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Christopher Higgins, PhD, PE Deanna Amneus , MS Student Laura Barker, MS Student December 6, 2012

Christopher Higgins, PhD, PE Deanna Amneus , MS Student Laura Barker, MS Student December 6, 2012. Strengthening Anchorage Details in Vintage Reinforced Concrete Bridges A Possible Titanium Application. Vintage Reinforced Concrete Bridges.

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Christopher Higgins, PhD, PE Deanna Amneus , MS Student Laura Barker, MS Student December 6, 2012

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  1. Christopher Higgins, PhD, PE Deanna Amneus, MS Student Laura Barker, MS Student December 6, 2012 Strengthening Anchorage Details in Vintage Reinforced Concrete BridgesA Possible Titanium Application

  2. Vintage Reinforced Concrete Bridges • Many constructed in 1950s (Eisenhower Defense Highway System) • Design standards have changed since built • Loads more frequent and heavier • Many are now cracked and deficient

  3. Research Problem • Problem with poor details (reinforcing steel terminated in locations that show cracking) that can lead to member failure • Many existing bridges with these reinforcing details cannot carry required truck loads by calculation • Need new methods to strengthen these bridges • Titanium looks promising: high strength, good stiffness match with adhesives, bendable and field adjustable, and durable. Material cost may not drive issue. Labor!

  4. Typical Specimen Cross-Section

  5. Typical Poor Cutoff Detail

  6. Load Setup (Modified from Higgins et al., 2004)

  7. Typical Cracking at Anchorage

  8. Typical Anchorage Failure

  9. Retrofit Approach for Strengthening Poor Cutoff Detail: Near-Surface Mounted Reinforcing Add External Reinforcing to strengthen beam

  10. Near-Surface Mounted Reinforcing • Epoxy placed in slots • Insert external reinforcing in slots • Saw-Cut slots in concrete • Clean & Dry

  11. Failure Modes for Carbon Fiber in NSM Application • Outer shell peeling • Slip of CFRP • Titanium may eliminate these modes (with hooks)

  12. Working with Titanium for Civil Engineering • Shear to length as for rebar • Cold bend with same radius as for steel rebar but overshoot to account for spring-back • Increase friction along surface to achieve better bond with epoxy

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