Award of Merit: Transportation Category
Rehabilitation of Dao Kanong Bridge
Submitted by IETL Co., Ltd.
Department of Public Works, BMA
IETL Co., Ltd.
IETL Co., Ltd.
Degussa Construction Chemicals
Nontri Company, Ltd.
The Dao Kanong Bridge, a 30-year-old reinforced concrete two-lane bridge with 21 spans, is located on Ratcha Burana Road in western Bangkok. The bridge was found to have an insufficient safety index (Bangkok Metropolitant Administration's highway standard) due to serious structural deterioration and heavy traffic load. Damage and deterioration from corrosion and separation of prestressed concrete planks could lead to abrupt failure of bridge decks, as it occurred to some bridges in Bangkok in the past.
The rehabilitation procedures had to be done within a limited time frame without disturbing traffic, both trucks and barges. The bridge could only be closed one lane at a time, and only for a few hours late at night, because this bridge is on one of the main truck routes in Bangkok.
Due to the unavailability of structural drawings and other important structural information, many nondestructive test (NDT) were carried out to evaluate existing conditions. Load tests were applied before, during, and after strengthening procedures to study structural behaviors and to evaluate strength and safety conditions.
Carbon fiber composites had been selected for substitution of corroded reinforcement and for strengthening main structural members. After all rehabilitation procedures were completed, the final load test confirmed ability of the bridge to carry the required service load level safely.