A Study on Development of Live Load Model for Passenger Vehicles-only Bridges

A Study on Development of Live Load Model for Pass
enger Vehicles-only Bridges

Korean Expressway Corporation
Choi Hyeok-jin
(Structure Engineer, PE)

A Study on Development
of Live Load Model for
1. Background
Passenger Car-only
Bridges 2. Road Specifications
3. Governing Factors

CONTENT 4. Specification Development

S

1. Background

1.1 Benefits of Designated Highways

1.2 Benefits of Passenger vehicles-Only Roads

1. Background
Designated Road

Safety

Economical

Efficiency

Public dissatisfaction

Complex design issues

Korean Expressway Corporation / Design Evaluation Division

1. Background
Car Only Highways

 Less Road Accidents
 Faster Travel Times
 More comfortable for long distances

 Road Barriers
 Straight roads for higher speeds
 Overpass construction


1. Background

Passenger Car/ Truck Comparison

Passenger Car Heavy Trucks


1. Background

Benefits of Passenger Vehicle Only Roads

Passenger Vehicle

Small Size
 Smaller Lanes
 Lower Height Clearances
Agility  Lighter Loads
 Uniformity of Speed

Speed


1. Background

Korean Vehicles By Weight
1 Ton or Less
4500000 88.5%
4000000

3500000

3000000

2500000
Passenger
2000000
Cars
1500000 76.1%
1000000

500000

0


1. Background

Traffic Statistics

Vehicle Ratios Cost of Traffic Jams
교통혼잡 비용 (조원)
30

25
10%
Passenger Vehicles 20

(73%) 15

10

5
Passenger Vehicles 0

(90%)Heavy Trucks 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Heavy Trucks
Urban Areas Cost of Traffic Jams to the Korean
Economy = US$ 19,000,000,000
All Roads


1. Background

Problems of New Road Construction

 Acquiring Land (Currently in Use)

 Land Prices (Appropriation)

 Environmental Impact

 Public Inconvenience

Smaller roads avoid many of these problems


2 Road Specifications

2.2 Examples of Passenger
Car Only Roads

2.3 Road Specifications


International Examples(1)
France Malaysia China
(Under construction) (Under construction) (public service)

• Paris Ring Road • Smart Tunnel • Fuxing Donglu
Abstract;
• A86 Highway Tunnel

V=70km/h V=60km/h V=40km/h
Speed limit
2 lanes/2 levels 2 lanes/2 levels 2 lanes/2 levels
4 lanes 4 lanes 4 lanes
length
(10.0km) (3.0km) (2.8km)
Period of
1997~2010 1995~2007 2002~2004
construction


International Examples(2)
France Malaysia China
(Under construction) (Under construction) (public service)
횡류식 적용
환기
- 급기 환기소 : 4개소
방식
- 배기 환기소 : 4개소

cross
Section

Road width 8.7m 8.85m 7.0m

Lane width 2.8m 3.25m 3.0m

vertical
2.55m 2.55m 2.60m
Clearance
Construction
TBM TBM, NATM, SHIELD SHIELD
method


Korean Examples

900
200

200
8.500 8.500

map 500 2.000 2@3.000=6.000 500 250 250 500 2@3.000=6.000 2.000 500

3.000

3.000

5.200
3.200
1.000

1.000
1.000

1.000
150 150

1.100
800 Seobu 9.250
highway 950 950 9.250 800
project 11.000 VAR. 11.000
(Soengsan Bridge~Anyangchun Bridge)

• 표준 폭원 및 시설한계
Cross
2 lanes/2 levels shoulder
section Design Lane Vertical
speed width Clearance left right
70km/hr 3.0m 3.0m 0.5m 2.0m
length 11.9km

※민자사업으로 제안된 사업(사업 시행여부 미확정)


Allowable Car Specifications

division1 division2 division3 division4

Passenger
1,000cc less 1,500cc less 1,500~2,000cc less 2,000cc or over
Car

Bus 1,000cc less under 15 people under 35 people 36 people or over

Load capacity under 1 Load capacity under 5 Load capacity under 1

ton ton ton
Truck 1,000cc less
loaded weight under 3.5 loaded weight under 10 loaded weight 3.5 ton or

ton ton over

Special loaded weight under 3.5 loaded weight under 10 loaded weight under 10
1,000cc less
Vehicle ton ton ton or over


Allowable Special Vehicles

Pump Truck Snow Plow
7.08ton 10.2ton Roller
8.8ton

 These vehicles, still under
12 tons, can be on the road,
but only when all other cars
Small Tanker
10.73ton
Extension Arm are vacated from the lane.
6.9ton


Road Specifications For
Passenger Cars

 Design Vehicle Dimensions unit : m

Wheel Overhang Turning
width Height Length
base Front Rear radius
2.0 2.8 6.0 3.7 1.0 1.3 7.0

 speed limit : over100km/hr on highway
 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)



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



Goal of Live Load Model Development

 A constant safety rate across all span lengths

 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.


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


Principal Factor of Live Load

Passenger car Truck

 Type/Weight of Vehicle
 Compounding affects of vehicles in tandem


Procedure for Development
of a Design Live Load Model

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


4. Specification Development

4.1 driving patterns
4.2 Maximum load effect
4.3 Live load model
4.4 economical benefits



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

• WIM ; Weigh-In-Motion Loop Sensor Piezo Sensor
- Loop Sensor : measures axle
lengths
- Piezo Sensor : measures vehicle
speed, weight , and number of axles.

※ WIM system allows a more Data
Locker
accurate weight for smaller
vehicles.


Survey of Driving Patterns

Driving Pattern Survey • Location : Pangyo IC~Singal JCT, Topyeong IC~Namyangju IC
(mixture rate/tandem rate) • Vehicles : Passenger car/ 1 ton truck (total 43,973 vehicles)

※We must discover the passenger car/truck mixture when travelling
in tandem.



Estimating Maximum Load Effects (1)

Maximum Load Effects by Largest single vehicle

• using top 10%, 20% values Trend Line Sample
from weight survey data Chart

• 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



Maximum Load Effects by Vehicles in tandem

 Groups of vehicles running in tandem
- different types running in tandem
– same types of vehicles running in tandem
 Using a Marcov Chain
P T
P 0.84120
18,185 0.06018
1,301

T 0.06018
1,301 0.00893
193




 Calculating load effects at variable span lengths (positive
moment, shear, and negative moment)

Largest single vehicle Vehicles in tandem

Vehicles in tandem



Bias Factor

Bias factor of positive moment

Constant
safety rate

In order to ensure a constant safety rate over variable span lengths we use
a Bias factor calculation(M75/MDESIGN)



Design Live Load

•uniformly distributed load + concentrated load.

※ span length 10m : 12ton vehicle allowable
※ span length 30m : 15ton vehicle allowable



Comparison of Costs with Regular Road
Sample bridge : PnP
DB-24, DL-24 CL-3.5
bridge

Less road width
# of girders 5 ⇒ 4

Cost savings of 18%

Lighter Load
2.7m

height: 14.8% less
2.3m

concrete: 18.5% less
rebar : 9.6% less

Cost savings of 7%

 Superstructure is 20 – 27% cheaper.

Summary 1

 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.


A Study on Development of Live Load Model for Passenger Vehicles-only Bridges

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A Study on Development of Live Load Model for Passenger Vehicles-only Bridges