1. Agenda 1. Overview of AASHTO LRFD 2. Culvert Design by LRFD
3. ETCulvert Overview
4. Interface Walk-thru
5. Common Design Questions
6. Advanced Topics
7. Questions

2. Starting a new problem Built-in problems
Start with either rebar or mesh
Use a built-in problem as a starting point, note that this is just a starting point, remember that anything can be changed, you can start with a 3-sided precast with rebar and end up with a 3-cell CIP with mesh. I start with the single cell with either mesh or rebar and go from there, as most of the input is quick, with 2 exceptions (concrete covers and agencies not listed in our agency list). You also see a scaled cross section of the culvert in the problem you have selected.

3. Starting a new problem Initialize using a seed file
Create a library of problem types
Seed files can be used to set defaults for various input items. The original seed file will not be effected during this process.

4. Open an Existing Problem
Standard Windows open file dialog
Double click on ETCulvert data files
A file folder will be created in your computers document library during the installation process, which becomes the default location for the open file dialog. Also, standard vehicle libraries will be installed by program during installation routine

5. Select Code and Agency
Code selection will change some of the options available in the input windows
Agency selection sets some input automatically
Here is one place where seed files may come in handy, if your particular governing agency is not listed. However, we are always adding new agencies, so contact us and lets talk.

6. Select Program Operation
Typically start with Design Mode for new files
For new files we recommend that you start in Design Mode.

7. Mode and Selected Code are shown in the Status Bar
Note that the current program operating mode and governing specification are always show in the status bar at the lower right hand corner of the screen.

8. Input Dimensions of the Culvert
Number of Cells (up to 4)
Clear span, clear height, lay length
All cells must be the same span and height.

9. Identify Fill Depths to Check
Check one fill depth or a range of fill depths
If range includes 1.99’, this value will be inserted
Be aware of the change in live load distribution logic at 2 foot. Also changes a range of other decisions as well (shear, distribution steel, etc)

10. Range of Fill Depths Text report shows controlling fill depth
Different reinforcement locations may be controlled by different fill depths
Controlling fill depth is show for the slab thicknesses and the reinforcement table in Design Mode.

11. Wall and Slab Dimensions
Some agencies may have minimum thicknesses for walls and slabs
Program will select minimum thickness if no agency selected
If no agency is selected, program will still select minimum values for the member thicknesses based on an internal algorithm that takes into account the clear span and clear height.

12. Material Properties
Most of the time you will probably only change the concrete strength
Good place for seed files, as the next item that changes the most are covers
Another place where seed files may come in handy is in the area of rebar covers, which in our experience seems to vary greatly across the country.

13. Bar Diameter
Used in Design Mode for calculating d when reinforcement is not yet sized
Should reduce if using mesh

14. Assign Loads Live Load – select/define the truck here
Can share truck files with others
Ask us for specific trucks, we may already have the truck you want defined, although defining new trucks is fairly simple, as we will see in the next slide.

15. Defining Trucks Variable axle spacing and magnitude
Also define lane and tandem loads

16. Defining Trucks Variable axle spacing and magnitude
Also define lane and tandem loads

17. Defining Trucks
Don’t forget to specify the combination of truck loads and lane loads
Truck + Lane or Tandem + lane is for LRFD, Truck or Tandem or Lane is for either STND or AREMA.

18. Retrieving and Saving Trucks
Retrieve a previously saved truck file
Or Save the current one
Done

19. Assign Loads Lane Load can be turned off here
When switching codes, trucks are NOT switched as well
You can switch the lane load on and off here, you could do that by assigned a zero lane load back on the vehicle properties input window, but it is just easier to do it here. Remember that when you switch specifications, the truck will NOT be switched, you have to do that manually.

20. Dead Loads Can apply either distributed or concentrated dead loads
Loads are applied to a 1’ strip

21. Lateral Soil Loads Program uses equivalent fluid pressure method
Soil weight is used for vertical loads
The program uses the equivalent fluid pressure method for lateral soil loads in both LRFD and STND.

22. Lateral Soil Loads (AREMA)
Here the weight of the soil is used for both vertical and horizontal loads
However, for AREMA, the program uses a percentage of the soil weight.

23. Load and Resistance Factors
Probably will not change these factors very often

24. Analysis Options
Member thicknesses can be either variable or fixed in Design Mode
Not available during Analysis Mode
You cannot change to fixed if the minimum member thickness was set to zero back on the physical properties screen. If the minimum was set > 0, you can fix that thickness so that it will not change during the design phase. Most of the time we try to avoid disabling controls on one window based on the input from another window. Most of the time that we do this in ETCulvert it is based on the specification that you have selected. This is one time where it is not related to the specification, but rather to the operating mode, as this option of fixing the member thickness is not available in Analysis Mode, only Design Mode.

25. Analysis Mode
After initial run in Design Mode, switch Analysis Mode to ‘tweak’ culvert design
Recommend that you always start with Design Mode, tell story of Ron in NY

26. Switching Reinforcement Types
Must be done in Design Mode
If you want to change the Reinforcement type, remember to change it before you switch to Analysis Mode. The reason we did this is because we need to fill an internal reinforcement table in Design Mode before you can change it in Analysis Mode. This is the other time I mentioned that the controls will be disabled not as a results of the selected specification.

27. Permit Loads
Remember to change to Strength II load factors on Analysis Options page
Remember to switch to Strength II load factors if you are analyzing or designing for permit loads.

28. Permit Loads
Also remember that only the operating rating is applicable
Also remember that you only need to check the operating ratings when using Strength II (which is why we put Str II) in the column heading.

29. Shear Reinforcement
Can add shear reinforcement in either Design or Analysis Mode
Will only calculate Vs in Analysis Mode
Algorithm to determine member thickness was not workable if include Vs in design mode, as the member thickness is controlled by the shear.

30. Recent Changes to ETCulvert
Added support for AREMA
Mesh can be any size (to one decimal point)
Changes to Text Report as requested by ACPA
Added support for pipe flexure equation
New Version Available (V2.50)

31. Output Options
Main View
Text Report
Graphs
3D Viewer
Results Grid

32. Text Report Input Data Reinforcement Schedule Unfactored Moments
Serviceability Check
Critical Section Tables (includes ratings)
Factored Results

33. Questions?

34. Agenda 1. Overview of AASHTO LRFD 2. Culvert Design by LRFD
3. ETCulvert Overview
4. Interface Walk-thru
5. Common Design Questions
6. Advanced Topics
7. Questions

35. Common Design Questions
Skewed Culverts
How are # of Lanes Determined
Pinned/Roller Supports
Single Layer of Reinforcement

36. Skewed Culverts: Case 1 Only the Exterior Culvert is Skewed
Skew angle is < 15 degrees
Skew angle is > 15 degrees

37. Skewed Culverts: Case 1 Only the Exterior Culvert is Skewed
Skew angle is < 15 degrees
Skew angle is > 15 degrees

38. Skewed Culverts: Case 1a
Straight culverts, skewed roadway
Skew angle is < 15 degrees
Skew angle is > 15 degrees

39. Skewed Culverts: Case 1a
Straight culverts, skewed roadway
Skew angle is < 15 degrees
Skew angle is > 15 degrees

40. Skewed Culverts: Case 2 All Culverts are Skewed
Magnitude of Skew is not Important
Use the Skew dimension as the Clear Span

41. Common Design Questions
Skewed Culverts
How are # of Lanes Determined
Pinned/Roller Supports
Single Layer of Reinforcement

42. How are # of Lanes Determined?
Traffic is Parallel to Main Reinforcement
Less than 2 foot of fill depth
Greater than 2 foot of fill depth
5 cases, with a maximum of 4 lanes
2 lane case is checked twice

43. How are # of Lanes Determined?
Traffic is Parallel to Main Reinforcement
Less than 2 foot of fill depth
Greater than 2 foot of fill depth
5 cases, with a maximum of 4 lanes
2 lane case is checked twice

44. How are # of Lanes Determined?
Traffic is Perpendicular
Code gives no guidance here
10 foot lanes are used, rounded up
May be overly conservative
Can limit maximum number of lanes

45. Number of Lanes Primarily used for perpendicular traffic
May be overly conservative in number of lanes selected
This is especially important when you are placing the truck perpendicular to the main reinforcement, as we assume 10 foot wide lanes (it makes the lane positioning algorithm way too complicated to try to place a 10 foot truck inside a 12 foot lane at varying positions). So the program might be overly conservative in the case of long clear spans and perpendicular traffic direction. Also be aware that in some cased the number of lanes will be set by the program (typically at 1) and cannot be overridden. This can happen in AREMA, and LRFD when you have less than 2 foot of fill.

46. Common Design Questions
Skewed Culverts
How are # of Lanes Determined
Pinned/Roller Supports
Single Layer of Reinforcement

47. Pinned/Roller Supports
3-Sided Culverts
Default Support Conditions

48. Pinned/Roller Supports
3-Sided Culverts
Alternate Support Conditions If Span/Depth Ratio > 4

49. Common Design Questions
Skewed Culverts
How are # of Lanes Determined
Pinned/Roller Supports
Single Layer of Reinforcement

50. Single Layer of Reinforcement
Cover Dimensions
Main Reinforcement
Temperature and Shrinkage Steel for Walls
Distribution Steel + T & S Steel for Top and Bottom Slabs
Check that Main Reinforcement satisfies T & S steel

51. Cover Dimensions Set Cover Dimensions such that Layers line up
Coordinate with Bar Diameter

52. Main Reinforcement A1, A2, A100, A200 and B2 Bars only
Program assumes singly reinforced
Main reinforcement is in the direction of the clear span.

53. Temperature and Shrinkage Steel for Walls
Can use the C1 bars in bar schedule
May be better to use calculated required

54. Distribution Steel + C1 Bars for Top and Bottom Slabs
Need greater of Distribution Steel (C100 and C200) + C1 Bars or 2 * C1 Bars
May be better to check required column

55. Final Check
Check that Main Reinforcement satisfies Temperature and Shrinkage requirements
Main reinforcement is parallel to the clear span.

56. Questions?

57. Agenda 1. Overview of AASHTO LRFD 2. Culvert Design by LRFD
3. ETCulvert Overview
4. Interface Walk-thru
5. Common Design Questions
6. Advanced Topics
7. Questions

58. Advanced Topics Loads Load and Resistance Factors Analysis Options
Longitudinal Steel

59. Loads – Traffic Direction
Traffic can be applied either parallel or perpendicular to main reinforcement
Most of the time it will be parallel
May want to consider using lanes perpendicular to the main reinforcement when the culvert is skewed, as LRFD states that you should take the skew into account, but does not tell you how.

60. Loads – Number of Lanes Important for perpendicular traffic
Program looks for worst case, but in some situations cannot be overridden
This is especially important when you are placing the truck perpendicular to the main reinforcement, as we assume 10 foot wide lanes (it makes the lane positioning algorithm way too complicated to try to place a 10 foot truck inside a 12 foot lane at varying positions). So the program might be overly conservative in the case of long clear spans and perpendicular traffic direction. Also be aware that in some cased the number of lanes will be set by the program (typically at 1) and cannot be overridden. This can happen in AREMA, and LRFD when you have less than 2 foot of fill.

61. Loads – Track Width (AREMA)
Accessible due to uncertainty
Truck gage width is not used for AREMA calculations
We added access to the track width (basically the tie length) for AREMA, due to the uncertainty of this value (sometimes AREMA states that this value should be taken as 8 foot, and sometimes at 8.5 foot.

62. Load and Resistance Factors
Factors for LRFD P-M Diagram
Phi for moment is not used unless axial load is ignored
Back on the load and resistance factors screen you have two phi factors related to the internal P-M diagram. The phi for moment is not used unless the axial load is ignored on the Analysis Options page (which we will cover on the next slide).

63. Ignore Axial Thrust P-M diagram will not be used
Program assumes pure flexure

64. Use Pipe Equation Use pipe equation from LRFD Mimics BOXCAR (1 of 3)
Multiplier available for Nu
Right below the option to ignore axial thrust, is the option to use the pipe equation to calculate the flexural resistance. This is also one of several options that mimics what was done in BOXCAR.

65. Skew Effects
Skew effects must be accounted for, but LRFD does not say how
When skew is greater than 15 degrees, will set traffic to perpendicular
This is based on a study conducted by NYSDOT. They determined that the skew can be properly accounted if you set traffic direction to perpendicular when the skew is greater than 15 degrees.

66. Combine Axles that Overlap
LRFD language demands that axles be combined when they overlap
We believe that this may be un-conservative for short spans
Probably does not matter for long spans, may be un-conservative for short spans, one of you are welcome to prove us either right or wrong.

67. Combine Axles that Overlap
Live Load distribution when not selected

68. Combine Axles that Overlap
Live Load distribution when selected

69. Always Distribute Wheel Loads
When fill depth is < 2’, will still treat wheel loads as distributed, not point
Mimics BOXCAR (2 of 3)
LRFD allows wheel loads to be distributed when the fill depth is less than 2 foot, this option accomplishes that. The 2nd of three options that mimics the behavior of BOXCAR.

70. Haunches in Structural Model
Re-distributes slab moment from positive region to negative region
Mimics BOXCAR (3 of 3)
3rd of three options that mimics BOXCAR.

71. Bottom Node on Roller (3-sided)
Suggested when span to depth ratio is greater than 4
Has effect of converting top slab to simple span
When the span to depth ratio approached 4:1, it was notices that the deflection at the mid-span of the top slab was greater than what was predicted in 3-sided culverts. Therefore, when you exceed this limit, think about modeling with a roller on the left node. This has the effect of setting the moments in the walls to zero, and converting the top slab to a simple span, instead of a frame.

72. Consider Haunches in Location of Critical Section
Used to locate the critical sections for flexure and shear
3 possible locations for flexure
2 possible locations for shear
Three possible options for locating the critical section for shear and flexure.

73. Illustration of dv vs d

74. Haunches not considered:
If you select to NOT consider haunches in the location of the critical section, probably the most conservative option.

75. Haunches considered:
If you select to consider the haunches in the location of the critical section, default option, does not change the location of the critical section for shear, only that for moment.

76. Extended beyond haunches:
Can also select to extend the location of the critical section for both flexure and shear, probably the least conservative option.

77. Use Maximum Moment with Maximum Shear
For use with those equations for Vc that use an interaction between V and M
Forces the program to use the moment at the flexural critical section
Forces the program to use the moment at the critical section for moment for the interaction equation used in the calculation of Vc, if unchecked will use the corresponding moment at the critical section for shear.

78. Always Check Iterative Beta
Forces program to always check general case (Appendix) for shear resistance
Will use largest value of Vc found
If unchecked will only use calculate one Vc value (using an internal decision table that is based on several factors). If checked will calculate 2 values for Vc and use the higher value. Note that sometimes when checked will still just calculate one value for Vc, if the internal decision table leads to the selection of the iterative beta method for Vc.

79. Upper Limit on As For use with Design Mode
Iterative beta method can produce very large member thicknesses
may need more slides to discuss this option better (need to study the effects so you can explain it correctly)
Was found in the Design Mode algorithm that we got crazy member thicknesses at times, so by limiting this option you can circumvent that and break out of the design mode algorithm looping.

80. Always Include Distribution
Both Design and Analysis Modes
Fill depths greater than 2’

81. Longitudinal Steel For non-distribution longitudinal steel
Follow specification recommendations
Only use % of cross section area
Only use temperature/shrinkage
Need to check this language, may be the larger of the two for ‘follow specifications’

82. Future Plans for ETCulvert
Include support for more sophisticated structural analysis options
Add soil-structure interaction
Add support for Canadian Highway Bridge Code
Allow access to reinforcement size/spacing pair library
Add wingwalls, footings, appurtenances
Additional user requests and agencies
Support for AASHTOWare

83. Questions?

84. Agenda 1. Overview of AASHTO LRFD 2. Culvert Design by LRFD
3. ETCulvert Overview
4. Interface Walk-thru
5. Common Design Questions
6. Advanced Topics
7. Questions