Monitoring data is collected during regular opening and closing of the bridge as well as during artificially induced reversible damage conditions. Several statistical parameters are extracted from the time-domain vibration signals as characteristic features to be fed to the ANNs for constructing the MLP-NNs and FNNs independently. The required training and testing sets are obtained by processing the acceleration data for both damaged and undamaged condition of the aforementioned mechanical components. The performances of the developed ANNs are first evaluated using unseen test sets. Second, the selected networks are used for long-term condition evaluation of the rack-pinion/open gear of the movable bridge. It is shown that the vibration monitoring data with selected statistical parameters and particular network architectures give successful results to predict the undamaged and damaged condition of the bridge. It is also observed that the MLP-NNs performed better than the FNNs in the presented case. The successful results indicate that ANNs are promising tools for maintenance monitoring of movable bridge components and it is also shown that the ANN results can be employed in simple approach for day-to-day operation and maintenance of movable bridges.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.51-57
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• 1999

Recently, long large bridges are built for mass transportation. Movable bearing shoes are important components of the bridges because they support movement of translation and rotation of bridge. In design stage of the long large bridges, detailed analyses using the finite element method are performed to guarantee safety and reliability. For that purpose, three-dimensional modeling is carried out by I-DEAS software and finite element analysis by ANSYS software. Results of the analyses are reviewed and important design factors for movable bearing shoes are discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.317-327
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• 2001

In this paper, a relation to calculate design moments for reinforced concrete(RC) bridges constructed by movable scaffolding system(MSS) is introduced. Through the time-dependent analysis of RC bridges considering the construction sequence, the structural responses related to the member forces and deflections are reviewed, and a governing equation for determination of the design moment, which includes the creep deformation, is derived on the basis of the displacement-force condition at every constructuion stage. By using the relation, the design moment and its variation over time can easily be obtained only with the elastic analysis results without additional time-dependent analysis. In addition, correlation studies with the results by rigorous numerical analyses are conducts to verify the applicability of the introduced relation, and a more reasonable guideline for the determination of design moments is proposed on the basis of the obtained moment envelop.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.203-211
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• 2008

Bridges have various functions. There are not only a connection between 2 zones, but also a objee as a landmark. But movable bridges used in canal in order to pass ships. We can classify according to type of driving system, for example, swing, bascule, lift, arching, rotation, etc. I will suggest classification of various driving mechanism in the world.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.167-174
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• 2005

Through time-dependent analyses of RC bridges constructed by a movable scaffolding system (MSS) considering the construction sequence and creep deformation of concrete, structural responses related to the member forces are reviewed. On the basis of the compatibility condition and equilibrium equation at every construction stage, basic equations that can describe the moment variation with time in movable scaffolding construction are derived. By using the introduced relations, the design moment and its variation over time can easily be obtained with only the elastic analysis results and without additional time-dependent analyses considering the construction sequences. In addition, the design moments determined by the introduced equations are compared with the results from a rigorous numerical analysis with the objective of establishing the relative efficiencies of the introduced equations.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.70-76
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• 1994

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.1-13
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• 2013

Most rahmen-type temporary bridges are constructed with limited bridge length to prevent excessive horizontal forces due to the thermal expansion of main girder. To achieve a long length temporary bridge several independent bridges are required and they can not share the bents, at the rahmen-type ends, with the adjacent ones. The additional bents require more cost and reduce the section space under bridges. In order to remove extra bents with keeping the rahmen effect at the bridge ends, this study proposes a new rahmen-type movable joint system for temporary bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.657-664
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• 2008

Rain-wind induced cable vibration can cause the damages in the cable-stayed bridge due to very little inherent damping characteristics and low fundamental frequency. External Dampers attached to stay cables near anchorages have been shown to be effective means at short stay-cables. However, installation locations of external dampers are limited to a particular range due to aesthetic and practical reasons for very long stay-cables. A recent study by the authors showed that the stay-cable vibration system can perform better than the optimal passive viscous damper, thereby demonstrating its applicability in large cable-stayed bridges. This paper extends the previous study on the taut string representation of the cable by adding cable sag and inclination. The response of the proposed system compared to those of the cable with and without an external damper, and the movable anchorage system provides very effective mitigation of cable vibration. Cable damping ratio is seen to be remarkably reduced by movable anchorage system for a wide range of cable sag. This result shows that the sag effects of the proposed system should be considered.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.812-817
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• 2004

Recently drastic improvement of railway technology has been accompanied by the construction of very high-speed tracks. It should be noticed that Continuously Welded Rail(CWR) has played significant role in technical development of railway and that installation of CWR is now being scheduled on existing lines as well as newly-built lines. In general, interaction between CWR and bridge deck takes place on bridge section and additional axial force and displacement is to be developed owing to temperature and braking/acceleration forces. This interaction is known to be mainly governed by span organizations and arrangements of foot bearings. In common practice, movable bearing is stationed and designed on the assumption that it is not able to transfer the horizontal force of upper decks. However, it is well known that horizontal resistance is developed in movable bearings due to friction and that friction coefficient of movable bearing is ranged from 0.03 to 0.20 depending on the material of bearings and magnitude of reactions. Therefore, it is easily reasoned out that friction of movable bearing can influence the mutual behavior of CWR and bridge decks. Suggested in this study is to investigate the validity and efficiency of friction effect of movable bearings in controlling the axial force and displacement of CWR on continuous railway bridges.

• Smart Structures and Systems
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• v.24 no.1
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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.