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The shear behaviors of reinforced concrete (RC) beams externally strengthened with engineered cementitious composite (ECC) layers were studied and the strengthening effect was evaluated based on a truss and arch model. The beams were designed without web reinforcement in the middle part and ECC was sprayed onto both sides of the beams to the designed thicknesses, which were 20 mm and 40 mm. A series of four-point bending experiments were conducted and analyzed. The development of the shear strain in each side of the beams was recorded by strain rosettes formed with three fiber Bragg grating (FBG) sensors. The thickness of ECC layers, reinforcement ratios, and shear span-to-depth ratios were considered and analyzed. This is an effective way to shear strengthen RC beams with ECC layers. The ultimate load of the strengthened specimen can be improved by 89% over the control specimen. Strengthening an RC beam into an under-reinforced beam should be avoided. The FBG sensors are suitable to measure and monitor the development of shear strain in the side of the strengthened specimen. Based on the truss and arch model, an evaluation of the shear strengthening effect was established and the results agree well with the experimental results.

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Transverse connection strengthening prestressed concrete T‐girder bridge is an effective method to enhance the integrality of the T‐girder bridge. In a previous work, a new kind of diaphragm transverse connections (DTCs) has been proposed and its validity has been proved. Aiming to study the influential parameters for the strengthening effect, finite element analysis is carried out based on a 30 m prestressed concrete T‐girder bridge in this study. The considered influential parameters are T‐girder spacing, T‐girder height, brace thickness, and installation location of the DTCs. The deflections and load distribution factors of the prestressed concrete T‐girder bridge are calculated to evaluate the impact of each parameter on the strengthening effect. Furthermore, the influence of brace thickness and T‐girder height on axial forces of the DTCs and connection force is studied. The results show that the strengthening effect with DTCs installed at midspan is the best option. With T‐girder height increasing, the deflections of the T‐girder reduce and the maximum load distribution factor increases. Besides, increasing the brace thickness of DTCs or decreasing the T‐girder spacing improves the strengthening effect. By comparing the axial force with the buckling critical force, it shows that the stability of the braces is adequate. Finally, design recommendations are given for the 30 m prestressed concrete T‐girder bridge strengthening.