EARTHQUAKE PROTECTION - ASHRAE Library/Technical Resources/Free Resources... · rod stiffener (when...
Transcript of EARTHQUAKE PROTECTION - ASHRAE Library/Technical Resources/Free Resources... · rod stiffener (when...
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ASHRAE
American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.H
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AS
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The following details can be used to help prevent the effects of earthquakes on:• Mechanical Systems • Piping • Ductwork • Suspended Equipment • Floor Mounted Equipment
• Electrical Systems • Cable Trays, Bus Ducts • Conduit
PROTECTIONEARTHQUAKE
• Plumbing Systems • Piping• Fire Protection Systems • Piping
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ASHRAE
Suspended systems such as piping, equipment and ductwork need seis-mic braces to keep them from swaying during an earthquake. Seismic braces can be flexible using aircraft quality cables, or rigid (solid) using steel sections such as pipe, angles, or strut channels. Braces are typi-cally installed 30-40 ft (10-13 m) apart, at system turns and at the end of runs. Braces are attached to the pipe/duct at horizontal supports such as clevis’s or trapezes. The other end is attached to structure such as over-head concrete slabs or structural steel. Suspended equipment requires a minimum of four braces, one at each corner. Floor mounted equipment needs to be anchored to the structural slab. This also includes equipment that is Vibration Isolated with seismic snubbers.
Pipe, Cable Trays, Bus Ducts & ConduitBracing Details
Cable Bracing
TRANSVERSE & LONGITUDINAL CABLE BRACE FOR HORIZONTAL SUSPENDED PIPEFIGURE 1
TRANSVERSE BRACE LONGITUDINAL BRACE
ROD STIFFENER(WHEN REQUIRED)
STIFFENER CLAMP
HANGER RODSWIVELFASTENER
(TYP.)
FORCESEISMIC
SWAY BRACE
CLEVISSTIFFENER
ROD STIFFENER(WHEN REQUIRED)
STIFFENER CLAMP
HANGER ROD
NO LOADON CABLE
SEISMICTENSION
LOAD(REACTION)
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Rigid or Solid Bracing
CABLE BRACE FOR TRAPEZE SUSPENDED PIPEFIGURE 2
CABLE BRACE
SEISMICFORCE
SWIVELFASTENER
(TYP.)
HANGER ROD
STIFFENER CLAMP
ROD STIFFENER(WHEN REQUIRED)
PIPE SECUREDTO TRAPEZE
SOLID BRACE IN COMPRESSIONFOR INDIVIDUALLY SUPPORTED PIPE
SOLID BRACE
SWIVELFASTENER
(TYP.)
CLEVIS STIFFENER
FIGURE 3
FORCESEISMIC
STIFFENERCLAMP
ROD STIFFENER(WHEN REQUIRED)
HANGER ROD
SOLID BRACE IN COMPRESSIONFOR TRAPEZE PIPE
FIGURE 4
SWIVELFASTENER
(TYP.)
PIPE SECUREDTO TRAPEZE
FORCESEISMIC
STIFFENER CLAMP
HANGER ROD
ROD STIFFENER(WHEN REQUIRED)SOLID BRACE
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Duct Bracing DetailsCable Bracing
CABLE BRACING OF SUSPENDED DUCTWORK
TRANSVERSE BRACE LONGITUDINAL BRACE
FIGURE 5
CABLEBRACE
SWIVELFASTENER(TYP.)
HANGERROD
STIFFENERCLAMP
ROD STIFFENER(WHEN REQUIRED)
DUCTWORK SECUREDTO TRAPEZE WITH SCREWS
Rigid or Solid Bracing
STIFFENERCLAMP
HANGER ROD
SOLID BRACE OF DUCTWORK ON TRAPEZE
L
ROD STIFFENER(WHEN REQUIRED)
SOLIDBRACE
FIGURE 6
FPV
PHF C.G.W
FPV
SWIVELFASTENER
TRAPEZE SUPPORT
SHEET METALSCREW
ADDITIONAL UPPER SUPPORT
H
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Suspended Equipment Bracing
STIFFENER CLAMP
ROD STIFFENER(WHEN REQUIRED)
TYPICAL SOLID BRACE ARRANGEMENT
SWIVELFASTENERS
(TYP.)
SOLID BRACEO = 30° TO 60°
FIGURE 8
ELEVATION
EQUIPMENT
HANGER RODSOLID BRACE(4)-TYPICAL
PLAN VIEW
HANGER ROD
EQUIPMENT
SOLIDBRACE
STIFFENERCLAMP
TYPICAL CABLE BRACE ARRANGEMENT
ELEVATION
O = 30° TO 60°
EQUIPMENT
ROD STIFFENER(WHEN REQUIRED)
HANGERROD
PLAN VIEW
FIGURE 7
CABLE BRACE(4)-TYPICAL
SWIVELFASTENER(TYP.)
CABLEBRACE
EQUIPMENT
HANGERROD
Suspended equipment requires bracing as shown in Figure 8 using rigid steel sections or Figure 7 using cables. Connections to the equipment such as piping, conduit or ductwork should be made with flexible connections.
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Floor Supported EquipmentFloor mounted equipment may be bolted down if no vibration isolation is required. If the equipment is isolated then the equipment must either have bumpers as shown in Figure 9 or snubbers as shown in Figure 10.
ANCHOR BRACKET
NO CLEARANCE
STRUCTURAL ANCHOR
ANCHOR BRACKET CONNECTED TO EQUIPMENT
1/4" NEOPRENE
FIGURE 9
DETAIL A-A
EQUIPMENT
ANCHOR BRACKET(2) PER SIDE
PLAN VIEW
EQUIPMENT
TWO BOLTSPER BRACKET
A A
SUPPLEMENTAL BASE - OPEN SPRINGS AND SNUBBERS
SEISMIC SNUBBERSLOCATED AT OR NEARCROSS BRACING
ISOLATOR(TYPICAL)
VIBRATION
FIGURE 10
CONCRETE INERTIA BASESTEEL FRAME OR
SEISMIC SNUBBER(TYPICAL)
(SHOULD BE CONNECTED
CONCRETE INERTIA BASE) TO STEEL FRAME OR
HEIGHT SAVING BRACKET(TYPICAL)
EQUIPMENT
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Anchor BoltsAnchor bolts are one of the most impor-tant parts of a correctly designed and installed Seismic Restraint System. The most widely used anchors for seismic restaints are the wedge, adhesive and undercut.
Proper installation of anchors isimportant.
Basic installation methods for shelland adhesive anchors is shown inFigure 12.
FIGURE 11
FIGURE 12
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Sites with additional information:
• ASHRAE, American Society of Heating Refrigerating and Air Conditioning Engineers, www.ASHRAE.org
• ASHRAE Technical Committee TC 2.7 Seismic & Wind Restraint Design, www.ASHRAE.org/technology/page/1727
• FEMA, www.FEMA.gov , Publications 412, 413 & 414
• USGS, United States Geological Survey, www.USGS.gov
• SMACNA, Sheet Metal and Air Conditioning Contractors National Association, www.SMACNA.org
• VISCMA, Vibration Isolation and Seismic Control Manufacturers Association, www.VISCMA.com
• ICC, International Code Council, www.ICCSAFE.org
• National Fire Protection Association, www.NFPA.org
• AHRI, Air Conditioning, Heating and Refrigeration Institute, www.ahrinet.org
This publication was written by ASHRAE’s Technical Committee TC 2.7, Seismic and Wind Restraint Design. All details in this document are from ASHRAE’s Publication,” A Practical Guide to Seismic Restraint”, 2000, or FEMA Document 412