PA Non-composite Adjacent Box Beam Bridges PennDOT June 2006 A presentation adapted from the AASHTO T-18 Bridge Inspection Technical Committee Meeting

KEY TOPICS SR 1014 Failure on 12/27/05, PennDOT ’ s Non-composite Adjacent Box Beam Action Items, Bridge Inventory Impacts, Preliminary Research Findings, Lessons learned.

Washington County, PA SR 1014 over I-70 December 28, 2006

SR 1014 over I-70 Built 1960 (ADT = 500) Spans of 54’, 89’, 89’, 42’ AASHTO Skew 51 ° Vertical Clearance over I ’ -5 ” Failed Beam 14’-5” I-70 EB

SR 1014 Bridge Cross Section 8 4’-0” + 7 ½” min. = 32’-31/2” Span 2 & 3 Span 1 & 4

SR 1014 FASCIA DETAILS 60 3/8” PS strands 250 ksi strand 5,900 psi concrete Cover ~ 1”+ Bituminous overlay without membrane

SR 1014 BEAM COLLAPSE Factors contributing to failure: Visible and hidden strand corrosion, Open Barrier Deflection joint, No load transfer through shear key, Original fabrication quality control, Collision damage, Salt spray, Deck drainage leaking thru parapet joint.

SR 1014 STRAND LOSSES The extent of non-detectable strand loss was revealed as beam dissection progressed: Visual Inspection Strands Lost Visual Assessment Post-Collapse 28 Strands Lost (+40%) Lab Assessment of Strand Failures 39 Strands Lost (+95%)

ACTION PLAN Re-inspect all adjacent box beams Structurally Deficient (SD) – By Feb 28 Remaining 700+ By August 15 Research - Test Beams New Condition Rating Guidelines New Rating Guidelines Issued moratorium on non-composite adjacent box beam bridges

1 st Generation of P/S Beams Built 1952~1962 as alternate designs. Typical Suspect Details include: Small diameter strands (1/4” & 5/16”), CaCl used for high early strength, Un-vented voids w/cardboard forms, Shear reinforcement details, Grout/shear keys (ongoing issue), Dimensionally-challenged.

Box Beam Bridge Inventory 801 total bridges, 101 SD bridges before re-inspections, 682 re-inspections completed as of 6/9/06, 213 SD bridges after re-inspections, 4 Bridges closed, 12 Bridges load posted, 17 Bridges width or lane restricted.

Research - Load Tests Two SR 1014 Beams were salvaged for full scale load tests, Load test of interior girder confirms additional non-detectable losses, Fascia Beam testing confirms open barrier joint contributions to failure, Test beam fails between exposed strands and open joint.

Lessons learned Adjacent box beams are robust, but not indestructible, Strand corrosion is very pervasive, No proven inspection method to determine deterioration, First generation beams had suspect details, Questionable quality control of 1 st beams, Open barrier joint attracts cracking, Poor load transfer = loss of redundancy, No cost effective rehab/repair schemes.

14 Thank you for your attention. Any questions?