Strengthening of Structural Members

Won Hyo Bridge, Seoul, South Korea

The 1,120 m long bridge over the Han River was completed in 1981. Because of inaccurate calculations of prestressing losses and deflections caused by creep and shrinkage of concrete, additional deflections of up to 30 cm occured. These resulted in 5 cm to 20 cm sagging at the hinges. The DSI rehabilitation concept called for external tendons, which on the one hand slightly reduced deflections and on the other strengthened the structure. The remaining sag could be eliminated by an additional asphalt layer. Twelve 19 x 0.6" DYWIDAG Tendons were applied in each cantilever and anchored in new concrete buttresses cast inside the box girders. These were connected to the concrete of the existing webs of the box girder through friction created by means of short Ø36 mm DYWIDAG Smooth Bar Tendons.