The Effects of Fire on Insulated Reinforced Concrete Members Strengthened With Fibre Reinforced Polymers

Abstract

Given the current global crisis of deteriorating infrastructure, structural rehabilitation has been the focus of much recent research in the field of civil engineering. Consequently, Fibre Reinforced Polymers (FRP’s) are becoming an increasingly common method for retrofitting deficient structures. However, skepticism regarding the structural performance of FRP’s during fire is preventing their widespread implementation in building applications. Because of the degradation of FRP material properties during heating, most current design codes completely neglect their structural contributions in fire design. The intention of this research thesis is to investigate the thermal and mechanical behaviour of insulated FRP retrofitted reinforced concrete structures at elevated temperatures. Two intermediate-scale reinforced concrete slabs were first strengthened with FRP and protected with spray-on insulation. Thermal results from fire testing of the slabs provided a basis on which to develop insulation schemes for larger specimens. These larger specimens consisted of two full-scale T-Beams and two full-scale columns, which were also strengthened with FRP and insulated. All of these specimens succeeded in obtaining four hour fire ratings upon fire testing. Though the FRP strengthening systems were compromised quickly during heating, the insulation provided sufficient protection to the T-beams and columns for them to resist the applied service loads throughout the duration of fire exposure. Detailed calculations were also conducted using thermal data from the full-scale specimen fire tests in order to predict the change in capacity of these structures with time. This thesis shows that, with careful considerations towards insulation and anchorage design, FRP-strengthened reinforced concrete structures are able to obtain fire ratings in excess of four hours.