Structural unit

Claim 1

A PERMANENT COMPOSITE BRIDGE STRUCTURE COMPRISING A PLURALITY OF HOLLOW ELONGATED BEAMS EXTENDING LENGTHWISE OF SAID BRIDGE STRUCTURE IN SIDE-BY-SIDE AND INTERCONNECTED LOAD TRANSFERRING RELATIONSHIP, EACH BEAM BEING OF TRIANGULAR CROSS-SECTION, EACH BEAM ALSO HAVING AN UPWARDLY DISPOSED BASE AND DOWNWARDLY INCLINED SIDES AND A DOWNWARDLY DISPOSED CORNER, THE SIDES OF SAID BEAMS COMPRISING LIGHTWEIGHT SHEET METAL, CORNER MEMBERS OF THICKER LIGHTWEIGHT METAL SECURED TO THE CORNERS OF THE BEAMS, THE DOWNWARDLY INCLINED SIDES OF ONE BEAM LYING IN SUBSTANTIALLY PARALLEL PLANES WITH THE SIMILARLY DISPOSED SIDES OF THE OTHER BEAMS, MEANS CONNECTING THE DOWNWARDLY DISPOSED CORNERS OF THE BEAMS, THE CORNER MEMBERS OF A BEAM LOCATED ADJACENT BOTH TO THE UPWARDLY DISPOSED BASE AND THE DOWNWARDLY INCLINED SIDES THEREOF BEING ARRANGED IN LOAD TRANSFERRING AND INTERCONNECTED RELATIONSHIP, A ROADBED SLAB DISPOSED UPON THE UPWARDLY DISPOSED BASES OF THE BEAMS, SAID ROADBED SLAB ACTNG AS THE PRIMARY COMPRESSION LOAD BEARING MEMBER IN THE BRIDGE STRUCTURE, MEANS INCLUDING SHEAR TIE ELEMENTS AFFIXED TO THE LAST MENTIONED CORNER MEMBERS OF THE BEAMS AND ARRANGED TRANSVERSELY TO THE LONGITUDINAL AXIS OF THE BRIDGE STRUCTURE, SAID SHEAR TIE ELEMENTS BEING EMBEDDED IN THE ROADBED SLAB AND ACTING TO FULLY INTEGRATE THE ROADBED SLAB WITH THE DOWNWARDLY INCLINED SIDES OF THE BEAMS WHEREBY THE DOWNWARDLY INCLINED SIDES OF THE BEAMS AND THE MEANS CONNECTING THE DOWNWARDLY DISPOSED CORNERS OF THE BEAMS WILL ACT AS THE PRIMARY TENSILE LOAD BEARING ELEMENTS OF THE BRIDGE STRUCTURE