LOAD RATING BY MANUAL CALCULATIONS

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LOAD RATING BY MANUAL CALCULATIONS
RC_ SLAB BRIDGE RATING Amjad Waheed, PE Ohio
Department of Transportation
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Agenda Day 1
800 am 815 am Introductions and House
Keeping 815 am 845 am Session 1 Load Rating
Basics 845 am 930 am Session 2 Basic Load
Rating Calculations 930 am 945 am Break 945
am 1145 am Session 3 Example Load Rating
Concrete Slab Bridge 1145 am 1200
pm Questions 1200 pm 100 pm Lunch 100 pm
230 pm Session 4 Example Load Rating Steel
Beam Bridges 230 pm 245 pm Break 245 pm
345 pm Session 4 Example Load Rating Steel
Beam Bridges (Cont) 345 pm 400 pm Questions
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What is Load Rating?
The safe live load carrying capacity of a highway
structure is called its load rating.
A1 Factor for dead loads A2 Factor for live
load C Capacity of the bridge D Dead loads I
Impact loads L Live loads
How to calculate the rating factor (RF)
Capacity for (LI)
RF
Actual (L I)
C A1 D
RF
A2 (L I)
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Factors for LFR Load Rating
Rating Type A1 Factor for dead loads A2 Factor for live load
Inventory Design level 1.3 2.17
Operating 1.3 1.3
Ref AASHTO Manual for Condition Evaluation of
Bridges 1994
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Rating Factor Equation
Inventory Rating
C A1 D
R.F.
A1 1.3 A2 2.167 1.3 1.67
A2 (L I)
C 1.3 D
R.F.
1.3 1.67 (L I)
C/1.3 D
R.F.
1.67 (L I)
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Rating Factor Equation
Operating Rating
C A1 D
R.F.
A1 1.3 A2 1.3
A2 (L I)
C 1.3 D
R.F.
1.3 (L I)
C/1.3 D
R.F.
(L I)
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Single-span slab bridge
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Live Load Distribution Factor
AASHTO Standard Specification for Highway
Bridges 3.24.3.2 CASE B Main Reinforcement
Parallel to Traffic
For wheel loads, the distribution width E 4 0.06S ? 7 S Effective Span length in feet 3.24.1
E 4 0.0613 4.78 S 13
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Impact Load (Impact Factor)
AASHTO Standard Specification for Highway
Bridges 3.8.2 Impact Formula
The amount of impact allowance, I, as a fraction of the live load I 50 / (L 125) ? 0.3 L Effective Span length in feet
I 50 / (13 125) 0.362 Use I 0.3
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Summary of Rating Results
Load Weight (GVW) Tons M LI ft. k/ft R.F. (28.09/ M LI) Safe Load Tons Ohio Legal
HS 20 36 14.1 1.992 71.20 -----
2F1 15 8.8 3.192 47.90 319
3F1 23 10.4 2.700 62.10 270
4F1 27 10.9 2.577 69.60 258
5C1 40 10.4 2.700 108.00 270
POSTING NOT REQUIRED
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Material Strengths
BMD - Figure 904
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Material Strengths
BMD - Figure 905
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Learning Curve
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ODOT Rating Contact Information

• Amjad Waheed, PE614.752.9972 (awaheed_at_dot.state.o
  h.us)
• Shelton A. Howard, PE614.752.9975
  (showard_at_dot.state.oh.us)
• Richard C. Irwin, PE614.752.9977
  (richard.irwin_at_dot.state.oh.us)
• Cindy Wang, PE614.466.1973 (cindy.wang_at_dot.state.
  oh.us)

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Thats all folks