PA Non-composite Adjacent

shrubflattenUrban and Civil

Nov 25, 2013 (3 years and 9 months ago)

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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
-
70

14

-
5


Failed Beam

14’
-
5”

I
-
70 EB

SR 1014 Bridge Cross Section

8 Members @ 4’
-
0” + 7 joints @ 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 2004


20 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?