ABSTRACT
The use of fiber reinforced polymer (FRP) materials has become common for increasing the structural element capacity. Near Surface Mounted (NSM) technique has been widely used for strengthening purpose as an alternative to the FRP externally bonded (EB) technique. In comparison with the EB technique, NSM technique has many advantages such as providing better anchorage and protection from external damage. This advantages led to reducing the risk of debonding failure. The bond performance of NSM FRP is ex-tensively studied in the past studies without consideration the influence of direct exposure to the service temperature. This study is the first attempt to evaluate the bond behavior when the NSM FRP is subjected to tension force and temperature at the same time. The level of temperatures considered in this study were ser-vice temperatures [range from -18 °C (0 °F) to 49 °C (120 °F)] which is more representative of structural elements in the field. The key parameters investigated include (1) the type of fiber, including glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP), (2) the level of temperature applied on concrete masonry unit (CMU), including ambient, freeze and hot condition. The specimens were strengthened and subjected to tension force simultaneously with applying temperature under single-lap direct shear. These specimens compared with specimens later tested after exposure to the cycles of heating and cooling temperature. The behavior of specimens was investigated in terms of ultimate pull-out force, and mode of failure. The results showed that the NSM technique exhibited excellent performance when subjected to cycles of heating and cooling prior to testing. The contribution of the NSM FRP bars to the shear strength of the CMU was affected so that high reduction of FRP-epoxy bond properties was exhibited when exposed to high service temperatures, while there was insignificant reduction when subjected to the ambient and freeze temperature.
