Long-Term Monitoring of Steel Strand Prestress Loss by using FRP-OFS


Prestress loss adversely affects the behavior of in-service prestressed structures in terms of deflection/camber, cracking, and ultimate capacity. It is thus important to determine the level of prestress force at various loading stages from the initial prestressing force transfer to the structure, through different in-service loads, to the ultimate load of the structure. Prestress loss is closely related to the geometric shape, distributed friction and slippage of prestressing strands. In this paper, a novel, integrated global and local structural health monitoring methodology is proposed and developed by combining the Brillouin Optical Time Domain Analysis/Refectory sensor and the Optical Fiber Bragg Grating (FBG) into one single fiber. The methodology was implemented in a smart fiber reinforced polymer (FRP) rebar with an embedded FBG optical fiber or a smart seven-wire steel strand by replacing the core steel wire with the FRP rebar. The performance of the smart rebar/strand has been validated with the static testing of a prestressed steel frame structure and a prestressed concrete beam. Extensive tests show that the smart steel strand can be used to accurately measure the prestress loss at each loading stage, which agrees well with that from the pressure loading cell and the theoretical values that can be determined based on the design code.

Meeting Name

4th International Conference on Structural Health Monitoring of Intelligent Infrastructure (2009: Jul. 22-24, Zurich, Switzerland)


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Brillouin Optical Time Domain Analysis; Fiber Reinforced Polymers; Long Term Monitoring; Pre-Stressed Steel; Prestressed Concrete Beams; Prestressed Structures; Prestressing Forces; Prestressing Strands; Prestressed Beams And Girders; Structural Frames; Structural Health Monitoring; Wire; Fiber Bragg Gratings

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


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© 2009 International Society for Structural Health Monitoring of Intelligent Infrastructure (ISHMII), All rights reserved.

Publication Date

01 Jul 2009

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