Post on 16-Apr-2022
transcript
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Precast Box Culverts & Precast Rigid Frames
2018 Bridge Construction Inspection School
Steve Malcolm
VDOT Staunton District
District Bridge Maintenance Manager
Learning Objectives
1. Identify basic components of box culverts and rigid frames.
2. Explain a procedure for field checking length of box culverts and rigid frames.
3. Show how box culverts and rigid frames are set into place.
4. Identify potential problem areas when setting box culverts and rigid frames.
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PRECAST BOX CULVERTS3
PRECAST BOX CULVERTS
Did you know?...
Staunton District has approximately 3,500 total structures in inventory
Nearly 1,500 Culverts
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Box culverts are to have a minimum 36 ft² opening in order to be taken into our structure inspection system.
PRECAST BOX CULVERTS
Typical Section for a set of plans
Headwall
Invert Location
Curtain wall *
* Can be formed or unformed (poured against undisturbed earth)
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Stakeout work shall be in accordance with the Department’s current Survey Manual (Issued 2009)http://www.virginiadot.org/business/resources/LocDes/SurveyManual/SurveyManualEntire.pdf
The Contractor shall provide the Engineer with a record copy of survey drawings, field notes and computations prior to the use of said stakeout information for construction.
PRECAST BOX CULVERTS
(refer to Survey Manual)
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Lengths and Inverts to be field verified
Procedure for checking Box Culvert (from VDOT Survey Manual)
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Sample stakeout from VDOT Survey Manual
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Curtain Wall Installation Tips:
• Placement according to design (length and width)
• Skew or square end sections
• Allow for joint growth
• Form according to invert grade
• Right of Way limits
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Curtain Wall Installation - Formed
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Curtain Wall Installation - Formed
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Curtain Wall Installation - Unformed
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Countersinking
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Curtain Wall Installation - Bedding
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Typical setting of box culvert sections
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Field verify size of box – Span x Height
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Lifting Slings and Cups
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Shims necessary when lifting holes are mislocated during fabrication
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Typical setting of box culvert sections
PRECAST BOX CULVERTS
Typical setting of box culvert sections
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Pulling sections together
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Pull pins and chains
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Pull hole size andpull pin diameter!
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Waterproofing joints and backfilling
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Staged construction
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Setting multiple barrels
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3” to 6” buffer zone betweenmultiple barrels - VDOT Spec. 302.03
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Setting width of buffer zone with dimensional lumber
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Buffer zone after concrete closure pour after the closure pou
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Precast Segmental Box Culvert
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Precast Segmental Box Culvert
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Problem areas – wing walls
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Problem areas – wing walls
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Problem areas – lack of cover from fabricator causes future maintenance issues (delamination and spalling)
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Approach guardrail and delineators
Need picture with approach guardrail!
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Multi-barrel mono box
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Refer to VDOT Spec. 302 for Box Culverts
Scarify a Road Surface (Show video)
Comments/Questions?
PRECAST BOX CULVERTS
PRECAST RIGID FRAMES
Precast units are similar to box culverts except…
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…they have no bottom.
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Walls of rigid frame units rest on cast-in-place footings.
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Used where high rock is present in stream bed.
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Sub-footing used to provide stable base for footing that supports frames.
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Plan sheet drawing for typical rigid frame design(Route 220 over Chimney Run in Bath County)
Plan sheet drawing for typical rigid frame design(Route 220 over Chimney Run in Bath County)
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Keyway Section (for Rigid Frame to sit in)
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Setting frame on Route 220 over Chimney Run in Bath County
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Sections usually transported on their side.
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Once sections are lifted from the truck…
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they are temporarily set back down…
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and are repositioned before being set onto the footing.
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Sections may also be skewed
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Frame sections are set on neoprene bearing pads
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Watch out for damaged sections and exposed reinforcing steel
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Pulling sections together
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Make sure sections come together
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Use high-strength, non-shrink grout to fill keway joints
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Typical wing joint details
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Backfilling and installing guard rail posts
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Completed project!
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In Review, Precast Rigid Frames:
Sit on sound rock and require no bottom slab (unlike box culverts)
Can be set in an efficient manner once footings are in place
Are designed to be used in various situations that may require skews or being on a grade
Comments/Questions?