A key consideration in the application of FRP reinforcement in concrete is the mechanical and bond performance at elevated temperature. Tensile tests on FRP bars previously carried out at the University of Edinburgh have demonstrated that, whilst significant reductions in ultimate tensile strength were observed after the onset of decomposition of the polymer resin, FRPs’ absolute tensile strength remained higher in comparison with steel reinforcing bars. It may therefore be reasonable to assume that the ‘critical temperature’ for FRP bars is above their glass transition temperature (Tg), provided that ‘cold’ anchorage zones can be assured. Thirty-two reinforced concrete (RC) beams were tested with either continuous or lap spliced FRP or steel reinforcement; tests were performed both at ambient temperature and under sustained load with transient localised heating. Glass and carbon FRP bars were both studied, as was conventional steel reinforcement. Cold anchorage of the reinforcement was maintained throughout testing. Minimum concrete cover ensured that FRP bar temperatures exceeded Tg during 90 minutes of heating. The results demonstrate that cold anchorage (i.e. maintained below Tg) of FRP bars is necessary to ensure their safe use as internal reinforcement in concrete, unless unrealistically deep concrete cover is provided. Where cold anchorage is provided, the performance of FRP bars is demonstrated – for the particular conditions of the current study – to be satisfactory under full service loads and at reinforcement temperatures exceeding 500°C.
|Title of host publication||Advanced Composites in Construction 2015|
|Subtitle of host publication||Proceedings of the 7th Biennial Conference on Advanced Composites in Construction held at St John's College, University of Cambridge on 9th to 11th September 2015|
|Editors||Janet Lees, Sue Keighley|
|Publication status||Published - 9 Sep 2015|