Patent Application
20200173163
The present invention relates generally to construction techniques for air separation plants, and more particularly to various systems and methods to secure air separation plant structures, such as a cold box structure, to concrete foundations as well as provide horizontal stability to the air separation plant structures.
Nationally recognized building codes require that structures or equipment used in an air separation plant such as cold box structures be secured to the foundation to safeguard against the destructive uplifting and shearing forces of seismic events and severe weather related events, i.e., strong winds, tornadoes, hurricanes, etc. The securing of such air separation plant structures and equipment is typically accomplished by connecting the frame of the structure or equipment to a concrete foundation through the use of steel anchor bolts embedded in the concrete foundation. The required thickness of the foundation and embedment depth of the anchor bolts are generally determined in accordance with the American Concrete Institute (ACI) Building Code Requirements for Structural Concrete (ACI 318-14). Anchor bolts are typically laid out in the foundation prior to pouring concrete, with threaded portions sticking up out of the concrete foundation high enough to be secured by a round washer and a nut. When the concrete dries, the anchor bolts would be used to secure the frame of the structure to the concrete foundation.
However, due to the large size of structures used in most air separation plants, conventional designs and procedures for anchoring such large structures to concrete foundations as described in ACI 318-14 Chapter 17 are not directly applicable. For example, many air separation plants have cold box structures that have a side dimension or diameter that can range from 10 feet (10′) to 17 feet (17′) and the height of such cold box structures can be up to 300 feet (300′). To secure such large structures to the on-site casted concrete foundation, very large size anchor bolts are typically used. Such large anchor bolts may range up to six inches (6″) in diameter with an embedment depth of six feet (6′) feet or more, whereas design using ACI 318-14 Chapter 17 is generally limited to anchors with four inch (4″) diameter and less. Some failure modes associated with anchoring of such large structures of an air separation plant with very large anchor bolts include pull-out or steel failure from excessive tensile loadings as well as concrete breakout/pryout, punching shear failures and steel failures from excessive shear loadings.
What is needed, therefore, is an improved method and system for securing air separation plant structures or equipment to reinforced concrete foundations without the use of traditional anchor bolts.
The present invention may be characterized as a system for fastening a frame of a cold box structure of an air separation plant to a concrete foundation, the system comprising: (i) a concrete foundation having a plurality of reinforced concrete piers projecting vertically from a top surface of the concrete foundation, wherein the reinforced concrete piers are arranged to project vertically from the top surface of the concrete foundation at locations adjacent to the outer perimeter of the cold box structure; (ii) a plurality of anchor bolts, each anchor bolt comprising an anchor bolt body having a first end and a threaded second end, with both ends configured to be projecting from the one of the plurality of the reinforced concrete piers in an orthogonal orientation to the vertical projection of the one of the plurality of reinforced concrete piers from the top surface of the concrete foundation, wherein the threaded second end of each of the one or more anchor bolts are configured to pass through a bore on a frame of the cold box structure; and (iii) one or more nuts configured to screw onto the threaded second end of each anchor bolt body to fasten the frame of the cold box structure to the plurality of reinforced concrete piers.
The present invention may also be characterized as a hollow steel structure assembly for fastening a cold box structure of an air separation plant to a concrete foundation, the hollow steel structure assembly comprising: one or more hollow steel structures, each hollow steel structures comprising a body defining a central axis, a length measured along the central axis and a width or diameter measured orthogonally to the central axis, the body further defining a first end configured to be embedded in the concrete foundation, and a second end configured to be projecting from the concrete foundation. The second end of the one or more hollow steel structures are configured to project from a top surface of the concrete foundation and further configured to project into the frame of the cold box structure. In some embodiments, the body of each of the one or more hollow steel structures may be a tapered configuration.
An alternative arrangement of the hollow steel structure assembly for fastening a cold box structure of an air separation unit to a concrete foundation provides the one or more hollow steel structures each having one or more alignment holes in the body proximate the second end. In such alternate embodiment, the second end of the one or more hollow steel structures are configured to project from a top surface of the concrete foundation and project adjacent to the outside perimeter of the cold box structure. The assembly would further include one or more anchor bolt assemblies configured to traverse through the alignment holes proximate the second end and couple the one or more hollow steel structures to the frame of the cold box structure in a horizontal orientation.
While the present specification concludes with claims distinctly pointing out the subject matter that Applicants regard as their invention, it is believed that the invention will be better understood when taken in connection with the accompanying drawings which:
Reinforced Concrete Piers
Turning to
Use of the reinforced concrete piers 20 for anchoring cold box structures 10 eliminates the need to design a complicated anchor bolt chairs for the large size vertical anchor bolts and simplifies the calculations for determining connection or anchoring strength. Additional advantages arising from the use of the reinforced concrete piers 20 include likely reduction in the thickness of the concrete foundation 15 when compared to concrete foundations where anchoring is accomplished using large-size vertical cast-in-place anchor bolts. This reduction in concrete foundation thickness is primarily a result of a smaller required embedment depth of the reinforcement of the concrete piers 20 and the monolithic nature of the pure concrete arrangement of the foundation and piers.
The concrete piers 20 preferably have a plurality of reinforcing bars embedded therein to provide sufficient longitudinal and transverse reinforcement to the pier and to confine the concrete when formed. Aligned horizontal thru-holes 25 are also placed in the reinforced concrete piers 20 as well as the cold box structure 10 to facilitate connection using horizontally disposed anchor bolts (not shown).
Hollow Steel Structures (HSS)
Turning now to
In various embodiments of the hollow steel structures shown in
The hollow steel structures 40 may optionally include a steel plate 50 (See
Although the present arrangement for securing cold box structures or equipment of an air separation plant to a reinforced concrete foundation has been discussed with reference to one or more preferred embodiments, as would occur to those skilled in the art that numerous changes and omissions can be made without departing from the spirit and scope of the present invention as set forth in the appended claims.
The present application claims the benefit of and priority to U.S. provisional patent application Ser. No. 62/772,817 filed on Nov. 29, 2018, the disclosure of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62772817 | Nov 2018 | US |
