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Load Rating1 LOAD RATING BY MANUAL CALCULATIONS RC_ SLAB BRIDGE RATING Amjad Waheed, PE Ohio Department of Transportation.

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Presentation on theme: "Load Rating1 LOAD RATING BY MANUAL CALCULATIONS RC_ SLAB BRIDGE RATING Amjad Waheed, PE Ohio Department of Transportation."— Presentation transcript:

1 Load Rating1 LOAD RATING BY MANUAL CALCULATIONS RC_ SLAB BRIDGE RATING Amjad Waheed, PE Ohio Department of Transportation

2 Load Rating Seminar 2 Agenda – Day 1 8:00 am – 8:15 amIntroductions and House Keeping 8:15 am – 8:45 amSession 1: Load Rating Basics 8:45 am – 9:30 amSession 2: Basic Load Rating Calculations 9:30 am – 9:45 amBreak 9:45 am – 11:45 amSession 3: Example – Load Rating Concrete Slab Bridge 11:45 am – 12:00 pmQuestions 12:00 pm – 1:00 pmLunch 1:00 pm – 2:30 pmSession 4: Example – Load Rating Steel Beam Bridges 2:30 pm – 2:45 pmBreak 2:45 pm – 3:45 pmSession 4: Example – Load Rating Steel Beam Bridges (Cont) 3:45 pm – 4:00 pmQuestions

3 Load Rating3 What is Load Rating? The safe live load carrying capacity of a highway structure is called its load rating. RF = C – A 1 * D A 2 * (L + I) A 1 = Factor for dead loads A 2 = 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)

4 Load Rating4 Factors for LFR Load Rating Rating Type A 1 = Factor for dead loads A 2 = Factor for live load Inventory * Design level Operating1.3 Ref: AASHTO Manual for Condition Evaluation of Bridges 1994

5 Rating Factor Equation Load Rating Seminar5 R.F. = C – A 1 * D A 2 * (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) A 1 = 1.3 A 2 = = 1.3 * 1.67

6 Rating Factor Equation Load Rating Seminar6 R.F. = C – A 1 * D A 2 * (L + I) Operating Rating R.F. = C – 1.3 * D 1.3 * (L + I) R.F. = C/1.3 – D (L + I) A 1 = 1.3 A 2 = 1.3

7 Load Rating7 Single-span slab bridge

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21 Load Rating21 AASHTO Standard Specification for Highway Bridges CASE B – Main Reinforcement Parallel to Traffic For wheel loads, the distribution width E = *S 7 S = Effective Span length in feet E = *13 = 4.78S = 13 Live Load Distribution Factor

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23 Load Rating23 AASHTO Standard Specification for Highway Bridges 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 / ( ) = 0.362Use I = 0.3 Impact Load (Impact Factor)

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31 Summary of Rating Results Load Rating Seminar31 Load Weight (GVW) Tons M L+I ft. k/ft R.F. = (28.09/ M L+I ) Safe Load Tons % Ohio Legal HS F % 3F % 4F % 5C % POSTING NOT REQUIRED

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37 Material Strengths Load Rating Seminar37 BMD - Figure 904

38 Material Strengths Load Rating Seminar38 BMD - Figure 905

39 Load Rating39 Learning Curve

40 Load Rating40 ODOT Rating Contact Information Amjad Waheed, PE Shelton A. Howard, PE Richard C. Irwin, PE Cindy Wang, PE

41 Load Rating41 Thats all folks


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