Embed Size (px)
Citation preview
Load Rating 1
LOAD RATING BY MANUAL LOAD RATING BY MANUAL CALCULATIONSCALCULATIONS
RC_ SLAB BRIDGE RATING
Amjad Waheed, PE
Ohio Department of Transportation
Load Rating Seminar 2
Agenda – Day 1Agenda – Day 18:00 am – 8:15 am Introductions and House Keeping8:15 am – 8:45 am Session 1: Load Rating Basics8:45 am – 9:30 am Session 2: Basic Load Rating
Calculations9:30 am – 9:45 am Break9:45 am – 11:45 am Session 3: Example – Load Rating
Concrete Slab Bridge 11:45 am – 12:00 pm Questions12:00 pm – 1:00 pm Lunch1:00 pm – 2:30 pm Session 4: Example – Load Rating Steel
Beam Bridges2:30 pm – 2:45 pm Break2:45 pm – 3:45 pm Session 4: Example – Load Rating Steel
Beam Bridges (Con’t)3:45 pm – 4:00 pm Questions
Load Rating 3
What is Load Rating?What is Load Rating?The safe live load carrying capacity of a highway structure is called its load rating.
RF = C – A1 * D
A2 * (L + I)
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)
RF = Capacity for (L+I)
Actual (L + I)
Load Rating 4
Factors for LFR Load RatingFactors for LFR Load Rating
Rating TypeRating Type AA11 = Factor for = Factor for
dead loadsdead loadsAA22 = Factor for = Factor for
live loadlive load
InventoryInventory
* Design level* Design level
1.3 2.17
OperatingOperating 1.3 1.3
Ref: AASHTO Manual for Condition Evaluation of Bridges 1994
Rating Factor EquationRating Factor Equation
Load Rating Seminar 5
R.F. = C – A1 * D
A2 * (L + I)
Inventory Rating
R.F. = C – 1.3 * D
1.3 * 1.67 * (L + I)
R.F. = C/1.3 – D
1.67 * (L + I)
A1 = 1.3A2 = 2.167 = 1.3 * 1.67
Rating Factor EquationRating Factor Equation
Load Rating Seminar 6
R.F. = C – A1 * D
A2 * (L + I)
Operating Rating
R.F. = C – 1.3 * D
1.3 * (L + I)
R.F. = C/1.3 – D
(L + I)
A1 = 1.3A2 = 1.3
Load Rating 7
Single-span slab bridgeSingle-span slab bridge
Load Rating 8
Load Rating 9
Load Rating 10
Load Rating Seminar 11
Load Rating Seminar 12
Load Rating Seminar 13
Load Rating Seminar 14
Load Rating Seminar 15
Load Rating Seminar 16
Load Rating Seminar 17
Load Rating Seminar 18
Load Rating Seminar 19
Load Rating Seminar 20
Load Rating 21
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 + 0.06*S 7’
S = Effective Span length in feet
3.24.1
E = 4 + 0.06*13 = 4.78’ S = 13’
Live Load Distribution Factor
Load Rating Seminar 22
Load Rating 23
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
Impact Load (Impact Factor)
Load Rating Seminar 24
Load Rating Seminar 25
Load Rating 26
Load Rating Seminar 27
Load Rating Seminar 28
Load Rating Seminar 29
Load Rating Seminar 30
Summary of Rating ResultsSummary of Rating Results
Load Rating Seminar 31
Load Weight (GVW) Tons
M L+I
ft. k/ft
R.F. = (28.09/
M L+I)
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%
Load Rating 32
Load Rating 33
Load Rating Seminar 34
Load Rating Seminar 35
Load Rating Seminar 36
Material StrengthsMaterial Strengths
Load Rating Seminar 37
BMD - Figure 904
Material StrengthsMaterial Strengths
Load Rating Seminar 38
BMD - Figure 905
Load Rating 39
Learning CurveLearning Curve
Load Rating 40
ODOT Rating Contact InformationODOT Rating Contact Information
Amjad Waheed, PE614.752.9972 ([email protected])
Shelton A. Howard, PE614.752.9975 ([email protected])
Richard C. Irwin, PE614.752.9977 ([email protected])
Cindy Wang, PE614.466.1973 ([email protected])
Load Rating 41
That’s all folks
