Sleeved bracing useful in the construction of earthquake resistant structures

• US 7,188,452 B2
• Filed: 03/11/2003
• Issued: 03/13/2007
• Est. Priority Date: 09/12/2000
• Status: Expired due to Term

• Current Assignee: Core-Brace, LLC (SME Industries, Inc.)
• Original Assignee: Benne Narasimha Murthy Sridhara
• Inventors: Sridhara, Benne Narasimha Murthy
• Primary Examiner(s): Friedman; Carl D.
• Assistant Examiner(s): Horton; Yvonne M.
• Application Number:
  US10/387,144
• Publication Number:
  US 20030205008A1
• Time in Patent Office: 1,463 Days
• Field of Search: 52/1, 521/671, 521/672, 521/673, 521/674, 521/678, 527/381, 527/391, 527/374, 188/266, 267/136, 267/140.12, 267/140.13, 2671414-141
• US Class Current: 52/167.3
• CPC Class Codes: E04H 9/0237 Structural braces with damping devices
• CPC Class Codes: E04H 9/028 Earthquake withstanding shelters

Abstract

A buckling restrained brace includes an elongate, hollow sleeve, an elongate yielding core extending substantially through the length of the sleeve, and a buckling constraining element between the yielding core and the inner surface of the hollow sleeve and spaced apart from at least one surface of the yielding core, leaving a gap therebetween. The buckling constraining element may be spaced apart from and, thus, the gap may exist between two or more surfaces of the yielding core. Additionally, an inner sleeve, or liner, may be positioned between the buckling constraining element and the yielding core, with the liner being spaced apart from at least one surface of the yielding core. The buckling restrained brace is useful in absorbing loads, such as seismically induced loads, that are exerted upon a steel frame.

Claims

1. A buckling restrained brace, comprising:

an elongate yielding core;

a hollow sleeve surrounding at least a portion of a length of said yielding core;

a buckling constraining element disposed within said hollow sleeve, said buckling constraining element surrounding at least a portion of said length of said yielding core and spaced apart from at least one surface thereof by a gaseous gap therebetween;

a liner positioned between said buckling constraining element and at least one surface of said yielding core and spaced apart from said at least one surface; and

coupling elements at ends of said yielding core and protruding at least partially from ends of said hollow sleeve.

2. The buckling restrained brace of claim 1, wherein a cross-sectional shape of said yielding core, taken transverse to a length thereof, is round.

3. The buckling restrained brace of claim 1, wherein a cross-sectional shape of said yielding core, taken transverse to a length thereof, is rectangular.

4. The buckling restrained brace of claim 1, wherein said yielding core comprises steel.

5. The buckling restrained brace of claim 1, wherein said hollow sleeve comprises steel.

6. The buckling restrained brace of claim 1, wherein said buckling constraining element comprises a buckling constraining material.

7. The buckling restrained brace of claim 6, wherein said buckling constraining material comprises a grout.

8. The buckling restrained brace of claim 7, wherein said buckling constraining material comprises a concrete.

9. The buckling restrained brace of claim 1, wherein said buckling constraining element comprises:

an inner sleeve positioned between said yielding core and said hollow sleeve so as to substantially surround said yielding core; and

a plurality of supports positioned between said hollow sleeve and said inner sleeve and spaced apart along a length of said inner sleeve for substantially maintaining a position of said inner sleeve within said hollow sleeve.

10. The buckling restrained brace of claim 1, wherein said buckling constraining element is spaced apart from at least two surfaces of said yielding core.

11. The buckling restrained brace of claim 10, wherein said buckling constraining element completely surrounds said yielding core.

12. The buckling restrained brace of claim 1, wherein said liner contacts said buckling constraining element.

13. The buckling restrained brace of claim 1, wherein a portion of each coupling element remains at least partially laterally surrounded by said hollow sleeve when a maximum tensile load is applied to said yielding core.

14. The buckling restrained brace of claim 1, wherein said buckling constraining element extends only partially along a length of said hollow sleeve.

15. The buckling restrained brace of claim 14, wherein an inner end of each coupling element and an adjacent end of said buckling constraining element are spaced apart a sufficient distance that, upon maximum compression of said yielding core, said inner end of each coupling element will not contact said adjacent end of said buckling constraining element.

16. The buckling restrained brace of claim 1, further comprising a lateral support element at each end of said yielding core, adjacent a corresponding coupling element.

17. The buckling restrained brace of claim 16, wherein said lateral support element comprises at least one washer through which said yielding core extends.

18. The buckling restrained brace of claim 17, wherein said lateral support element further comprises a spring on each side of and abutting said at least one washer, said yielding core also extending through each said spring.

19. The buckling restrained brace of claim 18, wherein said lateral support element further comprises a plate at an opposite side of each said spring, a first plate being positioned at an end of said buckling constraining element and a second plate being positioned at an inner end of an adjacent coupling element.

20. A method for manufacturing a buckling restrained brace, comprising:

assembling a yielding core and a hollow sleeve, said yielding core and said hollow sleeve comprising elongate members with said yielding core extending substantially through a length of said hollow sleeve;

positioning at least one spacer element adjacent to at least one surface of said yielding core;

introducing a buckling constraining element into said hollow sleeve, between an inner surface thereof and said yielding core;

permitting said buckling constraining material to at least partially harden; and

removing said at least one spacer element, a gaseous gap remaining between said at least one surface and said buckling constraining element.

21. The method of claim 20, wherein said positioning said at least one spacer element comprises providing said at least one spacer element adjacent to a plurality of surfaces of said yielding core.

22. The method of claim 20, further comprising:

coating at least one surface of said at least one spacer element with a release agent.

23. The method of claim 20, wherein said positioning said at least one spacer element comprises providing at least one pair of superimposed spacers.

24. The method of claim 23, wherein said removing comprises removing one spacer of said at least one pair, the other spacer of said at least one pair remaining within said hollow sleeve, in contact with said buckling constraining element.

25. The method of claim 23, wherein said introducing said buckling constraining material comprises introducing a grout.

26. The method of claim 25, wherein said introducing said grout comprises introducing a concrete.

27. The method of claim 20, wherein said introducing said buckling constraining material comprises introducing an inner sleeve having a plurality of supports secured thereto and radially protruding therefrom between said yielding core and said hollow sleeve.

28. A method for seismically bracing a steel frame, comprising:

securing a coupling element at each end of a buckling restrained brace to a structural element of the steel frame, said buckling restrained brace comprising;

an elongate yielding core;

a hollow sleeve surrounding at least a portion of a length of said yielding core;

a buckling constraining element disposed within said hollow sleeve, surrounding at least a portion of said length of said yielding core, and spaced apart from at least one surface thereof by a gaseous gap therebetween; and

coupling elements at ends of said yielding core and protruding at least partially from ends of said hollow sleeve;

absorbing an axial compressive load applied to an end of said yielding core, causing said yielding core to expand and reducing a distance between at least a portion of at least one surface of said yielding core and an inner surface of said buckling constraining element.

29. The method of claim 28, wherein, upon said absorbing said axial compressive load, said buckling constraining element prevents buckling of said yielding core.

30. The method of claim 28, further comprising:

absorbing tension applied axially to said yielding core.

31. The method of claim 30, wherein, upon said absorbing, a thickness of said yielding core decreases, increasing a distance between at least a portion of at least one surface of said yielding core and an inner surface of said buckling constraining element.

32. A buckling restrained brace, comprising:

an elongate yielding core;

a hollow sleeve surrounding at least a portion of a length of said yielding core;

a buckling constraining element disposed within said hollow sleeve, said buckling constraining element surrounding at least a portion of said length of said yielding core and spaced apart from at least one surface thereof by a gaseous gap therebetween;

a coupling element at each end of said yielding core and protruding at least partially from a corresponding end of said hollow sleeve; and

a lateral support element comprising at least one washer at each end of said yielding core, adjacent a corresponding coupling element, said end of said yielding core extending through said at least one washer.

33. The buckling restrained brace of claim 32, wherein a cross-sectional shape of said yielding core, taken transverse to a length thereof, is round.

34. The buckling restrained brace of claim 32, wherein a cross-sectional shape of said yielding core, taken transverse to a length thereof, is rectangular.

35. The buckling restrained brace of claim 32, wherein said yielding core comprises steel.

36. The buckling restrained brace of claim 32, wherein said hollow sleeve comprises steel.

37. The buckling restrained brace of claim 32, wherein said buckling constraining element comprises a buckling constraining material.

38. The buckling restrained brace of claim 37, wherein said buckling constraining material comprises a grout.

39. The buckling restrained brace of claim 38, wherein said buckling constraining material comprises a concrete.

40. The buckling restrained brace of claim 32, wherein a portion of each coupling element remains at least partially laterally surrounded by said hollow sleeve when a maximum tensile load is applied to said yielding core.

41. The buckling restrained brace of claim 32, wherein said buckling constraining element extends only partially along a length of said hollow sleeve.

42. The buckling restrained brace of claim 41, wherein an inner end of each coupling element and an adjacent end of said buckling constraining element are spaced apart a sufficient distance that, upon maximum compression of said yielding core, said inner end of each coupling element will not contact said adjacent end of said buckling constraining element.

43. The buckling restrained brace of claim 32, wherein said lateral support element further comprises a spring on each side of and abutting said at least one washer, said yielding core also extending through each said spring.

44. The buckling restrained brace of claim 43, wherein said lateral support element further comprises a plate at an opposite side of each said spring, a first plate being positioned at an end of said buckling constraining element and a second plate being positioned at an inner end of an adjacent coupling element.

45. A method for seismically bracing a steel frame, comprising:

securing a coupling element at each end of a buckling restrained brace to a structural element of the steel frame, said buckling restrained brace comprising;

an elongate yielding core;

a hollow sleeve surrounding at least a portion of a length of said yielding core;

a buckling constraining element disposed within said hollow sleeve, surrounding at least a portion of said length of said yielding core, and spaced apart from at least one surface thereof by a gaseous gap therebetween; and

coupling elements at ends of said yielding core and protruding at least partially from ends of said hollow sleeve; and

absorbing tension applied axially to said yielding core, causing a thickness of said yielding core to decrease and a distance between at least a portion of at least one surface of said yielding core and an inner surface of said buckling constraining element to increase.