Articles written in Sadhana

    • Seismic vulnerability assessment of a continuous steel box girder bridge considering influence of LRB properties


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      Bridges are one of the most crucial facilities of transportation networks. Therefore, evaluation of the seismic vulnerability of bridge structures is perpetually regarded topic for researchers. In this study, we developed seismic fragility curves for a continuous steel box girder bridge considering the effect of differentlevels of mechanical properties of lead rubber bearing (LRB) devices including initial stiffness and yield strength on the seismic performance of such structure. A powerful framework for an earthquake engineering simulation, OpenSees, is used to perform nonlinear analyses of the bridge model. In order to construct fragilitycurves for this structure, a set of 20 ground acceleration records is adopted and various scales of the peak ground acceleration (PGA) from 0.1 to 1.6 g are considered. Besides, a series of damage state of the bridgeis definedbased on a damage index, which is expressed in terms of the column displacement ductility ratio. Fragility analyses result reveals that reducing the initial stiffness of LRBs reduces the seismic vulnerability of bridge piers and vice versa. Meanwhile, the changes of the yield strength of LRBs have trivially effected on the seismic behaviour of the bridge piers. On the other hand, the short pier has performed more susceptibly than those of the high pier in both seismically-isolated and non-isolated bridge cases. Lastly, the results in this research alsoindicate that the bridge structures equipped with seismic isolation devices (e.g. LRBs) significantly mitigated the damages due to earthquakes.

    • Prediction of speed limit of cars moving on corroded steel girder bridges using artificial neural networks


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      This paper develops an artificial neural network (ANN) model for predicting the speed limit of cars moving on corroded steel girder bridges. A total of 311 datasets, which are created from the proposed analytical model, are used to construct the ANN model. The input parameters of the proposed ANN model include the car’s weight, diameter of tires, and the dimensions of girder bridges, which are the top flange width, top flange thickness, bottom flange width, bottom flange thickness, girder height, web thickness, and the span of girder. Meanwhile, the speed limit of cars is the output variable of the ANN model. The results show that the speed limitation of cars on the corrosive steel girder bridge is reduced pronounced after 100 years. Sensitivity analyses reveal that the influential parameters with respect to the maximum speed are the girder height and tire diameter, whereas the girder weigh and girder span have negative effects on the speed limit of cars. Moreover, a mathematical formula and a graphical user interface program are developed to calculate the speed limits of cars on the corrosive steel girder bridge. These practical tools are very helpful for practitioners in determining the speed limit of cars moving on steel girder bridges subjected to corrosion.

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