Thin prestressed concrete panel and apparatus for making the same

Abstract

A thin, prestressed concrete panel, having a thickness of about one and one-half inch thickness or less, and apparatus for making the same is disclosed. Pairs of prestressed tendons extend between the side and end portions of the panel. The tendons of each pair are positioned on each side of the mid-plane of the panel and spaced from such mid-plane so as to increase panel strength and prevent warping of the panel. A molding apparatus for casting the panel comprises a bottom plate, a pair of opposite side portions, and a pair of opposite end portions. Slots are defined in the side and end portions through which tendons are inserted prior to pouring concrete in the mold. Tensioning means are provided for prestressing the tendons in the longitudinal and lateral directions of the panel.

Description

[0001] This is a continuation-in-part of U.S. patent application Ser. No. 09 / 684,874, filed Oct. 6, 2000, which is incorporated herein by reference.THE FIELD OF INVENTION [0002] The present invention relates to the construction and manufacture of thin prestressed concrete panels useful for architectural cladding of buildings and other purposes. BACKGROUND OF THE INVENTION [0003] Exterior cladding of a building is subjected to attacks from climatic conditions such as freeze-thaw cycles, moisture intrusion, ultra-violet rays, wind and seismic loading and sometimes vibration from traffic and other sources, amongst other things. [0004] Precast concrete cladding systems have been used extensively on commercial buildings because of their durability and architectural appeal. However, precast concrete cladding, as used heretofore, is provided typically in heavy elements and its use has been limited to reinforced concrete or steel frame structures due to the load that it imposes on a buildin...

AI Technical Summary

Benefits of technology

[0005] In accordance with the invention, concrete panels are prepared by casting panels of about 1.5 inch thickness or less, which contain prestressed tendons. The tendons are oppositely positioned between the mid-plane of the panel and each of the opposite faces and may be spaced either equidistantly or at different distances from the adjacent face, in spaced grids. The positioning of opposing tendons between the mid-plane and the opposite faces increases panel resilience and will effect return of a panel to its original shape after being flexurally deformed by loads imposed normal to its faces, such return being effected even if a crack has developed in the tension face of the panel. OBJECTS OF THE INVENTION

[0006] It is, accordingly, an object of this invention to provide a prestressed concrete panel that is thin, light, durable and resilient.

[0007] Another object of the invention is to provide a prestressed concrete panel that may be field cut and easily installed on a structure.

[0008] Still another object of the invention is to provide an improved apparatus for casting prestressed concrete panels at a reduced cost.

Problems solved by technology

Exterior cladding of a building is subjected to attacks from climatic conditions such as freeze-thaw cycles, moisture intrusion, ultra-violet rays, wind and seismic loading and sometimes vibration from traffic and other sources, amongst other things.

However, precast concrete cladding, as used heretofore, is provided typically in heavy elements and its use has been limited to reinforced concrete or steel frame structures due to the load that it imposes on a building.

Consequently, a building designed to carry the lateral and gravity loads imposed by the heavy concrete skin system is costly.

Moreover, existing concrete panel systems are susceptible to permanent deformation from perpendicularly applied loads that create surface cracks in the tension face of the panel.

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