Techno Press

Structural Engineering and Mechanics   Volume 17, Number 3, March 2004, pages 467-482
Identification of prestress-loss in PSC beams using modal information
Jeong-Tae Kim, Chung-Bang Yun, Yeon-Sun Ryu and Hyun-Man Cho

Abstract     [Full Text]
    One of the uncertain damage parameters to jeopardize the safety of existing PSC bridges is the loss of the prestress force. A substantial prestress-loss can lead to severe problems in the serviceability and safety of the PSC bridges. In this paper, a nondestructive method to detect prestress-loss in beam-type PSC bridges using a few natural frequencies is presented. An analytical model is formulated to estimate changes in natural frequencies of the PSC bridges under various prestress forces. Also, an inverse-solution algorithm is proposed to detect the prestress-loss by measuring the changes in natural frequencies. The feasibility of the proposed approach is evaluated using PSC beams for which a few natural frequencies were experimentally measured for a set of prestress-loss cases. Numerical models of two-span continuous PSC beams are also examined to verify that the proposed algorithm works on more complicated cases.
Key Words
    damage identification; structural safety; prestressed concrete bridge; prestress-loss; modal test; natural frequency.
Jeong-Tae Kim; Smart Structure Engineering Laboratory, Department of Ocean Engineering, Pukyong National University, Busan 608-737, Korea
Chung-Bang Yun; Department of Civil and Environmental Engineering, KAIST, Daejon 305-701, Korea
Yeon-Sun Ryu and Hyun-Man Cho; Department of Ocean Engineering, Pukyong National University, Busan 608-737, Korea

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