When creating a structural family parameter, specify the parameter type in the Parameter Properties dialog.
In the Family Editor, click Create tab
Properties panel 
(Family Types). In the Family Types dialog, under Parameters, click Add. For Discipline, select Structural. For Type of Parameter, select one of the following.
Properties panel (Family Types). In the Family Types dialog, under Parameters, click Add. For Discipline, select Structural. For Type of Parameter, select one of the following. | Name | Description | Units |
|---|---|---|
| Force | Used to define the exertion of one object on another. Applies to Point Load force parameters. | force |
| Linear Force | Used to define the intensity of force per unit length. Applies to Line Loads force parameters. | force/length |
| Area Force | Used to define the intensity of force per unit area. Applies to Area Loads force parameters. | force/length^2 |
| Moment | Used to define the tendency of a force to rotate an object about an axis. Mathematically moment of force is defined as the cross product of the lever-arm distance vector and the force vector. Applies to Point Load moment parameters. | force*length |
| Linear Moment | Used to define the intensity of moment per unit length. Applies to Line Loads moment parameters. | force*length/length |
| Stress | Used to define the physical quantity that internal force exerts upon an adjoining particles. Mathematically stress is defined as division of the force vector per area. | force/length^2 |
| Unit Weight | Used to define the weight per unit volume of an object. | force/length^3 |
| Weight | Used to define the force exerted on an object by gravity. | force |
| Mass | Used to define the quantity of matter in a object. | mass |
| Mass per Unit Area | Used to define the mass density per unit area of a surface of an object. Applies to the floor mass per unit area. | mass/length^2 |
| Thermal Expansion Coefficient | Used to define the change in the length dimensions of an object to a change in temperature. For linear elements it is calculated as the material degree of expansion divided by the change in temperature for a unit length. | 1 / temperature |
| Point Spring Coefficient | Used to define the ratio of force affecting the spring at a point to its resulting displacement. Applies to the Spring Modulus parameter in Point Boundary Conditions. | force/length |
| Line Spring Coefficient | Used to define the ratio of force affecting the spring along a line to its resulting displacement. Applies to the Spring Modulus parameter in Line Boundary Conditions. | force/length^2 |
| Area Spring Coefficient | Used to define the ratio of force affecting the spring spanning an area to its resulting displacement. Applies to the Spring Modulus parameter in Area Boundary Conditions. | force/length^3 |
| Rotational Point Spring Coefficient | Used to define the torque ratio of force affecting the spring at a point to its resulting displacement. Applies to the Spring Modulus parameter in Point Boundary Conditions. | force*length/angle |
| Rotational Line Spring Coefficient | Used to define the torque ratio of force affecting the spring along a line to its resulting displacement. Applies to the Spring Modulus parameter in Line Boundary Conditions. | force*length/angle/length |
| Displacement/Deflection | Used to define the linear distance between the start and end points of the motion of an object. | length |
| Rotation | Used to define the arc distance of a rotation. | angle |
| Period | Used to measure the duration of a single cycle of a repeating action. | time |
| Frequency | Used to measure the number of cycles of a repeating action in a unit of time. | 1/time |
| Pulsation | Used to define the rate or arc distance traveled for a wave per unit of time. | 2*Pi/time |
| Velocity | Used to define the rate at which the position of an object changes in time. Mathematically velocity is defined as division of the distance per time. | length/time |
| Acceleration | Used to define the rate at which the position of an object changes its velocity. Mathematically velocity is defined as division of the velocity per time. | length/time^2 |
| Energy | Used to define the amount of force required to displace an object. | force*length |
| Reinforcement Volume | Used to define the assumed total volume of rebar in an object. | length^2 |
| Reinforcement Length | Used to define the assumed total length of rebar in an object. | length |
| Reinforcement Area | Used to define the assumed total area of rebar in an object. | length^3 |
| Reinforcement Area per Unit Length | Used to define the assumed total area of rebar per unit of a floor cross section length in an object. | length^2/length |
| Reinforcement Spacing | Used to define the assumed spacing between rebar in an object. | length |
| Reinforcement Cover | Used to define the assumed distance between rebar and the exterior surface of its host. | length |
| Bar Diameter | Used to define the assumed diameter of rebar used to reinforce the object. | length |
| Crack Width | Used to define the acceptable assumed widths of cracking in a reinforced object. | length |
| Section Dimension | Used to define a linear dimension of a framing element cross section. | length |
| Section Property | Used to define a detailing dimension of a framing element cross section. | length |
| Section Area | Used to define the area of a framing element cross section. | length^2 |
| Section Modulus | Used to define a geometric proportionality between stress and strain of a framing element cross section. Mathematically it is the division of the framing element section Moment of Inertia divided by the dimension to the external fiber from the section center of gravity. | length^3 |
| Moment of Inertia | Used to define the mass property of a rigid body that determines the torque needed for angular acceleration about an axis of rotation. Applies to the section properties on a framing element. | length^4 |
| Warping Constant | Used to define the consistent measure of stress used to calculate warping. | length^6 |
| Mass per Unit Length | Used to define the linear mass density of a framing element object. | mass/length |
| Weight per Unit Length | Used to define the linear weight of a framing element object. | force/length |
| Surface Area per Unit Length | Used to define the linear surface area of an object. Applies to the painting surface area of a framing element per unit length. | length^2/length |