Behavior and Strength of Passively Confined Concrete Filled Tubes


In this study, Confined Concrete Filled Tube (CCFT) is proposed and studied for the seismic design of reinforced concrete columns, exhibiting improved results in terms of stiffness, strength and ductility. Specifically, plastic instead of steel tubes were used to confine concrete in the Concrete Filled Tube (CFT) system since plastics are less expensive, lighter (approximately 1/6 of steel), retarding to fire effect, and immune to galvanic or electrolytic attack. Additional confinement to the CFT tubes was provided by an external Fiber Reinforced Polymer (FRP) layer. The use of the FRP layer can potentially delay and restrain local buckling of the plastic tube, which in turn mitigated undesirable failure modes, and enhanced ductility. Testes were carried out to better understand the composite action among FRP wrapping, tube, and concrete core. The efficacy of polymeric plastic tubes implemented in both CFT and CCFT specimens was demonstrated under uniaxial compressive tests. Uniaxial compressive tests results suggest that the use of such CCFT system, incorporating the FRP sheets and polymer plastic tubes, can dramatically increase the amount of energy absorbed and decrease the brittle failure, typically observed in the case of unconfined or poorly-confined concrete members. Due to the composite action among the FRP wrapping, plastic tube and concrete core, the CCFT specimens more significantly increased both strength and ductility of the composite columns.

Meeting Name

10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering (2014: Jul. 21-25, Anchorage, AK)


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Beams And Girders; Buckling; Columns (Structural); Composite Structures; Concretes; Ductility; Earthquakes; Engineering Geology; Fiber Reinforced Plastics; Seismic Design; Tubes (Components); Tubular Steel Structures; Concrete Filled Tubes; Confined Concrete Filled Tubes; Enhanced Ductility; Fiber Reinforced Polymers; Polymeric Plastics; Reinforced Concrete Column; Strength And Ductilities; Uniaxial Compressive Tests

Document Type

Article - Conference proceedings

Document Version


File Type





© 2014 Earthquake Engineering Research Institute (EERI), All rights reserved.

Publication Date

01 Jul 2014