View
24
Download
0
Category
Preview:
DESCRIPTION
Pavement Design Task Group Feedback. RPF meeting 23 November 2005. Sequence of events. RPF May 2005 Establish task group 1 st Meeting Discussion of role and operation of the task group Presentation on potential improvements to mechanistic-empirical (ME) design method - PowerPoint PPT Presentation
Citation preview
Copyright @ CSIR 2005 www.csir.co.za
Pavement Design Task Group Feedback
RPF meeting
23 November 2005
Copyright @ CSIR 2005 www.csir.co.za
Sequence of events
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• RPF May 2005– Establish task group
• 1st Meeting– Discussion of role and operation of the task group– Presentation on potential improvements to mechanistic-
empirical (ME) design method– Unpacking of ME design method core
• 2nd Meeting– Presentation on a project performance based design method– Presentation of simulation models– Discussion of the deliverable from the process
Copyright @ CSIR 2005 www.csir.co.za
Sequence of events
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• 3rd Meeting– Integration of the performance based information system
and the ME-design component into a single design method– Design sensitivity analysis based on the current ME design
method– Details of the performance based information system
• 4th Meeting– Unpacking the details of the ME-design component– Development of a R&D matrix and rating of the R&D areas
Copyright @ CSIR 2005 www.csir.co.za
Task group members
• Prof M de Beer (CSIR);• Prof E Horak (UP);• Mr M Henderson
(PAWC);• Prof K Jenkins (US);• Dr F Jooste (MAS);• Dr G Jordaan
(Tshepega);• Mr L Kannemeyer
(SANRAL);• Dr F M Long (MAS);
• Mr P Olivier (J&G);• Mr B Perrie (C&CI);• Mrs E Sadzik
(Gautrans);• Mr A Taute (Vela VKE);• Mr H L Theyse (CSIR);• Dr I van Wijk (Africon);
and• Dr H Wolff (Nyeleti).
Copyright @ CSIR 2005 www.csir.co.za
General recommendations:Deliverable from the task group
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• The task group will deliver a research and development (R&D) plan that will guide the development of a pavement design method for southern Africa that – allows for a range of design applications of different
importance and – caters for a user group with different levels of design
experience• R&D plan to be executed under the auspices of the
Road Pavement Research Advisory Committee (RPRAC)– Project management may be referred back to sub-groups of
the task group
Copyright @ CSIR 2005 www.csir.co.za
General recommendations
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• The R&D plan is aimed at developing an improved design method based on– A performance based information system– Mechanistic-empirical design concepts
• Initial intention to include rigid and block pavement design– Details of design sufficiently different to treat
separately– Urgent need to develop single design guide for all
types of pavements
Copyright @ CSIR 2005 www.csir.co.za
General recommendations
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• The R&D plan only covers R&D activities to develop improved design method– Dissemination of individual research results and design method as
a whole– Not descriptive in terms of delivery mechanisms such as software
packages– RPRAC may considered the development of a software package as
a form of delivery mechanism• The improved design method should close the gap between
ME-design and day-to-day engineering as far as possible• Conventional ME-design focus almost exclusively on the effect
of the imposed stresses– Recent research on unbound material shows the effect of field
variables such as density and saturation is equally important– The improved design method must incorporate the effect of field
variables
Copyright @ CSIR 2005 www.csir.co.za
General recommendations
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Initially a separate task group for design traffic– Design traffic estimation is an integral part of
pavement design– Design traffic task group combined with pavement
design task group– The improved design method should allow for
gradual transition from the E80 concept to mixed traffic design
• Revision of guideline documents containing sound engineering practice excluded form the R&D plan– Close integration required between guidelines and
the design method
Copyright @ CSIR 2005 www.csir.co.za
Integration of guidelines and design method
PavementDesign
Knowledge base
Sou
nd e
ngin
eerin
g pr
actic
e
Pav
eme
nt d
esig
n m
etho
ds
PavementDesign
Knowledge base
Sou
nd e
ngin
eerin
g pr
actic
e
Pav
eme
nt d
esig
n m
etho
ds
Copyright @ CSIR 2005 www.csir.co.za
Performance based information system
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Based on performance data collected from – Rehabilitation investigation documentation – APT test results
• Statement of fact rather than interpretation of data and modelling
Copyright @ CSIR 2005 www.csir.co.za
Design Method
Integration of performance based and ME-design components
Entry level
Intermediate level
Advanced level
ME-design component
Design scenario:• Routine design• Low design experience• Use only known materials• Conventional material classification
Design scenario:• Important design • Seasoned professional designer• Test input parameters for materials
Design scenario:• Very important design• Special investigations • Specialist designer• Unusual materials• Test input and performance of materials
Performance based
information system
Copyright @ CSIR 2005 www.csir.co.za
Design Option
Click here for Design Report
Click here for Situation Summary
Click here for Rehab. Report
Click here for Design Report
Click here…
Click here for Design Report
Click here…
Click here for Design Report
Click here…
• 8 Years to Resurface
• 1278 H/day
• 8 MESA to Rehab
• Terminal Rut = 16 mm
• Not Resurfaced
• 987 H/day
• 5 MESA to Rehab
• Terminal Rut = 12 mm
• 11 Years to Resurface
• 1250 H/day
• 9 MESA to Rehab
• Terminal Rut = 14 mm
• 10 Years to Resurface
• 1400 H/day
• 12 MESA to Rehab
• Terminal Rut = 17 mm
Performance Database
Performance based information system
Copyright @ CSIR 2005 www.csir.co.za
Mechanistic-empirical design component
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Basic ME procedure– Fully determines the accuracy of the ME-design
component– Requires engineering knowledge and
understanding
• Various implementation schemes– Allows for spatial and time-based variation– Enhances the interpretation of results– Requires mathematical and computer
programming skills
Copyright @ CSIR 2005 www.csir.co.za
Temperature
Moisturecontent
Density
Grading
Atterberglimits
Bindercontent
Binderproperties
Geometry
Axle loadhistogram
Other?
Other?
Contact stresshistogram
Grading
Fixedload
Fixedcontact stress
Mr = Constant
Mr = f (Temp)
Mr = f (Dens,saturation)
Mr = f (Bulk and shear
stress)
Mr = f (Strain)
Linearvisco-elastic
Other?
UCS
Stress and strain at break
Time/previousloading
HM
AU
nbou
ndS
tabi
lized
Mat
eria
l dat
a
Trafficdata
Resilientresponseanalysis
Input layers
CurrentFuture
Resilientresponse models
Damage models
Fatigue
Plastic strain/permanent deformation
Other?
Thermal cracking
HM
AU
nbou
nd
Plastic strain/permanent deformation
Other?
Other?
Sta
biliz
ed Stiffness reduction
Plastic strain/permanent deformation
Other?
Crushing
Sub
grad
e Plastic strain/permanent deformation
Other?
Structuralcapacityestimate
Com
pute
rso
lutio
n
Copyright @ CSIR 2005 www.csir.co.za
Basic me-design
module
Trafficloading
Spatial variationof field variables
Axle load
Frequency
Contact stress
Frequency
T1
RD1, S1
1b, 1
b
T2
RD2, S2
2b, 2
b
T3
RD3, S3
3b, 3
b
Tn
RDn, Sn
nb, n
b
Layer thicknessTemperatureBinder contentRelative densitySaturationGradingetc.
Pre-processing Post-processing
Extent of fatigue
Time Fatigue life
Frequency
Rut
Time Rut life
Frequency
Terminal rut
Riding quality
Time Riding quality life
Frequency
Unacceptable
Copyright @ CSIR 2005 www.csir.co.za
Research & Development Plan
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Main components of the R&D plan– Integration level project– Performance based information system– Demand analysis
• Traffic and natural environment– Material response models– Pavement response models– Damage models– Probabilistic and recursive implementation schemes
• R&D needs formulated for each component• Short, medium and long-term actions formulated for
each R&D need• Each action rated in term of benefit/impact and
effort/cost
Copyright @ CSIR 2005 www.csir.co.za
Execution of R&D plan:Integration of activities
Integration level project:• Integrate output from individual projects into a single design system• Develop documentation on the use of the system• Present seminars and workshops on the use of the design method`
Dem
and
an
alys
is:
•T
raff
ic•
Env
ironm
ent
Mat
eria
l res
ilien
t re
sp
on
se
mo
del
s
Pa
vem
ent
res
ilien
t re
spo
nse
m
od
els
Da
mag
e m
od
els
Imp
lem
enta
tio
n s
chem
es
Integration level project:• Integrate output from individual projects into a single design system• Develop documentation on the use of the system• Present seminars and workshops on the use of the design method`
Dem
and
an
alys
is:
•T
raff
ic•
Env
ironm
ent
Mat
eria
l res
ilien
t re
sp
on
se
mo
del
s
Pa
vem
ent
res
ilien
t re
spo
nse
m
od
els
Da
mag
e m
od
els
Imp
lem
enta
tio
n s
chem
es
Copyright @ CSIR 2005 www.csir.co.za
Execution of R&D plan:Stress effect theme
Pavement resilient response model:• Correct modelling of the complex tyre/pavement contact patch in terms of shape and stress distribution
Demand analysis:• A tyre/pavement contact stress information system• A traffic volume and axle load information system• Vehicle dynamics
Contact stress and axle load histograms
and response histograms
Damage models:• Calibrated for the effect of field variables and stress regime
Implementation scheme:• Probabilistic, linear recursive and non-linear recursive simulation of cumulative damage
Damage per individual load cycle
Copyright @ CSIR 2005 www.csir.co.za
Execution of R&D plan:Field variable effect theme
Pavement resilient response model:• Modelling the vertical variation in material response caused by vertical variation in field variables and stress condition
Material resilient response models:• Improved material response models calibrated for time dependent deterioration and field variable variation
Demand analysis:• An environmental information system• A field variable and engineering parameter information system including spatial and time variation
Design environment
Environment specific material response models
Damage models:• Calibrated for the effect of field variablesand stress regime
and response histograms
Implementation scheme:• Probabilistic, linear recursive and non-linear recursive simulation of cumulative damage
Damage per individual load cycle
Copyright @ CSIR 2005 www.csir.co.za
Rating of short-term R&D objectives
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Integration level project– Integrate output from R&D projects into single
design method– Reality checks and validation– Develop manual on use of method
Integration project
0
2
4
6
8
10
1 2 3 4 5 More
Bin
Fre
qu
ency
Expected benefit
Integration project
0
2
4
6
8
10
50%
100%
150%
300%
500%
Mor
e
Bin
Fre
qu
ency
Benefit/Effort
Copyright @ CSIR 2005 www.csir.co.za
Rating of short-term R&D objectives (continued)
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Material response models– Agreement between different deflection methods
Material response models
0
2
4
6
8
10
1 2 3 4 5 More
Bin
Fre
qu
ency
Expected benefit
Agreement between deflection methods
Material response models
0
2
4
6
8
10
50% 100% 150% 300% 500% More
Bin
Fre
qu
ency
Benefit/Effort
Agreement between deflection methods
Copyright @ CSIR 2005 www.csir.co.za
Rating of short-term R&D objectives Summary
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Integration project and performance based information system– Average benefit ratings between 3,8 and 3,9– Average benefit/effort between 114 and 190 %
• Demand analysis– 3 out of 6 items had average benefit ratings between
3,5 and 3,9 the other items were between 2,8 and 3,2– Average benefit/effort between 96 and 159 %
• Material resilient response models– Average benefit ratings between 3,6 and 4,1– Average benefit/effort between 99 and 141 %
Copyright @ CSIR 2005 www.csir.co.za
Rating of short-term R&D objectives Summary
Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)
• Pavement resilient response models– Average benefit ratings between 2,4 and 3,4– Average benefit/effort between 70 and 98 %
• Damage models– Average benefit ratings between 3,6 and 4,4– Average benefit/effort between 112 and 146 %
• Probabilistic and recursive implementation schemes– Average benefit ratings between 3,5 and 3,9– Average benefit/effort between 132 and 152 %
Copyright @ CSIR 2005 www.csir.co.za
Recommendation to RPRAC
• Select projects based on– Ratings– Recent and ongoing research that may
fast-track certain projects– The achievement of the objective of the
R&D plan to developed an improved design method for flexible pavements
Recommended