Bridge Design & Engineering 

Abstract: The Egnatia Motorway, discussed in this article, has been described as Europe's most difficult and most modern motorway. This US$2.5 billion, 687 km route runs across northern Greece's mountainous terrain which has brought many constructional challenges. The Egnatia crosses every river in the country, plus the existing north-south road and rail network, and this has meant designing and building a raft of technical works including bridges, tunnels, long cuts and embankments, on top of the hundreds of kilometers of road that have to be constructed. The Egnatia Motorway construction sites are being billed as a showcase of construction methods, with everything from conventional construction using formwork, precast 45-50 m beams mounted by special trolley, cantilevered assembly of elements either precast or cast in place, construction by launching from the shore being used.

Abstract: This article describes the design and construction of a replacement swing span bridge in New York, USA. The previous span has been cut out and will be replaced in November 2004. The new design, an on-line swing bridge with a through-truss main span and staged construction, allows an extra traffic lane and greater horizontal clearance of navigation channels. Two parallel Warren trusses serve as the main load-carrying members. Key to the staging concept is the design of the pivot pier with a reinforced concrete cap that spans over the existing centre pier. The pivot assembly houses a spherical roller thrust bearing which can resist both impact and seismic forces, with arrangements to allow wiring to pass through its centre. The new span was shipped from the state of Alabama and completion of the project is expected to take about four weeks, with complete bridge traffic closures limited to one weekend.

Abstract: Several decades of research and development into earthquake hazards have produced sufficient knowledge to allow engineers to protect bridges from risks such as ground shaking and soil failure, One hazard which is yet to be investigated in relation to bridges is earthquake induced tsunamis. Tsunamis is a series of waves generated by underwater earthquakes, volcanic eruptions, or landslides. The article examines new design guidelines that give advice on protecting bridges against damage from tsunamis. The threat of tsunamis and what can be done to guard against it is explained.

Abstract: The epicentre of the Bolu earthquake that hit Turkey in 1999 was only 12km from a new 2.4km long viaduct forming part of the new Anatolian Motorway between Istanbul and Ankara. The earthquake was 7.2 on the Richter scale and a peak ground acceleration of 0.8g was measured. The concrete viaduct was therefore subjected to an unscheduled full-scale test before it opened. Despite being seriously damaged the viaduct was still standing. The design for the rehabilitation of the viaduct was awarded to Professor Calvi of the University of Pavia and Professor Nigel Priestley from the University of California. The protection system for the structure was adjusted to take into account new seismic parameters demanded by the client. These included a return period of 2000 years and consideration of the near field effect as set out in the 2001 AASHTO seismic standards. Only a few bridge piles were damaged. The retrofitting system involved changing the system of deck bearings. The deck, which was originally simply supported by a ten-span continuous slab, was replaced by a continuous deck on seismic bearings. The longitudinal continuity of existing deck sections was achieved using a rigid transverse post-compressed diaphragm into which beams were embedded. Retrofitting subcontractor was Freyssinet Terra Armata.