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3.2.1-Span of Bending Members
In Sizer, you are able to enter the length of spans as being the design span as described below, the full span, which is the length of the member including the full bearing support on each end, or the clear span, which is the length between the interior faces of end supports. Given this input, Sizer adjusts the other spans based on the bearing lengths that are specified by you or automatically designed by the program.
For simple beams, and spans at the end of the beam, the design span is as defined in 3.2.1 - the clear span plus minimum required bearing. For interior supports, Sizer assumes that the design span extends from centerline to centerline of supports, rather than the face-to-face distance plus half the minimum required bearing length. This is a slightly conservative assumption.
The minimum required bearing is determined by the program based on perpendicular to grain resistance to the applied load at the support. A design setting allows you to establish your own minimum required bearing to avoid the situation where Sizer designs a bearing that is too small for practical purposes. The program also allows you to choose whether your minimum bearing or the one established by the program is used to define the design span for shear, moment, and deflection calculations.
Refer to Design Spans and Iterative Design for more information about sizer's span input, assumptions, and effect on design.
3.2.3-Notches
WoodWorks SIZER permits notches in solid sawn lumber, timber, SCL and glulam bending members. Notches can only be specified in Beam mode.The beam can have any subset of its supports notched, and allows a tapered notch at the top of the beam ends.
In WoodWorks Sizer, the presence of a notch is assumed to only affect the shear capacity of a beam (calculated in accordance with NDS 3.4), and the moment capacity of interior notches by using net section, but not the stiffness. For this reason notches at interior supports are severely restricted in NDS 3.2.3.2 as to their length and depth such that their effect in stiffness is minimal. Interior notches not meeting these limitations are not allowed by Sizer, and a warning appears in place of shear and moment design results.
As described in n NDS 3.1.2. Sizer does not check the bending moment at the end of the end notches using the net area of the notched portions, as specified in NDS 3.1.2. This could be an issue only at interior ends of compression notches with large values of the unsupported length “e”. Although the NDS and Sizer allow it, you are advised against the use of long compression-face notches.
The value e is measured from the inner edge of the bearing support, as per NDS Figure 3D, once that value has been established by the bearing design routine.
Sizer allows upper surface end notches to be tapered to allow for the adjustment in notch depth that is given by NDS 3.4.3.2 (e) and as recommended by NDS 3.2.3.1.