The use of glass fiber reinforced polymer (GFRP) bars as internal reinforcement for portions of massive concrete retaining walls to be penetrated by tunnel boring machines (TBMs), commonly referred to as softeyes, is becoming mainstream. The low shear strength and inherent brittleness of GFRP bars greatly facilitate penetration of the TBM, preventing damage to the disc cutters, and eliminating the risk of costly delays. The safe shear design of softeyes and large members in general must account for the strength decrease due to size effect. To date, this phenomenon has not been documented for FRP reinforced concrete (RC). In this paper, the results of laboratory tests on four large-scale concrete beams reinforced with GFRP bars in flexure and shear are presented and discussed. Preliminary results are reported that indicate a decrease in concrete shear strength attributable to size effect, which is offset by an implicit understrength factor in the current ACI 440 design formula. Further experimental research is ongoing to better characterize the extent of size effect in FRP RC.