Spillway Gate Hoist Machinery Rehab and … Gate Hoist Machinery Rehab and Replacement . ... (AFB...
Transcript of Spillway Gate Hoist Machinery Rehab and … Gate Hoist Machinery Rehab and Replacement . ... (AFB...
Design, Codes, and Opportunities
Steve Meicke
HDR Engineering, Inc.
Portland, OR
Spillway Gate Hoist
Machinery Rehab and
Replacement
Purpose and Background 2
• Hoist machinery rehab: opportunity
to increase safety and reliability
• ‘Refresher course’ for project
owners:
– Applicable design codes, recent
changes
– Load cases for design
– Torque limiting techniques
Why are Gates Important?
3
What could happen at your
project if your gate doesn’t
function properly?
Introduction 4
• Dam construction in the NW occurred in
the early to mid-1900’s
• Many spillway gate hoist systems are
nearing or past their designed useful life
• Past designs may not meet present day
design criteria
– Improved understanding of fatigue
– Past design guidance:
• Not well understood
• May be based on internal knowledge
• No widely accepted codes
• Motivated by different factors
Issues Facing Existing Hoists 5
• Primary: Age! Years of fatigue,
exposure to elements, corrosion, wear
• Other possible issues:
– Lack of redundancy
– Overstress due to under-design
– High maintenance requirements and
costs
– Cumulative fatigue damage
– More…
What’s next? Rehab or Replacement?
Primary Design Codes for Design 6
• USACE EM 1110-1-2610:
– Significant update in July 2013
– Provides general design criteria, best
practices for a wide range of gate
components.
• AASHTO LRFD Moveable Highway
Bridge Design Specifications:
– Specific formulas used in design
– Fills in gaps and expands upon criteria
from EM-2610
EM 2610 – Recent Revisions 7
• Overall: doubled in length, added 400
MB reference materials
• Load Cases:
– Normal Case: change from actual hoist
load to 100% motor full load torque
– Overload case: clarification on wire
rope load sharing
• Other revisions:
– Bearings (AFB and composite)
– Wire rope
AASHTO LRFD Specifications 8
• More detail and calculation oriented…
– Design guidance that EM-2610 lacks
• Many of the same formulas and figures
as EM-2610
• Specific formulas for design:
– fatigue theory, contact stresses for
open gearing, stress concentration
factors, etc.
– Much more…
Design Codes - Summary 9
• EM-2610: general guidance on load
cases and allowables, best practices
• AASHTO LRFD: detailed calculation
guidance, fills EM-2610 gaps
• EM-2610 and AASHTO have much in
common, but differences exist
– Design team should be clear which
criteria will be used for each component
– Design criteria memo!
Load Cases for Design (EM-2610) 11
• Normal Operating Case:
– 50 / 50 lifting load split
– Motor at 100% Full Load Torque (FLT)
– Allowable Stress: 20% of Ultimate
– Purchased components: manufacturer
ratings
• Normal operating case often drives
design!
Load Cases for Design (EM-2610) 12
• Overload Case:
– 70 / 30 lifting load split: represents
jammed gate, racked to one side
• Must check worst case of 100 / 0!
– Motor at 280% FLT for NEMA D*
– Allowable Stress: 75% of Yield
• Normal startup torque: is does not
constitute Overload
Torque Limiting Techniques
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Technique Pros Cons
Passive
Slip Clutch − Reliable
− Instant reaction − Additional maintenance
Current Limiting
Device − Inexpensive
− Prevents extended OL
− Response may not be
quick enough
Acitve Load / Torque Cell
with Feeback Loop
− Real-time feedback
− PM / failure diagnostics
− Fast response and motor
control possible
− Difficult to maintain
− Low reliability?
− Software support may
be an issue
− Most complex option
Effect to load cases mentioned previously?
Treatment of Torque Limiting Devices 14
• Project-by-project basis, based on
consequences of hoist failure
• Best practice is to assume these
devices will not perform when you need
them!
• Design hoist components to withstand
280% FLT and one-sided lifting
– Simple is beautiful
– May be cost prohibitive or not
necessary
Conclusions:
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• Spillway gate hoists: critical to safety
• Many existing systems nearing / past expected life
• Considerations for gate hoist rehab / replacement:
– Understand issues with your hoist
– Primary design codes, recent changes
– Load cases which drive design
– State of the art: torque limiting and control
Additional Design References:
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• Machinery Handbook
• Federal Wire Rope Specification RR-W-410
• Wire Rope User’s Manual
• EM-1110-2-3200: Wire Rope Selection Criteria for Gate
Operating Devices
• EM-1110-2-2702: Design of Spillway Tainter Gates
• AASHTO LRFD Moveable Highway Bridge Design
Specifications, revisions 2008
• AASHTO Movable Bridge Inspection, Evaluation and
Maintenance Manual 1998
• Peterson’s Stress Concentration Factors
• Steel Manual ASD
Mechanical / Structural Relationship
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Structural Mechanical
Load Case 2:
Normal Operating Loads Size prime mover to lift load
Design system – determine
reduction, friction, drum
diameter, etc.
Overload Case Normal Case
70 / 30 lifting split,
locked rotor motor torque
50 / 50 lifting split,
FLT of motor
Check 1-sided lifting loads!
Design… Design…
Load Case 4:
overload 100/0
lifting split
Design…
Load Changed? Loads
Complete
Preliminary Gate Design
No
Yes
Wire Rope Loads
Gate Weight
Trunnion Friction