# Large-Scale Experimental Static Testing on 50-Year-Old Prestressed Concrete Bridge Girders
## 2 Case Study
### Experimental Program  
The first stage of the research project involved a series of preliminary activities conducted before the dismantling of the viaduct in order to obtain a general overview on the conservation state. These activities concern visual inspections, conducted according to national and international standards [27], concrete coring from piers followed by carbonation tests and reinforcing bar sampling. Finally, dynamic test was carried out on the four spans (reported in Figure 2) before the dismantling in order to characterize the global dynamic behavior of the decks of the viaduct [28]. These preliminary results will be compared and validated with the outcome gathered after the experimental tests conducted at the testing site. The collected elements were subjected to an extensive on-site diagnostic study, including the mapping of the degradation pattern, drone surveys, rebound hammer test, magnetometric, ultrasonic investigations and electrochemical methods to evaluate corrosion potential and corrosion rate. Additional information about dynamic analyses and non-destructive testing can be found in previously published papers [29; 30; 31; 32; 33; 34]. The results of the non-destructive diagnostic study were used to distinguish three different categories, such as undamaged beams, deteriorated beams by corrosion and beams with damage induced by dismantling operations. Relying on these three classes, loading tests were scheduled, starting with beams showing a low level of damage of the cast in situ slab generated by lifting preparation [31; 32] (Figure 5). Figure 4: Deconstruction phases: (**a**) cutting; (**b**) drilling; (**c**) sling ropes; (**d**) lifting; (**e**) moving; (**f**) testing site setup. The tests reported in this paper involved B3-P47/46, B8-P47/46, B4-P47/46 and B9-P47/46 beams, classified as a girder in good condition, where BX-PYY/ZZ means: B is for I-shape section beams, X is the progressive numbering of I beams in the transverse section of the deck, and PYY/ZZ is the starting support, where P means pier and the following letters are the numbering of the support number (see Figure 2). As previously reported, small portions of the deck slab and bottom flange concrete at about 4 m from each beam end were damaged for lifting operations (red square in Figure 5). Girders B3-B4-B8-P47/46 and B9-P47/46 had no damage in the midspan zone and no damage in what concerns the bottom flange with no cutting of the strands. Other girders also had an induced damage caused by drilling at midspan and variable cutting of the strands at the bottom flange. The B3-P47/46 and B4-P47/46 girders showed 5 mm wide horizontal cracks at the edges caused by corrosion activity that transversally crossed the strands (Figure 6). The visual inspections revealed no other corrosion-induced damages. The presence of such kind of damage can be ascribed to the presence of structural joints. Two different load tests were planned, two-phases and single monotonic loading phase. The two-phase loading tests were designed with a first loading that reaches the stabilized crack opening, followed by complete unloading; subsequently a loading up to the ultimate load capacity or first signs of failure was scheduled. Since the cracking moment and decompression load are key parameters for providing a preliminary estimate  
Figure 5: Typical damage due to lifting operations: (**a**) damage at 4 m and (**b**) damage at 15 m from the beginning of the PC girder. Figure 6: Cracks on the end of the (**a**) B3-P47/46 and (**b**) B4-P47/46 beams. of prestress loss, much attention has been paid to detect these quantities. The estimation of the latter will be confirmed by comparing the results with local tests of residual prestressing on the same girders, such as saw-cuts and strand cutting already planned in the test program. The single monotonic loading test was planned to investigate the structural behavior up to failure without the effects induced by the first loading cycle. The B3-P47/46, B8-P47/46 and B9-P47/46 girders were loaded in two phases.