6. Seismic retrofitting method at bridge connections
In an earthquake that occurred recently, there was a case reported in which the connecting parts of bridges used to support girders having different heights were damaged due to the buckling of reinforcing bars, requiring a long restoration period. (Fig. 1). When such connecting parts need to be reinforced, cross girders and bearings become obstacles and make it difficult to install anchors to girder joint gaps and steel plate lining, like on pillars.
However, no effective reinforcing construction method has been established.
Therefore, a seismic retrofitting method has been developed that uses pressing bars, steel plates and post-construction anchors to eliminate the requirement of installing reinforcement materials at girder joint gaps (Fig. 2).
This method uses prestressing bars to improve the bending proof strength against the inertia force to the right, as shown in Fig. 2, and steel plates to improve the bending proof strength against the inertia force to the left, as shown in Fig. 2. Shear capacity can be improved by post-construction anchors.
By means of a loading test, it was confirmed that a part that was shear-fractured before reinforcement was not fractured after reinforcement, and the bending proof strength at the connection was improved 1.5 times compared to before reinforcement (Fig. 3).