Refined prestressed concrete elements
View Patent ↗Disclosed invention comprises innovations in the fabrication process and the associated design methodology for producing refined prestressed concrete elements/components. The innovations disclosed are fabrication using multiple stages, the use of ultra high strength materials for only critical subcomponents, utilizing thinner sections made of ultra high strength materials, and a unique method of inducing and controlling camber. The embodiments of this invention enable the accelerated construction of concrete structures that are both durable and cost effective. This disclosure demonstrates the significant improvements to the prior art in the areas of durability, constructability, and cost reduction for prestressed concrete components. The embodiments presented in this disclosure are for bridge superstructure applications.
1. A method of reducing camber variance among beams during fabrication, the method comprising:
applying prestress and/or post tension to an Ultra High Performance Concrete (UHPC) lower flange of a beam either before casting and curing of the UHPC lower flange and/or after the casting and curing of the UHPC lower flange, thereby forming a compressed UHPC lower flange of the beam;
applying an external force to the compressed UHPC lower flange to introduce a first amount of camber, which is of the compressed UHPC lower flange; and
during the applying of the external force, disposing a web of the beam on the compressed UHPC lower flange thereby resulting in a second amount of camber, which is of the beam, wherein
the web of the beam is formed of another concrete material different from the compressed UHPC lower flange, and
the another concrete material is a material other than UHPC.
2. The method of claim 1 , wherein the applying of the prestress includes prestressing of strands of the UHPC lower flange.
3. The method of claim 1 , wherein the applying of the post tension includes applying the post tension to tendons of the UHPC lower flange.
4. The method of claim 1 , wherein the applying of the prestress to the UHPC lower flange of the beam does not apply prestress and/or post tension to the web of the beam.
5. The method of claim 1 , wherein the disposing of the web further includes disposing a top flange of the beam on the compressed UHPC lower flange in the same process as the disposing of the web.
6. The method of claim 1 , wherein the applying of the external force to the compressed UHPC lower flange includes applying the external force to about a centroid of the compressed UHPC lower flange.
7. The method of claim 1 , further comprising:
after the applying of the prestress and before the applying of the external force, shoring the compressed UHPC lower flange.
8. The method of claim 1 , wherein the applying of the external force to the compressed UHPC lower flange includes setting the compressed UHPC lower flange to a desired geometric shape.
9. A method of reducing camber variance among beams during fabrication, the method comprising:
applying prestress and/or post tension to an Ultra High Performance Concrete (UHPC) lower flange of a beam either before casting and curing of the UHPC lower flange and/or after the casting and curing of the UHPC lower flange, thereby forming a compressed UHPC lower flange of the beam;
shoring the compressed UHPC lower flange of the beam;
applying an external force to the compressed UHPC lower flange to set the compressed UHPC lower flange to a desired geometric shape and introduce a first amount of camber, which is of the compressed UHPC lower flange; and
during the applying of the external force, disposing a web and a top flange of the beam on the compressed UHPC lower flange to form a completed beam thereby resulting in a second amount of camber, which is of the completed beam, wherein
at least one of the web and the top flange is formed of another concrete material different from the compressed UHPC lower flange, and
the another concrete material is a material other than UHPC.