SETI ENGINEERING S.R.L.
The “Ciolo” Bridge retrofitting and consolidation project aims to achieve the following minimum goals:
1) Structural consolidation
2) Seismic retrofitting in compliance with the 2018 NTC (Technical Standards for Buildings).
3) Structural rertofitting in compliance Wwith the new highway code (in terms both of safety and trafficability).
4) Adaptions for the abolition of Aarchitectural barriers
5) Installation of new barriers Iin order to prevent diving from the bridge
6) Durability of the structure with a new sevice life of at least 65 Yyears.
In order to accomplish these premises, the project consists in:
The seismic and structural retrofitting design of the bridge has been achieved thanks to a thorough modelling, which retraced the entire history of the building since its construction, until the current conditions of the site. Modeling took into account the presence of steel reinforcements embedded in concrete in 1993-94 (steel pillars and beams, reinforced concrete slabs connected by steel pins to the existing slabs, steel ties in order to join the old concrete to the new structures). It was possible to represent not only the state of the places (MODEL 1), but also the bridge model, complete of restoration operations and seismic and structural adaptation (MODEL 2) as correctly as possible, all thanks to Advance Design potential.
Before to obtaining the definitive modeling, our engineering company (SETI ENGINEERING SRL) had to run and compare the results of different modeling of the bridge, using different types of finite elements (see the JPG file: “7.DIFFERENT MODELS” in the attached folder 2).
The bridge was represented even with “beam” elements for the beams of the deck, associated with “plate” models for the arch, the columns, the upper slab and the lower slab, and using “rigid links” to get systems to work together. However, the results were not satisfactory. In the end, the final model provided the use of “plate” elements for the arch, the columns, the slabs and the deck of the bridge, and “beam” elements only for steel and concrete pillars, and for steel beams.
Comparing the results of the models, we have established that the latter type of modeling was the most representative of reality.
Design verifications were carried out with further simplified models, too (deck as a “beam” with a rectangular hollow section), in order to get the actual behavior of a multicellular box section.
Advance Design allowed a quick and easy modeling of the bridge, starting from the DXF file.
The possibility of carrying out the automatic generation of mobile traffic loads, after entering the conventional lanes and the relative load values envisaged by the NTC2018 regulation, is also of fundamental importance for the study of the bridge, for the analyzes, and for the structural design verifications. The seismic analysis was also carried out very quickly, as the input of the thermal loads.
The post processing (through color maps vision) allowed then the quick control of the results, in terms of:
– mode shapes;
– structural elements checks.