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3.5.1 - Deflection Calculations
Bending deflection is calculated in Sizer using matrix stiffness analysis. For glulam and sawn lumber, shear deflection is handled by a factor given in NDS Appendix F that has been applied to published moduli of elasticity E,
For custom SCL materials you create with Database Editor, the modulus of elasticity should be the "apparent" EI that approximates the effect of shear deflection.
For I-joists and CLT, the program approximates shear deflection by modifying the stiffness EI based on the formula for a simple span beam with uniform loading. This method can be inaccurate for other loading and span conditions.
3.5.2-Long Term Loading
There is provision in WoodWorks SIZER to design for the effect of long term loading on total deflection. The Long Term Deflection field under the Deflection Limits group in Load view permits you to specify the percentage of dead load deflection to include when determining total deflection:
Total Deflection = KCT x (Dead deflection) + (Deflection from all other load types)
The creep factor KCT is given in the NDS as 1.5 for seasoned lumber, glulam, I-joists, and SCL. It is 2.0 for unseasoned lumber or lumber used in wet service conditions,and for CLT. Sizer allows you to over-ride these factors in Loads view.
This adjustment cannot be made in conjunction with the provision in IBC 1604.3 - Deflection Load Combinations that allows for a 0.5 factor for the D + L load combinations