Comparative bond pullout performance of CFRP and steel reinforcing bars in concrete at elevated temperature

Cristian Maluk

Research output: ThesisMaster's Thesis

Abstract

Novel structures are emerging utilizing high performance, self-consolidating, fibre-reinforced concrete (HPSCC) reinforced with high-strength, lightweight, and non-corroding prestressed reinforcement. One example of this is a new type of HPSCC precast panels, with pretensioned carbon fibre reinforced polymer (CFRP) tendons, intended as load-bearing panels for building envelopes. As for all load-bearing structural members in building applications, the performance of these members under fire conditions must be understood before they can be used with confidence. In particular, the bond performance of CFRP prestressing reinforcement at elevated temperatures is not well known, although available research on the bond between glass fibre reinforced polymer bars and concrete at elevated temperatures suggests that loss of bond may govern the response.

The study presented in this thesis examines the performance of these new types of structural elements at high temperature or during exposure to fire, placing particular emphasis on the bond performance of CFRP tendon compared to that of steel wire prestressing reinforcement at elevated temperatures. The results of bond pullout tests executed at high temperature on CFRP and steel prestressing bars embedded in HPSCC, the thermal and mechanical properties of CFRP, steel, and HPSCC, and large scale fire tests on CFRP prestressed HPSCC panels are presented and discussed to shed light on the fire performance of these structural elements.

A heat transfer model was developed with the objective of predicting the temperatures within a pullout sample subjected to bond-pullout executed at high temperature. A thermal incompatibility model was created to predict the longitudinal crack formation in large scale fire tests.

Result suggested that degradation of the bond strength of CFRP bars at high temperature is governed by the degradation of the epoxy matrix from which the CFRP bar is made from. From the pullout test results, a relationship was found between the temperatures of bond failure and the prestress load at which the sample were sustained.
Original languageEnglish
Awarding Institution
  • Pontifical Catholic University of Chile
Supervisors/Advisors
  • Santa Maria, Hernan, Supervisor, External person
  • Bisby, Luke, Supervisor
Award date25 May 2010
Publisher
Publication statusPublished - 2010

Keywords

  • CFRP
  • HPSCC
  • advanced composites
  • bond strength
  • pullout test
  • fire endurance
  • high temperature
  • large scale fire test
  • image correlation analysis

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