proper concrete design methodology
DESCRIPTION
There are different types of pavement, highways, streets and local roads and parking lots, and each require a different design method. This presentation explains through the differences and then goes into detail specifically as to the method for designing concrete parking lots. The presentation ends with a brief discussion of the "new realities" in paving as concrete and asphalt are now essentially equal on first costs.TRANSCRIPT
Proper Concrete
Design Methodology
Roger Faulkner, PE
Director of Engineering & Promotion
Ohio Concrete
Overview
TYPES OF PAVEMENT
ASSOCIATED DESIGN METHODS
PARKING LOT DESIGN
PAVING – “The New Realities”
TYPES OF PAVEMENT
HighwaysDesign Speed: 55 mph and greater
High Frequency of Heavy Truck Loads
Streets and Local RoadsDesign Speed: 25 mph to 45 mph
Low to Medium Frequency of Heavy Truck Loads
Parking Lots and DrivesDesign Speed: Typically Less than 15 mph
Minimal (or None) to Low Frequency of Heavy Truck Loads
DESIGN METHODS
Highways
Linear Pavement – 2 or more lanes wide
Transverse Joints - Dowels
Edge Support – Tied Shoulders
Concrete Design Thickness – 9” or greater
AASHTO 1993 Highway Design Guide
ODOT Pavement Design Manual
ACPA “WinPAS” Software
DESIGN METHODS
Streets and Local Roads
Linear Pavement – 2 or more lanes wide
Transverse Joints – Dowels if Needed
Edge Support – Curb and Gutter or widened lane
Concrete Design Thickness – 6” to 8”
ACPA
“StreetPave” Software
DESIGN METHODS
Parking Lots and Drives
Complex Area Pavement – Width Varies
Joints – Square Panels or Length to Width <1.25
Edge Support – Integral Curb or Thickened Edge
Concrete Design Thickness – 4” to 8”
American Concrete Institute
ACI 330R-08 – “Guide for the Design and
Construction of Concrete Parking Lots”
PARKING LOT DESIGN
ACI 330R-08
Section 3.6 –
“Thickness Design”
Plain Concrete
Pavement
PARKING LOT DESIGN
ACI 330R-08, Section 3.6
Traffic Categories
PARKING LOT DESIGN
Subgrade Support
Typ. K=100 psi/in.
Concrete Flexural Strength
MOR (psi) = 10 x Square Root of f’c
For f’c= 3500 to 5000 psi
MOR = 600 to 670 psi
Table 3.4, Recommended 20 Year
Design Thicknesses, with no dowels
PARKING LOT DESIGN
PARKING LOT DESIGN
Steel Reinforcement
Per 3.8.1 – “The use of distributed steel
reinforcement will not add to the load-carrying
capacity of the pavement and should not be
used in anticipation of poor construction
practices.”
Replaced with Shorter Joint Spacings
PARKING LOT DESIGN
Joint Spacing
Per Section 3.7
Joint Patterns should be approx. square
Length Not > than 125% of Width
Spacing = 2 x thickness in Feet
Jointing Pattern can be used to delineate
parking lanes and parking stalls
PARKING LOT DESIGN
Tie-Bars
Per 3.8.3 – Tie only the first longitudinal joint
from the pavement edge to keep the outside slab
from separating
Tie Centerline Joints of Entrance Drives
No. 4, ½” dia. – Typ. 24” long (See Table 3.7)
30” spacing
PARKING LOT DESIGN
Dowels
Per 3.8.2 – Dowels generally not needed for
parking lots
Per Table 3.4 – Category D Thickness can be
reduced 1” to 7”, if dowels are used
PARKING LOT DESIGN
Table 3.4 of ACI 330R-08 Developed using ACPA“StreetPave” Computer Program MC003
It is a pavement design tool for low volume roads (streets & local roads)
It is based on the PCA’s pavement thickness design methodology
PCA assesses adequacy of concrete thickness using both fatigue and erosion criteria
Engineering Services Center “ESC”
CAD parking lot and intersection layout
Concrete Mix Design
Pavement Thickness and Joint Spacing
FREE Service!
PARKING LOT DESIGN
Paving - “The New Realities”
Concrete and Asphalt have reached parity on
Initial Cost
ODOT Initiated Alternate Pavement Bids
Those Projects Yielded HUGE Cost Savings
ODOT Alternate Bid Projects
5 Projects Bid in 2009 w/ Alternate Pavement Bids
State’s Estimate for the 5 Projects - $405 Million
Total Award for the 5 Projects - $345 Million
$60 Million Cost Savings or approx. 15%
Non-Alternate Bid Projects
3 Asphalt Only - $170 M Est., $157 M Award
$13 Million Savings – Ave. 7% Cost Savings
Alternate Bids Yield TWICE the Costs Savings!
ODOT Alternate Bid Projects
Key Aspects of Alternate Bid Process
Increased Competition
More bidders
Plus, competition between Asphalt and Concrete Industries
No Material Price Adjustments
ODOT Proposal Note 115, Price Adjustment Exclusions
Contractor Required to Submit Prices for Both
ODOT chooses the alternate
ODOT Drafts New Policy
Projects require an LCCA for both concrete and
asphalt pavement alternates
If LCCA’s >10%
Alternate with Lower LCCA is selected alternate
An Updated LCCA Required before Final Tracings
• If LCCA’s still >10% - project bid with original alternate
• If LCCA’s <10% - plans modified to bid with both concrete and
asphalt pavement alternates
If LCCA’s <10%
Plans developed to bid for both concrete and asphalt alternates
Questions?
Proper Concrete
Design Methodology
THANK YOU !