Page - 1049 - in Book of Full Papers - Symposium Hydro Engineering

3. EXPERIMENTAL RESULTS AND ANALYSIS 3.1. EXPERIMENTAL RESULTS (1) Experimental results observed by optical measurement If we choose to observe the strain of specimen in the vertical direction, we can obviously see the strain distribution of FRP plate at different time. Take the strain distribution of specimen SS-150 at different time for example and analyze the change in strain distribution of FRP plate as shown in Fig. 2. （a）Early load stage （b）Middle load stage （c）Later load stage （d）Extreme load stage Fig. 2 The strain distribution of the FRP plates at different times in the sample ss- 150 The de-bonding of FRP reinforced concrete bonding interface can be divided into following three stages as shown in the Fig. 2: (1) Early load stage: the strain on each part of FRP plate is very small. The peak value of strain, which is measured in a small region around the load end, which is =0.000345yy . As the load increases, when the peak value of strain reaches 0.000985, the strain in its neighboring regions exceeds 0.000779 and the position of peak value of strain basically remains unchanged. (2) Middle load stage: as the load continues to increase, the peak value of strain ( =0.00208yy ) keeps increasing while its position moves towards the free end of FRP plate. The overall strain of plate increases compared to early load stage. The minimum value of strain is 0.0005 and is measured at the free end of FRP plate. There is very small strain in the regions between the plate center and the free end, ranging from 0.0001 to 0.0003. 1049