An experimental program was conducted to study the effects of using 0.7 in. (17.8 mm) diameter prestressing strands on the performance of pretensioned concrete I-girders under shear-critical loading. Four full-scale Texas bulb-T girders (Tx-girders) with different concrete release strengths, member depths, shear span-depth ratios, and strand patterns were tested. The mild-steel reinforcement in the specimens was detailed according to the common practice in Texas for girders fabricated using conventional, smaller-diameter strands. All specimens exhibited considerable strand slip prior to failure. In three of the specimens, shear failure also resulted in prominent horizontal cracking at the interface between the web and the bottom flange. However, distributed yielding of the stirrups was confirmed in all specimens, indicating shear-tension failure. The capacities of all specimens were conservatively estimated using the general procedure in the AASHTO LRFD Bridge Design Specifications and the detailed method in ACI 318-14 provisions.