User Notes and Calculator Assumptions
- This calculator determines net and average cross-sectional properties based on user defined inputs. Net section properties represent the smallest cross-section of an assembly and are used for calculating assembly strength. Average section properties represent the average cross-section of an assembly and are used for calculating assembly stiffness. This calculator determines the net cross-sectional properties through a plane concurrent with a mortar joint while average section properties are determined through a plane concurrent with the mid-height or mid-length of a unit in the assembly.
- Highlighted cells are user inputs. All inputs and outputs use inch-pound units.
- The “Inputs-Outputs” sheet allows users to input the following assembly properties:
- Nominal width
- CMU density
- Grout spacing
- Unit configuration (hollow or solid)
- Mortar bedding (face shell or full)
Users can also select between net or average section properties as outputs as well as whether the cross-section is taken in a horizontal (for assemblies spanning vertically) or vertical (for assemblies spanning horizontally) direction. All cross-sectional property outputs are a per foot unit strip. All wall weight outputs are averaged pounds per square foot of wall surface. The tabs “Horizontal and Vertical Section Properties” do not require user inputs and are used solely to calculate section properties.
- The calculator is based on a unit consisting of two cells similar to that shown here. Users may modify the face shell and web thicknesses used in determining the cross-section properties and wall weights provided inputs still meet the minimum face shell and web thickness requirements of ASTM C90 (below).
- The calculator produces two output options simultaneously: the cross-sectional area, moment of inertia, section modulus, radius of gyration, and wall weight for the specific inputs provided as well as tabulated properties for all grout spacings up to 120 in. For grouted assemblies, the web adjacent to the grouted cells are assumed to be mortared.
