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Tunnel Design, Inspections, and National Standards

Tunnel Design, Inspections, and National Standards . Dan Walsh. Topics. Design of the D Street portal ceiling Tunnel inspections National standards for tunnel finish designs. Project Oversight. Epoxy. Federal Highway Administration. Sika Corporation. MassHighway

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Tunnel Design, Inspections, and National Standards

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  1. Tunnel Design,Inspections, and National Standards Dan Walsh

  2. Topics • Design of the D Street portal ceiling • Tunnel inspections • National standards for tunnel finish designs

  3. Project Oversight Epoxy Federal Highway Administration Sika Corporation MassHighway Mass. Turnpike Authority Powers Fasteners, Inc. Design and Construction Bechtel/Parsons Brinckerhoff (B/PB) Gannett Fleming, Inc. Newman Renner Colony, Inc. Conam Inspection, Inc. Modern Continental Construction, Inc.

  4. Design Loads • Anchor designed for 2,600 pounds • Finite element analysis • Model anchor loads • Determine structural redundancy • Examine different “hanger-out” scenarios

  5. Design Loads • Powers Fasteners anchoring system • Average expected load capacity of 25,400 pounds • Safety factor of 4 • Allowable load of 6,350 pounds • Anchor design load of 2,600 pounds

  6. Finite Element Analysis • One hanger removed, loads remained below 6,350 pounds • Two or more hangers removed, loads remained below 25,400 pounds

  7. Responsibility of Consultant • Gannett Fleming • Develop detailed design • Review submittals and prepare responses • Affixed engineer’s professional seal • Evaluation of each component of the ceiling system

  8. Anchor Specification • Failed to account that adhesives creep • Adhesive anchors in pure tension was an atypical application • Adhesives have different properties

  9. Anchor Specification • No specification regarding long-term properties • No requirement for testing for long-term performance • No consideration of service life • No provision for periodic inspection

  10. Anchor Approval • Opportunity to address creep in the approval process • Contractor’s proposed anchoring system • Draft version of ICBO Report ER-4514 • Fast Set epoxy approved for short-term loads only • Gannett Fleming authorized work to proceed

  11. Preaccident Anchor Failures • Opportunities to determine poor long-term characteristics of the adhesive • First opportunity in HOV tunnel (September 1999) • Suspected improper anchor installation • Powers evaluated the anchor installation (October 1999)

  12. Preaccident Anchor Failures • Remove and replace all failed anchors • Proof test to higher load of 6,350 pounds • Higher load would not identify poor long-term load characteristics • Anchor performance should have been monitored

  13. Preaccident Anchor Failures • Additional opportunity in eastbound I-90 connector tunnel (late 2001) • Remedy developed was ineffective • Considered the continuing failures as isolated instances

  14. Preaccident Anchor Failures • Problem attributed to installation, including overtorquing the nuts • Tests showed overtorquing did not reduce load capacity • Powers did not recommend to continue to monitor the anchor performance

  15. Summary • B/PB and Modern Continental should have instituted a program to monitor anchor performance • Powers response to the anchor displacements was deficient

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