Pinios River Bridge

The bridge carries the existing PATHE motorway over Pinios river at Tempi and has a total length of approx. 210 m. It consists of 5 spans with theoretical lengths 40,72+72,06+40,63+25,0+30,77=209,18 m. The bridge deck is 14,0 m wide and comprises an 11,0 m wide carriageway and two footways each 1,50 m wide.
Spans consist of prestressed concrete twin-box girders and simply supported beam grillages with high precast prestressed concrete I-beams. Transverse prestressing is also applied to the deck slabs.
At M1 and M2 the inclined columns are supported on vertical wall-type concrete piers.
Piers M3 and M4 are four- and three-column frames, respectively. Pier M1 is founded on prestressed concrete driven piles., while piers M2, M3, M4 rest on spread foundations.
Abutment A1 (at the south bank) is a multi-cellular box structure with total plan dimensions 10×14 m, while abutment A2 (at the north bank) is a typical gravity wall with two relief shelves.
Bridge investigations have detected significant defects that reduce both the bearing capacity of structural elements and the durability of the entire structure. Furthermore, analytical checks have shown that the existing bridge structure is not capable to resist either the increased traffic loads or the seismic loads prescribed by current codes.
Proposed interventions aim to mitigate these structural deficiencies and they can be divided into three categories:
1. Strengthening interventions aiming to increase the resistance of the structure against vertical service loads.
• Construction of a new strengthening slab 12 cm thick on top of the existing deck slab.
• Strengthening of the precast beams by means of external prestressing.
• Shear strengthening of the box webs by means of externally installed vertical prestressed steel bars, in combination with transversal steel girders attached to the outer surface of the box bottom slab.
• Replacement of all bridge bearings with new elastometallic bearings.
2. Strengthening interventions aiming to upgrade structural capacity against horizontal seismic loads.
• In the transverse direction, strength and stiffness of the existing piers is improved by the addition of steel bracing systems and lightly reinforced R/C jackets so they can resist the increased seismic loads.
• In the longitudinal direction, the retrofit proposal aims to modify the load path through which the longitudinal seismic component is transferred to foundations. The proposal comprises of the enforcement of superstructure continuity by cancelling intermediate joints between spans through the construction of continuity slabs and the addition of a new, stiff Λ-shaped R/C frame at the location of pier M3, connected to the continuous superstructure by means of shear key bearings.
3. Repair measures to restore durability of the bridge.