A BRIDGE CROSSING IN THE BAY OF RIO DE JANEIRO

IN MARCH 1974 THE ROAD BRIDGE OVER GUANABARA BAY WAS OPENED TO TRAFFIC. IT CONNECTS RIO DE JANEIRO WITH THE SUBURB OF NITEROI; 9.2 KILOMETRES OF THE 13.9 KILOMETRES LONG STRUCTURE ARE OVER WATER. THE BRIDGE, WHICH HAS A 26.4 METRE WIDE CARRIAGEWAY, CARRIES TWO THREE-LANE ROADWAYS AND IS DESIGNED FOR A TRAFFIC FLOW OF 50000 VEHICLES PER DAY. THE REINFORCED CONCRETE SPANS CONSISTING OF TWO CONTINUOUS GIRDERS ARE 80 METRES. EACH PAIR OF PIERS IS SUPPORTED BY A SINGLE FOUNDATION WITH TEN PILES. THESE PILES WHICH ARE 1.8 METRES DIAMETER ARE FOUNDED 70 METRES DEEP ON GROUND WITH HIGHER BEARING CAPACITY. BORING WORKS WERE CARRIED OUT USING AN AIR FLUSH TECHNIQUE FROM THE WIRTH ERKELENZ COMPANY. THE PIERS - MAXIMUM HEIGHT 60 METRES - WERE CONSTRUCTED USING SLIP FORMING. THE TWIN GIRDERS OF THE PRESTRESSED CONCRETE SUPERSTRUCTURE WERE ERECTED IN 4.8 METRE LONG HOLLOW BOX SECTIONS USING THE CAMPENON BERNARD SYSTEM. THESE ELEMENTS WERE PREFABRICATED, TRANSPORTED TO SITE, PROVISIONALLY PRESTRESSED AND FINALLY POST-TENSIONED ON COMPLETION OF A WHOLE SPAN. THE SLAB OVER BOTH GIRDERS IS TRANSVERSELY POST-TENSIONED. CONCRETE CONSTRUCTION WAS CARRIED OUT BY A BRAZILIAN JOINT VENTURE. FOR THE MAIN SPANS OF THE CENTRAL SECTION OF THE BRIDGE (5 SPANS: 74 - 200 - 300 - 200 - 74 METRE SPANS) A SUPERSTRUCTURE WAS CHOSEN CONSISTING OF TWO CANTILEVER STEEL BOX GIRDERS. THE BOX SECTIONS WERE FABRICATED IN ENGLAND BY THE JOINT VENTURE DORMAN LONG-CLEVELAND BRIDGE AND CONNECTED CLOSE TO THE SITE. THE AUTHOR DESCRIBES IN PARTICULAR THE STEEL CONSTRUCTION AND THE DEMANDING ERECTION SEQUENCE.