Physical Dimensions

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No. Boxes

Input the number of boxes, between 1 and 4.

Design Type

Select the type of culvert to be designed, either three of four sided.

Support Types

Select the type of supports to model the culvert. This option is only enabled if three-sided is selected for the design type. The options are pin-roller, pin-pin, and fixed-fixed (note that fixed-fixed is only available for cast-in-place culverts).

Clear Span

Input the culvert clear span as the dimension in the horizontal or x-direction of the open area of the culvert.  Typically this is measured between the inside faces of adjacent walls parallel to the span of the top and bottom slabs.

Clear Height

Input the culvert clear height as the dimension in the vertical or y-direction of the open area of the culvert.  Typically this is measured between the inside face of the top slab and the inside face of the bottom slab (or the bottom of the walls for 3-sided culverts).

Length

Input the culvert section length as the distance between joints, measured along the culvert centerline.  If your culvert has no joints, then input the entire length of the culvert.  This value is used in the creation of the bar schedule in both Design and Analysis Modes.  The culvert length will also be used as live load distribution width for fill depths less than 2 feet (STND and AREMA), if the assigned length is less than the calculated distribution width.

Eriksson Culvert is a design program, not a detailing program; the bar lengths in Eriksson Culvert are primarily for estimation purposes and are meant to provide a means to compare design options.  Actual drawing and production demands may require adjustments to bar lengths to accommodate local codes and construction practices or plant specific production methods.

Fill Depth

Input either a single fill depth or a range of fill depths. If analyzing the culvert over a range of fill depths then values for the maximum fill depth, minimum fill depth, and increment must be input. The culvert will then compute fill depths from the minimum depth to the maximum depth at the value of the increment, inclusive of both the maximum and minimum values. If the value of 1.99 ft is between the maximum and minimum values then it will also be included in the analysis. For example, if the minimum value is specified as 0 ft, the maximum values is specified as 2.3 ft, and the increment as 0.5 ft, then the fill depth values included in the analysis will be: 0.0, 0.5, 1.0, 1.5, 1.99, 2.0, and 2.3 ft.

      Use Range of Fill Depths

      Check this box to input a range of fill depths.

      Fill Depth/Max. Fill Depth

      Min. Fill Depth

      Input the minimum fill depth if analyzing the culvert over a range of fill depths.

Variable/Fixed Member Thicknesses

In Design Mode you have the option to choose between variable and fixed thicknesses for all members:

If “variable” is selected Eriksson Culvert will select the most efficient thickness for each member during the design process. Note that next to this option is “Min. Thickness”; by specifying a value for this, Eriksson Culvert will not select a member thickness smaller than this value. You may input 0 here, in which Eriksson Culvert will use a minimum of 3”.

If “fixed” is selected Eriksson Culvert will not size the member, and instead use the value specified in the “Thickness” option. Note that the minimum thickness you can enter is 3”.

In Analysis Mode, enter the exact values for the slabs and walls. Note that some agencies impose specific minimum slab thicknesses.  If you have not selected any specific governing agency, then the minimum thickness of all members is 3 inches.  Note that in analysis mode, you may not change the member thickness flag (fixed or variable) for any member.  Also, based on the clear span and clear height, the program may require you to input a member thickness in excess of the absolute minimums.  This is to insure that the program can assign rebar that fits within the section.

Added Thickness for Bottom Slab

Input additional thickness for the bottom slab needed for a V-Bottom in the bottom slab at the intersection of the bottom slab and the side walls.  This is also sometimes called a “fish bottom”.

Top Haunch

Input the X (horizontal) and Y (vertical) dimensions for the top haunch if there is one. To form a 45 degree haunch use the same dimension for both X and Y.  Both top haunches will have the same dimensions.

Note that the use of the haunch in the FEM analysis model is dependent on the options selected on the Analysis Options page.  See the discussion on that page for more information.

Bottom Haunch

Input the X (horizontal) and Y (vertical) dimensions for the bottom haunch if there is one. To form a 45 degree haunch use the same dimension for both X and Y.  Both bottom haunches will have the same dimensions.

Note that the use of the haunch in the FEM analysis model is dependent on the options selected on the Analysis Options page.  See the discussion on that page for more information.

Open

Culvert Skew Angle

Input the culvert skew angle defined as the centerline of culvert relative to a perpendicular to the over roadway, in degrees.

Skewed culvert orientation is used to satisfy right-of-way constraints and/or staged construction requirements on skewed alignments.  In the event a skewed orientation is necessary, skewed details are normally provided at the extreme ends or at staging lines of culvert construction.  This allows the majority of the culvert length to remain square and retain similar reinforcement details.

When using the STND and AREMA Specifications, this input is used to determine the live load distribution width for culverts, under less than 2 feet of fill.  When using the LRFD and CHBDC Specifications, this input is used to determine vehicular traffic direction in relation to main reinforcement, for all fill heights.

The program treats skewed cast-in-place and precast end details quite differently.

When a cast-in-place culvert has a skewed end detail, the program cuts transverse reinforcing bars to their required length so they fit the geometry of the skewed end.  The correct bar lengths are determined by the program from the skew input parameters for Left End Skew and Right End Skew, which are inputs for cast-in-place culverts only.  The cut transverse bars are assumed to be supported by a top slab edge beam and bottom slab cut-off wall along the skewed end of the culvert barrel.  The bar schedule output by the program for a skewed end cast-in-place culvert adjusts for all the cut transverse reinforcement.

For cast-in-place culverts under all specifications, run the program with the perpendicular clear span and the appropriate roadway and culvert end skews.

When a precast culvert has a skewed end detail, transverse reinforcement is assumed to be splayed to fit the geometry of the skew.  This splaying of reinforcement in a unit increases the length of the reinforcing bars and the clear span of the unit.  As a result of the differing skew philosophies used in each specification, we offer the following recommendations:

For a STND or AREMA Specification run, square precast units should be run with the perpendicular clear span and appropriate roadway skew angle, however, skewed precast units should be run with the skewed clear span and a roadway skew angle of zero degrees.

For an LRFD or CHBDC Specification run, square precast units should be run with the perpendicular clear span and appropriate roadway skew angle, however, skewed precast units should be run with the skewed clear span, a single lane of traffic parallel to main reinforcement and a roadway skew angle of zero degrees.  Note that the bar schedule output by the program for a skewed end precast unit is actually the bar schedule of a square unit. The size/spacing pairs and some of the lengths will be correct, but other lengths and most of the weights will be larger than actual construction.

Left End Skew

For cast-in-place culverts only, input the skew angle for the left end of the culvert defined as the angle between the left face of the culvert and the centerline of the culvert (‘LEFT SKEW’ in the following diagram).

Right End Skew

For cast-in-place culverts only, input the skew angle for the right end of the culvert defined as the angle between the right face of the culvert and the centerline of the culvert (‘RIGHT SKEW’ in the following diagram).