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Select which bars you would like epoxied, the options are ‘none’, ‘top steel if fill < 2ft’, ‘all top slab steel’, and ‘all steel’. If ‘top steel if fill < 2ft’ is selected the program will always assume the top layer of steel in the top slab is epoxy coated for fill depths less than 2 feet. Otherwise, all steel in the culvert is assumed to be uncoated at all fill depths. If ‘all steel’ is selected, the program will assume all steel is epoxy coated at all fill depths.
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If this option is selected then the stiffness of the haunches (if any) are incorporated into the structural model at the top and bottom of the exterior walls. This will cause a redistribution of the wall moments mid-height to the top and bottom of the walls.
Critical Sections:
Consider Haunches
Select this option to have haunches considered in the selection of the location of the critical section. If haunches are specified and this is checked then the program will design the member using moment and shear values beyond the face of support in accordance with whether or not the user has selected to extend the critical section (see below). If this is not checked then the program will design the member using moment values at the face of the intersecting members and shear values at the dv (or d for STND) from the face of the intersecting members regardless of the specified haunch lengths. This will provide a more conservative design.
Extend Critical Sections
If haunches are specified and this option is checked then the program will position the critical section for shear at a distance of dv(d) beyond the end of the haunch. If left unchecked, then the critical section for shear will be placed at a distance of dv(d) from the face of the intersecting member. For flexure, if this option is selected, then the critical section is located at the intersection of the haunch and the constant depth member (basically the end of the haunch). If unchecked, then the critical section for flexure is taken at the point at which the depth of the slab plus haunch is 1.5 times the depth of the slab.
Note that if this option is selected, the user is assuming that the face of support is located at the end of the haunch. This extension will only be applied to haunches that form an angle of less than 45 degrees to the supporting face.Critical Section Locations
The following options for critical section locations are given:
Flexure Critical Section Locations
Face of support
1.5 * depth of slab (this is the location where the depth of the slab + haunch equals 1.5 * depth of slab)
End of haunch
Shear Critical Section Locations
Face of support
dv beyond support
End of haunch
dv beyond haunch
Include Haunch Depth
You have the option in include haunch depth for all critical sections, no critical sections, or only flexure/shear critical sections. This will add the depth of the haunch to ds and dv, which can also effect the shear critical section locations.
Note: This option should only be used for reinforced nonsymmetrical haunches
Use Max Moment with Max Shear
The shear analysis will either use the maximum moment or the corresponding moment. If checked, the maximum moment at the face of the wall will be used in the interaction between Vu and Mu to calculate the shear capacity of the member. If unchecked, the moment at the critical section for shear will be used instead.
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Flexure
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By default the haunch is only used to position the critical section, although the haunch may also be used to stiffen the corners of the structural model. By selecting this option, the user may also direct the program to use the haunches in the calculation of the flexural and shear resistance.
Flexure:
Use Eq. 12.10.4.2.4a-1
If checked, the flexural moment capacity is calculated using LRFD Eq. 12.10.4.2.4a-1. The program applies a factor to the Nu term in the equation, thereby allowing the user to ignore the effects of axial thrust if desired. Note that this equation is modified in CHBDC. See the theory section for the revised equation.
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If checked, the program will calculate the shear capacity of the concrete using the iterative beta method in LRFD Appendix B5. This value is then compared to the shear capacity already calculated using the internal decision table (see Section 5.7/5.6) and the larger of the two values is used for the current member.
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If checked, the program will calculate the shear capacity of the top slab of a 3-sided culvert with more than 2 foot of fill using LRFD 5.14.5.3/5.12.7.3, which is usually only used in 4-sided culverts. However, some states allow this provision to be used for 3-sided culverts as well.
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In LRFD, when the shear capacity of the concrete is calculated using the iterative approach in Appendix B5, a preliminary estimate of the reinforcing steel is based on moment demand. Then the area of steel is used to calculate the shear capacity and checked against the shear demand. If the preliminary estimate of the area of reinforcing steel is unsatisfactory the program enters a loop inside the shear calculations to increase the area of steel until this requirement it met. This area of steel should be limited to around 2.0 in2in2/foot for practical purposes, and can be adjusted up or down here. If this limit of the reinforcing steel cannot be satisfied then the program increases the member thickness, recalculating the structural steel demand, and re-starts the shear demand loop.
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Select the appropriate exposure option for your design, the options are ‘normal’ and ‘severe’. This is used in computing the environmental durability factors, defined in ACI-350.
Additional Analysis Points:
Starting in v6.0.0, uses have the ability to add additional points that they would like data displayed for in the Text Report. To do this, select the appropriate checkboxes for the location you would like to add and enter the location. All locations are measured from the centerline of the orthogonal member.
For example, to add an additional an additional analysis point in the wall 10” below the centerline of the top slab, you would check the option for “Walls: Top” and enter “10.0” in the text box.
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Additionally, if you’d like to add additional analysis points 24” from the centerline of both walls, you’d select the “left” and “right” options and enter “24.0” to each textbox.
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Creating additional analysis points will display extra information in the following locations:
“Unfactored Moments/Shears Due to All Loads” tables:
“Unfactored Moments and Shears Due to Truck Loads” tables:
“Load Combination Results at Tenth Points” table:
