## 3 Discussion of Results
### Negative Bending Behavior of Undamaged and Post-Repair Girders  
The two remaining repaired specimens for each repair material were tested in negative bending as described previously. Three pristine girders with undamaged continuity joints were also tested in this manner to determine the effect of the repair material. The peak loads resisted by each of the girders tested in negative bending are shown in Table 3. The load vs.  
Figure 10: 1-MALP load vs. strain for each instrumented reinforcing bar.  
Figure 14: Load vs. strain plot for connected girder specimens repaired with UHPC.  
Figure 15: Load vs. deflection plot for connected girder specimens repaired with FRSCC.  
Figure 16: Load vs. strain plot for connected girder specimens repaired with FRSCC.  
Figure 17: Load vs. deflection plot for connected girder specimens repaired with MALP.  
Figure 18: Load vs. strain plot for connected girder specimens repaired with MALP.  
Each of the repaired girders failed at approximately the same load, which was larger than each of the pristine girder failure loads. This could show that the repairs acted mainly to confine the damaged compression zone, as well as to provide additional material in the compression zone to increase the girder capacity. Each of the control connected girder specimens failed by crushing in the compression zone. The deck reinforcement also yielded in each of the tested girders (see Figures 12, 14, 16 and 18). However, several of the strain gauges appeared to become damaged at various points post-yield and stopped collecting useable data. The data shown represent the useable collected data. The reinforcing steel in the repair area did not appear to be strained heavily throughout testing. However, a definite trend was observed where the reinforcing would be in compression until near the peak load in most cases, then the strain would reverse and go into tension (see Figures 14, 16 and 18). This could be an indication that the neutral axis was raised to a level that placed the repair reinforcing steel in tension due to increased crack growth. The low strain values could indicate that the now confined, damaged joint area could transfer compressive bending stresses.  
Each of the repaired girders exhibited stiffness reduction caused by yielding of the reinforcing, which appeared to occur at approximately 150 kN (see Figure 19). The stiffness of all the repaired girders appeared to show a gradual softening as the load progressed up to yielding, as opposed to a larger stiffness up to a cracking load, as with the apparent behavior of the pristine girders. While this behavior could indicate that the repair material acted solely as confinement for the damaged joint, cracks appeared on both the FRSCC and MALP repairs in both of the negative bending tests at approximately 165 kN. No cracks were observed in the UHPC repair throughout testing, possibly due to the distribution of steel fibers creating smaller cracks not visible on the surface. Additionally, the consistent performance of the FRSCC repairs and comparable performance to the UHPC repairs indicates good quality concrete. Examples of the condition of the repaired girders after testing are shown in Figure 20 for each repair material. The dark lines on the face of the connected girder specimens indicate crack locations during testing, which included flexural and shear cracking. Both the MALP and FRSCC specimens cracked in the repair material, but no visible cracking was observed in the UHPC. This could be due to the small size of cracks in UHPC [8]. While deck reinforcement yielding occurred at approximately the same load for each specimen, the post-yielding stiffness varied. Post-yielding stiffness of the FRSCC and MALP specimens appeared nearly identical to that of the control specimens, and the UHPC exhibited a softer post-yielding response (see Figure 19).  
Figure 19: Load vs. deflection plot for all connected girder specimens.