NEW TYPE OF CONTINUOUS SPAN BRIDGE OF COMPOSITE STEEL/CONCRETE CONSTRUCTION

IN THE FIRST PART THE AUTHOR DESCRIBES THE ERECTION OF A NEW TYPE OF BRIDGE WITH A CONTINUOUS COMPOSITE STEEL/CONCRETE STRUCTURE IN AUSTRALIA. THE STEEL I-BEAMS ON SIMPLE SUPPORTS ARE CONNECTED TO ONE ANOTHER ON SITE WITHOUT RIVETTING, BOLTING OR WELDING. AT EACH END ARE FITTED PLATES WITH VERTICAL WELDED JOINTS AS WELL AS ORDINARY CONNECTING DOWELS. CONCRETE CAST BETWEEN THE PLATES OF THE TWO BEAMS EXTENDS THE PIERS OF THE BRIDGE, THE LOWER PART OF THE PIER BEING LINKED TO THE VERTICAL EXTENSION BY ORDINARY REINFORCEMENT OR VERTICAL PRESTRESSING. OVER THIS A SHORT SECTION OF CONCRETE SLAB IS CAST. THEN THE CONCRETING OF THE BRIDGE DECK BETWEEN THE PIERS IS CARRIED OUT. FOLLOWING A SUCCESSFUL TEST ON A MODEL, A LARGE NUMBER OF BRIDGES HAVE BEEN CONSTRUCTED. IN THE SECOND PART OF THE ARTICLE, THE AUTHOR DESCRIBES A BRIDGE, WHICH IS THE FIRST OF THIS TYPE IN THE WORLD (ON THE RIVER HAWKESBURY, NORTH OF SYDNEY), CONSTRUCTED ON THE SAME PRINCIPLE. IT IS COMPOSED OF STEEL BOX GIRDERS, WITH A TRAPEZOIDAL SECTION OPEN AT THE TOP, RESTING ON TUBULAR PIERS OF A COMPOSITE STEEL/CONCRETE CONSTRUCTION. THE FOUNDATION PILES, THE BEARINGS AND THE DECK ARE DESCRIBED.