Experimental Evaluation of the Seismic Performance of Piping Subassemblies

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Experimental Evaluation of the Seismic
Performance of Piping Subassemblies

• Presenter Dr. Emmanuel Manos Maragakis
• Dr. Ahmad Itani, Robert Corbin and Elliott Goodwin

2
Personnel

• Authors
• Robert C. Corbin
• Elliot R. Goodwin
• Dr. Emmanuel Manos Maragakis (PI)
• Dr. Ahmad M. Itani (CoPI)
• Graduate Students
• Elliot R. Goodwin
• Robert C. Corbin

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Outline

• Motivation
• Objectives and Scope
• Experimental Program
• Input Motion Generation
• Experimental Protocol
• Experimental Results
• Experimental Comparisons
• Observations and Conclusions

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Motivation

• Why Minimize Nonstructural Damage?
• Life Safety
• Property Loss
• Direct Damage
• Consequential Damage
• Loss of Function

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Investment Costs
6
Background/Objectives

• Background
• Experimental Evaluation
• Steel/Welded and Steel/Threaded Piping Systems
  (Goodwin 2004)
• Copper/Soldered Piping Systems (Corbin 2006)
• Objectives
• Understand the seismic behavior of braced and
  unbraced piping systems
• Identify the capacity characteristics
• Investigate and compare responses

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Scope

• Scope
• Experimental Specimen
• Generated Input Motions
• Experimental Protocol
• Displacement and Acceleration Responses

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Experimental Configuration

• Modeled after University of California, Davis
  Medical Center piping system
• Modified to accommodate dimensions and geometry
  restrictions of testing facility
• Consisted of 100 feet of 3 inch and 4 inch
  diameter piping
• Four typical valves including a y-strainer, a
  check valve, and two gate valves
• Two water heaters
• One simulated heat exchanger
• Heat exchanger and water heaters were anchored to
  the shake table
• System was braced and hung from a stationary frame

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Test Set-up and Specimen Configuration
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Plan View
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Elevation View
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Piping System Setup
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Bracing Details
Transverse Brace Longitudinal Brace
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Bracing Layout
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Instrumentation
29 Stringpot (SP) (20 stroke) Displacement
Transducers
16 Crossbow (xbow) Kinemetrics
(2g) Accelerometers
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Input Motion Generation

• ICBO AC156
• A synthetic motion must be generated that
• Meets a desired response spectra based on 1997
  UBC
• Build, hold and decay envelope of 5, 10 and 15
  seconds, respectively
• SIMQKE Program
• A maximum acceleration of 1 g

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Synthetic Input Motions SIMQKE
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Input Motion Generation

• Northridge Near-Fault Ground Motions were
  utilized to perform dynamic analyses
• Earthquakes were generated utilizing the Specific
  Barrier Model (Wanitkorkul and Filiatrault)
• A total of 4 cases, 2, 5, 10, 20, probability
  of exceedance in 50 years
• 2 components per case, Fault-normal (Large) and
  Fault-parallel (Small)
• 25 earthquakes simulated for each component

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Synthetic Input Motions OpenSees
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Experimental Protocol

• 4 steel systems tested (SIMQKE Motions)
• Welded braced
• Welded unbraced
• Threaded braced
• Threaded unbraced
• 2 copper systems tested (Northridge Motions)
• Braced
• Unbraced
• Subjected to increasing intensities of the
  derived input motions in the principle axes, N-S
  and E-W, as well as a biaxial excitation at 45
  with respect to the principle axes

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Experimental Results

• Observations and Performance
• Steel/Welded Braced and Unbraced
• Steel/Threaded Braced and Unbraced
• Copper/Soldered Braced and Unbraced
• Instrument Comparisons
• Braced and Unbraced Subassemblies
• Copper/Soldered, Steel/Welded and Steel/Threaded
  Braced Subassemblies
• Copper/Soldered, Steel/Welded and Steel/Threaded
  Unbraced Subassemblies

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Experimental Results Welded Braced System

• Two failed braces
• Cable portion only
• Occurred at highest input motion (100 SIMQKE E-W
  )
• Permanent displacement of braces

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Experimental Results Welded Unbraced System

• Two failed hanger rods
• Occurred at highest input motion (100 SIMQKE
  Biaxial )

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Experimental Results Threaded Braced System

• Flanged connection to heat exchanger began to
  leak at relatively low amplitudes
• 50 of SIMQKE Generated Input Motion
• Leak formed at the vertical run above the heat
  exchanger at
• 70 of SIMQKE Generated Input Motion
• The testing protocol was stopped after the first
  100 SIMQKE motion

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Flange Connection Failure
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Selected Instrument Response nv17 Steel Piping
Subassembly
nv17
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Experimental Results Copper
Braced Subassembly

• 2 Probability of Exceedance of the Northridge
  Earthquake Ground Motion in the East/West
  Direction at 100 Strength
• Maximum displacement response 3.80 in
• Maximum acceleration response 2.64 g
• Experimental Observations
• Piping did not experience any damage
• Permanent displacement of several braces
• 3 inch piping risers permanently offset due to
  damage experienced by water heaters

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Experimental Results Copper
Braced Subassembly

• Cable and Brace Damage (Brace B7)

Sag
Displacement
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Experimental Results Copper
Unbraced Subassembly

• 2 Probability of Exceedance of the Northridge
  Earthquake Ground Motion in the North/South
  Direction at 100 Strength
• Maximum displacement response 11.14 in
• Maximum acceleration response 2.64 g

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Experimental Results Copper
Unbraced Subassembly

• Experimental Observations
• Displaced Hanger Rod
• 20 PE East/West Direction
• Drift of 2.3
• Hanger Rod Failure
• 10 PE North/South Direction
• Drift of 2.8
• Two Flange Failures
• 10 PE East/West Direction
• Drift of 2.6

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Experimental Results Copper
Unbraced Subassembly
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Experimental Results Copper
Unbraced Subassembly

• Failed Hanger Rod Connection

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Experimental Results Copper
Unbraced Subassembly

• Flange Connection Failure

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Experimental Comparisons Copper Braced vs.
Unbraced

• Displacement Responses
• Ranged between 1.12 to 16.8 times larger
• Acceleration Responses
• Ranged between 0.82 to 6.19 times larger
• Subjected to story drifts up to 3.13
• Braced subassembly suffered no damage
• Unbraced subassembly suffered minor damage
  beginning at 2.3 and extensive damage at 2.6

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Response Summary

• SP34 xbow12

• SP21 xbow2

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Experimental Comparisons Copper Steel
Braced Subassemblies

• Experimental Observations
• Copper/Soldered
• Withstood a story drift of 3.13
• Steel/Welded
• Withstood a story drift of 5
• Steel/Threaded
• Leaks formed at a story drift of 2.17
• Failed in response to a story drift of 4.34

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Experimental Comparisons Copper Steel
Braced Subassemblies

• Displacement Responses
• Copper/Soldered produced the smallest
• Steel systems ranged between 1.42 and 13.1 times
  larger
• Acceleration Responses
• All three subassemblies were very similar
• Steel systems ranged between 0.57 and 4.00 times
  larger

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Experimental Comparisons Copper
Steel Unbraced Subassemblies

• Experimental Observations
• Copper/Soldered
• Rod failure at 2.8 story drift
• Piping flanges failed at 2.6 story drift
• Steel/Welded
• Rod failure at 4.34 story drift
• Piping withstood a 4.34 story drift
• Steel/Threaded
• Minor joint leaks started at 1.08 story drift
• Joint failures at 2.17 story drift

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Experimental Comparisons Copper
Steel Unbraced Subassemblies

• Unbraced responses were inconsistent
• Displacement Responses
• Steel systems produced the largest longitudinal
  responses
• Ranged between 1.88 and 4.65 times larger
• Transverse and vertical responses were similar
• Acceleration Responses
• Longitudinal responses were similar
• Steel systems produced the largest transverse and
  vertical responses
• Ranged between 1.01 and 3.55 times larger

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Response Summary

• Longitudinal Responses of SP21 and xbow2

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Observations and Conclusions

• Piping systems were determined to be drift
  sensitive
• Braces significantly reduced system displacement
  response
• Braces did not reduce the system acceleration
  response

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Observations and Conclusions, continued

• Copper system
• Braced
• Survived 3.13 drift
• Unbraced
• Flanges were the weak points
• Welded system
• Braced and Unbraced
• Survived 4.34 drift
• Threaded system
• Braced
• Complete failure at 4.34 drift
• Unbraced
• Leaks began at 1.08 drift
• Complete failure at 2.17 drift
• Fittings were weak point

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Observations and Conclusions, continued

• 1997 UBC code limit on story drift is 2.5
• Braced
• Copper/Soldered experienced no damage
• Steel/Welded experienced no damage
• Steel/Threaded would have leaks
• Unbraced
• Copper/Soldered experienced damage
• Steel/Welded experienced no damage
• Steel/Threaded would have leaks at half of UBC
  requirement

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Thank YouQuestions?