## 3 Results of Strengthening According to the Author
### Author's Concept of Strengthening of pylons Nos. 9 and 10 of the Viaduct from 1993  
Figure 9 shows three viaduct supports. Each of them was treated differently:  
* the cables were strengthened at support No. 11,
* a steel cap was installed at support No. 10 to connect the cables at both sides of the pylon (with scaffolding),
* no works were performed at support No. 9.  
According to the author, the compression of the cable with external tendons at support No. 11 will be ineffective. Strengthening the curvilinear, corrosion-damaged cable could not be effective-sectional stressing was difficult for technological reasons, and the stress level of the external tendons was low due to the poor technical condition of the concrete. However, the lack of any strengthening of the cables at supports Nos. 9 and 10 was a technical and organizational mistake.  
After all, the technically correct solution to reduce the load on the concreted cable would be to add independent steel cables attached to the pylon, e.g., located in parallel to the existing diagonal stay cable. With such a solution, the concreted cable would be considerably unloaded. Additional suspension cables in the structure allow for better load distribution and redundancy-if one element is damaged, other elements will take a greater load and the object will not suddenly crash.  
The method of strengthening the structure of the facility could be as follows:  
* removing the suspended span-unload the support, including brackets,
* repair and reinforce of concrete supports, including brackets and concrete tendons,
* adaptation of the pylon and brackets to attach additional steel tendons suspending the brackets,
* fixing additional steel tendons to the pylon and brackets,
* strengthening the suspended span (or replacing it with a lighter one) and placing it on the reinforced joints at the ends of the supports.  
Such a solution would extend the life of the structure and reduce the risk of a sudden failure. This solution is much simpler than compression of the concreted cable and it could be used on the other two supports--Nos. 9 and 10.  
The author submitted his concept of strengthening the viaduct to Italian engineers, who were compressing the concreted cables at support No. 11. Figure 9(a) shows support No. 10 before strengthening, and in Figure 9(b) after strengthening. The concept of structural strengthening proposed by the author has not been accepted for various reasons. Certainly one of them-perhaps even the most important one-was the need to change the architecture of the structure. Additional steel cables would change the appearance of the viaduct designed by Prof. [PERSON], and this was incompatible with the basic assumption to the design goal of preserving the original appearance of the viaduct.  
Figure 9: View of the 3 supports of the viaduct—No. 11 with strengthened concreted cables, No. 10 with an additional steel cap and No. 9 without any structural changes (photo by [PERSON]; April 1993).  
At the end of the IRI course, a meeting was held with a representative of the Italian government. At the meeting, it was necessary to say in Italian what technical project in Italy had made the most impression on the participant of the course. The author stated that he was most impressed by the structure of Prof. [PERSON]'s Viaduct in Genoa, which should be properly strengthened as soon as possible because the current way of strengthening will be ineffective. The author presented his concept of strengthening (shown in Figure 10b) as one of the possible applications for strengthening the other two viaduct supports.  
The author stated that if the viaduct was not properly strengthened, it may collapse. The conversation took place 25 years before the collapse of the viaduct.