Title: Stress-Strain Characteristics of Concrete Columns Externally Confined with Advanced Fiber Composite Sheets

Author(s): Houssam Toutanji

Publication: Materials Journal

Volume: 96

Issue: 3

Appears on pages(s): 397-404

Keywords: carbon; columns (supports); compressive strength; confined concrete; glass fibers; stress-strain curves

DOI: 10.14359/639

Date: 5/1/1999

Abstract:
Fiber reinforced polymer composite (FRPC) wrap has been established as an effective method for strengthening and rehabilitation of concrete structures. This paper presents the results of experimental and analytical studies on the performance of concrete columns externally wrapped with carbon and glass FRPC sheets. Concrete columns were wrapped with three different types of FRP composites: two carbon and one glass. The confined and unconfined (control) specimens were loaded in uniaxial compression. Axial loads and axial and lateral strains were obtained to evaluate stress-strain behavior, ultimate strength, stiffness, and ductility of the wrapped specimens. Results show that external confinement of concrete by FRP composite sheets can significantly enhance the strength, ductility, and energy absorption capacity of the concrete specimens. An analytical model to predict the entire stress-strain relationship of concrete specimens wrapped with FRP composite sheets was developed. The proposed model consists of two distinct parts. In the first part, the behavior is similar to that of plain concrete, since lateral expansion of the confined concrete is insignificant. The second region, which is mainly dependent on the stiffness of the FRP composite, is recognized in which the FRP wrap is fully activated. Comparison between the experimental and analytical results indicates that the model provides satisfactory predictions of the stress-strain response. Results from a series of experimental tests on concrete confined with FRP sheets available in the literature are also compared favorably with results obtained by the model.