WINTER SCHOOL 2014
STRUCTURE CONTROL UNIT
Joshua P. Jones EIT
Assistant Structures Control Engineer
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WINTER SCHOOL 2014
STRUCTURE CONTROL UNIT
TOPICS OF DISCUSSION:
• BEARING PADS (LAMINATED ELASTOMERIC)
• DECK GRADE CALCULATIONS (S.I.P. ANGLES)
• MEASURING DECK THICKNESS
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
BEARING PADS - SUPPORT SUPERSTRUCTURE, DECK , AND
ALLOW STRUCTURE TO MOVE (EXPANSION AND
CONTRACTION DUE TO TEMPERATURE)
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
PAY CLOSE ATTENTION TO HOW BEARING PADS ARE LAID OUT
THESE ARE NOT SET LEVEL… MEANING THEY ARE SET ON A
CROSS SLOPE
CROSS SLOPE
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
BEAM IS SET AND THERE IS A GAP BETWEEN THE BEAM AND
BEARING…WHAT SHOULD I DO????
NOTE: THIS CAN OCCUR ON ALL SIDES OF BEARING PAD
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
WHEN TO GROUT BEARING PADS
BEARINGS. WHEN ELASTOMERIC BEARINGS ARE USED UNDER BEAMS, DETERMINE IF THERE IS FULL
CONTACT BETWEEN THE BEARING PAD AND BEARING SURFACES JUST AFTER THE BEAMS ARE SET
IN PLACE. TEMPORARILY REMOVE OR RELOCATE WATERPROOFING AND OTHER MATERIAL AS REQUIRED TO
EXPOSE ALL SIDES OF THE PAD. IF A GAP BETWEEN THE PAD AND BEARING SURFACES IS PRESENT,
PROCEED AS FOLLOWS UNLESS THE CONTRACT PLANS INDICATE THAT A LIFT-OFF CONDITION IS EXPECTED
WHEN THE BEAM IS INITIALLY SET ON THE PAD:
GAP THICKNESS > (3/8 INCH). IF A GAP ALONG ANY EDGE OF THE PAD EXCEEDS (3/8 INCH), GRIND
THE BEARING SURFACE OF THE SUBSTRUCTURE TO ELIMINATE THE GAP, EXCEPT GAPS ALONG THE
FRONT EDGE OF THE PAD (EDGE TOWARD THE MIDSPAN OF THE BEAM) WILL BE ALLOWED AS
SPECIFIED IN STEPS 1 AND 2 BELOW. PROVIDE A ROUGH TEXTURED BEARING SURFACE AFTER
GRINDING. VERIFY THAT THE MINIMUM REQUIRED VERTICAL CLEARANCE TO THE BOTTOM OF BEAMS, AS
INDICATED, IS MAINTAINED AFTER GRINDING.
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
Gap Thickness < (3/8 inch) IF GAPS ALONG ANY EDGE OF THE PAD ARE LESS THAN
OR EQUAL TO (3/8 INCH), PROCEED AS FOLLOWS:
GAP ALONG REAR EDGE OF PAD ONLY. IF A GAP OCCURS ANYWHERE ALONG THE
REAR EDGE OF THE PAD (EDGE TOWARD THE END OF THE BEAM), ELIMINATE THE
GAP BY PLACING A LEVELING BED OF POLYMER-MODIFIED MORTAR BENEATH THE
PAD AS SPECIFIED IN SECTION 1080.3(C)2.A.
GAP ALONG SIDE EDGES OF PAD. IF A GAP OCCURS ALONG THE SIDE EDGES OF
THE PAD, AND THERE IS FULL CONTACT AT THE FRONT AND REAR EDGES,
ELIMINATE THE GAP BY PLACING A LEVELING BED OF POLYMER-MODIFIED MORTAR
BENEATH THE PAD AS SPECIFIED IN SECTION 1080.3(C)2.A.
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
GAP ALONG FRONT EDGE OF PAD. IF A GAP OCCURS ALONG THE FRONT EDGE
(EDGE TOWARD THE MIDSPAN OF THE BEAM OF THE BEARING PAD), PROCEED AS
FOLLOWS:
STEP 1: DETERMINE THE AREA OF NON-CONTACT BETWEEN THE PAD AND BEAM. IF
THE AMOUNT OF NON-CONTACT IS LESS THAN 20% OF THE PAD AREA,
PROCEED TO STEP 2; OTHERWISE ELIMINATE GAP BY PLACING A LEVELING BED
OF POLYMER-MODIFIED MORTAR BENEATH THE PAD AS SPECIFIED IN SECTION
1080.3(C)2.A.
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
STEP 1:
GIVEN: PAD SIZE = 10”x 10”
10”
BRG
PAD
10”
TOTAL AREA = 10”x10”=100IN2
BOX BEAM
NON CONTACT AREA = 3”x10”= 30IN2
THEREFORE: 20% OF 100IN2 = (100IN2 x (20%/100))= 20 IN2
NON CONTACT AREA = 30IN2 > 20IN2 “GROUT PAD”
* IF NON-CONTACT AREA WAS 15IN2 < 20IN2
PROCEED TO STEP 2
BRG
3”
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
STEP 2: MEASURE THE MAXIMUM GAP THICKNESS ALONG THE FRONT
EDGE AND PROCEED AS FOLLOWS:
SPANS < (100 FEET)
• GAP THICKNESS ≤ (3/32 INCH): LEAVE GAP IN PLACE.
•
(3/32 INCH) < GAP THICKNESS ≤ (3/8 INCH): ELIMINATE THE GAP BY
PLACING A LEVELING BED OF POLYMER-MODIFIED MORTAR BENEATH
THE PAD AS SPECIFIED IN SECTION 1080.3(C)2.A.
SPANS ≥ (100 FEET)
• GAP THICKNESS ≤ (1/8 INCH): LEAVE GAP IN PLACE.
•
(1/8 INCH) < GAP THICKNESS ≤ (3/8 INCH): ELIMINATE THE GAP BY
PLACING A LEVELING BED OF POLYMER-MODIFIED MORTAR BENEATH
THE PAD AS SPECIFIED IN SECTION 1080.3(C)2.A.
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WHEN TO GROUT BEARING PADS CONT’D
LEVELING BED OF POLYMER-MODIFIED MORTAR, PLACEMENT PROCEDURE.
1.
2.
3.
4.
5.
6.
7.
IMMEDIATELY BEFORE LIFTING BEAM, PREPARE MORTAR ACCORDING
TO THE MANUFACTURER’S RECOMMENDATIONS. DO NOT EXTEND
MORTAR BY ADDING COARSE AGGREGATE.
LIFT BEAM AS NECESSARY.
REMOVE PAD.
APPLY A BED OF MORTAR TO THE BEAM SEAT, COVERING AN AREA
APPROXIMATELY 50 MM (2 INCHES) BEYOND THE PERIMETER OF THE
BEARING PAD. APPLY THE MORTAR IN A THICKNESS APPROXIMATELY
(1/8 INCH) GREATER THAN THE MAXIMUM ACTUAL GAP THICKNESS.
PLACE THE PAD ON THE MORTAR.
RESET THE BEAM ON THE PAD WHILE THE MORTAR REMAINS PLASTIC.
CURE THE MORTAR, AS APPLICABLE, ACCORDING TO THE
MANUFACTURER’S RECOMMENDATION. PLACE MORTAR ACCORDING TO
TEMPERATURE RESTRICTIONS RECOMMENDED BY THE MANUFACTURER.
DO NOT PLACE A LEVELING BED OF MORTAR BEFORE THE INITIAL
SETTING OF BEAMS.
MATERIAL NEEDS TO BE BULLETIN 15
APPROVED!!!
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
BRIDGE CONSTRUCTION STANDARDS (BCs) OR PUB. 219
STYROFOAM IS USED TO
KEEP CONCRETE FROM
ENTERING BEARING AREA
WHEN POURING
CONTINUITY DIAPHRAGMS
SEE BC-788M
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
HOW TO MINIMIZE GAPS BETWEEN BEARINGS AND BEAMS???
STEP 1:
MAKE SURE YOUR BEARING AREA ELEVATIONS ARE WITHIN TOLERANCES
AS OUTLINED IN PUBLICATION 408 SECTION 1001.3(K) 9. BEARING AREAS
OF SUBSTRUCTURE
[STEEL + 0.01 FT. (~ 1/8”), CONCRETE + 0.02 FT. (~ ¼”)]
STEP 2:
CHECK BEARING AREAS WITH 4FT SMART LEVEL 8 DIFFERENT WAYS
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
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BEARINGS P/S CONCRETE BRIDGE SUPERSTRUCTURES
PUBLICATION 408 SECTION 1080.3 (C)
ANY QUESTIONS
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DECK GRADES 101
DEFINITIONS:
BEAM CAMBER - SLIGHT ARCH THAT IS BUILT INTO
PRESTRESSED BEAMS BY MEANS OF PRESSTRESSED
CABLES
ELEVATION - THE DISTANCE ABOVE A KNOWN
POINT OR DATUM USUALLY ON GENERAL PLAN AND
ELEVATION SHEET
PROFILE GRADE - “FINISHED GRADE” BASED ON
HORIZONTAL AND VERTICAL ALIGNMENTS
CROSS SLOPE - IS A GEOMETRIC FEATURE OF
PAVEMENT SURFACES; THE TRANSVERSAL SLOPE [%]
WITH RESPECT TO THE HORIZON.
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DECK GRADES 101
WHY CHECK DECK GRADES?
 DRAINAGE
 CHECK BEAM CAMBER
 VERIFY PLAN AND
VERTICAL/HORIZONTAL PROFILE
GRADES PRIOR TO STEEL TYING AND DECK
PLACEMENT
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DECK GRADES 101
WHY IS IT IMPORTANT TO MAINTAIN
VERTICAL AND HORIZONTAL PROFILE
GRADES?
 SAFETY… THE STRUCTURE WAS DESIGNED PER PLAN.
 CHANGING GRADES… “MAKING GRADES WORK” IS NOT
ALLOWED!!!
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DECK GRADES 101
SCENARIO:




BEAMS ARE SET IN PLACE
SURVEYORS SHOT LEFT AND RIGHT OF ALL BEAMS AT 10TH POINTS
PLAN DOES NOT SHOW ANY LEFT AND RIGHT BEAM ELEVATIONS?
HMMMM!!!
PLAN DOES SHOW TOP OF DECK ELEVATION AT C/L OF BEAM?
HOW DO I CALCULATE FROM C/L OF BEAM TOP OF DECK ELEVATIONS TO
LEFT AND RIGHT OF BEAM???
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DECK GRADES 101
LT
BEAM1
RT
STAY IN
PLACE FORM
(S.I.P.) 2 ½”
DEPTH
BEAM3
LT
RT
CL
BEAM
BEAM2
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DECK GRADES 101
WHAT YOU HAVE TO KNOW BEFORE YOU START
1.
2.
3.
4.
STATIONS
ELEVATIONS
BEAM SIZE
DECK THICKNESS
WHAT YOU NEED TO UNDERSTAND
1.
2.
3.
4.
SLOPE IS DEFINED AS THE RATIO OF THE "RISE" DIVIDED BY
THE "RUN“ THIS IS A GIVEN BY % “CALLED CROSS SLOPE”
EXAMPLE 2% CROSS SLOPE (GIVEN ON PLAN)
POSITIVE SLOPE IS UPWARD, ADD (+)
NEGATIVE SLOPE DOWNWARD, SUBTRACT (-)
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DECK GRADES 101
BREAK POINTS
1,2,3,4,5
TOP OF DECK
ELEVATIONS AT
CENTER LINE OF
BEAM
CROSS SLOPES
NOT LEVEL ???
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DECK GRADES 101
SPAN 1
THIS IS A GOOD PLACE TO FIND DIMENSIONS!
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INFORMATION NEEDED TO
CALCULATE DECK GRADES TAKEN
FROM DESIGN DRAWINGS
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BEAM CAMBER ~ 2.03”
(SEE BEAM CAMBER DIAGRAM “A”)
HORIZONTAL LINE
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DECK GRADES 101
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DECK GRADES 101
FIELD SURVEY DATA
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DECK GRADES 101
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DECK GRADES 101
DETAIL:
11 = ACTUAL DECK THICKNESS AT EDGE OF BEAM
13 = HAUNCH THICKNESS
14 & 15 = S.I.P. ANGLE HEIGHT & C/F TO PAN ANGLE
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DECK GRADES 101
2L/10 “Example Problem”
1 = 337.86’ Finish Elevation at Baseline (taken from design drawings)
2 = Offset from baseline to edge of beam (11’ 6” – 11’) = 6” or 0.5’ (dimensions taken from
design drawings)
3 = Roadway or X slope 2% = 2/100= 0.02 (taken from design drawings) (positive grade
going up)
4 = Offset from baseline to edge of beam 2’ (half of beam width) – 0.5’ = 1.5’
5 = Roadway or X slope -2% = -2/100= -0.02 (taken from design drawings) (negative
grade going down)
6 = Correction (Offset * X slope) = (0.5’*0.02)+(1.5’*-0.02) = -0.02’
7 = Theoretical finished grade at beam 337.86’+-0.02’ (Correction) = 337.84’
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DECK GRADES 101
2L/10 “Example Problem” Cont’d
8 = Anticipated deflections (camber calculations) 0.03’ (Solved for on previous page)
9 = Theoretical finished grade + deflections 337.84’ + .03’ = 337.87’
10 = Top of Beam Elevation RT = 337.16’ (Field Survey Data)
11 = Actual deck thickness at beam 337.87 (Theoretical finished grade + deflections) 337.16 (Field Survey Data) = 0.71’
12 = Plan deck thickness = 8” or 0.67’ (Taken from design drawings)
13 = Haunch thickness = 0.71’ (Actual deck thickness at beam) -0.67’ (Plan deck thickness)
= 0.04’
14 =S.I.P. Angle height = -2 ½”or -0.208’ (deck pan thickness) + 0.04’ (Haunch thickness)
= -0.16’
15 = Converts -0.16’ to a fraction for field measuring = 1 15/16”
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DECK GRADES 101
This process is the same calculation for each edge of beam
 Find base line elevation
(CL of beam Top of Deck Elevation)
 Determine offset length
 Determine cross slope
(Convert to decimal – or + grade)
 Work from known elevation to edge of beam
 Use design drawing information
 Use survey data
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DECK GRADES 101
LT
BEAM1
RT
STAY IN
PLACE FORM
(S.I.P.) 2 ½”
DEPTH
BEAM3
LT
RT
CL
BEAM
BEAM2
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DECK GRADES 101
METAL TAB FOR
WELDING (S.I.P.)
ANGLE
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DECK GRADE CALCULATION:
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DECK GRADES 101
LEGEND FOR SPREAD SHEET
1 = FINISH ELEVATION AT BASELINE
2 = OFFSET FROM BASELINE TO EDGE OF BEAM
3 = ROADWAY OR SHOULDER SLOPE (X)
4 = OFFSET FROM BASELINE TO EDGE OF BEAM (ADDITIONAL COLUMN FOR BREAK POINTS)
5 = ROADWAY OR SHOULDER SLOPE (X) (ADDITIONAL COLUMN FOR BREAK POINTS)
6 = CORRECTION (OFFSET * CROSS SLOPE)
7 = THEORETICAL FINISHED GRADE AT EDGE OF BEAM
8 = ANTICIPATED DEFLECTIONS
9 = THEORETICAL FINISHED GRADE AT EDGE OF BEAM + ANTICIPATED DEFLECTIONS
10 = TOP OF DECK ELEVATIONS (FIELD SURVEY)
11 = ACTUAL DECK THICKNESS AT EDGE OF BEAM
12 = PLAN DECK THICKNESS
13 = HAUNCH THICKNESS
14 = S.I.P. ANGLE HEIGHT
15 CUT/FILL TO PAN ANGLE
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DECK GRADE CALCULATION:
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DECK GRADE CALCULATION:
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DECK GRADE CALCULATION:
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DECK GRADE CALCULATION FORM:
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DECK GRADES TABULATED FORM
THIS IS A RARE CASE!!!
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DECK GRADES 101
ANY QUESTIONS
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
MEASURING CONCRETE DEPTH
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
The following policy is required to standardize the inspection and documentation procedures for
measuring the total deck thickness and the concrete cover over the top mat of reinforcing steel
when performing the inspection of bridge deck construction. The inspection measurements must
be entered directly into an approved sourced document and included in the permanent project
records. It is recommended hat the "Wire Mesh Depth Check" section in the rear of Form CS-472,
the Concrete Inspectors Daily Record Book or a "black field book" be used to record all
measurements in a format similar to the accompanying example.
Report all measurements in a table format (Refer to examples attached). Identify the contract
number, structure number, span, pour sequence, starting, ending and test stations, and the
location of all pier and deck joints. For long or wide spans, the table can be continued on as many
pages as required. ON the left side of the table, indicate the test location stations.
Recheck the entire area where grade adjustments are performed and enter the new depth check
measurements in the table. Continue to perform the "dry run" inspection until further adjustments
are required.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
A."Dry Run" Inspection
The "dry run" inspection of the finishing machine should be checked at
longitudinal intervals not exceeding 3 m (10 feet) along the length of the
bridge deck. Place permanent test station markings on the vertical edge form
work to be used as reference points during the concrete placement operation.
The stationing should be easily visible.
During the "dry run" check, measure the distance from the distance from the
bottom of the finishing machine roller(s) to the top of the deck form work to
obtain the total deck thickness, and measure the distance from the bottom of
the roller(s) to the top mat of reinforcing steel to obtain the depth of concrete
cover.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
As a minimum, perform "dry run" depth checks at each 3 m (10 feet) test
station, at each end of the transverse span between girders, at grade break
points, and adjacent to the outside girder and gutter line of the overhang form
work. In addition, measure the total deck width at each test section.
During the "dry run" inspection, run the finishing machine transversely along
the entire length of all expansion dams, bulkhead forms, etc., to check the
grade and profile.
Record all measurements directly into the corresponding table location in the
source document. Compare the "dry run" measurements against the contract
drawings and specifications tolerances. In accordance with Publication 408,
Section 1001.3(b)1., "Place reinforcements so the indicated cover does not
deviate from position by more than 5 mm (¼ inch)". The contractor must
adjust the grade of the screed rail or bar supports (slab bolsters or re-bar
chairs) as required to meet specification requirements.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
B. Plastic Concrete Depth Checks
During the concrete placement operation, the inspector must perform random
plastic concrete depth checks at each 3 m (10 feet) test station. As a
minimum, perform three depth checks to measure the total deck thickness
and reinforcing steel cover as the same location checked during the inspection
of the "dry run". The depth checks should be performed at the location of the
finishing machine. Record the measurements directly into the table below the
corresponding "dry run" measurements.
A wide blade putty knife works well to measure the concrete cover over the
top mat of reinforcing steel. The knife blade should be turned perpendicular to
the longitudinal direction of the upper reinforcing bar to obtain an accurate
measurement.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
A small diameter metal rod works well to measure the concrete cover over the
top mat of reinforcing steel. The knife blade should be turned perpendicular to
the longitudinal direction of the upper reinforcing bar to obtain an accurate
measurement.
Different tools can be used to perform the plastic concrete depth checks as
long as accurate measurements are obtained.
The purpose of performing the plastic concrete depth check is to check that
the actual dead load camber deflection of all the girders is occurring as
anticipated and in proper relationship to each other. The plastic concrete depth
checks also assure that the top mat of reinforcing steel remains in proper
position during the concrete placement operation.
If significant deficiencies are encountered, the placement operation should be
stopped and the situation must be investigated to determine possible causes.
If corrective action cannot be taken, a bulkhead form should be placed and the
operation stopped.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
C. Hardened Concrete Testing
After the concrete has hardened, and after the completion of the specified
curing period, the depth of the top mat of reinforcing steel may be measured
by use of a pachometer in accordance with PTM No. 419.
Pachometer testing should be performed at deck locations where concrete
cover deficiencies are identified by the plastic concrete depth check
measurement, or as directed by the Engineer.
When required, the total depth of the hardened deck can be determined by
obtaining full depth cores in areas suspected of having deficient deck
thickness. Record all measurements directly into the corresponding area of the
table.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
PA Test Method No. 419
These types of pachometers
are capable of measuring
the depth of reinforcing
steel of 125 mm (5") or
more within ± 3 mm (±
1/8") overall accuracy.
These are portable units
that measure steel
reinforcing bar depth by
means of magnetic
detection of ferrous metal.
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
ANY QUESTIONS
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MEASURING DEPTH OF COVER/TOTAL DEPTH OF
PLASTIC CONCRETE ON BRIDGE DECKS
Joshua P. Jones EIT
Assistant Structure Control Engineer
Office
Cell
Email
(717) 783-5162
(717) 943-2597
joshjones@pa.gov
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