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Determination of Design Span
For spans, the program considers the design span to be the clear span between support edges plus:
Interior supports
For interior supports, ½ the actual bearing length is added, whether it is user input or designed by the program
End supports
For end supports, it is ½ the lesser of the following:
the minimum required bearing length
the user input actual bearing length.
Minimum Required Bearing Length
The minimum required bearing length is calculated the program currently does. . In addition, a setting has been added to provide a minimum absolute bearing length regardless of the force on the support, and another to indicate that that minimum should override the calculated minimum based on force when determining the design spans. See A: 1.c) above for these settings.
Iterative Design
Unless Design span is chosen as the span choice, the calculation of minimum bearing length affects the design span length. This in turn affects the reactions that are on the supports, which in turn affects the min required bearing length, which in turn affects the design span…
Similarly, if Unknown bearing length is selected, the reactions determined affect the bearing length required, which in turn affect the position of the edge of the support from which design span is measured, which affects the design span, which affects the reactions used for bearing design…
For these reasons, the program now performs iterative analysis and bearing design on the member, first determining reactions with the longest span possible given the bearing and span choices, then determining the bearing lengths required, then calculating design span, then readjusting. The program iterates until the difference in design span between two iterations is not noticeable (0.1 mm). Generally 3-4 iterations are required.
Loads over Supports
Point Loads
A load that is within the design span, but over a portion of a known support that is within the span, is treated as a point load within the design span and analysed for shear, moment, bearing, etc, as before.
Point loads that are applied outside of the design span, that is, to the left of the support point of known bearing at a left end support and to the right of the support point of a right end support, are applied directly to the bearing design of the support and are not considered part of the design span.
Line loads
The portion of the line load that is within the design span, but over a portion of a known support that is within the span, is still treated as a load within the design span and analysed for shear, moment, bearing, etc, as before
Sizer can now apply the portion of the line load that extends outside of the design span, that is, to the left of the support point of known bearing at a left beam end, directly to the bearing design of the support.
This is implemented for all line loads - full, partial, uniform, trapezoidal, triangular.
You can disable this capability via an option ion the load input view - Line loads applied to design span only
Notches
The uses the designed or user-input bearing length as the width of tension edge notches, rather than the minimum required bearing length, as before.
The terminology Min. has been dropped, as it is now the actual length of the notch.
Shear-at-a-distance d
According to NDS 3.4.3.1 (a) line loads within a distance d of a support do not contribute to shear, and point loads within d are factored by their relative distance from the supported for their contribution to shear. Figure 3C makes it clear that the distance d is measured from the edge of the support,.
Formerly Sizer measured d from the reaction point, creating conservative values of design shear. Now the program measures the distance d from the edge of the support, for both end supports and interior supports.