A Study on Development of Live Load Model for Pass
enger Vehicles-only Bridges
Korean Expressway Corporation
Choi Hyeok-jin
(Structure Engineer, PE)
CONTENT
S
1. Background
2. Road Specifications
3. Governing Factors
4. Specification Development
A Study on Development
of Live Load Model for
Passenger Car-only
Bridges
1.1 Benefits of Designated Highways
1.2 Benefits of Passenger vehicles-Only Roads
1. Background
Korean Expressway Corporation / Design Evaluation Division
Designated Road
Safety
Economical
Efficiency
Public dissatisfaction
Complex design issues
1. Background
Korean Expressway Corporation / Design Evaluation Division
Car Only Highways
Road Barriers
Straight roads for higher speeds
Overpass construction
Less Road Accidents
Faster Travel Times
More comfortable for long distances
1. Background
Korean Expressway Corporation / Design Evaluation Division
1. Background
Passenger Car/ Truck Comparison
Passenger Car Heavy Trucks
Korean Expressway Corporation / Design Evaluation Division
Passenger Vehicle
Small Size
Agility
Speed
Smaller Lanes
Lower Height Clearances
Lighter Loads
Uniformity of Speed
Benefits of Passenger Vehicle Only Roads
1. Background
Korean Expressway Corporation / Design Evaluation Division
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
1 Ton or Less
88.5%
Korean Vehicles By Weight
Passenger
Cars
76.1%
1. Background
Korean Expressway Corporation / Design Evaluation Division
Traffic Statistics
Vehicle Ratios
Urban Areas
All Roads
Heavy Trucks
Passenger Vehicles
(73%)
Heavy Trucks
Passenger Vehicles
(90%)
교통혼잡 비용 (조원)
0
5
1 0
1 5
2 0
2 5
3 0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
10%
Cost of Traffic Jams
Cost of Traffic Jams to the Korean
Economy = US$ 19,000,000,000
1. Background
Korean Expressway Corporation / Design Evaluation Division
Acquiring Land (Currently in Use)
Land Prices (Appropriation)
Environmental Impact
Public Inconvenience
Problems of New Road Construction
1. Background
Smaller roads avoid many of these problems
Korean Expressway Corporation / Design Evaluation Division
2.2 Examples of Passenger
Car Only Roads
2.3 Road Specifications
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
International Examples(1)
Abstract;• Paris Ring Road
• A86 Highway
• Smart Tunnel • Fuxing Donglu
Tunnel
Speed limitV=70km/h
2 lanes/2 levels
V=60km/h
2 lanes/2 levels
V=40km/h
2 lanes/2 levels
length4 lanes
(10.0km)
4 lanes
(3.0km)
4 lanes
(2.8km)
Period of
construction1997~2010 1995~2007 2002~2004
France
(Under construction)
China
(public service)
Malaysia
(Under construction)
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
International Examples(2)
cross
Section
Road width 8.7m 8.85m 7.0m
Lane width 2.8m 3.25m 3.0m
vertical
Clearance2.55m 2.55m 2.60m
Construction
methodTBM TBM, NATM, SHIELD SHIELD
France
(Under construction)
China
(public service)
Malaysia
(Under construction)횡단면도 횡류식 적용
- 급기 환기소 : 4개소
- 배기 환기소 : 4개소
환기
방식
횡단면도 횡류식 적용
- 급기 환기소 : 4개소
- 배기 환기소 : 4개소
환기
방식
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
Korean Examples
Design
speed
Lane
width
Vertical
Clearance
shoulder
left right
70km/hr 3.0m 3.0m 0.5m 2.0m
• 표준 폭원 및 시설한계
map
projectSeobu highway
(Soengsan Bridge~Anyangchun Bridge)
Cross
section2 lanes/2 levels
length 11.9km
800950 9.250
11.000
1.0
00
[email protected]=6.000 2.000500
3.0
00
20
0
8.500
250
150
500
90
01
.10
03
.20
0
5.2
00
1.0
00
800 9509.250
11.000
1.0
00
[email protected]=6.0002.000 500
3.0
00
20
0
8.500
250
150
500
1.0
00
VAR.
※민자사업으로 제안된 사업(사업 시행여부 미확정)
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
Allowable Car Specifications
Passenger
Car1,000cc less 1,500cc less 1,500~2,000cc less 2,000cc or over
Bus 1,000cc less under 15 people under 35 people 36 people or over
Truck 1,000cc less
Load capacity under 1
ton
loaded weight under 3.5
ton
Load capacity under 5
ton
loaded weight under 10
ton
Load capacity under 1
ton
loaded weight 3.5 ton or
over
Special
Vehicle1,000cc less
loaded weight under 3.5ton
loaded weight under 10ton
loaded weight under 10ton or over
division1 division2 division3 division4
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
Allowable Special Vehicles
Pump Truck
7.08ton
Small Tanker
10.73ton
Snow Plow
10.2tonRoller
8.8ton
Extension Arm
6.9ton
These vehicles, still under
12 tons, can be on the road,
but only when all other cars
are vacated from the lane.
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
Road Specifications For
Passenger Cars
Design Vehicle Dimensions
speed limit : over100km/hr on highway
width Height LengthWheel base
Overhang Turning radiusFront Rear
2.0 2.8 6.0 3.7 1.0 1.3 7.0
unit : m
maximum slope: 1~2% more than common roadways
Design Speed Flat area Mount area
100km/hr 4% 6%
80km/hr 6% 7%
60km/hr 7% 9%
Verical Clearance: 3m [car height(2.8m)+extra(0.2m)
2 Road Specifications
Korean Expressway Corporation / Design Evaluation Division
3.1 Goal of Live Load Model Development
3.2 Principal Factors of Live Load
3.3 Procedure for Development of a Design Live
Load Model
3. Governing Factors
Korean Expressway Corporation / Design Evaluation Division
A constant safety rate across all span lengths
Goal of Live Load Model Development
3. Governing Factors
Development of economically feasible safe load that
befits bridge life cycle.
Load patterns that are easy to use in design
process, and are familiar to designers.
Korean Expressway Corporation / Design Evaluation Division
Principal Factors of Live Load
Distance between vehicles (= 1.2m)
Load distribution of axle load
Vehicle type [passenger car, truck]
Vehicle weight [vehicle + load weight]
Compounding affect of vehicles in tandem
3. Governing Factors
Korean Expressway Corporation / Design Evaluation Division
Passenger car Truck
Principal Factor of Live Load
Type/Weight of Vehicle
Compounding affects of vehicles in tandem
3. Governing Factors
Korean Expressway Corporation / Design Evaluation Division
Survey of vehicle loads and driving patterns
Determine the trend line by Probability Chart
Estimate maximum load effects by span length
Determine design live load
Procedure for Development
of a Design Live Load Model
3. Governing Factors
Korean Expressway Corporation / Design Evaluation Division
4.1 driving patterns
4.2 Maximum load effect
4.3 Live load model
4.4 economical benefits
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
• WIM ; Weigh-In-Motion
- Loop Sensor : measures axle
lengths
- Piezo Sensor : measures vehicle
speed, weight , and number of axles.
Loop Sensor Piezo Sensor
Data
Locker
WIM System
Survey of Vehicle Loads
• Location : Central Inland Highway(South bound ,Yeoju JCT ~ Janghowon IC)
• Vehicles : Passenger car/ 1 ton truck (total 60,494 vehicles)
※ WIM system allows a more
accurate weight for smaller
vehicles.
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
Driving Pattern Survey
(mixture rate/tandem rate)• Location : Pangyo IC~Singal JCT, Topyeong IC~Namyangju IC
• Vehicles : Passenger car/ 1 ton truck (total 43,973 vehicles)
Survey of Driving Patterns
※We must discover the passenger car/truck mixture when travelling
in tandem.
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
• using top 10%, 20% values
from weight survey data
• using the Gumbel Probability
Chart
- an equation can convert
probability distribution to a one-
dimensional linear formula
• Trend Line(y=a+bx)
y=Gumbel probability
x=weight
Trend Line Sample
Chart
Estimating Maximum Load Effects (1)
4. Specification Development
Maximum Load Effects by Largest single vehicle
Korean Expressway Corporation / Design Evaluation Division
Groups of vehicles running in tandem
- different types running in tandem
– same types of vehicles running in tandem
P
P
T
T
18,185 1,301
1,301 193
0.84120 0.06018
0.06018 0.00893
Using a Marcov Chain
Estimating Maximum Load Effects (2)
4. Specification Development
Maximum Load Effects by Vehicles in tandem
Korean Expressway Corporation / Design Evaluation Division
Largest single vehicle
Calculating load effects at variable span lengths (positive moment, shear, and negative moment)
Estimating Maximum Load Effects (2)
Vehicles in tandem
Vehicles in tandem
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
Bias factor of positive moment
In order to ensure a constant safety rate over variable span lengths we use
a Bias factor calculation(M75/MDESIGN)
Constant
safety rate
Bias Factor
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
•uniformly distributed load + concentrated load.
※ span length 10m : 12ton vehicle allowable
※ span length 30m : 15ton vehicle allowable
Design Live Load
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
Comparison of Costs with Regular Road
Superstructure is 20 – 27% cheaper.
DB-24, DL-24 CL-3.5
2.3
m2.7
m
Sample bridge : PnP
bridge
Less road width
# of girders 5 ⇒ 4
Cost savings of 18%
Lighter Load
height: 14.8% less
concrete: 18.5% less
rebar : 9.6% less
Cost savings of 7%
4. Specification Development
Korean Expressway Corporation / Design Evaluation Division
Benefits of Passenger Car Only Roads are that they are
cheaper, smaller, and safer than regular roads.
Passenger Car Only roads are needed because of urban
area overdevelopment and high land costs in cities.
Estimating maximum load effects for both categories,
greatest load and groups of vehicles running in tandem, using
span lengths from 10 meters to 100 meters.
Summary 1