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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.
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If “variable” is selected ETCulvert 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, ETCulvert Eriksson Culvert will not select a member thickness smaller than this value. You may input 0 here, in which ETCulvert Eriksson Culvert will use a minimum of 3”.
If “fixed” is selected ETCulvert 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”.
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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.
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).