Transcript Rigid vs. Flexible: PowerPoint presentation

Rigid Vs Flexible
ALL STORM PIPING PRODUCTS
ARE NOT CREATED EQUAL!
Presentation by:
www.concrete-pipe.org
2
RCP VS Flexible Pipe Systems
Hole is same but nothing else!
• IF YOU TAKE ANYTHING AWAY
WITH YOU TODAY WE WANT YOU
TO CLEARLY UNDERSTAND:
 RIGID PIPE IS DIFFERENT FROM FLEX.
PIPE
 Different in MANY WAYS:
•
•
•
•
•
STUCTURAL STRENGTH
INSTALLATIONS
INSPECTION
POST INSTALLTION
SPECIFICATIONS AND DETAILS
3
Engineering Analysis:
• Structural Strength
• Installation
• Inspection
AGENDA
Specifications and Std Details:
• Materials, installation, inspection, structural verification
SAFETY & RISK
 Hydraulic common sense (1/2” corrugations = .010? No!)
 Risk of Pre-Mature Structural Failure (KY & OH HDPE
Issues)
 Flammability is REAL ISSUE
Economic Analysis:
• REAL ECONOMICS
 Consider Installation Cost Vs Lifetime Value
4
Definition of “Pipe”
Dictionary.com: “a hollow cylinder of metal, wood,
or other material, used for the conveyance of
water, gas, steam, petroleum, etc.
Webster’s On-Line: “a long tube or hollow body for
conducting a liquid, gas, or finely divided solid or
for structural purposes”
Oxford English Dictionary: “a tube used to convey
water, gas, oil, etc.”
A Buried Pipe Must Perform
Two Critical Functions?
Buried Pipe
Conduit
/Hole
Structure
5
6
RCP Provides Conduit + Structure
Structure
Conduit
Concrete Pipe
OTHER PIPES
????STRUCTURE?????
• Wall thickness for HDPE remains constant
for all fill height or live loading conditions
• “Pipe” stiffness is time dependent and
constantly decreases under load
• “Pipe” stiffness decrease for HDPE & CMP
as pipe Dia gets larger!
• “Pipe” has little or no structural
strength
Flex. Pipe Wall = NO Strength to Structure
? ?? ?
?
?
?
Conduit
Structure
By Low Bidder
Flexible Pipe
RCP – STRCTURAL CONFIRMATION!
ASTM C-76 Class III RCP
D0.01 = 1,350 lb / lf / ft (dia.)
DULT =2,000 lb / lf / ft (dia.)
60” ASTM C-76 Class III
D0.01 = 6,750 lb / lf
DULT = 10,000 lb / lf
Total Load Required for 8’ Pipe:
D0.01 = (8)(6,750)
= 54,000 lbs.
DULT = (8)(10,000)
= 80,000 lbs.
Understand what this means?
9
Structure Confirmed before
60” RCP is tested before it leaves
Shipment
the point of manufacture to prove it
can carry the load of a loaded
Tractor and trailer with no lateral
support!
THIS FACT AND PROVEN SERVICE
LIFE Should give you CLEAR
UNDERSTANDING OF
DIFFERENCES OF RCP Vs
FLEXIBLE
LOAD INCREASES WITH PIPE
DIAMETER
Strength
W
D
w w w
D-LOAD =
LOAD
DIAMETER
3D
TOTAL LOAD = 1 W
TOTAL LOAD = 3 W
The backfill or fill load increases in direct proportion to pipe diameter.
It is essential for pipe strength to increase with pipe diam. regardless of the pipe.
Is this thinking logical? Does this make sense?
0.01” Crack Strength in a 3-E-B
ASTM C-76 RCP Strengths
20,000
18,000
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
Class 5
Class
4
Class
5,400 lb /3
2,700 lb / lf
lf
Class
2
12 15 18 24 30 36 42 48 54 60 72
1,350 lb / lf / ft (dia.)
Pipe Diameter
RCP Increases Strength with Pipe Diameter to Carry Increased Load.
Structural Strength – HDPE & CMP
The Decrease in Pipe Strength
Occurs at the Same Time the Load
is Increasing.
Pipe stiffness
16 Gage
24”
36”
42”
48”
HDPE PIPE
34 psi
22 psi
19 psi
17 psi
CMP
224psi
62 psi
40 psi
27 psi
What Should This Alert You To About Installation?
14
Engineers are asked to gravitate to thin gage for CMP
Corrugation Profiles
• 2 2/3” x 1/2”
X
• 3” x 1”
Y
• 5” x 1’
7-1/2”
3/4”
• 3/4” x 3/4” x 7-1/2”
(Spiral Rib)
L
16
.064
H
14
12
10
.079 .109 .138
8
7
.168 .188
Pipe Strength vs. Installation Contribution
100%
Strength Contribution, %
90%
80%
70%
60%
50%
Pipe
40%
Soil
30%
20%
10%
0%
RCP
50 psi
22 psi
Pipe Type or Stiffness
14 psi
15
Pipe Different means Installation &
Inspection Must be Different
17
Standard Installations for RCP





Type 1: Highest quality installation using select
granular soils with high compaction requirements
for haunching and bedding.
Type 2: Allows silty granular soils with less
compaction required for haunching and bedding.
Type 3: Allows use of soils with less stringent
compaction requirements for haunching and
bedding.
Type 4: Allows use of onsite native material for
haunching and bedding with no compaction
required. (6” of Bedding is required if rock
foundation)
All Backfill Requirements above to spring line
ONLY
SIDD Type 1 Installation For RCP
OVERFILL
Do
Do
Do
6
HAUNCH
COMPACTION
HAUNCH
COMPACTION
LOWER
SIDEFILL
ZONE
LOWER
SIDEFILL
ZONE
Do
MIDDLE BEDDING,
UNCOMPACTED
3
1.33Do
0.67Do
0.83Do
SIDD Type 4 Installation For RCP
SITE EXCAVATED
BACKFILL
Do
6
Do
HAUNCH
SITE
EXCAVATEDM
ATERIAL
HAUNCH
SITE
EXCAVATEDM
ATERIAL
Do
SCARIFY
MIDDLE BEDDING
3
1.33Do
0.5Do
NEW KYTC RCP INSTALLATION
Flexible Pipe
Traffic Load
Earth Load
Final Backfill
R1
Haunching
Load
resisted
by
backfill!
Initial Backfill
Bedding
Foundation
For every action there is an equal and opposite reaction.
AASHTO Section 30 Thermoplastic Pipe
30.5.4. Structural Backfill
• 200mm (8 inch) loose lift thickness
• 90% compaction required
• Compact both sides simultaneously
• Structural fill 300mm (1 foot) above pipe
• “….shall be worked into haunch area and
compacted by hand”
• Compaction equipment within 1000mm (3 feet) of
the pipe shall be approved by the engineer
• Minimum Cover for Construction Loads
23
ASTM D 2321-Thermoplastic Pipe
• Minimum densities 85% to 95%
• Recognizes “numerous flexible pipe
products” & “inherent variability of natural
ground conditions”
• Install and compact in 6” maximum layers
• Use hand tampers or vibratory compactors
• Haunching: Work in around pipe by hand to
ensure uniform support
• Do not permit compaction equipment to
contact and damage the pipe
Specifications/Std Drawings
Must Address Differences
RIGID PIPE
STRUCTURAL
BACKFILL 95%
(HAUNCH)
(Type 1 Installation)
FLEXIBLE PIPE
SOIL/GRANULAR
EMBANKMENT 85%
COMPACTION
(Type 4 Installation)
STRUCTURAL BACKFILL
96% COMPACTION
12”
6”
1.33xO.D
1.33xO.D
1.25xO.D.+1.0’
If You Do Not Build The
Block
Flexible pipe
STRUCTURAL BACKFILL
96% COMPACTION
See UTA, KY & Ohio L/V
Inspections of Installed
HDPE Pipe
12”
6”
1.25xO.D.+1.0’
What Do You Want The Structural
Integrity of Your Design To Depend
On?
RCP
80% - 90% of Structure from Pipe
LOW BID INC.
85% - 95% of Structure from Backfill Material
26
Inspection During Construction
• During Install.
 Flexible Pipe = confirm design calcs &
conditions + Firm Foundation + Homed
joints + Structure/Design must be
confirmed by compaction testing of pipe
envelope material (the structure)
 Rigid check class = plan design
(structure confirmed at plant 3EB) +
Firm Foundation + Joints in home
position before backfill placed
 Backfill for flex. Pipe = Structural
Integrity of the flex. Pipe system!
28
Post Construction Inspection
• Post Installation Inspection
 Flexible check deflection 100% of pipe
(over deflection will lead to failure)
 Must combine video with some way to
measure deflection L/V or Mandrel
 Rigid visual inspect 100%
 Video 30” and smaller
 We are not concerned about critical
inspection of our product
AASHTO SECTION 30.5.6
29
NEW INSPECTION REQUIREMENTS FOR HDPE PIPE
(AS ADOPTED BY THE AASHTO SUBCOMMITTEE ON BRIDGES AND STRUCTURES – JUNE 29, 2005)
•
•
•
•
•
•
All pipes shall undergo inspection during and after installation.
Final inspections shall be conducted no sooner than 30 days after
completion of installation and final fill.
The pipe shall be evaluated to determine whether the internal diameter
of the barrel has been reduced more than 5 percent when measured
not less than 30 days following completion of installation.
For locations where pipe deflection exceeds 5 percent of the inside
diameter, an evaluation shall be conducted by the Contractor and
submitted to the Engineer for review and approval considering the
severity of the deflection, structural integrity, environmental conditions,
and the design service life of the pipe. Pipe remediation or replacement
shall be required for locations where the evaluation finds that the
deflection could be problematic. For locations where pipe deflection
exceeds 7.5 percent of the inside diameter, remediation or replacement
of the pipe is required.
Installed pipe deflections that exceed 5 percent of the initial inside
diameter may indicate that the installation was substandard.
appropriate remediation, if any, will depend upon the severity of the
deflection.
In all pipe installations, at least 10 percent of the total number of pipe
runs representing at least 10 percent of the total project footage on the
project shall be randomly selected by the Engineer and inspected for
deflection. Also, as determined by the 100 percent visual inspection in
Section 30.5.6.1, all areas in which deflection can be visually detected
shall be inspected for deflection.
30
AASHTO SECTION 26.5.7
NEW INSPECTION REQUIREMENTS FOR CMP
(AS ADOPTED BY THE AASHTO SUBCOMMITTEE ON BRIDGES AND STRUCTURES – JUNE 29, 2005)
•
•
•
•
CMP shall be inspected after placement in the trench, as required
during backfilling, and after completion of installation to ensure
that final installation conditions allow the pipe to perform as
designed.
Final internal inspections shall be conducted on all buried CMP
installations to evaluate issues that may affect long term
performance. Final inspections shall be conducted no sooner
than 30 days after completion of installation and final fill.
It should be noted that the AASHTO Flexible Culvert Liaison
Committee has been directed to write deflection criteria for
inclusion in the installation specification for CMP this year.
As of ’06 7.5 max deflection established!
AASHTO SECTION 27.6.1
31
NEW INSPECTION REQUIREMENTS FOR RCP
(AS ADOPTED BY THE AASHTO SUBCOMMITTEE ON BRIDGES AND STRUCTURES – JUNE 29, 2005)
• Internal inspections shall be conducted on all buried rigid pipe
installations to evaluate issues that may affect long-term
performance, such as cracks, joint quality and alignment.
Inspections shall be conducted no sooner than 30 days after
completion of installation and final fill.
• Hairline longitudinal cracks in the crown or invert indicate that
the steel has accepted part of the load. Cracks equal to or
less than 0.01 in. (0.25 mm) in width are considered minor
and only need to be noted in the inspection report.
• Inspection records for pipes with crack widths exceeding 0.01
in. (0.25 mm), shall be kept on file for monitoring conditions
during subsequent inspections. Crack measurements and
photographs shall be taken for monitoring conditions during
subsequent inspections.
32
Specifications and Std. Details
• Review and use national Stds as a
guide to complete your own Specs
for the diff. piping products
• Materials & Manufacturing
• Installation
• Inspection
• Allow us to be a resource & provide
you with all the national stds. and
suggested specification outline for
all Products
Risk & Liability Issues
ab
•
•
•
•
Hydraulics
Flammability
Pre-Mature Structural Failures
Environmental Issues
34
Hydraulics
• Laboratory testing is done with
perfect laminar flow conditions and
the pipe is not subjected to external
loading
• Both concrete and plastic pipe have
achieved laboratory “n” values of
0.009
• What additional losses can be
attributed to the “rippling” of the
interior liner under field loading
conditions?
Hydraulics
36
38
Hydraulic Efficiency
24” Pipe
Slope = 0.5%
LAB
VALUE
0.012
24”
245
17.32 cfs
ACTUAL
VALUE
=
=
=
=
Manning’s n
Inside Diameter
2/3
1/2
1.49/n x A x R x S
Q
=
=
=
=
0.018
23.62”
156
11.03 cfs
HDPE pipe will only carry 64 percent of the 17.32 cfs water that it was
intended to carry. Need to use 30” HDPE pipe instead.
Recap - Hydraulics
• Manning’s “n” value Critical
• “n” for HDPE, closer to value
of CMP
• Risk to Owner/Engineer =
undersized pipe, upstream
flooding, asset losses,
liability
40
Flammability
Low Risk ? -- High Maintenance
-- Value?
42
Premature Failure Are a
Cost that affects us all!
43
Culvert Failures…
How much do they
ACTUALLY cost?
I – 35 W Bridge Collapse
Minneapolis, MN
Economic Analysis
Life Cycle Cost Analysis
• Measures the present value of all
relevant costs of installing, operating
and maintaining alternative drainage
systems over a specified period of
time.





engineering
construction
maintenance
rehabilitation
replacement
46
WASTEWATER = DINCLUDES SANITARY
AND STORM SEWER
It is unwise to pay too much, but
it is worse to pay too little.
When you pay too much, you lose a little money. When
you pay too little, you sometimes lose everything, because
the thing you bought was incapable of doing the thing it
was bought to do.
The common law of business balance prohibits paying a
little and getting a lot-it can’t be done. If you deal with
the lowest bidder, it is well to add something for the risk
you run. And, if you do that, you will have enough to pay
for something better.
JOHN RUSKIN 1819-1900, renowned English critic, social
commentator, and economist of the Victorian Age
48
RCP VS Flexible Pipe Systems
DIFFERENT IN MANY WAYS!
• IF YOU TAKE ANYTHING AWAY WITH
YOU TODAY WE WANT YOU TO
CLEARLY UNDERSTAND:
 RIGID PIPE IS DIFFERENT FROM FLEX.
PIPE
 Recognize The Differences:
• MUST BE DESIGNED DIFFERENT
• MUST BE INSTALLED DIFFERENT
• MUST BE INSPECTED DIFFERENT
 SPECIFICATIONS AND DETAILS SHOULD
BE DIFFERENT
49
Sleep Better With Concrete
Pipe