## 4 Description of the Experimental Campaign
### Description of the Dapped-End Beams  
Two dapped-end beams were designed with the same geometry as shown in Figure 4. Both are T beams, 75 cm deep with an 80 cm wide flange and a total length of 4.9 m.  
Each specimen represents one of the longitudinal beams of the part of the deck of the bridge rigidly connected on top of the pier: the so-called hammer. The pier provides the central support (as shown in Figure 4) and the drop-in spans load the hammer's half joints on the two sides. Each specimen, being 1/3 scale, represents a real cantilever span of 6.6 m realised with a 2.25 m deep beam. The specimens are tested upside down in the laboratory, being vertically loaded at the center by a hydraulic jack and simply restrained on both sides on the half-joints. This choice increases the stability of the test. In fact, an unstable configuration during testing may arise having only one central support and loading the two dapped ends. On the contrary, a single central jack is more controllable and the load that in reality is applied by the drop in span in the dapped ends is simulated by means of the bearings' reactions in the lab. Both specimens are designed to reach local failure within or close to the half-joint avoiding classical bending or shear failure of the current T section. One specimen is realised with orthogonal reinforcement in the dapped end and the other with an inclined one. Details on the arrangement of reinforcement are shown in Figures 5 and 6. The two different reinforcement arrangements are designed to simulate the two common arrangements in real bridge beams. Figure 4: The geometry of beams. Dimensions in cm. (**a**) Longitudinal view. (**b**) Cross section. (**c**) 3D view. The beams were designed with a strut and tie model (STM) according to [30]. The STMs adopted are shown in Figure 7. In both beams, the left half-joint was created with correct design reinforcement and the right one with reduced reinforcement to simulate steel bars corrosion. The side with reduced reinforcement was afterwards strengthened with steel plates. The choice of using rebars with smaller diameters to simulate deterioration is due to the boundary conditions of this experimental campaign. The research program was part of a funding competition between universities and the funding institution gave a four months time window to accomplish the research. Accelerated corrosion processes, may need from 30 days for very simple specimens [31] up to 70 days for complex specimens as in the present case [32]. Therefore, even accelerated corrosion was too time demanding to respect the time limit. Figure 5: Reinforcement arrangement in the discontinuity zone. (**a**) Orthogonal layout. (**b**) Inclined layout. Figure 6: Detail of the reinforcement arrangement. (**a**) Orthogonal layout. (**b**) Inclined layout. The following reinforcement reductions were applied in the damaged dapped end of the beam with orthogonal reinforcement:  
* **Horizontal reinforcement in the dapped end**. From 2\(\Phi\)12 (As4) in the sound side to 2\(\Phi\)8 (As5) in the damaged one: \(-\)56%. * **Vertical reinforcement in the dapped end**. From 4\(\Phi\)10/10 (Stirrups B) + 2\(\Phi\)10 (Stirrups C) in the sound side to 2\(\Phi\)10/10 (Stirrups B) + 2\(\Phi\)6/10 (Stirrups D) + 2\(\Phi\)6 (Stirrups E) in the damaged one: \(-\)43%. The following reinforcement reductions were applied in the damaged dapped end of the beam with inclined reinforcement:  
* **Horizontal reinforcement in the dapped end**. From 2\(\Phi\)8 (As6) in the sound side to 2\(\Phi\)6 (As9) in the damaged one: \(-\)44%. * **Vertical reinforcement in the dapped end**. From 3\(\Phi\)8/20 (Stirrups A) in the sound side to 2\(\Phi\)8/20 (Stirrups A) + 1\(\Phi\)6 (As12) in the damaged one: \(-\)15%. * **Inclined reinforcement in the dapped end**. From 2\(\Phi\)8 (As7) + 2\(\Phi\)10 (As8) in the sound side to 2\(\Phi\)6 (As10) + 2\(\Phi\)6 (As11) in the damaged one: \(-\)56%.