Retrofitting Design and Physical Modeling for Pier-Scour Protection

The bridge piers of the old Gupo Bridge collapsed during Typhoon Maemi, in 2003. Due to the highway construction for the Dadae Harbor in the leftbank side of the Gupo and Subway Bridges, the rightbank floodplain should be excavated to ensure the flow full channel area. Bridge piers affected by the excavation are Pier 11 and 12 of the Subway Bridge and Pier 15 and 16 of the Gupo Bridge. The proposed design for the Gupo and Subway Bridge piers is using the sheet pile and riprap to protect the piers. The sheet piles around each pier can be either square or rectangular. Detailed design calculations for the proposed design such as scour depth and scour-hole width around bridge piers, and riprap and filter protections are conducted. Also, the experimental physical modeling is carried out to compare with scour calculation results and to validate the stability of the proposed countermeasure.