In this paper, enhancement of Yubm-bashi bridge, 191.5 meter in bridge length and 2 main Gerber girders out of 7 spans, is reported. The enhancement work for a main girder is indispensable for the span elongation due to building a new pier in order to replace an existing pier. It is also discussed that the reason why high strength steel bar is employed for the enhancement. Furthermore, the monitoring control system of the work is described. Finally, applicability of the high strength steel bar for the enhancement work is considered by comparing FEM analysis results and observed one.
