PROJECT:  Detailed design of two dual high speed lines railway launched bridges, section Tithorea - Domokos in Ch 14+825 (SG 14) and 13+500 (SG15) with a total length of 395m and 440m respectively, seismically isolated.
CLIENT: ERGAOSE S.A.
ASSOCIATED OFFICES: A Preza - S. Pilitsis - D. Tolis and colleagues.
                                                    DENCO S.A. (Seismic isolation consultant)
BRIEF DESCRIPTION:

The bridges structural system is a one cell box cross section continuous beam with typical spans 45m long having total length 395m (SG 14) and 440m (SG15) respectively. The SG 15 is partly on a curve in plan. The bearings are friction pendulum spherical bearings rest on single cell box piers of up to 32.45m (SG 14), 38.25m (SG 15). The foundation is on piles. Foundation design as well as pier retaining of pier excavations, made ​​by colleague S. Pilitsis

IN PARTICULAR:
 
The superstructure consists of nine continuous prestressed  spans for SG 14 and ten for the SG 15 with central spans typically 45m. Superstructure rests on piers through seismic isolation devices.
 
The seismic isolation system is based on the use of movable spherical bearings (friction pendulum bearings, FPS) and hydraulic viscous dampers that act as dynamic locking devices (shock transmission units) for service loads. All pier bearings are able to move on  both horizontal directions, while the abutments, due to railway line requirements, have restrains in the transverse direction. The calculation of seismic loads was a nonlinear integration in time with the structural analysis program SAP. Maximum vertical load of bearings 25MN
 
The cross section of bridge has the shape of one cell box girder with structural height 3.75m and total width, with overhangs, 13.90m
 
Launching was in typical sections of 22.5m using as tip a steel cantilever 29m long.

The bridges are in plan curved R = 900m, especially the SG 15 is partly curved (consisting of an extra difficulty in design).
 
The piers consist of one cell box cross section 4.0x6.0m at the level of superstructure supporting beam with the dimension 4.00m (towards the span of the bridge) to vary increased by height with a slope 1 / 60. The wall thickness is 50cm and construction uses climbing formwork of reinforced concrete
 
Pier superstructure supporting beam has the shape of a reversed T beam. The web of that beam (on which rests the bridge) has a height of 2.25m.
 
Pile caps are 3.00m thick and built on bored piles with a diameter of 1.20m or 1.50m.
 
DESIGN:
 
The study was conducted in two related phases:
A' Phase: Launching.
The analysis was following the construction phases and movement of the deck. For that purpose the development of a program code in lisp (approximately about 7600 lines of code) was necessary to provide input / modification data of a continually modified bridge structural system in the analysis program (sofistik). By that means analysis was monitoring the movement of superstructure (with steps of about 3.75m) during launching, since the analysis program was not otherwise able to resolve the launching process. In each of these positions, the superstructure was loaded for dead load, bearing tolerances and temperature difference (except those for prestressing losses and creep, per launching phase) producing envelopes of structure internal forces. Number of independent load cases (support tolerances - temperature) examined was 2366 in SG14 and 2766 in SG 15, in a total of 130 structural systems for SG 14 and 144 for SG 15.
 
B' Phase: Operation in service - earthquake
The second associated phase (by the meaning of the A phase applied forces and loading of the deck) was considering the superstructure to its final position, with the final prestressing forces, service and other possible loads during operation as well as internal forces due to the nonlinear earthquake solution.
 
The bridges have been completed but the project is not in operation yet.
 
Design years: 2006
Design standards: DS804, Greek Earthquake Design Standard