Prefabricated, prestressed bridge system and method of making same

1. A method for making a prefabricated, prestressed bridge module comprising:

providing and arranging one or more steel beams having U-shaped cross sections and supported on three or more supporting formwork elements such that the first supporting formwork element is at a first outer end of the one or more steel beams, the second supporting formwork element is at a middle of the one or more steel beams, the third supporting formwork element is at a second outer end of the one or more steel beams;

adding shear connectors to the one or more steel beams;

positioning and extending rebar through the one or more steel beams in a direction perpendicular to the one or more steel beams and above at least two of the supporting formwork elements;

pouring concrete to form concrete diaphragms on top of and around the rebar at locations above the supporting formwork elements, the diaphragms each extending into cavities defined by the U-shaped steel beams and extending between the U-shaped steel beams;

adjusting one or more of the supporting formwork elements to stress the one or more steel beams; and

fabricating a concrete deck to form a surface atop the diaphragms and the one or more steel beams such that resulting compression stress of the concrete deck secures in place the stresses imparted to the one or more steel beams, the deck resting on a top of the U-shaped steel beams and diaphragms and not extending below the top of the steel beams.

2. The method of claim 1 , wherein said providing and arranging step comprises providing and arranging only the first supporting formwork element, the second supporting formwork element, and the third supporting formwork element.

3. The method of claim 2 , wherein said adjusting step comprises lowering the first and third supporting formwork elements.

4. The method of claim 2 , wherein said adjusting step comprises raising the second supporting formwork element.

5. The method of claim 3 , wherein said adjusting step further comprises applying external loads to the concrete diaphragms atop the first and third supporting formwork elements.

6. The method of claim 4 , wherein said adjusting step further comprises applying external loads to the concrete diaphragms atop the first and third supporting formwork elements.

7. The method of claim 1 , wherein said adjusting step comprises applying external loads to all of the concrete diaphragms that are not on top of the second supporting formwork element.

8. A prefabricated, prestressed bridge module comprising:

one or more steel beams having a U-shaped cross section and arranged on three or more supporting formwork elements such that the first supporting formwork element is at a first outer end of the one or more steel beams, the second supporting formwork element is at a middle of the one or more steel beams, the third supporting formwork element is at a second outer end of the one or more steel beams;

shear connectors on the one or more steel beams;

rebar that runs through the one or more steel beams in a direction perpendicular to the one or more steel beams and above at least two of the supporting formwork elements;

concrete material poured to form concrete diaphragms on top of and around the rebar at locations above the supporting formwork elements;

the supporting formwork elements being adjusted to stress the one or more steel beams; and

a concrete deck fabricated atop the diaphragms and the one or more steel beams such that resulting compression stress of the concrete deck secures in place the stresses imparted to the one or more steel beams.

9. The prefabricated, prestressed bridge module of claim 8 , wherein said three or more supporting formwork elements consist of the first supporting formwork element, the second supporting formwork element, and the third supporting formwork element.

10. The prefabricated, prestressed bridge module of claim 9 , wherein the first and third supporting formwork elements are lowered to stress the one or more steel beams.

11. The prefabricated, prestressed bridge module of claim 9 , wherein the second formwork element is raised to stress the one or more steel beams.

12. The prefabricated, prestressed bridge module of claim 10 , wherein an external load is applied to the concrete diaphragms atop the first and third supporting formwork elements.

13. The prefabricated, prestressed bridge module of claim 11 , wherein an external load is applied to the concrete diaphragms atop the first and third supporting formwork elements.

14. The prefabricated, prestressed bridge module of claim 8 , wherein external loads are applied to all of the concrete diaphragms that are not on top of the second supporting formwork element.

15. A prefabricated, prestressed bridge system comprising:

two or more of the prefabricated, prestressed bridge modules as defined in claim 8 secured together.

16. The prefabricated, prestressed bridge system of claim 15 , wherein

two or more prefabricated, prestressed bridge modules are secured together with tensioning rods such that said tensioning rods are threaded through holes in each of said prefabricated, prestressed bridge modules and tightened.

17. The prefabricated, prestressed bridge system of claim 15 , wherein

each of said two or more prefabricated, prestressed bridge modules have elongated concrete diaphragms;

said prefabricated, prestressed bridge modules are secured together with one or more cast in place connections poured between the concrete decks of the prefabricated, prestressed bridge modules and above the elongated diaphragms of the prefabricated, prestressed bridge modules.