Cuál método de diseño se debe utilizar Design for What ...
Transcript of Cuál método de diseño se debe utilizar Design for What ...
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Cuál método de diseño se debe utilizar para una aplicación específica
TALLER DE DISEÑO DE PAVIMENTOS DE
CONCRETO
November 7, 2014
Robert Rodden, P.E.
Senior Director of
Pavement Technology
Design for What?
Different cement-based materialsJointed- or continuously-reinforced
Roller-compacted concrete (RCC)
Pervious concrete
Composite pavements
Different applications/trafficAircraft loading
Industrial loading
Other odd loading
Short joint spacing
How Did We Get to Jointed Plain Being the Norm for Over-the-Road Traffic?
Design Challenge | Solution
Horseshoes/Steel Wheels & Mud | Concrete
Early Concrete Pavement Details
The first concrete pavements/slabs were:
≈ 6” (150 mm) thick… no structural design because focus was rut prevention
6-8 ft (1.8-2.4 m) squares based on mixer capacity… yes, joint spacing was dictated by mixer capacity!
No crack control joints or dowels/steel
Design Challenge | Solution
Speed of Vehicles Increases so People Notice Joint Roughness & Want to Maximize Production to Minimize Cost | Minimize Construction Joints
less
and more
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Advances Brought New Challenges
More efficient equipment and placement methods were soon developed
Slabs got longer
The public wanted 2-lane roadways for safety
Slabs got wider
… both of these lead to new challenges
First mile of PCCP(1909)
Concrete Wants to Shrink
Drying Shrinkage
Hydration Uses Water
Thermal Shrinkage
Hot then Cold
HOT AT SET∆ ∗ ∆ ∗
ChemicalShrinkage
COOLED OFF
Shrinkage + Restraint = CRACKS!?!
HOT AT SET, HIGH MOISTURE, UNHYDRATED CEMENT
COOL, DRY, HYDRATED CEMENT
TEFLON | No Friction/Restraint
If no restraint
With restraint
Subgrade/Subbase | Restraint
Design Challenge | Solution
Shrinkage Cracking | Thicken CL; Let It Crack Transversely
40-80 ft
(12-24m)
15-20 ft
(4.6-6.1 m)
Design Challenge | Solution
Crack Opening | Reinforce to Hold Crack Tightly
THE BIRTH OF Jointed Reinforced Concrete Pavement - JRCP (1913 or Earlier)
Plan
Profile
Steel: 0.06-0.25% Joints: 40-100 ft (12-30 m)Cracks: 15-20 ft (4.6-6.1 m)
14-20 ft(4.3-6.1 m)
Design Challenge | Solution
Crack Maintenance | Create Straight Transverse JointsPlan
Profile
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Design Challenge | Solution
Construction Joint Faulting/Chipping | Dowel Joints
JPCP Profile
THE BIRTH OF DOWELED Jointed Plain Concrete Pavement - JPCP (1917)
JRCP Profile
Long Panels = Higher Risk of BlowupsBlowup
RiskHigh
Low
JRCP w/ 80-100 ft joints
(24-30 m)
JRCP w/ <40 ft joints
(<12 m)
JPCP w/ 40-80 ft joints
(12-24 m)
JPCP w/ 15-25 ft joints
(4.6-7.6 m)
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Design Challenge | Solution
Blowup | Include Expansion Joint if JRCP or long JPCP
Design Challenge | Solution
Crack Faulting | Reinforce MORE to Hold Crack Tightly
THE BIRTH OF Continuously Reinforced Concrete Pavement - CRCP (1923)
Plan
Profile
Steel: 0.6-0.85% Cracks: 2-6 ft (0.6-1.8 m)
WWII + TRAFFIC = Faulting of Undoweled Design Challenge | Solution
Pumping/Faulting | Add a Subbase
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The Jointing Dilemma Continued…
During WWII (1939-1945), Bureau of Public Roads encouraged steel-free designs to free up steel for the war effort. So the norm became undoweled JPCP with expansion joints at 105-120 ft (32-37 m), which had contraction joints open and poor performance. These pavements were relatively free of cracking, spalling and blowups, but the faulting was serious.
After WWII, typically either undoweled JPCP with short joints and no expansion joints or long jointed JRCP with contraction/expansion joints at 50 to 100 ft (15 to 30 m).
…and Continued
In the 1940s the US Bureau of Public Roads did a study on expansion joints
Showed that they progressively close over the years, causing greater openings at nearby contraction joints and resulting in loss of aggregate interlock and sealant failure.
Showed that expansion joints are not necessary unless contraction joints spaced at greater than 60 ft (18 m), aggregates are expansive, or temp during construction is near freezing.
We Even Tried a “Hinge Joint” Design
http://www.fhwa.dot.gov/pavement/concrete/hpcp/hpcp05.cfm
The Three Traditional Types
Design Challenge JPCP JRCP CRCP
Transverse Joint Spacing 14-20 ft (4.3-6.1 m) 22-100+ ft (6.7-30 m) N/A
Transverse Crack Spacing N/A 15-20 ft (4.6-6.1 m) 2-6 ft (0.6-1.8 m)
Rut-Resistant Surface Yes Yes Yes
Shrinkage Accounted for by Jointing Cracking Cracking
Reinforcing N/A 0.06 – 0.25% 0.6-0.85%
Expansion Joints Used No Sometimes Maybe
Tiebars Used in Long Joints Yes Yes Yes
Longitudinal Joint Spacing 12-14 ft (3.7-4.3 m) 12-14 ft (3.7-4.3 m) 12-14 ft (3.7-4.3 m)
Trying to Minimize the Number of Man-Made Joints – WHY?
YES YES YES
AASHTO 62-93 Design Yes Yes Yes
AASHTO DARWin-ME Design Yes NO Yes
U.S. Design Standards for Roadways
AASHTOWarePavement ME (previously known as DARWin-ME and MEPDG)
AASHTO 93 (software as ACPA WinPAS)
ACPA StreetPave
325 & 330
Most Roadway Concrete in the US is JPCP
JPCP
JRCP
CRCP
Pavement-ME and StreetPave do not supported Jointed
Reinforced Concrete Pavement (JRCP)
design
0% 20% 40% 60% 80% 100%
ArizonaArkansasDelaware
FloridaHawaiiIdaho
IndianaIowa
KansasMichiganMissouriMontanaNevada
North CarolinaOhio
OklahomaSouth CarolinaSouth Dakota
TennesseeUtah
VirginiaWashington
West VirginiaWisconsinWyoming
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Continuously Reinforced Concrete Pavement (CRCP) Design
Guidance on CRCP Design
FHWA & CRSI initiative: http://www.crcpavement.org/
AASHTO 93 or ME can design
Several state agencies havetheir own custom design
IL – custom ME design
TX – TSLAB86
Roller-Compacted Concrete (RCC) Thickness Design
RCC Thickness Design
RCC-Pave available from PCA:http://www.cement.org/bookstore/profile.asp?id=2309
Same “core” as ACPA AirPave / PCA’s AIRPORTUnlimited fatigue when stress ratio ≤ 0.50; no faulting / IRI models
Some suggest using StreetPaveACPA does not support this
ACPA working on new RCC fatiguemodels right now
RCC design currently like the Wild West
RCC Fatigue
Pervious Concrete Thickness Design
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Reasons for ACPA’s PerviousPave
Several hydrological design methods exist
No universal structural design method before PerviousPavesome used Westergaard solutions
some suggested to use StreetPave – recommended in at least two widely-circulated resources/journals
Delatte’s TRB 2007 Paper:
“The author investigated adaptation of ACPA StreetPave software…”
From StreetPave to PerviousPave
Key changes :
Exclusion of erosion
Different design variablesmaximum strength andcorrelation to modulus
no dowel bars
traffic distribution defaults
allowable subgrades/subbases
Inclusion of hydrological design
acpa.org/PerviousPave
Composite Pavement Thickness Design:Asphalt on Concrete
Asphalt on Concrete Composite
Some consider renewable surface
Asphalt surface might provide thermal benefits that ultimately reduce concrete slab curling which then extends performance
NCHRP Report S2-R21-RR-2 from July 2013:
http://onlinepubs.trb.org/onlinepubs/shrp2/SHRP2_S2-R21-RR-2.pdf
MEPDG-based design
Composite Pavement Thickness Design:Concrete on Concrete
Concrete on Concrete Composite
Wet-on-wet concrete placement that might provide structural, cost, sustainability, performance, etc. benefit(s)
NCHRP Report S2-R21-RR-3 from July 2013:
http://onlinepubs.trb.org/onlinepubs/shrp2/SHRP2_S2-R21-RR-3.pdf
MEPDG-based design in this report but other design methods might also be valid, depending on setup
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Aircraft Loading
Boeing 777-200ERGear Spacing 84 feet 11 inchesEquates to 3.4 California Profilograph lengths
Image Courtesy Boeing Commercial Aircraft Company
Aircraft Loading
One aircraft wheel load can easily exceed the total gross weight of many vehicles, including semi-tractor trailers
Aircraft wheel loads are approaching 65,000 lb (29,500 kg) and tire pressures exceed 200 psi (1.4 MPa)
Tri-Services (Army, Air Force, Navy)
PCASE = Pavement-Transportation Computer Assisted Structural Engineering
US Army Corps of Engineers product
https://transportation.wes.army.mil/pcase
ACPA’s AirPave
AirPave is based on calculated pavement responses (mechanics –independent of climate)
Developed as an update to PCA’s AIRPORT, originally developed by Bob Packard
Design is strictly mechanistic and limit stress ratio; no faulting / IRI
acpa.org/AirPave
Now it is more of an analysis tool…
FAARField
FAA standard for airfield pavement design
Rigid pavement design based on 3D finite element analyses
http://www.faa.gov/airports/engineering/design_software/
Industrial Loading
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Industrial Loading
Design MethodOver-the-Road
TrucksIndustrial Vehicles
Distributed Loads
Concentrated Loads
AASHTO 93 / ACPA WinPAS X
AASHTOWare Pavement ME X
ACI 330.X (non-software) X X X
ACPA AirPave X X
ACPA IndustrialPave (SOON!) X X X X
ACPA StreetPave X
EverFE X X
TCPavements OptiPave X
NOTE: ACI 330.X uses ACPA’s StreetPave in its Over-the-Road Trucks design tables and ACPA’s AirPave in its Industrial Vehicles design tables; the document also mentions OptiPave and both AASHTO software
IndustrialPave
Beta almost complete
Includes:Over-the-Road Trucks – based on StreetPave
Industrial Vehicles – based on AirPave
Distributed Loads – based on AirPave
Concentrated Loads – based on ACI 318 equations
Thinking about including RCC design in the software
Other Odd Loading
Other Odd Loading
Of course can use Westergaard or AirPave
Best bet is usually to turn to some finite element analysis
EverFE
FREE!!!!
3D user-friendly FEA software
Based on calculated pavement responses (mechanics –independent of climate)
Focus is ???
Design is strictly mechanistic
http://www.civil.umaine.edu/everfe/
EverFE is Very Powerful!
Dowel alignment, joint spacing / layout effects, etc.
12 ft12 ft 12 ft 12 ft 12 ft
15 ft
6 ft 12 ft12 ft 12 ft 12 ft
15 ft
6 ft
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Thank you.Questions? FEEDBACK!
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Robert Rodden, P.E.
Senior Director of Pavement Technology
American Concrete Pavement Association
[email protected] | 847.423.8706