| As the bridges plan an important role in the highway traffic, the bridge engineering has developed into a systemic course including the academic analysis, structure designing, construction controlling and project management subjects.With the economic development and the increment of the traffic, the damages and the disfigurements appear in the existing bridge structures, which have been badly interfering the normal use of the existing bridge structures. Therefore, it is quite important to do the detecting, evaluating, repairing and servicing work relating to the existing bridge structures.Most of the bridges have been designed according to the old bridge criterion(JTJ023-85), comparing with the old one , the new criterion(JTG D62-2004) has made greater changes in the value of the material properties, designing formulas and the calculations of the action effect. To valuate the qualities of the existing bridges, we should apply the new bridge criterion. So this dissertation provides certain rules and evidences for the evaluative work and strengthening by comparing the old and new criterions.This dissertation takes three viaduct bridges in the expressway from Zhengzhou city to Luoyang city as an example. On the basis of the new criterions (JTG D62-2004), this dissertation contains the analysis of the constant load and the vehicle load of bridge, the secondary internal strength due to temperature difference, the secondary internal strength due to the settlement of foundation, the internal secondary strength due to pre-stress and the combination of controlled member force. In addition to this, the bending capacities of the cross section and the sheer capacities of inclined section in the ultimate limit state and the deflection in the service ability limit state are analyzed in this dissertation .In according with the results of analysis, the strengthening plans are proposed in the bridges which have been active service. |
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