Static structures (e.g. – buildings) – With component having discrete prestressing means – Anchorage
Reexamination Certificate
1999-05-14
2001-04-03
Chilcot, Richard (Department: 3635)
Static structures (e.g., buildings)
With component having discrete prestressing means
Anchorage
C264S228000
Reexamination Certificate
active
06209274
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to venting apparatuses and methods. More particularly, the present invention relates to a vent flow apparatus and method for venting and preventing air pockets in conduit or duct type apparatuses designed for flow of a material therethrough, with particular applicability for post-tensioning apparatuses for concrete or other suitable structures.
BACKGROUND ART
For elongated conduit or duct type apparatuses for passage of material therethrough, it is common for the material passing through such conduit to incompletely to fill certain internal portions thereof so as to cause formation of air pockets therein. For example, elevated portions of a curved conduit have been found to be particularly susceptible to formation of air pockets in internal sections thereof. This susceptibility of air pocket formation can occur in a variety of environments or areas and typically does not depend on the type of material passing through the conduit.
Post-tensioning apparatuses or systems for concrete or other suitable structures typically utilize elongated conduits or ducts for passage of a hardenable material such as grout through the conduit. Since it is also common for post-tensioning apparatuses to include curved conduits comprising portions of higher and lower elevations, such post-tensioning apparatuses have particular susceptibility to formation of air pockets in elevated portions thereof where grout will usually not completely fill. As can be appreciated by those of skill in the art of post-tensioning apparatuses and methods, it has therefore been common in the past to utilize vertical vent pipes which communicate with elevated, curved portions of an elongated conduit on one end and communicate on the opposite end with environment outside the material, such as concrete, that surrounds the post-tensioning system in order to pass grout through the vent pipe to completely fill the conduit, including the elevated portions thereof.
The use of such vent pipes suffers from many disadvantages, including forming a weak point in the post-tensioning system, acting as a natural pathway for contaminants to enter the internal portions of the post-tensioning system such as de-icing salts, and also providing much difficulty in the concrete pouring and finishing processes. Even in post-tensioning systems of the type disclosed in Parent patent application U.S. Ser. No. 08/797,690, commonly owned herewith and specifically incorporated by reference herein, there typically are body section portions adjacent to an intermediate anchor head which typically are prone to formation of air pockets in internal portions thereof despite the use of a transfer means for routing grout from a first body section, around and past the intermediate anchor head, and into an adjacent, second body section.
In light of the prior art as discussed hereinabove, it is apparent that there remains much room for improvement in the art of venting and preventing formation of air pockets in conduit or duct type apparatuses for passage of material therethrough, particularly for post-tensioning systems for concrete or other suitable structures.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, a vent flow apparatus and method are provided for general application in venting and filling air pockets in conduit or duct type apparatuses designed for passage of material therethrough. The vent flow apparatus comprises a hollow vent flow conduit having both an entry opening and a downstream exit opening with both of the openings being in communication with a duct for flow of material therethrough. The entry opening of the vent flow conduit is in communication with the duct at a first location of greater cross-sectional area of the duct than a second location of communication of the exit opening of the vent flow conduit with the duct. Typically, the first location of communication of the entry opening of the vent flow conduit with the duct is elevationally higher than the second location of communication of the exit opening of the vent flow conduit with the duct, although it is envisioned in accordance with this invention that other arrangements could also exist. In a preferred embodiment, the vent flow apparatus comprises a tube positioned entirely within the duct. The vent flow conduit has particular applicability for post-tensioning systems for concrete or other suitable structures which include a duct for passage of a hardenable material therethrough. Utilizing the method of the present invention, an elongated conduit, such as that of a post-tensioning system for a concrete structure or any other suitable elongated conduit of associated with another suitable system or environment, can be filled completely with material without formation of air pockets and without the use of external vent pipes.
In an embodiment adapted for applicability with post-tensioning systems which include a transfer means for routing grout from a first body section, around and past an intermediate anchor head, and into a second body section, the vent flow conduit is preferably positioned within the post-tensioning apparatus such that the entry opening of the vent flow conduit terminates in and communicates with a first location within a duct adjacent to the intermediate anchor head such that the first location is of greater cross-sectional area than a second location where the exit opening of the vent flow conduit terminates in and communicates with the transfer means utilized to route grout from the first body section, around and past the intermediate anchor head through the transfer means, and into an adjacent, second body section. In this embodiment, the vent flow conduit also preferably comprises a tube positioned entirely within the post-tensioning system. Utilizing the method of this embodiment of the present invention, the post-tensioning apparatus can be completely filled without air pockets by the hardenable material.
As can be appreciated by those of skill in the art, external tendons frequently, and in some circumstances always, will not have vents at high points inside the saddle due to access problems. As such, the vent flow apparatus and method of the present invention also has particular applicability for use with such external tendons.
It is therefore an object of the present invention to provide a novel vent flow conduit with general applicability for use in conduit or duct type apparatuses for passage of material therethrough in order to prevent formation of air pockets in internal portions thereof.
It is another object of the present invention to provide a novel vent flow conduit with particular applicability for post-tensioning systems for concrete or other suitable structures, including post-tensioning systems for concrete or other suitable structures which include first and second body sections interconnected in series by an intermediate anchor head and which utilize a transfer means for routing grout from the first body section, around and past the intermediate anchor head, and then into the second body section.
It is a further object of the present invention to provide a novel vent flow conduit which is simple to utilize and provides much-needed advantages in preventing formation of air pockets in conduit or duct type apparatuses for passage of material therethrough, such as post-tensioning systems for concrete or other suitable structures.
Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow.
REFERENCES:
patent: 4799307 (1989-01-01), Reigstad et al.
patent: 5540030 (1996-07-01), Morrow
patent: 5939003 (1999-08-01), Crigler et al.
patent: 2603928 (1988-03-01), None
Chilcot Richard
Jenkins & Wilson, P.A .
VSL International
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