Buckling Restrained Braced Frame Application for a Power Plant Boiler Building - PowerPoint PPT Presentation


Title: Buckling Restrained Braced Frame Application for a Power Plant Boiler Building


1
Buckling Restrained Braced Frame Application for
a Power PlantBoiler Building
  • Harold O. Sprague, Jr., P.E.Project Manager

2
Introduction Harold O. Sprague, PE
  • Former Iron Worker
  • Professional Engineer 29 years ago
  • ICC Structural Steel Special Inspector
  • Building Code Development
  • BSSC, ASCE 7 STC, Blast Committee
  • FEMA Urban Search Rescue Structures Specialist
  • Adjunct Prof. of Engr. University of Missouri -
    KC
  • Black Veatch - Engineer, RD, Blast Seismic

3
Agenda
  • Project background
  • The problem
  • Code Acceptance of BRBs
  • Dynamic Analysis
  • BRB Manufactures Features
  • Lessons Learned
  • Cost of BRBF vs. OCBF

4
Acknowledgements
  • Jones, Dan, P.E. Black Veatch structural
    engineer
  • Kohns, Larry, P.E. - Black Veatch structural
    engineer
  • Petersen, Mark, P.E., G.E. Black Veatch
    geotechnical engineer
  • Zheng, Wei, Ph.D., P.E. - Black Veatch
    geotechnical engineer
  • Wiley, Alan, P.E. Black Veatch lead
    structural analysis
  • Hart, Tom, P.E., R.G. Black Veatch
    geotechnical engineer
  • Brainard, Ray - Black Veatch geotechnical
    engineer
  • Powell, Steven D., S.E. Star Seismic LLC
  • Hashash, Youssef, PhD, P.E., professor at the
    University of Illinois
  • Whittaker, Andrew, PhD, S.E., professor at
    SUNY-Buffalo
  • Power, Maury Geomatrix geotechnical engineer

5
Plum Point Energy Station Project
  • 665 MW Coal Fired electric generation facility
  • Osceola, Arkansas (Northeast Arkansas)
  • Greenfield site
  • State of the art emission controls
  • Construction Start April 2006
  • Commercial Operation Summer 2010


6
Plum Point - Generation Building Elevation
Boiler
Coal Silos
Air Quality Control System
Turbine
7
Boiler Building
8
Plum Point Project Location
9
Seismicity in the United States
10
New Madrid Quakes 1811 - 1812
  • December 16, 1811 2 shocks Magnitude 8.5
  • January 23, 1812 Magnitude 8.4
  • February 7, 1812 Magnitude 8.0
  • Felt in Boston
  • Damage in Charleston, SC
  • Jared Brooks,
  • Louisville, KY 1,872 events

11
New Madrid Quakes
  • Buildings damaged over an area size of Texas
  • Eight shocks felt in Montreal, Canada (1200 miles
    away)
  • 2 million square miles, over half the U.S. was
    shaken largest area ever known to be affected
    by an earthquake

12
New Madrid Seismic Activity
13
Seismic Design Conditions for Plum Point
  • Mapped Ground Motion
  • Ss 2.60g
  • Mapped Ground Motion
  • S1 0.67g
  • Site Class F
  • Site Specific Response Spectra required

14
Choosing a Framing System
  • Large seismic demands at Plum Point site
    suggested rethinking our framing system
  • Typically use conventional braced frame (OCBF).
  • Estimated steel for Generation Building using
    OCBF 18,000 tons

15
The Problem?
  • Conventional concentric braced frames result in
    stiff structures
  • Stiff structures result in large inertial seismic
    forces in structure, components, and in
    foundations

16
Ground Motion
Flexible Structure
17
Ground Motion
Rigid Structure
18
The Problem
  • Concentric bracing is designed for two possible
    failure modes
  • Tension Stress
  • Compression Buckling
  • Compression buckling controls design and
    therefore create a stiff structure.

Show John Hancock tower or heavy braced building
19
The Solution Buckling Restrained Braced
Frame
20
Conventional Brace Behavior
BRB Behavior
Core
Outer casing
De-Coupled Stress and Buckling (Mechanics
Definition)
21
BRB Basics
Steel Casing (Tube)
Yielding Core
End Connections
Restraining Mechanism (Concrete Grout)
Debonded Gap
22
The Solution
  • Provides much more ductile structure reducing
    seismic demand
  • Reduces member sizes, connection sizes, and size
    of foundation (and number of piles).

23
BRB Evolution
  • BRB technology developed in Japan in mid 1980s
  • U.S. started research and testing in 1999
  • 2003 National Earthquake Hazards Reduction
    Program Recommended Provisions for Seismic
    Regulations for New Buildings and Other
    Structures
  • AC238 - Acceptance Criteria For
    Buckling-restrained Braced Frame Subassemblages

24
Code Acceptance of BRBs
  • AISC 341-05 Seismic Provisions Manual 2005.
    Developed BRB testing and design requirements.
  • ASCE 7-05 Standard for Design Loads for
    Buildings and Other Structures. First building
    design standard to accept the BRBF system.
  • IBC 2006 International Building Code 2006
    recognized BRBFs as an approved structural
    system.
  • Arkansas Building Code 2002 (based on IBC 2000
    with supplements)
  • Arkansas granted a deviation request to use
    portions of IBC 2006

25
Design Requirements for BRBFs
  • Seismic Design Coefficients (ASCE 7-05)
  • Response Modification Factor (R value) 7
    Highly ductile system. Reduce forces by factor
    of seven.
  • Deflection Amplification Factor (Cd) 5.5
    Multiplier to obtain your design story drift.
  • System Overstrength Factor (Oo) 2.0
    Collector element design.

26
Site Specific Seismic Hazard
27
Plum Point Site
28
BRB Manufacturers BRB Features
Only major manufacturers in this market
  • Nippon Steel
  • CoreBrace
  • Star Seismic

29
BRB Manufacturers BRB Features
Nippon Steel
  • Founded in 1970 (Japanese Company)
  • Originator of BRB in mid 1980s Professor Wada
    of Tokyo Institute of Technology worked with
    Nippon.
  • First BRBF built in Japan in 1988 using Nippons
    braces.
  • Un-Bonded Brace is trademark name for their
    BRB.
  • Core has a cruciform shape. Casing is a steel
    tube.
  • End connection is a standard bolted connection
    with splice plates on all four legs of the core.

30
BRB Manufacturers BRB Features
CoreBrace
  • Founded in 2002 Located in Utah. Parent
    company is SME Steel.
  • CoreBrace is trademark name for their BRB
  • Core has a cruciform shape. Casing is a steel
    tube.
  • Two end connection options
  • - Standard bolted connection (similar to
    Nippons)
  • - Modified bolted connection splice plates
    are welded on in the shop, so uses half the bolts
    compared to standard.

31
BRB Manufacturers BRB Features
Star Seismic
  • Founded in 2002 Located in Utah.
  • 3rd Generation BRB, PowerCat is trademark
    name for their BRB.
  • Fabricated in Salina, Kansas.
  • Core is a flat plate. Casing is a steel tube.
  • For large braces (gt800 kips) ganged smaller
    braces
  • Two end connection options
  • - True Pin connection single round pin
  • - Welded connection easier to align than
    single pin.

32
BRB Manufacturers BRB Features
Star Seismic - continued
  • True pin connection is Star Seismic feature
  • Allows rotation, more predictable behavior
  • Reduces installation labor.

33
BRB Manufacturers BRB Features
Star Seismic - continued
  • Another benefit of the true pin connection is it
    allows for a much more compact connection.
    Advantages to a compact connection
  • Allows for a longer brace. Longer brace provides
    a more flexible and ductile structure.
  • Eliminates stiffeners in the gusset. A major
    cost benefit on a seismic job.
  • Uses up less space, so more room for utilities
    and less interferences.

34
BRB Manufacturers BRB Features
Star Seismic - continued
  • Disadvantage to the single pin connection is
    tight tolerances.
  • Erection tolerance is only 1/32
  • Almost impossible for shop to fabricate your
    structure to these tolerances.
  • Heavy boiler steel would need more erection
    tolerance

35
BRB Manufacturers BRB Features
Star Seismic - continued
  • Eccentric Pin feature
  • Initially developed for the Plum Point project to
    overcome tolerance issues of their standard
    single pin.
  • Two outside portions of the pin are concentric.
    The center is offset to provide chosen erection
    tolerance.
  • Plum Point chose a tolerance of 3/16 since it
    matched tolerance of oversize hole for 7/8 bolt.

36
BRB Manufacturers BRB Features
Star Seismic - continued
  • Collar feature
  • Provides support for the unbraced core where it
    leaves the encasement to connect to the gusset.
  • Forces all external moments (from wind and
    seismic movement) to the outside casing (steel
    tube)
  • Collar in combination with compact connection
    eliminates need for gusset stiffeners.

37
Lessons Learned BRB Erection
  • Due to clevis type single pin connection, the
    brace and upper connecting beam should be erected
    together.

38
454 kip (Service load) BRB, L 40
39
Equivalent OCB for 454 kip BRB, L 40 (W14x398)
40
Cost of BRBF vs OCBF
  • The following cost comparison is for a BRBF
    versus an OCBF for the Plum Point Generation
    Building.
  • BRBF design per IBC 2006
  • OCBF design per Arkansas Bldg Code 2002

41
Cost of BRBF vs OCBF
  • If looking at the brace components only (brace
    and gussets), the average net savings using BRB
    over OCB for Plum Point
  • 2068 average per brace
  • 565 braces x 2068 1,168,000

42
Cost of BRBF vs OCBF
  • Total net savings if using BRB over OCB for Plum
    Point

43
Questions?
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Buckling Restrained Braced Frame Application for a Power Plant Boiler Building

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Title: Buckling Restrained Braced Frame Application for a Power Plant Boiler Building


1
Buckling Restrained Braced Frame Application for
a Power PlantBoiler Building
  • Harold O. Sprague, Jr., P.E.Project Manager

2
Introduction Harold O. Sprague, PE
  • Former Iron Worker
  • Professional Engineer 29 years ago
  • ICC Structural Steel Special Inspector
  • Building Code Development
  • BSSC, ASCE 7 STC, Blast Committee
  • FEMA Urban Search Rescue Structures Specialist
  • Adjunct Prof. of Engr. University of Missouri -
    KC
  • Black Veatch - Engineer, RD, Blast Seismic

3
Agenda
  • Project background
  • The problem
  • Code Acceptance of BRBs
  • Dynamic Analysis
  • BRB Manufactures Features
  • Lessons Learned
  • Cost of BRBF vs. OCBF

4
Acknowledgements
  • Jones, Dan, P.E. Black Veatch structural
    engineer
  • Kohns, Larry, P.E. - Black Veatch structural
    engineer
  • Petersen, Mark, P.E., G.E. Black Veatch
    geotechnical engineer
  • Zheng, Wei, Ph.D., P.E. - Black Veatch
    geotechnical engineer
  • Wiley, Alan, P.E. Black Veatch lead
    structural analysis
  • Hart, Tom, P.E., R.G. Black Veatch
    geotechnical engineer
  • Brainard, Ray - Black Veatch geotechnical
    engineer
  • Powell, Steven D., S.E. Star Seismic LLC
  • Hashash, Youssef, PhD, P.E., professor at the
    University of Illinois
  • Whittaker, Andrew, PhD, S.E., professor at
    SUNY-Buffalo
  • Power, Maury Geomatrix geotechnical engineer

5
Plum Point Energy Station Project
  • 665 MW Coal Fired electric generation facility
  • Osceola, Arkansas (Northeast Arkansas)
  • Greenfield site
  • State of the art emission controls
  • Construction Start April 2006
  • Commercial Operation Summer 2010


6
Plum Point - Generation Building Elevation
Boiler
Coal Silos
Air Quality Control System
Turbine
7
Boiler Building
8
Plum Point Project Location
9
Seismicity in the United States
10
New Madrid Quakes 1811 - 1812
  • December 16, 1811 2 shocks Magnitude 8.5
  • January 23, 1812 Magnitude 8.4
  • February 7, 1812 Magnitude 8.0
  • Felt in Boston
  • Damage in Charleston, SC
  • Jared Brooks,
  • Louisville, KY 1,872 events

11
New Madrid Quakes
  • Buildings damaged over an area size of Texas
  • Eight shocks felt in Montreal, Canada (1200 miles
    away)
  • 2 million square miles, over half the U.S. was
    shaken largest area ever known to be affected
    by an earthquake

12
New Madrid Seismic Activity
13
Seismic Design Conditions for Plum Point
  • Mapped Ground Motion
  • Ss 2.60g
  • Mapped Ground Motion
  • S1 0.67g
  • Site Class F
  • Site Specific Response Spectra required

14
Choosing a Framing System
  • Large seismic demands at Plum Point site
    suggested rethinking our framing system
  • Typically use conventional braced frame (OCBF).
  • Estimated steel for Generation Building using
    OCBF 18,000 tons

15
The Problem?
  • Conventional concentric braced frames result in
    stiff structures
  • Stiff structures result in large inertial seismic
    forces in structure, components, and in
    foundations

16
Ground Motion
Flexible Structure
17
Ground Motion
Rigid Structure
18
The Problem
  • Concentric bracing is designed for two possible
    failure modes
  • Tension Stress
  • Compression Buckling
  • Compression buckling controls design and
    therefore create a stiff structure.

Show John Hancock tower or heavy braced building
19
The Solution Buckling Restrained Braced
Frame
20
Conventional Brace Behavior
BRB Behavior
Core
Outer casing
De-Coupled Stress and Buckling (Mechanics
Definition)
21
BRB Basics
Steel Casing (Tube)
Yielding Core
End Connections
Restraining Mechanism (Concrete Grout)
Debonded Gap
22
The Solution
  • Provides much more ductile structure reducing
    seismic demand
  • Reduces member sizes, connection sizes, and size
    of foundation (and number of piles).

23
BRB Evolution
  • BRB technology developed in Japan in mid 1980s
  • U.S. started research and testing in 1999
  • 2003 National Earthquake Hazards Reduction
    Program Recommended Provisions for Seismic
    Regulations for New Buildings and Other
    Structures
  • AC238 - Acceptance Criteria For
    Buckling-restrained Braced Frame Subassemblages

24
Code Acceptance of BRBs
  • AISC 341-05 Seismic Provisions Manual 2005.
    Developed BRB testing and design requirements.
  • ASCE 7-05 Standard for Design Loads for
    Buildings and Other Structures. First building
    design standard to accept the BRBF system.
  • IBC 2006 International Building Code 2006
    recognized BRBFs as an approved structural
    system.
  • Arkansas Building Code 2002 (based on IBC 2000
    with supplements)
  • Arkansas granted a deviation request to use
    portions of IBC 2006

25
Design Requirements for BRBFs
  • Seismic Design Coefficients (ASCE 7-05)
  • Response Modification Factor (R value) 7
    Highly ductile system. Reduce forces by factor
    of seven.
  • Deflection Amplification Factor (Cd) 5.5
    Multiplier to obtain your design story drift.
  • System Overstrength Factor (Oo) 2.0
    Collector element design.

26
Site Specific Seismic Hazard
27
Plum Point Site
28
BRB Manufacturers BRB Features
Only major manufacturers in this market
  • Nippon Steel
  • CoreBrace
  • Star Seismic

29
BRB Manufacturers BRB Features
Nippon Steel
  • Founded in 1970 (Japanese Company)
  • Originator of BRB in mid 1980s Professor Wada
    of Tokyo Institute of Technology worked with
    Nippon.
  • First BRBF built in Japan in 1988 using Nippons
    braces.
  • Un-Bonded Brace is trademark name for their
    BRB.
  • Core has a cruciform shape. Casing is a steel
    tube.
  • End connection is a standard bolted connection
    with splice plates on all four legs of the core.

30
BRB Manufacturers BRB Features
CoreBrace
  • Founded in 2002 Located in Utah. Parent
    company is SME Steel.
  • CoreBrace is trademark name for their BRB
  • Core has a cruciform shape. Casing is a steel
    tube.
  • Two end connection options
  • - Standard bolted connection (similar to
    Nippons)
  • - Modified bolted connection splice plates
    are welded on in the shop, so uses half the bolts
    compared to standard.

31
BRB Manufacturers BRB Features
Star Seismic
  • Founded in 2002 Located in Utah.
  • 3rd Generation BRB, PowerCat is trademark
    name for their BRB.
  • Fabricated in Salina, Kansas.
  • Core is a flat plate. Casing is a steel tube.
  • For large braces (gt800 kips) ganged smaller
    braces
  • Two end connection options
  • - True Pin connection single round pin
  • - Welded connection easier to align than
    single pin.

32
BRB Manufacturers BRB Features
Star Seismic - continued
  • True pin connection is Star Seismic feature
  • Allows rotation, more predictable behavior
  • Reduces installation labor.

33
BRB Manufacturers BRB Features
Star Seismic - continued
  • Another benefit of the true pin connection is it
    allows for a much more compact connection.
    Advantages to a compact connection
  • Allows for a longer brace. Longer brace provides
    a more flexible and ductile structure.
  • Eliminates stiffeners in the gusset. A major
    cost benefit on a seismic job.
  • Uses up less space, so more room for utilities
    and less interferences.

34
BRB Manufacturers BRB Features
Star Seismic - continued
  • Disadvantage to the single pin connection is
    tight tolerances.
  • Erection tolerance is only 1/32
  • Almost impossible for shop to fabricate your
    structure to these tolerances.
  • Heavy boiler steel would need more erection
    tolerance

35
BRB Manufacturers BRB Features
Star Seismic - continued
  • Eccentric Pin feature
  • Initially developed for the Plum Point project to
    overcome tolerance issues of their standard
    single pin.
  • Two outside portions of the pin are concentric.
    The center is offset to provide chosen erection
    tolerance.
  • Plum Point chose a tolerance of 3/16 since it
    matched tolerance of oversize hole for 7/8 bolt.

36
BRB Manufacturers BRB Features
Star Seismic - continued
  • Collar feature
  • Provides support for the unbraced core where it
    leaves the encasement to connect to the gusset.
  • Forces all external moments (from wind and
    seismic movement) to the outside casing (steel
    tube)
  • Collar in combination with compact connection
    eliminates need for gusset stiffeners.

37
Lessons Learned BRB Erection
  • Due to clevis type single pin connection, the
    brace and upper connecting beam should be erected
    together.

38
454 kip (Service load) BRB, L 40
39
Equivalent OCB for 454 kip BRB, L 40 (W14x398)
40
Cost of BRBF vs OCBF
  • The following cost comparison is for a BRBF
    versus an OCBF for the Plum Point Generation
    Building.
  • BRBF design per IBC 2006
  • OCBF design per Arkansas Bldg Code 2002

41
Cost of BRBF vs OCBF
  • If looking at the brace components only (brace
    and gussets), the average net savings using BRB
    over OCB for Plum Point
  • 2068 average per brace
  • 565 braces x 2068 1,168,000

42
Cost of BRBF vs OCBF
  • Total net savings if using BRB over OCB for Plum
    Point

43
Questions?
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