DISCUSSION OF 8994 & 8995. JINDO AND DOLSAN BRIDGES: DESIGN AND CONSTRUCTION.

Abstract

The Authors have stated that the tidal currents and the narrow width specified were the two factors that dominated the selection of the bridge form. Going one step back, it would be the geology and topography of the site, combined with the tidal currents, that dictated that the crossing had to be a bridge instead of a bored or immersed tube tunnel. The bridge had to have a long centre span and two short side spans. However, it is not clear why the narrow width was specified. The Authors have not provided information about the traffic flows predicted over this and the Dolsan Bridge, and according to Paper 8994 this seems to have been done by others beforehand. However, it would appear from the precautions taken against premature fatigue damage in the deck welds that a considerable volume of heavy traffic is expected. One is therefore left to wonder whether the provision of only two lanes in such large and expensive bridges is a wide decision. Could the Authors comment on this and also on the loading adopted, taking into consideration the recent studies on long span bridge loading both in the UK and in the USA?2. The reasons for the choice of cable stayed bridges for these two sites are well covered in the Paper, but could the Authors say more about the reasons for selecting steel? Although the cable stayed bridges built soon after the Second World War were of steel, there have been many of concrete and recently there has been hybrid-deck construction. A recently completed bridge in Spain, which claims to have the world's longest main span of 440 m, is of concrete box construction. So what were the comparative costs between concrete and steel and to what extent did the shipbuilding expertise in the Republic of Korea contribute to the decision?3. Turning to detailed matters, it was notable that the roadway deck stiffener was continuous, yet fillet welded over its full perimeter to the stub diaphragm plate. Do the Authors not consider that there may be fatigue problems arising from fillet welding across the bottom flange, and/or improper welds arising from bad fit up of the stiffener in its cut-out?4. Regarding the back stay anchorage and rocker link of Jindo, how frequently does the rocker arm move? It is inevitable that the bushes will wear in time and need replacement. Has provision been made for inspection of these and replacement without having to release the back stays at the same time?5. It is stated by the Authors that shipping collision had to be allowed for inPapers published: Proc. Instn