Material Properties

Material properties are defined on the Material Properties Spreadsheet and then are referred to as you build beams, columns, and walls. You may perform analysis using any type of material; simply define the properties for the material here. You may use up to 500 materials in a single model although most models will only have one or two. For example, your model might be made up of members of various grades of steel along with different concrete materials, timber or aluminum.

Material Properties Spreadsheet

The Material Properties Spreadsheet records the material properties to be used in the model and may be accessed by selecting Materials on the Spreadsheets Menu. The entries are explained below.

The values for A36 steel are the default material set. You of course don't have to use the A36 properties; you can change these and also add as many other materials as you need. You may then save your preferred materials as the default materials by clicking the Save as Defaults  button on the Window Toolbar.

Label is the material label you wish to use to describe the entered material properties. This label is how you will reference the set of properties later when defining beams, columns, and walls.

E is Young's modulus that describes the material stiffness.

G is the shear modulus and may be left blank if you would like it calculated automatically. The equation for “G” is:

Note

• If you enter a value for Shear Modulus that does not match the value calculated using the above equation you will be given a warning.
• The default Plywood material has a much lower G value than the formula above would suggest. This is because plywood is NOT an isotropic material. Also, the generic value (from the NDS or APA's Plywood Design Specification) has been reduced somewhat to account for assumed nail slip.

Nu is Poisson's ratio. Besides being used for the “G” calculation, this value is also used for shear deformation calculations. The value of Poisson's ratio may not exceed '0.5'.

Therm is the coefficient of thermal expansion and is entered per 10^5 (100,000) degrees. This coefficient is used in the calculation of thermal loads.

Density is the material density and is used in the calculation of the member and plate self weight. This density times the area gives the self weight per unit length for the members; density times plate volume gives the total weight of a given plate.

Yield is the yield stress and is used only for Hot Rolled and Cold Formed steel design. 

Hot Rolled Specific Material Data

The Hot Rolled tab records a number of hot rolled steel specific material properties that do not exist for the other materials. These entries are described below:

Ry is the ratio of the expected yield stress to the specified minimum yield stress. This value is used in determining the required strength of an element for the seismic detailing checks.

Fu is the specified minimum tensile strength. This value is used per AISC 358 to calculate C_pr which is in turn used to calculate the probable maximum moment at a plastic hinge in the seismic detailing calculations.

Rt is currently not used by the program. In a future version of the program this value will be used to calculate the expected tensile strength for the seismic detailing checks.

Cold Formed Specific Material Data

The Cold Formed tab records a cold formed material property that may not exist for the other materials. This entry is described below:

Fu (Ultimate) is the ultimate tensile stress.

Wood Specific Material Data

The Wood tab records a number of wood specific material properties that do not exist for the other materials. These entries are described below:

Type - Currently there are four wood types available: Solid Sawn, Glulam, SCL (this includes LVLs), and Custom.

Database - Based on your Type selection, the Database menu will filter to the appropriate databases.

Species - Based on your Database selection, the Species menu will filter to the appropriate databases. This is the wood species designation from your selected design code.

Grade is the wood grade designation from your selected design code. This has a drop down list where you can select the appropriate grade.

The Cm check-box determines if the wet service / moisture content factor should be applied. If you put a check in the Cm field, the appropriate factors will be applied to the allowable stresses and Young’s Modulus (E).

The Ci check-box determines if the incision factor should be applied. If you put a check in the Ci field, the appropriate factors will be applied to the allowable stresses and Young’s Modulus (E).

Emod is a factor that is applied to the Young’s modulus modifier to reflect the NDS Appendix F criteria. This is not applicable to the CSA O86 design code.

Note:

• Refer to Custom Wood to specify a custom wood material. 

Commercial Species Groups:

When either the NDS 05/08, 12, 15, or 2018 wood design code is selected, the Solid Sawn Species menu lists two new species listed that are not specifically shown in the NDS code. These are the Commercial Species Group I - DF/SP and Commercial Species Group II - HF/SPFe Fir. These are meant to be simplified groupings of the most commonly used wood species. It is meant to simplify the selection procession for wood member design in the United States.

The design values for Group I take the NDS allowable stress values for two of the most widely used species (Doug Fir-Larch and Southern Pine) and uses the lower bound allowable stress value for each size and grade.

Similarly, the design values for Group II take the allowable stress values for Hem Fir and Spruce-Pine-Fir and use the lower bound allowable stress values for each size and grade.

Concrete Specific Material Data

The Concrete tab records a few concrete specific material properties that do not exist for the other materials. These entries are described below:

f'c is the concrete compressive strength used for concrete design.

Lambda, λ is the lightweight concrete modification factor. This factor only applies to the ACI 318-14, ACI 318-11, ACI 318-08 and CSA A23.3-04 codes. For all other codes the Density value of the material determines any strength reduction. The program will automatically calculate the correct value if it is left blank. Only values between 0.75 and 1.0 will be considered.

Flex Steel is the reinforcement yield strength for flexural bars in members and vertical bars in walls. Shear Steel is the reinforcement yield strength for shear bars in members and horizontal bars in walls.

Masonry Specific Material Data

The Masonry tab records masonry specific material properties. Here we will describe items that do not exist for other materials.

Masonry Self Weight can be accounted for by two different methods. Entering a number for the density will result in masonry walls which have a self weight equal to that density multiplied by the wall cross-sectional area. Otherwise, click within the cell to launch the masonry self weight dialog:

Set the Using Block and Grout Properties option to have the program automatically calculate the self weight of the wall using the weights from tableB3 of the Reinforced Masonry Engineering Handbook (RMEH). The self weight will be listed as Custom.

f'm is the masonry compressive strength used for masonry design.

Flex and Shear Steel are the rebar yield strengths for flexural and shear bars used to reinforce the masonry.

Note:

• Masonry Shear Steel is automatically set to the Flex steel strength.
• Masonry materials are used only for walls in wall footings. See the Wall Footing Definitions spreadsheet for more information.