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Renovation of old steel drawbridge at Euripus Strait.

PROJECT:  Renovation of old steel drawbridge at Euripus Strait

CLIENT: Construction company I.G. Korontzis S.A.
ASSOCIATED OFFICES: J. Malliaris and colleagues

BRIEF DESCRIPTION:
 
The project was under the frame of the bridge general maintenance, change of mechanical equipment and deck surfacing (it was wooden). Designs were final, including fabrication/shop drawings. In addition, on-site technical supervision services provided to the contractor, concerning design application. In detail:
 
Drawbridge: Full design, taking in account the additional loads of the new deck, with interventions, structural strengthening and remodeling of bridge horizontal structural system to undertake the seismic forces in the region with the implementation of newer anti-seismic regulations. Modification of the central couplings of the bridge with a completely new, specially invented, device.
 
Finally, repair design of Viotia housing tunnel (prestressed concrete) from the damage caused by an accident, during construction.
 
The central opening of the bridge is 42m long, the total length of the steel body is 58.8m and the width of the deck is 10.5m. Traffic loads, due to position, are very heavy and intense.
 
The bridge consists of two subsections that are withdrawn to housing tunnels in order to open the navigation channel. Each subsection is carried by two main steel trusses structurally functioning as two-sided cantilever. One part of the cantilever is used to bridge the opening (half of the Strait) and the other part to support the first by means of bearing to the roof of the housing tunnel. The two sections are connected in the middle of the opening by special mechanical / hydraulic couplings. The interventions are:
  • Strengthening of the main trusses and crossing trusses for the new loads with several member replacements, and the bridge transporting structural system.
  • Creation of a new horizontal structural system at the top chord of main trusses and proper supports for the takeover of seismic forces in the region (ao = 0,24 g).
  • Replacement of central couplings with new ones hydraulically functioning, so the connection to have small tolerances (thus not creating differential vertical deflection) and to be able to connect the two horizontal stiffer now subsections with possible tolerances due to the body movement.
 
Temporary works: Since the construction would cut n two the city of Chalcis a temporary footbridge had to be constructed. Fully designed with two alternatives:
  • Temporary movable footbridge: Cable stayed movable bridge with span opening ~ 40.0m and deck width 3.20m. The bridge was using two pillars of 12.20m height and the structural height of the steel superstructure was 1.45m. Its construction finally rejected due to financial reasons
  • Temporary footbridge: Steel truss bridge with the deck supported on the truss bottom chord. Simple span with an opening of 45m and deck width of 3.15 m, structural height of truss 2.50m. The project was constructed, operated (under very heavy traffic) and demolished. Designed in three prefabricated sections (so to be transported 120km) without preassembly (due to restrictions of the selected workshop) yet the erection on site was flawless. For this project, apart from the final design, prepared fabrication/shop drawings and technical support on site (workshop and construction site).
  • Assessment of the strength of the existing concrete structures and design necessary structure reinforcements to support the seating of the footbridge.
 
The project has been completed and in operation.
 
 
Design / supervision years: 1995-8
Design standards: DIN1072, Greek Earthquake Design Standard.

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